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Traefik & Consul Catalog

A Story of Tags, Services & Instances

Consul Catalog

Attach tags to your services and let Traefik do the rest!

Configuration Examples

Configuring Consul Catalog & Deploying / Exposing Services

Enabling the consul catalog provider

[providers.consulCatalog]
providers:
  consulCatalog: {}
--providers.consulcatalog=true

Attaching tags to services

- traefik.http.routers.my-router.rule=Host(`example.com`)

Routing Configuration

See the dedicated section in routing.

Provider Configuration

refreshInterval

Optional, Default=15s

Defines the polling interval.

[providers.consulCatalog]
  refreshInterval = "30s"
  # ...
providers:
  consulCatalog:
    refreshInterval: 30s
    # ...
--providers.consulcatalog.refreshInterval=30s
# ...

prefix

required, Default="traefik"

The prefix for Consul Catalog tags defining Traefik labels.

[providers.consulCatalog]
  prefix = "test"
  # ...
providers:
  consulCatalog:
    prefix: test
    # ...
--providers.consulcatalog.prefix=test
# ...

requireConsistent

Optional, Default=false

Forces the read to be fully consistent.

It is more expensive due to an extra round-trip but prevents ever performing a stale read.

For more information, see the consul documentation on consistency.

[providers.consulCatalog]
  requireConsistent = true
  # ...
providers:
  consulCatalog:
    requireConsistent: true
    # ...
--providers.consulcatalog.requireConsistent=true
# ...

stale

Optional, Default=false

Use stale consistency for catalog reads.

This makes reads very fast and scalable at the cost of a higher likelihood of stale values.

For more information, see the consul documentation on consistency.

[providers.consulCatalog]
  stale = true
  # ...
providers:
  consulCatalog:
    stale: true
    # ...
--providers.consulcatalog.stale=true
# ...

cache

Optional, Default=false

Use local agent caching for catalog reads.

[providers.consulCatalog]
  cache = true
  # ...
providers:
  consulCatalog:
    cache: true
    # ...
--providers.consulcatalog.cache=true
# ...

endpoint

Defines the Consul server endpoint.

address

Defines the address of the Consul server.

Optional, Default="127.0.0.1:8500"

[providers.consulCatalog]
  [providers.consulCatalog.endpoint]
    address = "127.0.0.1:8500"
    # ...
providers:
  consulCatalog:
    endpoint:
      address: 127.0.0.1:8500
    # ...
--providers.consulcatalog.endpoint.address=127.0.0.1:8500
# ...

scheme

Optional, Default=""

Defines the URI scheme for the Consul server.

[providers.consulCatalog]
  [providers.consulCatalog.endpoint]
    scheme = "https"
    # ...
providers:
  consulCatalog:
    endpoint:
      scheme: https
    # ...
--providers.consulcatalog.endpoint.scheme=https
# ...

datacenter

Optional, Default=""

Defines the datacenter to use. If not provided in Traefik, Consul uses the default agent datacenter.

[providers.consulCatalog]
  [providers.consulCatalog.endpoint]
    datacenter = "test"
    # ...
providers:
  consulCatalog:
    endpoint:
      datacenter: test
    # ...
--providers.consulcatalog.endpoint.datacenter=test
# ...

token

Optional, Default=""

Token is used to provide a per-request ACL token which overwrites the agent's default token.

[providers.consulCatalog]
  [providers.consulCatalog.endpoint]
    token = "test"
    # ...
providers:
  consulCatalog:
    endpoint:
      token: test
    # ...
--providers.consulcatalog.endpoint.token=test
# ...

endpointWaitTime

Optional, Default=""

Limits the duration for which a Watch can block. If not provided, the agent default values will be used.

[providers.consulCatalog]
  [providers.consulCatalog.endpoint]
    endpointWaitTime = "15s"
    # ...
providers:
  consulCatalog:
    endpoint:
      endpointWaitTime: 15s
    # ...
--providers.consulcatalog.endpoint.endpointwaittime=15s
# ...

httpAuth

Optional

Used to authenticate the HTTP client using HTTP Basic Authentication.

username

Optional, Default=""

Username to use for HTTP Basic Authentication.

[providers.consulCatalog.endpoint.httpAuth]
  username = "test"
providers:
  consulCatalog:
    endpoint:
      httpAuth:
        username: test
--providers.consulcatalog.endpoint.httpauth.username=test
password

Optional, Default=""

Password to use for HTTP Basic Authentication.

[providers.consulCatalog.endpoint.httpAuth]
  password = "test"
providers:
  consulCatalog:
    endpoint:
      httpAuth:
        password: test
--providers.consulcatalog.endpoint.httpauth.password=test

tls

Optional

Defines TLS options for Consul server endpoint.

ca

Optional

ca is the path to the CA certificate used for Consul communication, defaults to the system bundle if not specified.

[providers.consulCatalog.endpoint.tls]
  ca = "path/to/ca.crt"
providers:
  consulCatalog:
    endpoint:
      tls:
        ca: path/to/ca.crt
--providers.consulcatalog.endpoint.tls.ca=path/to/ca.crt
caOptional

Optional

The value of tls.caOptional defines which policy should be used for the secure connection with TLS Client Authentication to Consul.

If tls.ca is undefined, this option will be ignored, and no client certificate will be requested during the handshake. Any provided certificate will thus never be verified.

When this option is set to true, a client certificate is requested during the handshake but is not required. If a certificate is sent, it is required to be valid.

When this option is set to false, a client certificate is requested during the handshake, and at least one valid certificate should be sent by the client.

[providers.consulCatalog.endpoint.tls]
  caOptional = true
providers:
  consulCatalog:
    endpoint:
      tls:
        caOptional: true
--providers.consulcatalog.endpoint.tls.caoptional=true
cert

Optional

cert is the path to the public certificate to use for Consul communication.

When using this option, setting the key option is required.

[providers.consulCatalog.endpoint.tls]
  cert = "path/to/foo.cert"
  key = "path/to/foo.key"
providers:
  consulCatalog:
    endpoint:
      tls:
        cert: path/to/foo.cert
        key: path/to/foo.key
--providers.consulcatalog.endpoint.tls.cert=path/to/foo.cert
--providers.consulcatalog.endpoint.tls.key=path/to/foo.key
key

Optional

key is the path to the private key for Consul communication.

When using this option, setting the cert option is required.

[providers.consulCatalog.endpoint.tls]
  cert = "path/to/foo.cert"
  key = "path/to/foo.key"
providers:
  consulCatalog:
    endpoint:
      tls:
        cert: path/to/foo.cert
        key: path/to/foo.key
--providers.consulcatalog.endpoint.tls.cert=path/to/foo.cert
--providers.consulcatalog.endpoint.tls.key=path/to/foo.key
insecureSkipVerify

Optional

If insecureSkipVerify is true, the TLS connection to Consul accepts any certificate presented by the server regardless of the hostnames it covers.

[providers.consulCatalog.endpoint.tls]
  insecureSkipVerify = true
providers:
  consulCatalog:
    endpoint:
      tls:
        insecureSkipVerify: true
--providers.consulcatalog.endpoint.tls.insecureskipverify=true

exposedByDefault

Optional, Default=true

Expose Consul Catalog services by default in Traefik. If set to false, services that don't have a traefik.enable=true tag will be ignored from the resulting routing configuration.

For additional information, refer to Restrict the Scope of Service Discovery.

[providers.consulCatalog]
  exposedByDefault = false
  # ...
providers:
  consulCatalog:
    exposedByDefault: false
    # ...
--providers.consulcatalog.exposedByDefault=false
# ...

defaultRule

Optional, Default=Host(`{{ normalize .Name }}`)

The default host rule for all services.

For a given service, if no routing rule was defined by a tag, it is defined by this defaultRule instead. The defaultRule must be set to a valid Go template, and can include sprig template functions. The service name can be accessed with the Name identifier, and the template has access to all the labels (i.e. tags beginning with the prefix) defined on this service.

The option can be overridden on an instance basis with the traefik.http.routers.{name-of-your-choice}.rule tag.

[providers.consulCatalog]
  defaultRule = "Host(`{{ .Name }}.{{ index .Labels \"customLabel\"}}`)"
  # ...
providers:
  consulCatalog:
    defaultRule: "Host(`{{ .Name }}.{{ index .Labels \"customLabel\"}}`)"
    # ...
--providers.consulcatalog.defaultRule="Host(`{{ .Name }}.{{ index .Labels \"customLabel\"}}`)"
# ...

constraints

Optional, Default=""

The constraints option can be set to an expression that Traefik matches against the service tags to determine whether to create any route for that service. If none of the service tags match the expression, no route for that service is created. If the expression is empty, all detected services are included.

The expression syntax is based on the Tag(`tag`), and TagRegex(`tag`) functions, as well as the usual boolean logic, as shown in examples below.

Constraints Expression Examples
# Includes only services having the tag `a.tag.name=foo`
constraints = "Tag(`a.tag.name=foo`)"
# Excludes services having any tag `a.tag.name=foo`
constraints = "!Tag(`a.tag.name=foo`)"
# With logical AND.
constraints = "Tag(`a.tag.name`) && Tag(`another.tag.name`)"
# With logical OR.
constraints = "Tag(`a.tag.name`) || Tag(`another.tag.name`)"
# With logical AND and OR, with precedence set by parentheses.
constraints = "Tag(`a.tag.name`) && (Tag(`another.tag.name`) || Tag(`yet.another.tag.name`))"
# Includes only services having a tag matching the `a\.tag\.t.+` regular expression.
constraints = "TagRegex(`a\.tag\.t.+`)"
[providers.consulCatalog]
  constraints = "Tag(`a.tag.name`)"
  # ...
providers:
  consulCatalog:
    constraints: "Tag(`a.tag.name`)"
    # ...
--providers.consulcatalog.constraints="Tag(`a.tag.name`)"
# ...

For additional information, refer to Restrict the Scope of Service Discovery.