open-consul/agent/consul/config.go

// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0

package consul

import (
	"fmt"
	"net"
	"os"
	"time"

	"github.com/hashicorp/memberlist"
	"github.com/hashicorp/raft"
	"github.com/hashicorp/serf/serf"
	"golang.org/x/time/rate"

	"github.com/hashicorp/consul/agent/checks"
	consulrate "github.com/hashicorp/consul/agent/consul/rate"
	"github.com/hashicorp/consul/agent/structs"
	libserf "github.com/hashicorp/consul/lib/serf"
	"github.com/hashicorp/consul/tlsutil"
	"github.com/hashicorp/consul/types"
	"github.com/hashicorp/consul/version"
)

const (
	DefaultDC          = "dc1"
	DefaultRPCPort     = 8300
	DefaultLANSerfPort = 8301
	DefaultWANSerfPort = 8302

	// DefaultRaftMultiplier is used as a baseline Raft configuration that
	// will be reliable on a very basic server. See docs/install/performance.html
	// for information on how this value was obtained.
	DefaultRaftMultiplier uint = 5

	// MaxRaftMultiplier is a fairly arbitrary upper bound that limits the
	// amount of performance detuning that's possible.
	MaxRaftMultiplier uint = 10

	// LogStoreBackend* are well-known string values used to configure different
	// log store backends.
	LogStoreBackendBoltDB = "boltdb"
	LogStoreBackendWAL    = "wal"
)

var (
	DefaultRPCAddr = &net.TCPAddr{IP: net.ParseIP("0.0.0.0"), Port: DefaultRPCPort}

	// ProtocolVersionMap is the mapping of Consul protocol versions
	// to Serf protocol versions. We mask the Serf protocols using
	// our own protocol version.
	protocolVersionMap map[uint8]uint8
)

func init() {
	protocolVersionMap = map[uint8]uint8{
		1: 4,
		2: 4,
		3: 4,
	}
}

// (Enterprise-only) NetworkSegment is the address and port configuration
// for a network segment.
type NetworkSegment struct {
	Name       string
	Bind       string
	Port       int
	Advertise  string
	RPCAddr    *net.TCPAddr
	SerfConfig *serf.Config
}

// Config is used to configure the server
type Config struct {
	// Bootstrap mode is used to bring up the first Consul server.
	// It is required so that it can elect a leader without any
	// other nodes being present
	Bootstrap bool

	// BootstrapExpect mode is used to automatically bring up a collection of
	// Consul servers. This can be used to automatically bring up a collection
	// of nodes.
	BootstrapExpect int

	// Datacenter is the datacenter this Consul server represents.
	Datacenter string

	// PrimaryDatacenter is the authoritative datacenter for features like ACLs
	// and Connect.
	PrimaryDatacenter string

	// DataDir is the directory to store our state in.
	DataDir string

	// DefaultQueryTime is the amount of time a blocking query will wait before
	// Consul will force a response. This value can be overridden by the 'wait'
	// query parameter.
	DefaultQueryTime time.Duration

	// MaxQueryTime is the maximum amount of time a blocking query can wait
	// before Consul will force a response. Consul applies jitter to the wait
	// time. The jittered time will be capped to MaxQueryTime.
	MaxQueryTime time.Duration

	// DevMode is used to enable a development server mode.
	DevMode bool

	// NodeID is a unique identifier for this node across space and time.
	NodeID types.NodeID

	// Node name is the name we use to advertise. Defaults to hostname.
	NodeName string

	// RaftConfig is the configuration used for Raft in the local DC
	RaftConfig *raft.Config

	// (Enterprise-only) ReadReplica is used to prevent this server from being added
	// as a voting member of the Raft cluster.
	ReadReplica bool

	// NotifyListen is called after the RPC listener has been configured.
	// RPCAdvertise will be set to the listener address if it hasn't been
	// configured at this point.
	NotifyListen func()

	// RPCAddr is the RPC address used by Consul. This should be reachable
	// by the WAN and LAN
	RPCAddr *net.TCPAddr

	// RPCAdvertise is the address that is advertised to other nodes for
	// the RPC endpoint. This can differ from the RPC address, if for example
	// the RPCAddr is unspecified "0.0.0.0:8300", but this address must be
	// reachable. If RPCAdvertise is nil then it will be set to the Listener
	// address after the listening socket is configured.
	RPCAdvertise *net.TCPAddr

	// RPCSrcAddr is the source address for outgoing RPC connections.
	RPCSrcAddr *net.TCPAddr

	// GRPCPort is the port the public gRPC server listens on.
	GRPCPort int

	// GRPCTLSPort is the port the public gRPC TLS server listens on.
	GRPCTLSPort int

	// (Enterprise-only) The network segment this agent is part of.
	Segment string

	// (Enterprise-only) Segments is a list of network segments for a server to
	// bind on.
	Segments []NetworkSegment

	// SerfLANConfig is the configuration for the intra-dc serf
	SerfLANConfig *serf.Config

	// SerfWANConfig is the configuration for the cross-dc serf
	SerfWANConfig *serf.Config

	// SerfFloodInterval controls how often we attempt to flood local Serf
	// Consul servers into the global areas (WAN and user-defined areas in
	// Consul Enterprise).
	SerfFloodInterval time.Duration

	// ReconcileInterval controls how often we reconcile the strongly
	// consistent store with the Serf info. This is used to handle nodes
	// that are force removed, as well as intermittent unavailability during
	// leader election.
	ReconcileInterval time.Duration

	// ProtocolVersion is the protocol version to speak. This must be between
	// ProtocolVersionMin and ProtocolVersionMax.
	ProtocolVersion uint8

	TLSConfig tlsutil.Config

	// RejoinAfterLeave controls our interaction with Serf.
	// When set to false (default), a leave causes a 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

	// AdvertiseReconnectTimeout is the duration after which this node should be
	// assumed to not be returning and thus should be reaped within Serf. This
	// can only be set for Client agents
	AdvertiseReconnectTimeout time.Duration

	// Build is a string that is gossiped around, and can be used to help
	// operators track which versions are actively deployed
	Build string

	ACLResolverSettings ACLResolverSettings

	// ACLEnabled is used to enable ACLs
	ACLsEnabled bool

	// ACLInitialManagementToken is used to bootstrap the ACL system. It should be specified
	// on the servers in the PrimaryDatacenter. When the leader comes online, it ensures
	// that the initial management token is available. This provides the initial token.
	ACLInitialManagementToken string

	// ACLTokenReplication is used to enabled token replication.
	//
	// By default policy-only replication is enabled. When token
	// replication is off and the primary datacenter is not
	// yet upgraded to the new ACLs no replication will be performed
	ACLTokenReplication bool

	// ACLReplicationRate is the max number of replication rounds that can
	// be run per second. Note that either 1 or 2 RPCs are used during each replication
	// round
	ACLReplicationRate int

	// ACLReplicationBurst is how many replication RPCs can be bursted after a
	// period of idleness
	ACLReplicationBurst int

	// ACLReplicationApplyLimit is the max number of replication-related
	// apply operations that we allow during a one second period. This is
	// used to limit the amount of Raft bandwidth used for replication.
	ACLReplicationApplyLimit int

	// ACLEnableKeyListPolicy is used to gate enforcement of the new "list" policy that
	// protects listing keys by prefix. This behavior is opt-in
	// by default in Consul 1.0 and later.
	ACLEnableKeyListPolicy bool

	AutoConfigEnabled              bool
	AutoConfigIntroToken           string
	AutoConfigIntroTokenFile       string
	AutoConfigServerAddresses      []string
	AutoConfigDNSSANs              []string
	AutoConfigIPSANs               []net.IP
	AutoConfigAuthzEnabled         bool
	AutoConfigAuthzAuthMethod      structs.ACLAuthMethod
	AutoConfigAuthzClaimAssertions []string
	AutoConfigAuthzAllowReuse      bool

	// TombstoneTTL is used to control how long KV tombstones are retained.
	// This provides a window of time where the X-Consul-Index is monotonic.
	// Outside this window, the index may not be monotonic. This is a result
	// of a few trade offs:
	// 1) The index is defined by the data view and not globally. This is a
	// performance optimization that prevents any write from incrementing the
	// index for all data views.
	// 2) Tombstones are not kept indefinitely, since otherwise storage required
	// is also monotonic. This prevents deletes from reducing the disk space
	// used.
	// In theory, neither of these are intrinsic limitations, however for the
	// purposes of building a practical system, they are reasonable trade offs.
	//
	// It is also possible to set this to an incredibly long time, thereby
	// simulating infinite retention. This is not recommended however.
	//
	TombstoneTTL time.Duration

	// TombstoneTTLGranularity is used to control how granular the timers are
	// for the Tombstone GC. This is used to batch the GC of many keys together
	// to reduce overhead. It is unlikely a user would ever need to tune this.
	TombstoneTTLGranularity time.Duration

	// Minimum Session TTL
	SessionTTLMin time.Duration

	// maxTokenExpirationDuration is the maximum difference allowed between
	// ACLToken CreateTime and ExpirationTime values if ExpirationTime is set
	// on a token.
	ACLTokenMaxExpirationTTL time.Duration

	// ACLTokenMinExpirationTTL is the minimum difference allowed between
	// ACLToken CreateTime and ExpirationTime values if ExpirationTime is set
	// on a token.
	ACLTokenMinExpirationTTL time.Duration

	// ServerUp callback can be used to trigger a notification that
	// a Consul server is now up and known about.
	ServerUp func()

	// UserEventHandler callback can be used to handle incoming
	// user events. This function should not block.
	UserEventHandler func(serf.UserEvent)

	// ConfigReplicationRate is the max number of replication rounds that can
	// be run per second. Note that either 1 or 2 RPCs are used during each replication
	// round
	ConfigReplicationRate int

	// ConfigReplicationBurst is how many replication rounds can be bursted after a
	// period of idleness
	ConfigReplicationBurst int

	// ConfigReplicationApply limit is the max number of replication-related
	// apply operations that we allow during a one second period. This is
	// used to limit the amount of Raft bandwidth used for replication.
	ConfigReplicationApplyLimit int

	// FederationStateReplicationRate is the max number of replication rounds that can
	// be run per second. Note that either 1 or 2 RPCs are used during each replication
	// round
	FederationStateReplicationRate int

	// FederationStateReplicationBurst is how many replication rounds can be bursted after a
	// period of idleness
	FederationStateReplicationBurst int

	// FederationStateReplicationApply limit is the max number of replication-related
	// apply operations that we allow during a one second period. This is
	// used to limit the amount of Raft bandwidth used for replication.
	FederationStateReplicationApplyLimit int

	// CoordinateUpdatePeriod controls how long a server batches coordinate
	// updates before applying them in a Raft transaction. A larger period
	// leads to fewer Raft transactions, but also the stored coordinates
	// being more stale.
	CoordinateUpdatePeriod time.Duration

	// CoordinateUpdateBatchSize controls the maximum number of updates a
	// server batches before applying them in a Raft transaction.
	CoordinateUpdateBatchSize int

	// CoordinateUpdateMaxBatches controls the maximum number of batches we
	// are willing to apply in one period. After this limit we will issue a
	// warning and discard the remaining updates.
	CoordinateUpdateMaxBatches int

	// CheckOutputMaxSize control the max size of output of checks
	CheckOutputMaxSize int

	// RequestLimitsMode will disable or enable rate limiting.  If not disabled, it
	// enforces the action that will occur when RequestLimitsReadRate
	// or RequestLimitsWriteRate is exceeded.  The default value of "disabled" will
	// prevent any rate limiting from occuring.  A value of "enforce" will block
	// the request from processings by returning an error.  A value of
	// "permissive" will not block the request and will allow the request to
	// continue processing.
	RequestLimitsMode string

	// RequestLimitsReadRate controls how frequently RPC, gRPC, and HTTP
	// queries are allowed to happen. In any large enough time interval, rate
	// limiter limits the rate to RequestLimitsReadRate tokens per second.
	RequestLimitsReadRate rate.Limit

	// RequestLimitsWriteRate controls how frequently RPC, gRPC, and HTTP
	// writes are allowed to happen. In any large enough time interval, rate
	// limiter limits the rate to RequestLimitsWriteRate tokens per second.
	RequestLimitsWriteRate rate.Limit

	// RPCHandshakeTimeout limits how long we will wait for the initial magic byte
	// on an RPC client connection. It also governs how long we will wait for a
	// TLS handshake when TLS is configured however the timout applies separately
	// for the initial magic byte and the TLS handshake and inner magic byte.
	RPCHandshakeTimeout time.Duration

	// RPCHoldTimeout is how long an RPC can be "held" before it is errored.
	// This is used to paper over a loss of leadership by instead holding RPCs,
	// so that the caller experiences a slow response rather than an error.
	// This period is meant to be long enough for a leader election to take
	// place, and a small jitter is applied to avoid a thundering herd.
	RPCHoldTimeout time.Duration

	// RPCClientTimeout limits how long a client is allowed to read from an RPC
	// connection. This is used to set an upper bound for non-blocking queries to
	// eventually terminate so that RPC connections are not held indefinitely.
	// Blocking queries will use MaxQueryTime and DefaultQueryTime to calculate
	// their own timeouts.
	RPCClientTimeout time.Duration

	// RPCRateLimit and RPCMaxBurst control how frequently RPC calls are allowed
	// to happen. In any large enough time interval, rate limiter limits the
	// rate to RPCRateLimit tokens per second, with a maximum burst size of
	// RPCMaxBurst events. As a special case, if RPCRateLimit == Inf (the infinite
	// rate), RPCMaxBurst is ignored.
	//
	// See https://en.wikipedia.org/wiki/Token_bucket for more about token
	// buckets.
	RPCRateLimit rate.Limit
	RPCMaxBurst  int

	// RPCMaxConnsPerClient is the limit of how many concurrent connections are
	// allowed from a single source IP.
	RPCMaxConnsPerClient int

	// LeaveDrainTime is used to wait after a server has left the LAN Serf
	// pool for RPCs to drain and new requests to be sent to other servers.
	LeaveDrainTime time.Duration

	// AutopilotConfig is used to apply the initial autopilot config when
	// bootstrapping.
	AutopilotConfig *structs.AutopilotConfig

	// ServerHealthInterval is the frequency with which the health of the
	// servers in the cluster will be updated.
	ServerHealthInterval time.Duration

	// AutopilotInterval is the frequency with which the leader will perform
	// autopilot tasks, such as promoting eligible non-voters and removing
	// dead servers.
	AutopilotInterval time.Duration

	// MetricsReportingInterval is the frequency with which the server will
	// report usage metrics to the configured go-metrics Sinks.
	MetricsReportingInterval time.Duration

	// ConnectEnabled is whether to enable Connect features such as the CA.
	ConnectEnabled bool

	// ConnectMeshGatewayWANFederationEnabled determines if wan federation of
	// datacenters should exclusively traverse mesh gateways.
	ConnectMeshGatewayWANFederationEnabled bool

	// DisableFederationStateAntiEntropy solely exists for use in unit tests to
	// disable a background routine.
	DisableFederationStateAntiEntropy bool

	// OverrideInitialSerfTags solely exists for use in unit tests to ensure
	// that a serf tag is initially set to a known value, rather than the
	// default to test some consul upgrade scenarios with fewer races.
	OverrideInitialSerfTags func(tags map[string]string)

	// CAConfig is used to apply the initial Connect CA configuration when
	// bootstrapping.
	CAConfig *structs.CAConfiguration

	// ConfigEntryBootstrap contains a list of ConfigEntries to ensure are created
	// If entries of the same Kind/Name exist already these will not update them.
	ConfigEntryBootstrap []structs.ConfigEntry

	// AutoEncryptAllowTLS is whether to enable the server responding to
	// AutoEncrypt.Sign requests.
	AutoEncryptAllowTLS bool

	RPCConfig RPCConfig

	LogStoreConfig RaftLogStoreConfig

	// PeeringEnabled enables cluster peering.
	PeeringEnabled bool

	PeeringTestAllowPeerRegistrations bool

	Locality *structs.Locality

	// Embedded Consul Enterprise specific configuration
	*EnterpriseConfig
}

func (c *Config) InPrimaryDatacenter() bool {
	return c.PrimaryDatacenter == "" || c.Datacenter == c.PrimaryDatacenter
}

// CheckProtocolVersion validates the protocol version.
func (c *Config) CheckProtocolVersion() error {
	if c.ProtocolVersion < ProtocolVersionMin {
		return fmt.Errorf("Protocol version '%d' too low. Must be in range: [%d, %d]", c.ProtocolVersion, ProtocolVersionMin, ProtocolVersionMax)
	}
	if c.ProtocolVersion > ProtocolVersionMax {
		return fmt.Errorf("Protocol version '%d' too high. Must be in range: [%d, %d]", c.ProtocolVersion, ProtocolVersionMin, ProtocolVersionMax)
	}
	return nil
}

// CheckACL validates the ACL configuration.
// TODO: move this to ACLResolverSettings
func (c *Config) CheckACL() error {
	switch c.ACLResolverSettings.ACLDefaultPolicy {
	case "allow":
	case "deny":
	default:
		return fmt.Errorf("Unsupported default ACL policy: %s", c.ACLResolverSettings.ACLDefaultPolicy)
	}
	switch c.ACLResolverSettings.ACLDownPolicy {
	case "allow":
	case "deny":
	case "async-cache", "extend-cache":
	default:
		return fmt.Errorf("Unsupported down ACL policy: %s", c.ACLResolverSettings.ACLDownPolicy)
	}
	return nil
}

// DefaultConfig returns a default configuration.
func DefaultConfig() *Config {
	hostname, err := os.Hostname()
	if err != nil {
		panic(err)
	}

	conf := &Config{
		Build:             version.Version,
		Datacenter:        DefaultDC,
		NodeName:          hostname,
		RPCAddr:           DefaultRPCAddr,
		RaftConfig:        raft.DefaultConfig(),
		SerfLANConfig:     libserf.DefaultConfig(),
		SerfWANConfig:     libserf.DefaultConfig(),
		SerfFloodInterval: 60 * time.Second,
		ReconcileInterval: 60 * time.Second,
		ProtocolVersion:   ProtocolVersion2Compatible,
		ACLResolverSettings: ACLResolverSettings{
			ACLsEnabled:      false,
			Datacenter:       DefaultDC,
			NodeName:         hostname,
			ACLPolicyTTL:     30 * time.Second,
			ACLTokenTTL:      30 * time.Second,
			ACLRoleTTL:       30 * time.Second,
			ACLDownPolicy:    "extend-cache",
			ACLDefaultPolicy: "allow",
		},
		ACLReplicationRate:                   1,
		ACLReplicationBurst:                  5,
		ACLReplicationApplyLimit:             100, // ops / sec
		ConfigReplicationRate:                1,
		ConfigReplicationBurst:               5,
		ConfigReplicationApplyLimit:          100, // ops / sec
		FederationStateReplicationRate:       1,
		FederationStateReplicationBurst:      5,
		FederationStateReplicationApplyLimit: 100, // ops / sec
		TombstoneTTL:                         15 * time.Minute,
		TombstoneTTLGranularity:              30 * time.Second,
		SessionTTLMin:                        10 * time.Second,
		ACLTokenMinExpirationTTL:             1 * time.Minute,
		ACLTokenMaxExpirationTTL:             24 * time.Hour,

		// These are tuned to provide a total throughput of 128 updates
		// per second. If you update these, you should update the client-
		// side SyncCoordinateRateTarget parameter accordingly.
		CoordinateUpdatePeriod:     5 * time.Second,
		CoordinateUpdateBatchSize:  128,
		CoordinateUpdateMaxBatches: 5,

		CheckOutputMaxSize: checks.DefaultBufSize,

		RequestLimitsMode:      "disabled",
		RequestLimitsReadRate:  rate.Inf, // ops / sec
		RequestLimitsWriteRate: rate.Inf, // ops / sec

		RPCRateLimit: rate.Inf,
		RPCMaxBurst:  1000,

		// TODO (slackpad) - Until #3744 is done, we need to keep these
		// in sync with agent/config/default.go.
		AutopilotConfig: &structs.AutopilotConfig{
			CleanupDeadServers:      true,
			LastContactThreshold:    200 * time.Millisecond,
			MaxTrailingLogs:         250,
			ServerStabilizationTime: 10 * time.Second,
		},

		CAConfig: &structs.CAConfiguration{
			Provider: "consul",
			Config: map[string]interface{}{
				"LeafCertTTL":         structs.DefaultLeafCertTTL,
				"IntermediateCertTTL": structs.DefaultIntermediateCertTTL,
				"RootCertTTL":         structs.DefaultRootCertTTL,
			},
		},

		// Stay under the 10 second aggregation interval of
		// go-metrics. This ensures we always report the
		// usage metrics in each cycle.
		MetricsReportingInterval: 9 * time.Second,
		ServerHealthInterval:     2 * time.Second,
		AutopilotInterval:        10 * time.Second,
		DefaultQueryTime:         300 * time.Second,
		MaxQueryTime:             600 * time.Second,

		PeeringTestAllowPeerRegistrations: false,

		EnterpriseConfig: DefaultEnterpriseConfig(),
	}

	// Increase our reap interval to 3 days instead of 24h.
	conf.SerfLANConfig.ReconnectTimeout = 3 * 24 * time.Hour
	conf.SerfWANConfig.ReconnectTimeout = 3 * 24 * time.Hour

	// WAN Serf should use the WAN timing, since we are using it
	// to communicate between DC's
	conf.SerfWANConfig.MemberlistConfig = memberlist.DefaultWANConfig()

	// Ensure we don't have port conflicts
	conf.SerfLANConfig.MemberlistConfig.BindPort = DefaultLANSerfPort
	conf.SerfWANConfig.MemberlistConfig.BindPort = DefaultWANSerfPort

	// Allow dead nodes to be replaced after 30 seconds.
	conf.SerfLANConfig.MemberlistConfig.DeadNodeReclaimTime = 30 * time.Second
	conf.SerfWANConfig.MemberlistConfig.DeadNodeReclaimTime = 30 * time.Second

	// Raft protocol version 3 only works with other Consul servers running
	// 0.8.0 or later.
	conf.RaftConfig.ProtocolVersion = 3

	// Disable shutdown on removal
	conf.RaftConfig.ShutdownOnRemove = false

	// Check every 5 seconds to see if there are enough new entries for a snapshot, can be overridden
	conf.RaftConfig.SnapshotInterval = 30 * time.Second

	// Snapshots are created every 16384 entries by default, can be overridden
	conf.RaftConfig.SnapshotThreshold = 16384

	return conf
}

// CloneSerfLANConfig clones an existing serf.Config used on the LAN by
// reconstructing it from defaults and re-applying changes made in the agent
// configs.
//
// This function is tricky to keep from rotting so we enforce that it MUST work
// by cloning our own serf LAN configuration on startup and only using the
// cloned one so any configs we need to change have to be changed here for them
// to work at all.
func CloneSerfLANConfig(base *serf.Config) *serf.Config {
	cfg := DefaultConfig().SerfLANConfig

	// from consul.DefaultConfig()
	cfg.ReconnectTimeout = base.ReconnectTimeout
	cfg.MemberlistConfig.BindPort = base.MemberlistConfig.BindPort
	cfg.MemberlistConfig.DeadNodeReclaimTime = base.MemberlistConfig.DeadNodeReclaimTime

	// from agent.newConsulConfig()
	cfg.MemberlistConfig.BindAddr = base.MemberlistConfig.BindAddr
	cfg.MemberlistConfig.BindPort = base.MemberlistConfig.BindPort
	cfg.MemberlistConfig.CIDRsAllowed = base.MemberlistConfig.CIDRsAllowed
	cfg.MemberlistConfig.AdvertiseAddr = base.MemberlistConfig.AdvertiseAddr
	cfg.MemberlistConfig.AdvertisePort = base.MemberlistConfig.AdvertisePort
	cfg.MemberlistConfig.GossipVerifyIncoming = base.MemberlistConfig.GossipVerifyIncoming
	cfg.MemberlistConfig.GossipVerifyOutgoing = base.MemberlistConfig.GossipVerifyOutgoing
	cfg.MemberlistConfig.GossipInterval = base.MemberlistConfig.GossipInterval
	cfg.MemberlistConfig.GossipNodes = base.MemberlistConfig.GossipNodes
	cfg.MemberlistConfig.ProbeInterval = base.MemberlistConfig.ProbeInterval
	cfg.MemberlistConfig.ProbeTimeout = base.MemberlistConfig.ProbeTimeout
	cfg.MemberlistConfig.SuspicionMult = base.MemberlistConfig.SuspicionMult
	cfg.MemberlistConfig.RetransmitMult = base.MemberlistConfig.RetransmitMult
	cfg.MemberlistConfig.MetricLabels = base.MemberlistConfig.MetricLabels

	// agent/keyring.go
	cfg.MemberlistConfig.Keyring = base.MemberlistConfig.Keyring

	// tests
	cfg.KeyringFile = base.KeyringFile
	cfg.ReapInterval = base.ReapInterval
	cfg.TombstoneTimeout = base.TombstoneTimeout
	cfg.MemberlistConfig.SecretKey = base.MemberlistConfig.SecretKey
	cfg.MetricLabels = base.MetricLabels

	return cfg
}

// RPCConfig settings for the RPC server
//
// TODO: move many settings to this struct.
type RPCConfig struct {
	EnableStreaming bool
}

// RequestLimits is configuration for serverrate limiting that is a part of
// ReloadableConfig.
type RequestLimits struct {
	Mode      consulrate.Mode
	ReadRate  rate.Limit
	WriteRate rate.Limit
}

// ReloadableConfig is the configuration that is passed to ReloadConfig when
// application config is reloaded.
type ReloadableConfig struct {
	RequestLimits         *RequestLimits
	RPCClientTimeout      time.Duration
	RPCRateLimit          rate.Limit
	RPCMaxBurst           int
	RPCMaxConnsPerClient  int
	ConfigEntryBootstrap  []structs.ConfigEntry
	RaftSnapshotThreshold int
	RaftSnapshotInterval  time.Duration
	RaftTrailingLogs      int
	HeartbeatTimeout      time.Duration
	ElectionTimeout       time.Duration
}

type RaftLogStoreConfig struct {
	Backend         string
	DisableLogCache bool
	Verification    RaftLogStoreVerificationConfig
	BoltDB          RaftBoltDBConfig
	WAL             WALConfig
}

type RaftLogStoreVerificationConfig struct {
	Enabled  bool
	Interval time.Duration
}

type RaftBoltDBConfig struct {
	NoFreelistSync bool
}

type WALConfig struct {
	SegmentSize int
}