package nomad import ( "context" "fmt" "strings" "text/template" "time" "github.com/cenkalti/backoff/v4" "github.com/hashicorp/nomad/api" ptypes "github.com/traefik/paerser/types" "github.com/traefik/traefik/v2/pkg/config/dynamic" "github.com/traefik/traefik/v2/pkg/job" "github.com/traefik/traefik/v2/pkg/log" "github.com/traefik/traefik/v2/pkg/provider" "github.com/traefik/traefik/v2/pkg/provider/constraints" "github.com/traefik/traefik/v2/pkg/safe" "github.com/traefik/traefik/v2/pkg/types" ) const ( // providerName is the name of this provider. providerName = "nomad" // defaultTemplateRule is the default template for the default rule. defaultTemplateRule = "Host(`{{ normalize .Name }}`)" // defaultPrefix is the default prefix used in tag values indicating the service // should be consumed and exposed via traefik. defaultPrefix = "traefik" ) var _ provider.Provider = (*Provider)(nil) type item struct { ID string // service ID Name string // service name Namespace string // service namespace Node string // node ID Datacenter string // region Address string // service address Port int // service port Tags []string // service tags ExtraConf configuration // global options } // Provider holds configurations of the provider. type Provider struct { DefaultRule string `description:"Default rule." json:"defaultRule,omitempty" toml:"defaultRule,omitempty" yaml:"defaultRule,omitempty"` Constraints string `description:"Constraints is an expression that Traefik matches against the Nomad service's tags to determine whether to create route(s) for that service." json:"constraints,omitempty" toml:"constraints,omitempty" yaml:"constraints,omitempty" export:"true"` Endpoint *EndpointConfig `description:"Nomad endpoint settings" json:"endpoint,omitempty" toml:"endpoint,omitempty" yaml:"endpoint,omitempty" export:"true"` Prefix string `description:"Prefix for nomad service tags." json:"prefix,omitempty" toml:"prefix,omitempty" yaml:"prefix,omitempty" export:"true"` Stale bool `description:"Use stale consistency for catalog reads." json:"stale,omitempty" toml:"stale,omitempty" yaml:"stale,omitempty" export:"true"` Namespace string `description:"Sets the Nomad namespace used to discover services." json:"namespace,omitempty" toml:"namespace,omitempty" yaml:"namespace,omitempty" export:"true"` ExposedByDefault bool `description:"Expose Nomad services by default." json:"exposedByDefault,omitempty" toml:"exposedByDefault,omitempty" yaml:"exposedByDefault,omitempty" export:"true"` RefreshInterval ptypes.Duration `description:"Interval for polling Nomad API." json:"refreshInterval,omitempty" toml:"refreshInterval,omitempty" yaml:"refreshInterval,omitempty" export:"true"` client *api.Client // client for Nomad API defaultRuleTpl *template.Template // default routing rule } type EndpointConfig struct { // Address is the Nomad endpoint address, if empty it defaults to NOMAD_ADDR or "http://localhost:4646". Address string `description:"The address of the Nomad server, including scheme and port." json:"address,omitempty" toml:"address,omitempty" yaml:"address,omitempty"` // Region is the Nomad region, if empty it defaults to NOMAD_REGION or "global". Region string `description:"Nomad region to use. If not provided, the local agent region is used." json:"region,omitempty" toml:"region,omitempty" yaml:"region,omitempty"` // Token is the ACL token to connect with Nomad, if empty it defaults to NOMAD_TOKEN. Token string `description:"Token is used to provide a per-request ACL token." json:"token,omitempty" toml:"token,omitempty" yaml:"token,omitempty" loggable:"false"` TLS *types.ClientTLS `description:"Configure TLS." json:"tls,omitempty" toml:"tls,omitempty" yaml:"tls,omitempty" export:"true"` EndpointWaitTime ptypes.Duration `description:"WaitTime limits how long a Watch will block. If not provided, the agent default values will be used" json:"endpointWaitTime,omitempty" toml:"endpointWaitTime,omitempty" yaml:"endpointWaitTime,omitempty" export:"true"` } // SetDefaults sets the default values for the Nomad Traefik Provider. func (p *Provider) SetDefaults() { p.Endpoint = &EndpointConfig{} p.Prefix = defaultPrefix p.ExposedByDefault = true p.RefreshInterval = ptypes.Duration(15 * time.Second) p.DefaultRule = defaultTemplateRule } // Init the Nomad Traefik Provider. func (p *Provider) Init() error { defaultRuleTpl, err := provider.MakeDefaultRuleTemplate(p.DefaultRule, nil) if err != nil { return fmt.Errorf("error while parsing default rule: %w", err) } p.defaultRuleTpl = defaultRuleTpl return nil } // Provide allows the Nomad Traefik Provider to provide configurations to traefik // using the given configuration channel. func (p *Provider) Provide(configurationChan chan<- dynamic.Message, pool *safe.Pool) error { var err error p.client, err = createClient(p.Namespace, p.Endpoint) if err != nil { return fmt.Errorf("failed to create nomad API client: %w", err) } pool.GoCtx(func(routineCtx context.Context) { ctxLog := log.With(routineCtx, log.Str(log.ProviderName, providerName)) logger := log.FromContext(ctxLog) operation := func() error { ctx, cancel := context.WithCancel(ctxLog) defer cancel() // load initial configuration if err := p.loadConfiguration(ctx, configurationChan); err != nil { return fmt.Errorf("failed to load initial nomad services: %w", err) } // issue periodic refreshes in the background // (Nomad does not support Watch style observations) ticker := time.NewTicker(time.Duration(p.RefreshInterval)) defer ticker.Stop() // enter loop where we wait for and respond to notifications for { select { case <-ctx.Done(): return nil case <-ticker.C: } // load services due to refresh if err := p.loadConfiguration(ctx, configurationChan); err != nil { return fmt.Errorf("failed to refresh nomad services: %w", err) } } } failure := func(err error, d time.Duration) { logger.Errorf("Provider connection error %+v, retrying in %s", err, d) } if retryErr := backoff.RetryNotify( safe.OperationWithRecover(operation), backoff.WithContext(job.NewBackOff(backoff.NewExponentialBackOff()), ctxLog), failure, ); retryErr != nil { logger.Errorf("Cannot connect to Nomad server %+v", retryErr) } }) return nil } func (p *Provider) loadConfiguration(ctx context.Context, configurationC chan<- dynamic.Message) error { items, err := p.getNomadServiceData(ctx) if err != nil { return err } configurationC <- dynamic.Message{ ProviderName: providerName, Configuration: p.buildConfig(ctx, items), } return nil } func createClient(namespace string, endpoint *EndpointConfig) (*api.Client, error) { config := api.Config{ Address: endpoint.Address, Region: endpoint.Region, WaitTime: time.Duration(endpoint.EndpointWaitTime), Namespace: namespace, } if endpoint.TLS != nil { config.TLSConfig = &api.TLSConfig{ CACert: endpoint.TLS.CA, ClientCert: endpoint.TLS.Cert, ClientKey: endpoint.TLS.Key, Insecure: endpoint.TLS.InsecureSkipVerify, } } return api.NewClient(&config) } // configuration contains information from the service's tags that are globals // (not specific to the dynamic configuration). type configuration struct { Enable bool // .enable } // globalConfig returns a configuration with settings not specific to the dynamic configuration (i.e. ".enable"). func (p *Provider) globalConfig(tags []string) configuration { enabled := p.ExposedByDefault labels := tagsToLabels(tags, p.Prefix) if v, exists := labels["traefik.enable"]; exists { enabled = strings.EqualFold(v, "true") } return configuration{Enable: enabled} } func (p *Provider) getNomadServiceData(ctx context.Context) ([]item, error) { // first, get list of service stubs opts := &api.QueryOptions{AllowStale: p.Stale} opts = opts.WithContext(ctx) stubs, _, err := p.client.Services().List(opts) if err != nil { return nil, err } var items []item for _, stub := range stubs { for _, service := range stub.Services { logger := log.FromContext(log.With(ctx, log.Str("serviceName", service.ServiceName))) globalCfg := p.globalConfig(service.Tags) if !globalCfg.Enable { logger.Debug("Filter Nomad service that is not enabled") continue } matches, err := constraints.MatchTags(service.Tags, p.Constraints) if err != nil { logger.Errorf("Error matching constraint expressions: %v", err) continue } if !matches { logger.Debugf("Filter Nomad service not matching constraints: %q", p.Constraints) continue } instances, err := p.fetchService(ctx, service.ServiceName) if err != nil { return nil, err } for _, i := range instances { items = append(items, item{ ID: i.ID, Name: i.ServiceName, Namespace: i.Namespace, Node: i.NodeID, Datacenter: i.Datacenter, Address: i.Address, Port: i.Port, Tags: i.Tags, ExtraConf: p.globalConfig(i.Tags), }) } } } return items, nil } // fetchService queries Nomad API for services matching name, // that also have the .enable=true set in its tags. func (p *Provider) fetchService(ctx context.Context, name string) ([]*api.ServiceRegistration, error) { var tagFilter string if !p.ExposedByDefault { tagFilter = fmt.Sprintf(`Tags contains %q`, fmt.Sprintf("%s.enable=true", p.Prefix)) } // TODO: Nomad currently (v1.3.0) does not support health checks, // and as such does not yet return health status information. // When it does, refactor this section to include health status. opts := &api.QueryOptions{AllowStale: p.Stale, Filter: tagFilter} opts = opts.WithContext(ctx) services, _, err := p.client.Services().Get(name, opts) if err != nil { return nil, fmt.Errorf("failed to fetch services: %w", err) } return services, nil }