package agent

import (
	"encoding/base64"
	"errors"
	"fmt"
	"io"
	"net"
	"os"
	"os/exec"
	"os/user"
	"path/filepath"
	"runtime"
	"sort"
	"strconv"
	"strings"
	"time"

	sockaddr "github.com/hashicorp/go-sockaddr"
	"github.com/hashicorp/go-sockaddr/template"
	client "github.com/hashicorp/nomad/client/config"
	"github.com/hashicorp/nomad/helper"
	"github.com/hashicorp/nomad/nomad"
	"github.com/hashicorp/nomad/nomad/structs"
	"github.com/hashicorp/nomad/nomad/structs/config"
	"github.com/hashicorp/nomad/version"
)

// Config is the configuration for the Nomad agent.
//
// time.Duration values have two parts:
// - a string field tagged with an hcl:"foo" and json:"-"
// - a time.Duration field in the same struct and a call to duration
//   in config_parse.go ParseConfigFile
//
// All config structs should have an ExtraKeysHCL field to check for
// unexpected keys
type Config struct {
	// Region is the region this agent is in. Defaults to global.
	Region string `hcl:"region"`

	// Datacenter is the datacenter this agent is in. Defaults to dc1
	Datacenter string `hcl:"datacenter"`

	// NodeName is the name we register as. Defaults to hostname.
	NodeName string `hcl:"name"`

	// DataDir is the directory to store our state in
	DataDir string `hcl:"data_dir"`

	// PluginDir is the directory to lookup plugins.
	PluginDir string `hcl:"plugin_dir"`

	// LogLevel is the level of the logs to put out
	LogLevel string `hcl:"log_level"`

	// LogJson enables log output in a JSON format
	LogJson bool `hcl:"log_json"`

	// LogFile enables logging to a file
	LogFile string `hcl:"log_file"`

	// LogRotateDuration is the time period that logs should be rotated in
	LogRotateDuration string `hcl:"log_rotate_duration"`

	// LogRotateBytes is the max number of bytes that should be written to a file
	LogRotateBytes int `hcl:"log_rotate_bytes"`

	// LogRotateMaxFiles is the max number of log files to keep
	LogRotateMaxFiles int `hcl:"log_rotate_max_files"`

	// BindAddr is the address on which all of nomad's services will
	// be bound. If not specified, this defaults to 127.0.0.1.
	BindAddr string `hcl:"bind_addr"`

	// EnableDebug is used to enable debugging HTTP endpoints
	EnableDebug bool `hcl:"enable_debug"`

	// Ports is used to control the network ports we bind to.
	Ports *Ports `hcl:"ports"`

	// Addresses is used to override the network addresses we bind to.
	//
	// Use normalizedAddrs if you need the host+port to bind to.
	Addresses *Addresses `hcl:"addresses"`

	// normalizedAddr is set to the Address+Port by normalizeAddrs()
	normalizedAddrs *Addresses

	// AdvertiseAddrs is used to control the addresses we advertise.
	AdvertiseAddrs *AdvertiseAddrs `hcl:"advertise"`

	// Client has our client related settings
	Client *ClientConfig `hcl:"client"`

	// Server has our server related settings
	Server *ServerConfig `hcl:"server"`

	// ACL has our acl related settings
	ACL *ACLConfig `hcl:"acl"`

	// Telemetry is used to configure sending telemetry
	Telemetry *Telemetry `hcl:"telemetry"`

	// LeaveOnInt is used to gracefully leave on the interrupt signal
	LeaveOnInt bool `hcl:"leave_on_interrupt"`

	// LeaveOnTerm is used to gracefully leave on the terminate signal
	LeaveOnTerm bool `hcl:"leave_on_terminate"`

	// EnableSyslog is used to enable sending logs to syslog
	EnableSyslog bool `hcl:"enable_syslog"`

	// SyslogFacility is used to control the syslog facility used.
	SyslogFacility string `hcl:"syslog_facility"`

	// DisableUpdateCheck is used to disable the periodic update
	// and security bulletin checking.
	DisableUpdateCheck *bool `hcl:"disable_update_check"`

	// DisableAnonymousSignature is used to disable setting the
	// anonymous signature when doing the update check and looking
	// for security bulletins
	DisableAnonymousSignature bool `hcl:"disable_anonymous_signature"`

	// Consul contains the configuration for the Consul Agent and
	// parameters necessary to register services, their checks, and
	// discover the current Nomad servers.
	Consul *config.ConsulConfig `hcl:"consul"`

	// Vault contains the configuration for the Vault Agent and
	// parameters necessary to derive tokens.
	Vault *config.VaultConfig `hcl:"vault"`

	// NomadConfig is used to override the default config.
	// This is largely used for testing purposes.
	NomadConfig *nomad.Config `hcl:"-" json:"-"`

	// ClientConfig is used to override the default config.
	// This is largely used for testing purposes.
	ClientConfig *client.Config `hcl:"-" json:"-"`

	// DevMode is set by the -dev CLI flag.
	DevMode bool `hcl:"-"`

	// Version information is set at compilation time
	Version *version.VersionInfo

	// List of config files that have been loaded (in order)
	Files []string `hcl:"-"`

	// TLSConfig provides TLS related configuration for the Nomad server and
	// client
	TLSConfig *config.TLSConfig `hcl:"tls"`

	// HTTPAPIResponseHeaders allows users to configure the Nomad http agent to
	// set arbitrary headers on API responses
	HTTPAPIResponseHeaders map[string]string `hcl:"http_api_response_headers"`

	// Sentinel holds sentinel related settings
	Sentinel *config.SentinelConfig `hcl:"sentinel"`

	// Autopilot contains the configuration for Autopilot behavior.
	Autopilot *config.AutopilotConfig `hcl:"autopilot"`

	// Plugins is the set of configured plugins
	Plugins []*config.PluginConfig `hcl:"plugin"`

	// ExtraKeysHCL is used by hcl to surface unexpected keys
	ExtraKeysHCL []string `hcl:",unusedKeys" json:"-"`
}

// ClientConfig is configuration specific to the client mode
type ClientConfig struct {
	// Enabled controls if we are a client
	Enabled bool `hcl:"enabled"`

	// StateDir is the state directory
	StateDir string `hcl:"state_dir"`

	// AllocDir is the directory for storing allocation data
	AllocDir string `hcl:"alloc_dir"`

	// Servers is a list of known server addresses. These are as "host:port"
	Servers []string `hcl:"servers"`

	// NodeClass is used to group the node by class
	NodeClass string `hcl:"node_class"`

	// Options is used for configuration of nomad internals,
	// like fingerprinters and drivers. The format is:
	//
	//  namespace.option = value
	Options map[string]string `hcl:"options"`

	// Metadata associated with the node
	Meta map[string]string `hcl:"meta"`

	// A mapping of directories on the host OS to attempt to embed inside each
	// task's chroot.
	ChrootEnv map[string]string `hcl:"chroot_env"`

	// Interface to use for network fingerprinting
	NetworkInterface string `hcl:"network_interface"`

	// NetworkSpeed is used to override any detected or default network link
	// speed.
	NetworkSpeed int `hcl:"network_speed"`

	// CpuCompute is used to override any detected or default total CPU compute.
	CpuCompute int `hcl:"cpu_total_compute"`

	// MemoryMB is used to override any detected or default total memory.
	MemoryMB int `hcl:"memory_total_mb"`

	// MaxKillTimeout allows capping the user-specifiable KillTimeout.
	MaxKillTimeout string `hcl:"max_kill_timeout"`

	// ClientMaxPort is the upper range of the ports that the client uses for
	// communicating with plugin subsystems
	ClientMaxPort int `hcl:"client_max_port"`

	// ClientMinPort is the lower range of the ports that the client uses for
	// communicating with plugin subsystems
	ClientMinPort int `hcl:"client_min_port"`

	// Reserved is used to reserve resources from being used by Nomad. This can
	// be used to target a certain utilization or to prevent Nomad from using a
	// particular set of ports.
	Reserved *Resources `hcl:"reserved"`

	// GCInterval is the time interval at which the client triggers garbage
	// collection
	GCInterval    time.Duration
	GCIntervalHCL string `hcl:"gc_interval" json:"-"`

	// GCParallelDestroys is the number of parallel destroys the garbage
	// collector will allow.
	GCParallelDestroys int `hcl:"gc_parallel_destroys"`

	// GCDiskUsageThreshold is the disk usage threshold given as a percent
	// beyond which the Nomad client triggers GC of terminal allocations
	GCDiskUsageThreshold float64 `hcl:"gc_disk_usage_threshold"`

	// GCInodeUsageThreshold is the inode usage threshold beyond which the Nomad
	// client triggers GC of the terminal allocations
	GCInodeUsageThreshold float64 `hcl:"gc_inode_usage_threshold"`

	// GCMaxAllocs is the maximum number of allocations a node can have
	// before garbage collection is triggered.
	GCMaxAllocs int `hcl:"gc_max_allocs"`

	// NoHostUUID disables using the host's UUID and will force generation of a
	// random UUID.
	NoHostUUID *bool `hcl:"no_host_uuid"`

	// DisableRemoteExec disables remote exec targeting tasks on this client
	DisableRemoteExec bool `hcl:"disable_remote_exec"`

	// TemplateConfig includes configuration for template rendering
	TemplateConfig *ClientTemplateConfig `hcl:"template"`

	// ServerJoin contains information that is used to attempt to join servers
	ServerJoin *ServerJoin `hcl:"server_join"`

	// HostVolumes contains information about the volumes an operator has made
	// available to jobs running on this node.
	HostVolumes []*structs.ClientHostVolumeConfig `hcl:"host_volume"`

	// ExtraKeysHCL is used by hcl to surface unexpected keys
	ExtraKeysHCL []string `hcl:",unusedKeys" json:"-"`

	// CNIPath is the path to search for CNI plugins, multiple paths can be
	// specified colon delimited
	CNIPath string `hcl:"cni_path"`

	// BridgeNetworkName is the name of the bridge to create when using the
	// bridge network mode
	BridgeNetworkName string `hcl:"bridge_network_name"`

	// BridgeNetworkSubnet is the subnet to allocate IP addresses from when
	// creating allocations with bridge networking mode. This range is local to
	// the host
	BridgeNetworkSubnet string `hcl:"bridge_network_subnet"`
}

// ClientTemplateConfig is configuration on the client specific to template
// rendering
type ClientTemplateConfig struct {

	// FunctionBlacklist disables functions in consul-template that
	// are unsafe because they expose information from the client host.
	FunctionBlacklist []string `hcl:"function_blacklist"`

	// DisableSandbox allows templates to access arbitrary files on the
	// client host. By default templates can access files only within
	// the task directory.
	DisableSandbox bool `hcl:"disable_file_sandbox"`
}

// ACLConfig is configuration specific to the ACL system
type ACLConfig struct {
	// Enabled controls if we are enforce and manage ACLs
	Enabled bool `hcl:"enabled"`

	// TokenTTL controls how long we cache ACL tokens. This controls
	// how stale they can be when we are enforcing policies. Defaults
	// to "30s". Reducing this impacts performance by forcing more
	// frequent resolution.
	TokenTTL    time.Duration
	TokenTTLHCL string `hcl:"token_ttl" json:"-"`

	// PolicyTTL controls how long we cache ACL policies. This controls
	// how stale they can be when we are enforcing policies. Defaults
	// to "30s". Reducing this impacts performance by forcing more
	// frequent resolution.
	PolicyTTL    time.Duration
	PolicyTTLHCL string `hcl:"policy_ttl" json:"-"`

	// ReplicationToken is used by servers to replicate tokens and policies
	// from the authoritative region. This must be a valid management token
	// within the authoritative region.
	ReplicationToken string `hcl:"replication_token"`

	// ExtraKeysHCL is used by hcl to surface unexpected keys
	ExtraKeysHCL []string `hcl:",unusedKeys" json:"-"`
}

// ServerConfig is configuration specific to the server mode
type ServerConfig struct {
	// Enabled controls if we are a server
	Enabled bool `hcl:"enabled"`

	// AuthoritativeRegion is used to control which region is treated as
	// the source of truth for global tokens and ACL policies.
	AuthoritativeRegion string `hcl:"authoritative_region"`

	// BootstrapExpect tries to automatically bootstrap the Consul cluster,
	// by withholding peers until enough servers join.
	BootstrapExpect int `hcl:"bootstrap_expect"`

	// DataDir is the directory to store our state in
	DataDir string `hcl:"data_dir"`

	// ProtocolVersion is the protocol version to speak. This must be between
	// ProtocolVersionMin and ProtocolVersionMax.
	ProtocolVersion int `hcl:"protocol_version"`

	// RaftProtocol is the Raft protocol version to speak. This must be from [1-3].
	RaftProtocol int `hcl:"raft_protocol"`

	// NumSchedulers is the number of scheduler thread that are run.
	// This can be as many as one per core, or zero to disable this server
	// from doing any scheduling work.
	NumSchedulers *int `hcl:"num_schedulers"`

	// EnabledSchedulers controls the set of sub-schedulers that are
	// enabled for this server to handle. This will restrict the evaluations
	// that the workers dequeue for processing.
	EnabledSchedulers []string `hcl:"enabled_schedulers"`

	// NodeGCThreshold controls how "old" a node must be to be collected by GC.
	// Age is not the only requirement for a node to be GCed but the threshold
	// can be used to filter by age.
	NodeGCThreshold string `hcl:"node_gc_threshold"`

	// JobGCInterval controls how often we dispatch a job to GC jobs that are
	// available for garbage collection.
	JobGCInterval string `hcl:"job_gc_interval"`

	// JobGCThreshold controls how "old" a job must be to be collected by GC.
	// Age is not the only requirement for a Job to be GCed but the threshold
	// can be used to filter by age.
	JobGCThreshold string `hcl:"job_gc_threshold"`

	// EvalGCThreshold controls how "old" an eval must be to be collected by GC.
	// Age is not the only requirement for a eval to be GCed but the threshold
	// can be used to filter by age.
	EvalGCThreshold string `hcl:"eval_gc_threshold"`

	// DeploymentGCThreshold controls how "old" a deployment must be to be
	// collected by GC.  Age is not the only requirement for a deployment to be
	// GCed but the threshold can be used to filter by age.
	DeploymentGCThreshold string `hcl:"deployment_gc_threshold"`

	// HeartbeatGrace is the grace period beyond the TTL to account for network,
	// processing delays and clock skew before marking a node as "down".
	HeartbeatGrace    time.Duration
	HeartbeatGraceHCL string `hcl:"heartbeat_grace" json:"-"`

	// MinHeartbeatTTL is the minimum time between heartbeats. This is used as
	// a floor to prevent excessive updates.
	MinHeartbeatTTL    time.Duration
	MinHeartbeatTTLHCL string `hcl:"min_heartbeat_ttl" json:"-"`

	// MaxHeartbeatsPerSecond is the maximum target rate of heartbeats
	// being processed per second. This allows the TTL to be increased
	// to meet the target rate.
	MaxHeartbeatsPerSecond float64 `hcl:"max_heartbeats_per_second"`

	// StartJoin is a list of addresses to attempt to join when the
	// agent starts. If Serf is unable to communicate with any of these
	// addresses, then the agent will error and exit.
	// Deprecated in Nomad 0.10
	StartJoin []string `hcl:"start_join"`

	// RetryJoin is a list of addresses to join with retry enabled.
	// Deprecated in Nomad 0.10
	RetryJoin []string `hcl:"retry_join"`

	// RetryMaxAttempts specifies the maximum number of times to retry joining a
	// host on startup. This is useful for cases where we know the node will be
	// online eventually.
	// Deprecated in Nomad 0.10
	RetryMaxAttempts int `hcl:"retry_max"`

	// RetryInterval specifies the amount of time to wait in between join
	// attempts on agent start. The minimum allowed value is 1 second and
	// the default is 30s.
	// Deprecated in Nomad 0.10
	RetryInterval    time.Duration
	RetryIntervalHCL string `hcl:"retry_interval" json:"-"`

	// RejoinAfterLeave controls our interaction with the cluster after leave.
	// When set to false (default), a leave causes Consul to not rejoin
	// the cluster until an explicit join is received. If this is set to
	// true, we ignore the leave, and rejoin the cluster on start.
	RejoinAfterLeave bool `hcl:"rejoin_after_leave"`

	// (Enterprise-only) NonVotingServer is whether this server will act as a
	// non-voting member of the cluster to help provide read scalability.
	NonVotingServer bool `hcl:"non_voting_server"`

	// (Enterprise-only) RedundancyZone is the redundancy zone to use for this server.
	RedundancyZone string `hcl:"redundancy_zone"`

	// (Enterprise-only) UpgradeVersion is the custom upgrade version to use when
	// performing upgrade migrations.
	UpgradeVersion string `hcl:"upgrade_version"`

	// Encryption key to use for the Serf communication
	EncryptKey string `hcl:"encrypt" json:"-"`

	// ServerJoin contains information that is used to attempt to join servers
	ServerJoin *ServerJoin `hcl:"server_join"`

	// ExtraKeysHCL is used by hcl to surface unexpected keys
	ExtraKeysHCL []string `hcl:",unusedKeys" json:"-"`
}

// ServerJoin is used in both clients and servers to bootstrap connections to
// servers
type ServerJoin struct {
	// StartJoin is a list of addresses to attempt to join when the
	// agent starts. If Serf is unable to communicate with any of these
	// addresses, then the agent will error and exit.
	StartJoin []string `hcl:"start_join"`

	// RetryJoin is a list of addresses to join with retry enabled, or a single
	// value to find multiple servers using go-discover syntax.
	RetryJoin []string `hcl:"retry_join"`

	// RetryMaxAttempts specifies the maximum number of times to retry joining a
	// host on startup. This is useful for cases where we know the node will be
	// online eventually.
	RetryMaxAttempts int `hcl:"retry_max"`

	// RetryInterval specifies the amount of time to wait in between join
	// attempts on agent start. The minimum allowed value is 1 second and
	// the default is 30s.
	RetryInterval    time.Duration
	RetryIntervalHCL string `hcl:"retry_interval" json:"-"`

	// ExtraKeysHCL is used by hcl to surface unexpected keys
	ExtraKeysHCL []string `hcl:",unusedKeys" json:"-"`
}

func (s *ServerJoin) Merge(b *ServerJoin) *ServerJoin {
	if s == nil {
		return b
	}

	result := *s

	if b == nil {
		return &result
	}

	if len(b.StartJoin) != 0 {
		result.StartJoin = b.StartJoin
	}
	if len(b.RetryJoin) != 0 {
		result.RetryJoin = b.RetryJoin
	}
	if b.RetryMaxAttempts != 0 {
		result.RetryMaxAttempts = b.RetryMaxAttempts
	}
	if b.RetryInterval != 0 {
		result.RetryInterval = b.RetryInterval
	}

	return &result
}

// EncryptBytes returns the encryption key configured.
func (s *ServerConfig) EncryptBytes() ([]byte, error) {
	return base64.StdEncoding.DecodeString(s.EncryptKey)
}

// Telemetry is the telemetry configuration for the server
type Telemetry struct {
	StatsiteAddr             string        `hcl:"statsite_address"`
	StatsdAddr               string        `hcl:"statsd_address"`
	DataDogAddr              string        `hcl:"datadog_address"`
	DataDogTags              []string      `hcl:"datadog_tags"`
	PrometheusMetrics        bool          `hcl:"prometheus_metrics"`
	DisableHostname          bool          `hcl:"disable_hostname"`
	UseNodeName              bool          `hcl:"use_node_name"`
	CollectionInterval       string        `hcl:"collection_interval"`
	collectionInterval       time.Duration `hcl:"-"`
	PublishAllocationMetrics bool          `hcl:"publish_allocation_metrics"`
	PublishNodeMetrics       bool          `hcl:"publish_node_metrics"`

	// DisableTaggedMetrics disables a new version of generating metrics which
	// uses tags
	DisableTaggedMetrics bool `hcl:"disable_tagged_metrics"`

	// BackwardsCompatibleMetrics allows for generating metrics in a simple
	// key/value structure as done in older versions of Nomad
	BackwardsCompatibleMetrics bool `hcl:"backwards_compatible_metrics"`

	// PrefixFilter allows for filtering out metrics from being collected
	PrefixFilter []string `hcl:"prefix_filter"`

	// FilterDefault controls whether to allow metrics that have not been specified
	// by the filter
	FilterDefault *bool `hcl:"filter_default"`

	// DisableDispatchedJobSummaryMetrics allows ignoring dispatched jobs when
	// publishing Job summary metrics. This is useful in environments that produce
	// high numbers of single count dispatch jobs as the metrics for each take up
	// a small memory overhead.
	DisableDispatchedJobSummaryMetrics bool `hcl:"disable_dispatched_job_summary_metrics"`

	// Circonus: see https://github.com/circonus-labs/circonus-gometrics
	// for more details on the various configuration options.
	// Valid configuration combinations:
	//    - CirconusAPIToken
	//      metric management enabled (search for existing check or create a new one)
	//    - CirconusSubmissionUrl
	//      metric management disabled (use check with specified submission_url,
	//      broker must be using a public SSL certificate)
	//    - CirconusAPIToken + CirconusCheckSubmissionURL
	//      metric management enabled (use check with specified submission_url)
	//    - CirconusAPIToken + CirconusCheckID
	//      metric management enabled (use check with specified id)

	// CirconusAPIToken is a valid API Token used to create/manage check. If provided,
	// metric management is enabled.
	// Default: none
	CirconusAPIToken string `hcl:"circonus_api_token"`
	// CirconusAPIApp is an app name associated with API token.
	// Default: "nomad"
	CirconusAPIApp string `hcl:"circonus_api_app"`
	// CirconusAPIURL is the base URL to use for contacting the Circonus API.
	// Default: "https://api.circonus.com/v2"
	CirconusAPIURL string `hcl:"circonus_api_url"`
	// CirconusSubmissionInterval is the interval at which metrics are submitted to Circonus.
	// Default: 10s
	CirconusSubmissionInterval string `hcl:"circonus_submission_interval"`
	// CirconusCheckSubmissionURL is the check.config.submission_url field from a
	// previously created HTTPTRAP check.
	// Default: none
	CirconusCheckSubmissionURL string `hcl:"circonus_submission_url"`
	// CirconusCheckID is the check id (not check bundle id) from a previously created
	// HTTPTRAP check. The numeric portion of the check._cid field.
	// Default: none
	CirconusCheckID string `hcl:"circonus_check_id"`
	// CirconusCheckForceMetricActivation will force enabling metrics, as they are encountered,
	// if the metric already exists and is NOT active. If check management is enabled, the default
	// behavior is to add new metrics as they are encountered. If the metric already exists in the
	// check, it will *NOT* be activated. This setting overrides that behavior.
	// Default: "false"
	CirconusCheckForceMetricActivation string `hcl:"circonus_check_force_metric_activation"`
	// CirconusCheckInstanceID serves to uniquely identify the metrics coming from this "instance".
	// It can be used to maintain metric continuity with transient or ephemeral instances as
	// they move around within an infrastructure.
	// Default: hostname:app
	CirconusCheckInstanceID string `hcl:"circonus_check_instance_id"`
	// CirconusCheckSearchTag is a special tag which, when coupled with the instance id, helps to
	// narrow down the search results when neither a Submission URL or Check ID is provided.
	// Default: service:app (e.g. service:nomad)
	CirconusCheckSearchTag string `hcl:"circonus_check_search_tag"`
	// CirconusCheckTags is a comma separated list of tags to apply to the check. Note that
	// the value of CirconusCheckSearchTag will always be added to the check.
	// Default: none
	CirconusCheckTags string `hcl:"circonus_check_tags"`
	// CirconusCheckDisplayName is the name for the check which will be displayed in the Circonus UI.
	// Default: value of CirconusCheckInstanceID
	CirconusCheckDisplayName string `hcl:"circonus_check_display_name"`
	// CirconusBrokerID is an explicit broker to use when creating a new check. The numeric portion
	// of broker._cid. If metric management is enabled and neither a Submission URL nor Check ID
	// is provided, an attempt will be made to search for an existing check using Instance ID and
	// Search Tag. If one is not found, a new HTTPTRAP check will be created.
	// Default: use Select Tag if provided, otherwise, a random Enterprise Broker associated
	// with the specified API token or the default Circonus Broker.
	// Default: none
	CirconusBrokerID string `hcl:"circonus_broker_id"`
	// CirconusBrokerSelectTag is a special tag which will be used to select a broker when
	// a Broker ID is not provided. The best use of this is to as a hint for which broker
	// should be used based on *where* this particular instance is running.
	// (e.g. a specific geo location or datacenter, dc:sfo)
	// Default: none
	CirconusBrokerSelectTag string `hcl:"circonus_broker_select_tag"`

	// ExtraKeysHCL is used by hcl to surface unexpected keys
	ExtraKeysHCL []string `hcl:",unusedKeys" json:"-"`
}

// PrefixFilters parses the PrefixFilter field and returns a list of allowed and blocked filters
func (t *Telemetry) PrefixFilters() (allowed, blocked []string, err error) {
	for _, rule := range t.PrefixFilter {
		if rule == "" {
			continue
		}
		switch rule[0] {
		case '+':
			allowed = append(allowed, rule[1:])
		case '-':
			blocked = append(blocked, rule[1:])
		default:
			return nil, nil, fmt.Errorf("Filter rule must begin with either '+' or '-': %q", rule)
		}
	}
	return allowed, blocked, nil
}

// Ports encapsulates the various ports we bind to for network services. If any
// are not specified then the defaults are used instead.
type Ports struct {
	HTTP int `hcl:"http"`
	RPC  int `hcl:"rpc"`
	Serf int `hcl:"serf"`
	// ExtraKeysHCL is used by hcl to surface unexpected keys
	ExtraKeysHCL []string `hcl:",unusedKeys" json:"-"`
}

// Addresses encapsulates all of the addresses we bind to for various
// network services. Everything is optional and defaults to BindAddr.
type Addresses struct {
	HTTP string `hcl:"http"`
	RPC  string `hcl:"rpc"`
	Serf string `hcl:"serf"`
	// ExtraKeysHCL is used by hcl to surface unexpected keys
	ExtraKeysHCL []string `hcl:",unusedKeys" json:"-"`
}

// AdvertiseAddrs is used to control the addresses we advertise out for
// different network services. All are optional and default to BindAddr and
// their default Port.
type AdvertiseAddrs struct {
	HTTP string `hcl:"http"`
	RPC  string `hcl:"rpc"`
	Serf string `hcl:"serf"`
	// ExtraKeysHCL is used by hcl to surface unexpected keys
	ExtraKeysHCL []string `hcl:",unusedKeys" json:"-"`
}

type Resources struct {
	CPU           int    `hcl:"cpu"`
	MemoryMB      int    `hcl:"memory"`
	DiskMB        int    `hcl:"disk"`
	ReservedPorts string `hcl:"reserved_ports"`
	// ExtraKeysHCL is used by hcl to surface unexpected keys
	ExtraKeysHCL []string `hcl:",unusedKeys" json:"-"`
}

// CanParseReserved returns if the reserved ports specification is parsable.
// The supported syntax is comma separated integers or ranges separated by
// hyphens. For example, "80,120-150,160"
func (r *Resources) CanParseReserved() error {
	_, err := structs.ParsePortRanges(r.ReservedPorts)
	return err
}

// devModeConfig holds the config for the -dev and -dev-connect flags
type devModeConfig struct {
	// mode flags are set at the command line via -dev and -dev-connect
	defaultMode bool
	connectMode bool

	bindAddr string
	iface    string
}

// newDevModeConfig parses the optional string value of the -dev flag
func newDevModeConfig(devMode, connectMode bool) (*devModeConfig, error) {
	if !devMode && !connectMode {
		return nil, nil
	}
	mode := &devModeConfig{}
	mode.defaultMode = devMode
	if connectMode {
		if runtime.GOOS != "linux" {
			// strictly speaking -dev-connect only binds to the
			// non-localhost interface, but given its purpose
			// is to support a feature with network namespaces
			// we'll return an error here rather than let the agent
			// come up and fail unexpectedly to run jobs
			return nil, fmt.Errorf("-dev-connect is only supported on linux.")
		}
		u, err := user.Current()
		if err != nil {
			return nil, fmt.Errorf(
				"-dev-connect uses network namespaces and is only supported for root: %v", err)
		}
		if u.Uid != "0" {
			return nil, fmt.Errorf(
				"-dev-connect uses network namespaces and is only supported for root.")
		}
		// Ensure Consul is on PATH
		if _, err := exec.LookPath("consul"); err != nil {
			return nil, fmt.Errorf("-dev-connect requires a 'consul' binary in Nomad's $PATH")
		}
		mode.connectMode = true
	}
	err := mode.networkConfig()
	if err != nil {
		return nil, err
	}
	return mode, nil
}

func (mode *devModeConfig) networkConfig() error {
	if runtime.GOOS == "darwin" {
		mode.bindAddr = "127.0.0.1"
		mode.iface = "lo0"
		return nil
	}
	if mode != nil && mode.connectMode {
		// if we hit either of the errors here we're in a weird situation
		// where syscalls to get the list of network interfaces are failing.
		// rather than throwing errors, we'll fall back to the default.
		ifAddrs, err := sockaddr.GetDefaultInterfaces()
		errMsg := "-dev=connect uses network namespaces: %v"
		if err != nil {
			return fmt.Errorf(errMsg, err)
		}
		if len(ifAddrs) < 1 {
			return fmt.Errorf(errMsg, "could not find public network inteface")
		}
		iface := ifAddrs[0].Name
		mode.iface = iface
		mode.bindAddr = "0.0.0.0" // allows CLI to "just work"
		return nil
	}
	mode.bindAddr = "127.0.0.1"
	mode.iface = "lo"
	return nil
}

// DevConfig is a Config that is used for dev mode of Nomad.
func DevConfig(mode *devModeConfig) *Config {
	if mode == nil {
		mode = &devModeConfig{defaultMode: true}
		mode.networkConfig()
	}
	conf := DefaultConfig()
	conf.BindAddr = mode.bindAddr
	conf.LogLevel = "DEBUG"
	conf.Client.Enabled = true
	conf.Server.Enabled = true
	conf.DevMode = mode != nil
	conf.EnableDebug = true
	conf.DisableAnonymousSignature = true
	conf.Consul.AutoAdvertise = helper.BoolToPtr(true)
	conf.Client.NetworkInterface = mode.iface
	conf.Client.Options = map[string]string{
		"driver.raw_exec.enable": "true",
		"driver.docker.volumes":  "true",
	}
	conf.Client.GCInterval = 10 * time.Minute
	conf.Client.GCDiskUsageThreshold = 99
	conf.Client.GCInodeUsageThreshold = 99
	conf.Client.GCMaxAllocs = 50
	conf.Client.TemplateConfig = &ClientTemplateConfig{
		FunctionBlacklist: []string{"plugin"},
		DisableSandbox:    false,
	}
	conf.Telemetry.PrometheusMetrics = true
	conf.Telemetry.PublishAllocationMetrics = true
	conf.Telemetry.PublishNodeMetrics = true

	return conf
}

// DefaultConfig is a the baseline configuration for Nomad
func DefaultConfig() *Config {
	return &Config{
		LogLevel:   "INFO",
		Region:     "global",
		Datacenter: "dc1",
		BindAddr:   "0.0.0.0",
		Ports: &Ports{
			HTTP: 4646,
			RPC:  4647,
			Serf: 4648,
		},
		Addresses:      &Addresses{},
		AdvertiseAddrs: &AdvertiseAddrs{},
		Consul:         config.DefaultConsulConfig(),
		Vault:          config.DefaultVaultConfig(),
		Client: &ClientConfig{
			Enabled:               false,
			MaxKillTimeout:        "30s",
			ClientMinPort:         14000,
			ClientMaxPort:         14512,
			Reserved:              &Resources{},
			GCInterval:            1 * time.Minute,
			GCParallelDestroys:    2,
			GCDiskUsageThreshold:  80,
			GCInodeUsageThreshold: 70,
			GCMaxAllocs:           50,
			NoHostUUID:            helper.BoolToPtr(true),
			DisableRemoteExec:     false,
			ServerJoin: &ServerJoin{
				RetryJoin:        []string{},
				RetryInterval:    30 * time.Second,
				RetryMaxAttempts: 0,
			},
			TemplateConfig: &ClientTemplateConfig{
				FunctionBlacklist: []string{"plugin"},
				DisableSandbox:    false,
			},
		},
		Server: &ServerConfig{
			Enabled:   false,
			StartJoin: []string{},
			ServerJoin: &ServerJoin{
				RetryJoin:        []string{},
				RetryInterval:    30 * time.Second,
				RetryMaxAttempts: 0,
			},
		},
		ACL: &ACLConfig{
			Enabled:   false,
			TokenTTL:  30 * time.Second,
			PolicyTTL: 30 * time.Second,
		},
		SyslogFacility: "LOCAL0",
		Telemetry: &Telemetry{
			CollectionInterval: "1s",
			collectionInterval: 1 * time.Second,
		},
		TLSConfig:          &config.TLSConfig{},
		Sentinel:           &config.SentinelConfig{},
		Version:            version.GetVersion(),
		Autopilot:          config.DefaultAutopilotConfig(),
		DisableUpdateCheck: helper.BoolToPtr(false),
	}
}

// Listener can be used to get a new listener using a custom bind address.
// If the bind provided address is empty, the BindAddr is used instead.
func (c *Config) Listener(proto, addr string, port int) (net.Listener, error) {
	if addr == "" {
		addr = c.BindAddr
	}

	// Do our own range check to avoid bugs in package net.
	//
	//   golang.org/issue/11715
	//   golang.org/issue/13447
	//
	// Both of the above bugs were fixed by golang.org/cl/12447 which will be
	// included in Go 1.6. The error returned below is the same as what Go 1.6
	// will return.
	if 0 > port || port > 65535 {
		return nil, &net.OpError{
			Op:  "listen",
			Net: proto,
			Err: &net.AddrError{Err: "invalid port", Addr: fmt.Sprint(port)},
		}
	}
	return net.Listen(proto, net.JoinHostPort(addr, strconv.Itoa(port)))
}

// Merge merges two configurations.
func (c *Config) Merge(b *Config) *Config {
	result := *c

	if b.Region != "" {
		result.Region = b.Region
	}
	if b.Datacenter != "" {
		result.Datacenter = b.Datacenter
	}
	if b.NodeName != "" {
		result.NodeName = b.NodeName
	}
	if b.DataDir != "" {
		result.DataDir = b.DataDir
	}
	if b.PluginDir != "" {
		result.PluginDir = b.PluginDir
	}
	if b.LogLevel != "" {
		result.LogLevel = b.LogLevel
	}
	if b.LogJson {
		result.LogJson = true
	}
	if b.LogFile != "" {
		result.LogFile = b.LogFile
	}
	if b.LogRotateDuration != "" {
		result.LogRotateDuration = b.LogRotateDuration
	}
	if b.LogRotateBytes != 0 {
		result.LogRotateBytes = b.LogRotateBytes
	}
	if b.LogRotateMaxFiles != 0 {
		result.LogRotateMaxFiles = b.LogRotateMaxFiles
	}
	if b.BindAddr != "" {
		result.BindAddr = b.BindAddr
	}
	if b.EnableDebug {
		result.EnableDebug = true
	}
	if b.LeaveOnInt {
		result.LeaveOnInt = true
	}
	if b.LeaveOnTerm {
		result.LeaveOnTerm = true
	}
	if b.EnableSyslog {
		result.EnableSyslog = true
	}
	if b.SyslogFacility != "" {
		result.SyslogFacility = b.SyslogFacility
	}
	if b.DisableUpdateCheck != nil {
		result.DisableUpdateCheck = helper.BoolToPtr(*b.DisableUpdateCheck)
	}
	if b.DisableAnonymousSignature {
		result.DisableAnonymousSignature = true
	}

	// Apply the telemetry config
	if result.Telemetry == nil && b.Telemetry != nil {
		telemetry := *b.Telemetry
		result.Telemetry = &telemetry
	} else if b.Telemetry != nil {
		result.Telemetry = result.Telemetry.Merge(b.Telemetry)
	}

	// Apply the TLS Config
	if result.TLSConfig == nil && b.TLSConfig != nil {
		result.TLSConfig = b.TLSConfig.Copy()
	} else if b.TLSConfig != nil {
		result.TLSConfig = result.TLSConfig.Merge(b.TLSConfig)
	}

	// Apply the client config
	if result.Client == nil && b.Client != nil {
		client := *b.Client
		result.Client = &client
	} else if b.Client != nil {
		result.Client = result.Client.Merge(b.Client)
	}

	// Apply the server config
	if result.Server == nil && b.Server != nil {
		server := *b.Server
		result.Server = &server
	} else if b.Server != nil {
		result.Server = result.Server.Merge(b.Server)
	}

	// Apply the acl config
	if result.ACL == nil && b.ACL != nil {
		server := *b.ACL
		result.ACL = &server
	} else if b.ACL != nil {
		result.ACL = result.ACL.Merge(b.ACL)
	}

	// Apply the ports config
	if result.Ports == nil && b.Ports != nil {
		ports := *b.Ports
		result.Ports = &ports
	} else if b.Ports != nil {
		result.Ports = result.Ports.Merge(b.Ports)
	}

	// Apply the address config
	if result.Addresses == nil && b.Addresses != nil {
		addrs := *b.Addresses
		result.Addresses = &addrs
	} else if b.Addresses != nil {
		result.Addresses = result.Addresses.Merge(b.Addresses)
	}

	// Apply the advertise addrs config
	if result.AdvertiseAddrs == nil && b.AdvertiseAddrs != nil {
		advertise := *b.AdvertiseAddrs
		result.AdvertiseAddrs = &advertise
	} else if b.AdvertiseAddrs != nil {
		result.AdvertiseAddrs = result.AdvertiseAddrs.Merge(b.AdvertiseAddrs)
	}

	// Apply the Consul Configuration
	if result.Consul == nil && b.Consul != nil {
		result.Consul = b.Consul.Copy()
	} else if b.Consul != nil {
		result.Consul = result.Consul.Merge(b.Consul)
	}

	// Apply the Vault Configuration
	if result.Vault == nil && b.Vault != nil {
		vaultConfig := *b.Vault
		result.Vault = &vaultConfig
	} else if b.Vault != nil {
		result.Vault = result.Vault.Merge(b.Vault)
	}

	// Apply the sentinel config
	if result.Sentinel == nil && b.Sentinel != nil {
		server := *b.Sentinel
		result.Sentinel = &server
	} else if b.Sentinel != nil {
		result.Sentinel = result.Sentinel.Merge(b.Sentinel)
	}

	if result.Autopilot == nil && b.Autopilot != nil {
		autopilot := *b.Autopilot
		result.Autopilot = &autopilot
	} else if b.Autopilot != nil {
		result.Autopilot = result.Autopilot.Merge(b.Autopilot)
	}

	if len(result.Plugins) == 0 && len(b.Plugins) != 0 {
		copy := make([]*config.PluginConfig, len(b.Plugins))
		for i, v := range b.Plugins {
			copy[i] = v.Copy()
		}
		result.Plugins = copy
	} else if len(b.Plugins) != 0 {
		result.Plugins = config.PluginConfigSetMerge(result.Plugins, b.Plugins)
	}

	// Merge config files lists
	result.Files = append(result.Files, b.Files...)

	// Add the http API response header map values
	if result.HTTPAPIResponseHeaders == nil {
		result.HTTPAPIResponseHeaders = make(map[string]string)
	}
	for k, v := range b.HTTPAPIResponseHeaders {
		result.HTTPAPIResponseHeaders[k] = v
	}

	return &result
}

// normalizeAddrs normalizes Addresses and AdvertiseAddrs to always be
// initialized and have sane defaults.
func (c *Config) normalizeAddrs() error {
	if c.BindAddr != "" {
		ipStr, err := parseSingleIPTemplate(c.BindAddr)
		if err != nil {
			return fmt.Errorf("Bind address resolution failed: %v", err)
		}
		c.BindAddr = ipStr
	}

	addr, err := normalizeBind(c.Addresses.HTTP, c.BindAddr)
	if err != nil {
		return fmt.Errorf("Failed to parse HTTP address: %v", err)
	}
	c.Addresses.HTTP = addr

	addr, err = normalizeBind(c.Addresses.RPC, c.BindAddr)
	if err != nil {
		return fmt.Errorf("Failed to parse RPC address: %v", err)
	}
	c.Addresses.RPC = addr

	addr, err = normalizeBind(c.Addresses.Serf, c.BindAddr)
	if err != nil {
		return fmt.Errorf("Failed to parse Serf address: %v", err)
	}
	c.Addresses.Serf = addr

	c.normalizedAddrs = &Addresses{
		HTTP: net.JoinHostPort(c.Addresses.HTTP, strconv.Itoa(c.Ports.HTTP)),
		RPC:  net.JoinHostPort(c.Addresses.RPC, strconv.Itoa(c.Ports.RPC)),
		Serf: net.JoinHostPort(c.Addresses.Serf, strconv.Itoa(c.Ports.Serf)),
	}

	addr, err = normalizeAdvertise(c.AdvertiseAddrs.HTTP, c.Addresses.HTTP, c.Ports.HTTP, c.DevMode)
	if err != nil {
		return fmt.Errorf("Failed to parse HTTP advertise address (%v, %v, %v, %v): %v", c.AdvertiseAddrs.HTTP, c.Addresses.HTTP, c.Ports.HTTP, c.DevMode, err)
	}
	c.AdvertiseAddrs.HTTP = addr

	addr, err = normalizeAdvertise(c.AdvertiseAddrs.RPC, c.Addresses.RPC, c.Ports.RPC, c.DevMode)
	if err != nil {
		return fmt.Errorf("Failed to parse RPC advertise address: %v", err)
	}
	c.AdvertiseAddrs.RPC = addr

	// Skip serf if server is disabled
	if c.Server != nil && c.Server.Enabled {
		addr, err = normalizeAdvertise(c.AdvertiseAddrs.Serf, c.Addresses.Serf, c.Ports.Serf, c.DevMode)
		if err != nil {
			return fmt.Errorf("Failed to parse Serf advertise address: %v", err)
		}
		c.AdvertiseAddrs.Serf = addr
	}

	return nil
}

// parseSingleIPTemplate is used as a helper function to parse out a single IP
// address from a config parameter.
func parseSingleIPTemplate(ipTmpl string) (string, error) {
	out, err := template.Parse(ipTmpl)
	if err != nil {
		return "", fmt.Errorf("Unable to parse address template %q: %v", ipTmpl, err)
	}

	ips := strings.Split(out, " ")
	switch len(ips) {
	case 0:
		return "", errors.New("No addresses found, please configure one.")
	case 1:
		return ips[0], nil
	default:
		return "", fmt.Errorf("Multiple addresses found (%q), please configure one.", out)
	}
}

// normalizeBind returns a normalized bind address.
//
// If addr is set it is used, if not the default bind address is used.
func normalizeBind(addr, bind string) (string, error) {
	if addr == "" {
		return bind, nil
	}
	return parseSingleIPTemplate(addr)
}

// normalizeAdvertise returns a normalized advertise address.
//
// If addr is set, it is used and the default port is appended if no port is
// set.
//
// If addr is not set and bind is a valid address, the returned string is the
// bind+port.
//
// If addr is not set and bind is not a valid advertise address, the hostname
// is resolved and returned with the port.
//
// Loopback is only considered a valid advertise address in dev mode.
func normalizeAdvertise(addr string, bind string, defport int, dev bool) (string, error) {
	addr, err := parseSingleIPTemplate(addr)
	if err != nil {
		return "", fmt.Errorf("Error parsing advertise address template: %v", err)
	}

	if addr != "" {
		// Default to using manually configured address
		_, _, err = net.SplitHostPort(addr)
		if err != nil {
			if !isMissingPort(err) && !isTooManyColons(err) {
				return "", fmt.Errorf("Error parsing advertise address %q: %v", addr, err)
			}

			// missing port, append the default
			return net.JoinHostPort(addr, strconv.Itoa(defport)), nil
		}

		return addr, nil
	}

	// Fallback to bind address first, and then try resolving the local hostname
	ips, err := net.LookupIP(bind)
	if err != nil {
		return "", fmt.Errorf("Error resolving bind address %q: %v", bind, err)
	}

	// Return the first non-localhost unicast address
	for _, ip := range ips {
		if ip.IsLinkLocalUnicast() || ip.IsGlobalUnicast() {
			return net.JoinHostPort(ip.String(), strconv.Itoa(defport)), nil
		}
		if ip.IsLoopback() {
			if dev {
				// loopback is fine for dev mode
				return net.JoinHostPort(ip.String(), strconv.Itoa(defport)), nil
			}
			return "", fmt.Errorf("Defaulting advertise to localhost is unsafe, please set advertise manually")
		}
	}

	// Bind is not localhost but not a valid advertise IP, use first private IP
	addr, err = parseSingleIPTemplate("{{ GetPrivateIP }}")
	if err != nil {
		return "", fmt.Errorf("Unable to parse default advertise address: %v", err)
	}
	return net.JoinHostPort(addr, strconv.Itoa(defport)), nil
}

// isMissingPort returns true if an error is a "missing port" error from
// net.SplitHostPort.
func isMissingPort(err error) bool {
	// matches error const in net/ipsock.go
	const missingPort = "missing port in address"
	return err != nil && strings.Contains(err.Error(), missingPort)
}

// isTooManyColons returns true if an error is a "too many colons" error from
// net.SplitHostPort.
func isTooManyColons(err error) bool {
	// matches error const in net/ipsock.go
	const tooManyColons = "too many colons in address"
	return err != nil && strings.Contains(err.Error(), tooManyColons)
}

// Merge is used to merge two ACL configs together. The settings from the input always take precedence.
func (a *ACLConfig) Merge(b *ACLConfig) *ACLConfig {
	result := *a

	if b.Enabled {
		result.Enabled = true
	}
	if b.TokenTTL != 0 {
		result.TokenTTL = b.TokenTTL
	}
	if b.TokenTTLHCL != "" {
		result.TokenTTLHCL = b.TokenTTLHCL
	}
	if b.PolicyTTL != 0 {
		result.PolicyTTL = b.PolicyTTL
	}
	if b.PolicyTTLHCL != "" {
		result.PolicyTTLHCL = b.PolicyTTLHCL
	}
	if b.ReplicationToken != "" {
		result.ReplicationToken = b.ReplicationToken
	}
	return &result
}

// Merge is used to merge two server configs together
func (a *ServerConfig) Merge(b *ServerConfig) *ServerConfig {
	result := *a

	if b.Enabled {
		result.Enabled = true
	}
	if b.AuthoritativeRegion != "" {
		result.AuthoritativeRegion = b.AuthoritativeRegion
	}
	if b.BootstrapExpect > 0 {
		result.BootstrapExpect = b.BootstrapExpect
	}
	if b.DataDir != "" {
		result.DataDir = b.DataDir
	}
	if b.ProtocolVersion != 0 {
		result.ProtocolVersion = b.ProtocolVersion
	}
	if b.RaftProtocol != 0 {
		result.RaftProtocol = b.RaftProtocol
	}
	if b.NumSchedulers != nil {
		result.NumSchedulers = helper.IntToPtr(*b.NumSchedulers)
	}
	if b.NodeGCThreshold != "" {
		result.NodeGCThreshold = b.NodeGCThreshold
	}
	if b.JobGCInterval != "" {
		result.JobGCInterval = b.JobGCInterval
	}
	if b.JobGCThreshold != "" {
		result.JobGCThreshold = b.JobGCThreshold
	}
	if b.EvalGCThreshold != "" {
		result.EvalGCThreshold = b.EvalGCThreshold
	}
	if b.DeploymentGCThreshold != "" {
		result.DeploymentGCThreshold = b.DeploymentGCThreshold
	}
	if b.HeartbeatGrace != 0 {
		result.HeartbeatGrace = b.HeartbeatGrace
	}
	if b.HeartbeatGraceHCL != "" {
		result.HeartbeatGraceHCL = b.HeartbeatGraceHCL
	}
	if b.MinHeartbeatTTL != 0 {
		result.MinHeartbeatTTL = b.MinHeartbeatTTL
	}
	if b.MinHeartbeatTTLHCL != "" {
		result.MinHeartbeatTTLHCL = b.MinHeartbeatTTLHCL
	}
	if b.MaxHeartbeatsPerSecond != 0.0 {
		result.MaxHeartbeatsPerSecond = b.MaxHeartbeatsPerSecond
	}
	if b.RetryMaxAttempts != 0 {
		result.RetryMaxAttempts = b.RetryMaxAttempts
	}
	if b.RetryInterval != 0 {
		result.RetryInterval = b.RetryInterval
	}
	if b.RetryIntervalHCL != "" {
		result.RetryIntervalHCL = b.RetryIntervalHCL
	}
	if b.RejoinAfterLeave {
		result.RejoinAfterLeave = true
	}
	if b.NonVotingServer {
		result.NonVotingServer = true
	}
	if b.RedundancyZone != "" {
		result.RedundancyZone = b.RedundancyZone
	}
	if b.UpgradeVersion != "" {
		result.UpgradeVersion = b.UpgradeVersion
	}
	if b.EncryptKey != "" {
		result.EncryptKey = b.EncryptKey
	}
	if b.ServerJoin != nil {
		result.ServerJoin = result.ServerJoin.Merge(b.ServerJoin)
	}

	// Add the schedulers
	result.EnabledSchedulers = append(result.EnabledSchedulers, b.EnabledSchedulers...)

	// Copy the start join addresses
	result.StartJoin = make([]string, 0, len(a.StartJoin)+len(b.StartJoin))
	result.StartJoin = append(result.StartJoin, a.StartJoin...)
	result.StartJoin = append(result.StartJoin, b.StartJoin...)

	// Copy the retry join addresses
	result.RetryJoin = make([]string, 0, len(a.RetryJoin)+len(b.RetryJoin))
	result.RetryJoin = append(result.RetryJoin, a.RetryJoin...)
	result.RetryJoin = append(result.RetryJoin, b.RetryJoin...)

	return &result
}

// Merge is used to merge two client configs together
func (a *ClientConfig) Merge(b *ClientConfig) *ClientConfig {
	result := *a

	if b.Enabled {
		result.Enabled = true
	}
	if b.StateDir != "" {
		result.StateDir = b.StateDir
	}
	if b.AllocDir != "" {
		result.AllocDir = b.AllocDir
	}
	if b.NodeClass != "" {
		result.NodeClass = b.NodeClass
	}
	if b.NetworkInterface != "" {
		result.NetworkInterface = b.NetworkInterface
	}
	if b.NetworkSpeed != 0 {
		result.NetworkSpeed = b.NetworkSpeed
	}
	if b.CpuCompute != 0 {
		result.CpuCompute = b.CpuCompute
	}
	if b.MemoryMB != 0 {
		result.MemoryMB = b.MemoryMB
	}
	if b.MaxKillTimeout != "" {
		result.MaxKillTimeout = b.MaxKillTimeout
	}
	if b.ClientMaxPort != 0 {
		result.ClientMaxPort = b.ClientMaxPort
	}
	if b.ClientMinPort != 0 {
		result.ClientMinPort = b.ClientMinPort
	}
	if result.Reserved == nil && b.Reserved != nil {
		reserved := *b.Reserved
		result.Reserved = &reserved
	} else if b.Reserved != nil {
		result.Reserved = result.Reserved.Merge(b.Reserved)
	}
	if b.GCInterval != 0 {
		result.GCInterval = b.GCInterval
	}
	if b.GCIntervalHCL != "" {
		result.GCIntervalHCL = b.GCIntervalHCL
	}
	if b.GCParallelDestroys != 0 {
		result.GCParallelDestroys = b.GCParallelDestroys
	}
	if b.GCDiskUsageThreshold != 0 {
		result.GCDiskUsageThreshold = b.GCDiskUsageThreshold
	}
	if b.GCInodeUsageThreshold != 0 {
		result.GCInodeUsageThreshold = b.GCInodeUsageThreshold
	}
	if b.GCMaxAllocs != 0 {
		result.GCMaxAllocs = b.GCMaxAllocs
	}
	// NoHostUUID defaults to true, merge if false
	if b.NoHostUUID != nil {
		result.NoHostUUID = b.NoHostUUID
	}

	if b.DisableRemoteExec {
		result.DisableRemoteExec = b.DisableRemoteExec
	}

	if b.TemplateConfig != nil {
		result.TemplateConfig = b.TemplateConfig
	}

	// Add the servers
	result.Servers = append(result.Servers, b.Servers...)

	// Add the options map values
	if result.Options == nil {
		result.Options = make(map[string]string)
	}
	for k, v := range b.Options {
		result.Options[k] = v
	}

	// Add the meta map values
	if result.Meta == nil {
		result.Meta = make(map[string]string)
	}
	for k, v := range b.Meta {
		result.Meta[k] = v
	}

	// Add the chroot_env map values
	if result.ChrootEnv == nil {
		result.ChrootEnv = make(map[string]string)
	}
	for k, v := range b.ChrootEnv {
		result.ChrootEnv[k] = v
	}

	if b.ServerJoin != nil {
		result.ServerJoin = result.ServerJoin.Merge(b.ServerJoin)
	}

	if len(a.HostVolumes) == 0 && len(b.HostVolumes) != 0 {
		result.HostVolumes = structs.CopySliceClientHostVolumeConfig(b.HostVolumes)
	} else if len(b.HostVolumes) != 0 {
		result.HostVolumes = structs.HostVolumeSliceMerge(a.HostVolumes, b.HostVolumes)
	}

	return &result
}

// Merge is used to merge two telemetry configs together
func (a *Telemetry) Merge(b *Telemetry) *Telemetry {
	result := *a

	if b.StatsiteAddr != "" {
		result.StatsiteAddr = b.StatsiteAddr
	}
	if b.StatsdAddr != "" {
		result.StatsdAddr = b.StatsdAddr
	}
	if b.DataDogAddr != "" {
		result.DataDogAddr = b.DataDogAddr
	}
	if b.DataDogTags != nil {
		result.DataDogTags = b.DataDogTags
	}
	if b.PrometheusMetrics {
		result.PrometheusMetrics = b.PrometheusMetrics
	}
	if b.DisableHostname {
		result.DisableHostname = true
	}

	if b.UseNodeName {
		result.UseNodeName = true
	}
	if b.CollectionInterval != "" {
		result.CollectionInterval = b.CollectionInterval
	}
	if b.collectionInterval != 0 {
		result.collectionInterval = b.collectionInterval
	}
	if b.PublishNodeMetrics {
		result.PublishNodeMetrics = true
	}
	if b.PublishAllocationMetrics {
		result.PublishAllocationMetrics = true
	}
	if b.CirconusAPIToken != "" {
		result.CirconusAPIToken = b.CirconusAPIToken
	}
	if b.CirconusAPIApp != "" {
		result.CirconusAPIApp = b.CirconusAPIApp
	}
	if b.CirconusAPIURL != "" {
		result.CirconusAPIURL = b.CirconusAPIURL
	}
	if b.CirconusCheckSubmissionURL != "" {
		result.CirconusCheckSubmissionURL = b.CirconusCheckSubmissionURL
	}
	if b.CirconusSubmissionInterval != "" {
		result.CirconusSubmissionInterval = b.CirconusSubmissionInterval
	}
	if b.CirconusCheckID != "" {
		result.CirconusCheckID = b.CirconusCheckID
	}
	if b.CirconusCheckForceMetricActivation != "" {
		result.CirconusCheckForceMetricActivation = b.CirconusCheckForceMetricActivation
	}
	if b.CirconusCheckInstanceID != "" {
		result.CirconusCheckInstanceID = b.CirconusCheckInstanceID
	}
	if b.CirconusCheckSearchTag != "" {
		result.CirconusCheckSearchTag = b.CirconusCheckSearchTag
	}
	if b.CirconusCheckTags != "" {
		result.CirconusCheckTags = b.CirconusCheckTags
	}
	if b.CirconusCheckDisplayName != "" {
		result.CirconusCheckDisplayName = b.CirconusCheckDisplayName
	}
	if b.CirconusBrokerID != "" {
		result.CirconusBrokerID = b.CirconusBrokerID
	}
	if b.CirconusBrokerSelectTag != "" {
		result.CirconusBrokerSelectTag = b.CirconusBrokerSelectTag
	}

	if b.DisableTaggedMetrics {
		result.DisableTaggedMetrics = b.DisableTaggedMetrics
	}

	if b.BackwardsCompatibleMetrics {
		result.BackwardsCompatibleMetrics = b.BackwardsCompatibleMetrics
	}

	if b.PrefixFilter != nil {
		result.PrefixFilter = b.PrefixFilter
	}

	if b.FilterDefault != nil {
		result.FilterDefault = b.FilterDefault
	}

	if b.DisableDispatchedJobSummaryMetrics {
		result.DisableDispatchedJobSummaryMetrics = b.DisableDispatchedJobSummaryMetrics
	}

	return &result
}

// Merge is used to merge two port configurations.
func (a *Ports) Merge(b *Ports) *Ports {
	result := *a

	if b.HTTP != 0 {
		result.HTTP = b.HTTP
	}
	if b.RPC != 0 {
		result.RPC = b.RPC
	}
	if b.Serf != 0 {
		result.Serf = b.Serf
	}
	return &result
}

// Merge is used to merge two address configs together.
func (a *Addresses) Merge(b *Addresses) *Addresses {
	result := *a

	if b.HTTP != "" {
		result.HTTP = b.HTTP
	}
	if b.RPC != "" {
		result.RPC = b.RPC
	}
	if b.Serf != "" {
		result.Serf = b.Serf
	}
	return &result
}

// Merge merges two advertise addrs configs together.
func (a *AdvertiseAddrs) Merge(b *AdvertiseAddrs) *AdvertiseAddrs {
	result := *a

	if b.RPC != "" {
		result.RPC = b.RPC
	}
	if b.Serf != "" {
		result.Serf = b.Serf
	}
	if b.HTTP != "" {
		result.HTTP = b.HTTP
	}
	return &result
}

func (r *Resources) Merge(b *Resources) *Resources {
	result := *r
	if b.CPU != 0 {
		result.CPU = b.CPU
	}
	if b.MemoryMB != 0 {
		result.MemoryMB = b.MemoryMB
	}
	if b.DiskMB != 0 {
		result.DiskMB = b.DiskMB
	}
	if b.ReservedPorts != "" {
		result.ReservedPorts = b.ReservedPorts
	}
	return &result
}

// LoadConfig loads the configuration at the given path, regardless if its a file or
// directory. Called for each -config to build up the runtime config value. Do not apply any
// default values, defaults should be added once in DefaultConfig
func LoadConfig(path string) (*Config, error) {
	fi, err := os.Stat(path)
	if err != nil {
		return nil, err
	}

	if fi.IsDir() {
		return LoadConfigDir(path)
	}

	cleaned := filepath.Clean(path)
	config, err := ParseConfigFile(cleaned)
	if err != nil {
		return nil, fmt.Errorf("Error loading %s: %s", cleaned, err)
	}

	config.Files = append(config.Files, cleaned)
	return config, nil
}

// LoadConfigDir loads all the configurations in the given directory
// in alphabetical order.
func LoadConfigDir(dir string) (*Config, error) {
	f, err := os.Open(dir)
	if err != nil {
		return nil, err
	}
	defer f.Close()

	fi, err := f.Stat()
	if err != nil {
		return nil, err
	}
	if !fi.IsDir() {
		return nil, fmt.Errorf(
			"configuration path must be a directory: %s", dir)
	}

	var files []string
	err = nil
	for err != io.EOF {
		var fis []os.FileInfo
		fis, err = f.Readdir(128)
		if err != nil && err != io.EOF {
			return nil, err
		}

		for _, fi := range fis {
			// Ignore directories
			if fi.IsDir() {
				continue
			}

			// Only care about files that are valid to load.
			name := fi.Name()
			skip := true
			if strings.HasSuffix(name, ".hcl") {
				skip = false
			} else if strings.HasSuffix(name, ".json") {
				skip = false
			}
			if skip || isTemporaryFile(name) {
				continue
			}

			path := filepath.Join(dir, name)
			files = append(files, path)
		}
	}

	// Fast-path if we have no files
	if len(files) == 0 {
		return &Config{}, nil
	}

	sort.Strings(files)

	var result *Config
	for _, f := range files {
		config, err := ParseConfigFile(f)
		if err != nil {
			return nil, fmt.Errorf("Error loading %s: %s", f, err)
		}
		config.Files = append(config.Files, f)

		if result == nil {
			result = config
		} else {
			result = result.Merge(config)
		}
	}

	return result, nil
}

// isTemporaryFile returns true or false depending on whether the
// provided file name is a temporary file for the following editors:
// emacs or vim.
func isTemporaryFile(name string) bool {
	return strings.HasSuffix(name, "~") || // vim
		strings.HasPrefix(name, ".#") || // emacs
		(strings.HasPrefix(name, "#") && strings.HasSuffix(name, "#")) // emacs
}