0e44094d1a
Consul provides a feature of Service Definitions where the tags associated with a service can be modified through the Catalog API, overriding the value(s) configured in the agent's service configuration. To enable this feature, the flag enable_tag_override must be configured in the service definition. Previously, Nomad did not allow configuring this flag, and thus the default value of false was used. Now, it is configurable. Because Nomad itself acts as a state machine around the the service definitions of the tasks it manages, it's worth describing what happens when this feature is enabled and why. Consider the basic case where there is no Nomad, and your service is provided to consul as a boring JSON file. The ultimate source of truth for the definition of that service is the file, and is stored in the agent. Later, Consul performs "anti-entropy" which synchronizes the Catalog (stored only the leaders). Then with enable_tag_override=true, the tags field is available for "external" modification through the Catalog API (rather than directly configuring the service definition file, or using the Agent API). The important observation is that if the service definition ever changes (i.e. the file is changed & config reloaded OR the Agent API is used to modify the service), those "external" tag values are thrown away, and the new service definition is once again the source of truth. In the Nomad case, Nomad itself is the source of truth over the Agent in the same way the JSON file was the source of truth in the example above. That means any time Nomad sets a new service definition, any externally configured tags are going to be replaced. When does this happen? Only on major lifecycle events, for example when a task is modified because of an updated job spec from the 'nomad job run <existing>' command. Otherwise, Nomad's periodic re-sync's with Consul will now no longer try to restore the externally modified tag values (as long as enable_tag_override=true). Fixes #2057
182 lines
4.9 KiB
Go
182 lines
4.9 KiB
Go
package api
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import (
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"fmt"
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"time"
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)
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// CheckRestart describes if and when a task should be restarted based on
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// failing health checks.
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type CheckRestart struct {
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Limit int `mapstructure:"limit"`
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Grace *time.Duration `mapstructure:"grace"`
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IgnoreWarnings bool `mapstructure:"ignore_warnings"`
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}
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// Canonicalize CheckRestart fields if not nil.
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func (c *CheckRestart) Canonicalize() {
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if c == nil {
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return
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}
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if c.Grace == nil {
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c.Grace = timeToPtr(1 * time.Second)
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}
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}
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// Copy returns a copy of CheckRestart or nil if unset.
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func (c *CheckRestart) Copy() *CheckRestart {
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if c == nil {
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return nil
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}
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nc := new(CheckRestart)
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nc.Limit = c.Limit
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if c.Grace != nil {
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g := *c.Grace
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nc.Grace = &g
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}
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nc.IgnoreWarnings = c.IgnoreWarnings
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return nc
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}
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// Merge values from other CheckRestart over default values on this
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// CheckRestart and return merged copy.
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func (c *CheckRestart) Merge(o *CheckRestart) *CheckRestart {
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if c == nil {
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// Just return other
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return o
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}
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nc := c.Copy()
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if o == nil {
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// Nothing to merge
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return nc
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}
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if o.Limit > 0 {
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nc.Limit = o.Limit
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}
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if o.Grace != nil {
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nc.Grace = o.Grace
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}
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if o.IgnoreWarnings {
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nc.IgnoreWarnings = o.IgnoreWarnings
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}
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return nc
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}
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// ServiceCheck represents the consul health check that Nomad registers.
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type ServiceCheck struct {
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//FIXME Id is unused. Remove?
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Id string
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Name string
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Type string
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Command string
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Args []string
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Path string
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Protocol string
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PortLabel string `mapstructure:"port"`
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AddressMode string `mapstructure:"address_mode"`
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Interval time.Duration
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Timeout time.Duration
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InitialStatus string `mapstructure:"initial_status"`
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TLSSkipVerify bool `mapstructure:"tls_skip_verify"`
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Header map[string][]string
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Method string
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CheckRestart *CheckRestart `mapstructure:"check_restart"`
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GRPCService string `mapstructure:"grpc_service"`
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GRPCUseTLS bool `mapstructure:"grpc_use_tls"`
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TaskName string `mapstructure:"task"`
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}
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// Service represents a Consul service definition.
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type Service struct {
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//FIXME Id is unused. Remove?
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Id string
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Name string
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Tags []string
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CanaryTags []string `mapstructure:"canary_tags"`
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EnableTagOverride bool `mapstructure:"enable_tag_override"`
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PortLabel string `mapstructure:"port"`
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AddressMode string `mapstructure:"address_mode"`
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Checks []ServiceCheck
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CheckRestart *CheckRestart `mapstructure:"check_restart"`
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Connect *ConsulConnect
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Meta map[string]string
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CanaryMeta map[string]string
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}
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// Canonicalize the Service by ensuring its name and address mode are set. Task
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// will be nil for group services.
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func (s *Service) Canonicalize(t *Task, tg *TaskGroup, job *Job) {
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if s.Name == "" {
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if t != nil {
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s.Name = fmt.Sprintf("%s-%s-%s", *job.Name, *tg.Name, t.Name)
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} else {
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s.Name = fmt.Sprintf("%s-%s", *job.Name, *tg.Name)
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}
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}
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// Default to AddressModeAuto
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if s.AddressMode == "" {
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s.AddressMode = "auto"
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}
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// Canonicalize CheckRestart on Checks and merge Service.CheckRestart
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// into each check.
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for i, check := range s.Checks {
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s.Checks[i].CheckRestart = s.CheckRestart.Merge(check.CheckRestart)
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s.Checks[i].CheckRestart.Canonicalize()
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}
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}
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// ConsulConnect represents a Consul Connect jobspec stanza.
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type ConsulConnect struct {
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Native bool
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SidecarService *ConsulSidecarService `mapstructure:"sidecar_service"`
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SidecarTask *SidecarTask `mapstructure:"sidecar_task"`
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}
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// ConsulSidecarService represents a Consul Connect SidecarService jobspec
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// stanza.
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type ConsulSidecarService struct {
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Tags []string
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Port string
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Proxy *ConsulProxy
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}
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// SidecarTask represents a subset of Task fields that can be set to override
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// the fields of the Task generated for the sidecar
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type SidecarTask struct {
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Name string
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Driver string
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User string
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Config map[string]interface{}
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Env map[string]string
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Resources *Resources
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Meta map[string]string
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KillTimeout *time.Duration `mapstructure:"kill_timeout"`
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LogConfig *LogConfig `mapstructure:"logs"`
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ShutdownDelay *time.Duration `mapstructure:"shutdown_delay"`
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KillSignal string `mapstructure:"kill_signal"`
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}
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// ConsulProxy represents a Consul Connect sidecar proxy jobspec stanza.
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type ConsulProxy struct {
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LocalServiceAddress string `mapstructure:"local_service_address"`
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LocalServicePort int `mapstructure:"local_service_port"`
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Upstreams []*ConsulUpstream
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Config map[string]interface{}
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}
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// ConsulUpstream represents a Consul Connect upstream jobspec stanza.
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type ConsulUpstream struct {
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DestinationName string `mapstructure:"destination_name"`
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LocalBindPort int `mapstructure:"local_bind_port"`
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}
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