traefik/pkg/provider/nomad/nomad.go

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package nomad
import (
"context"
"errors"
"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
}
// ProviderBuilder is responsible for constructing namespaced instances of the Nomad provider.
type ProviderBuilder struct {
Configuration `yaml:",inline" export:"true"`
// Deprecated: Use Namespaces option instead
Namespace string `description:"Sets the Nomad namespace used to discover services." json:"namespace,omitempty" toml:"namespace,omitempty" yaml:"namespace,omitempty"`
Namespaces []string `description:"Sets the Nomad namespaces used to discover services." json:"namespaces,omitempty" toml:"namespaces,omitempty" yaml:"namespaces,omitempty"`
}
// BuildProviders builds Nomad provider instances for the given namespaces configuration.
func (p *ProviderBuilder) BuildProviders() []*Provider {
if p.Namespace != "" {
log.WithoutContext().Warnf("Namespace option is deprecated, please use the Namespaces option instead.")
}
if len(p.Namespaces) == 0 {
return []*Provider{{
Configuration: p.Configuration,
name: providerName,
// p.Namespace could be empty
namespace: p.Namespace,
}}
}
var providers []*Provider
for _, namespace := range p.Namespaces {
providers = append(providers, &Provider{
Configuration: p.Configuration,
name: providerName + "-" + namespace,
namespace: namespace,
})
}
return providers
}
// Configuration represents the Nomad provider configuration.
type Configuration 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"`
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"`
}
// SetDefaults sets the default values for the Nomad Traefik Provider Configuration.
func (c *Configuration) SetDefaults() {
defConfig := api.DefaultConfig()
c.Endpoint = &EndpointConfig{
Address: defConfig.Address,
Region: defConfig.Region,
Token: defConfig.SecretID,
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}
if defConfig.TLSConfig != nil && (defConfig.TLSConfig.Insecure || defConfig.TLSConfig.CACert != "" || defConfig.TLSConfig.ClientCert != "" || defConfig.TLSConfig.ClientKey != "") {
c.Endpoint.TLS = &types.ClientTLS{
CA: defConfig.TLSConfig.CACert,
Cert: defConfig.TLSConfig.ClientCert,
Key: defConfig.TLSConfig.ClientKey,
InsecureSkipVerify: defConfig.TLSConfig.Insecure,
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}
}
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c.Prefix = defaultPrefix
c.ExposedByDefault = true
c.RefreshInterval = ptypes.Duration(15 * time.Second)
c.DefaultRule = defaultTemplateRule
}
// Provider holds configuration along with the namespace it will discover services in.
type Provider struct {
Configuration
name string
namespace string
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://127.0.0.1:4646".
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.
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.Configuration.SetDefaults()
}
// Init the Nomad Traefik Provider.
func (p *Provider) Init() error {
if p.namespace == api.AllNamespacesNamespace {
return errors.New("wildcard namespace not supported")
}
defaultRuleTpl, err := provider.MakeDefaultRuleTemplate(p.DefaultRule, nil)
if err != nil {
return fmt.Errorf("error while parsing default rule: %w", err)
}
p.defaultRuleTpl = defaultRuleTpl
// In case they didn't initialize Provider with BuildProviders
if p.name == "" {
p.name = providerName
}
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, p.name))
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: p.name,
Configuration: p.buildConfig(ctx, items),
}
return nil
}
func createClient(namespace string, endpoint *EndpointConfig) (*api.Client, error) {
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config := api.Config{
Address: endpoint.Address,
Namespace: namespace,
Region: endpoint.Region,
SecretID: endpoint.Token,
WaitTime: time.Duration(endpoint.EndpointWaitTime),
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}
if endpoint.TLS != nil {
config.TLSConfig = &api.TLSConfig{
CACert: endpoint.TLS.CA,
ClientCert: endpoint.TLS.Cert,
ClientKey: endpoint.TLS.Key,
Insecure: endpoint.TLS.InsecureSkipVerify,
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}
}
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 // <prefix>.enable is the corresponding label.
Canary bool // <prefix>.nomad.canary is the corresponding label.
}
// getExtraConf returns a configuration with settings which are not part of the dynamic configuration (e.g. "<prefix>.enable").
func (p *Provider) getExtraConf(tags []string) configuration {
labels := tagsToLabels(tags, p.Prefix)
enabled := p.ExposedByDefault
if v, exists := labels["traefik.enable"]; exists {
enabled = strings.EqualFold(v, "true")
}
var canary bool
if v, exists := labels["traefik.nomad.canary"]; exists {
canary = strings.EqualFold(v, "true")
}
return configuration{Enable: enabled, Canary: canary}
}
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)))
extraConf := p.getExtraConf(service.Tags)
if !extraConf.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.getExtraConf(i.Tags),
})
}
}
}
return items, nil
}
// fetchService queries Nomad API for services matching name,
// that also have the <prefix>.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
}