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traefik/docs/user-guide/kv-config.md

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Key-value store configuration

Both static global configuration and dynamic configuration can be sorted in a Key-value store.

This section explains how to launch Træfik using a configuration loaded from a Key-value store.

Træfik supports several Key-value stores:

Static configuration in Key-value store

We will see the steps to set it up with an easy example.

!!! note We could do the same with any other Key-value Store.

docker-compose file for Consul

The Træfik global configuration will be retrieved from a Consul store.

First we have to launch Consul in a container.

The docker-compose file allows us to launch Consul and four instances of the trivial app emilevauge/whoamI :

consul:
  image: progrium/consul
  command: -server -bootstrap -log-level debug -ui-dir /ui
  ports:
    - "8400:8400"
    - "8500:8500"
    - "8600:53/udp"
  expose:
    - "8300"
    - "8301"
    - "8301/udp"
    - "8302"
    - "8302/udp"

whoami1:
  image: emilevauge/whoami

whoami2:
  image: emilevauge/whoami

whoami3:
  image: emilevauge/whoami

whoami4:
  image: emilevauge/whoami

Upload the configuration in the Key-value store

We should now fill the store with the Træfik global configuration, as we do with a TOML file configuration.
To do that, we can send the Key-value pairs via curl commands or via the Web UI.

Fortunately, Træfik allows automation of this process using the storeconfig subcommand.
Please refer to the store Træfik configuration section to get documentation on it.

Here is the toml configuration we would like to store in the Key-value Store :

logLevel = "DEBUG"

defaultEntryPoints = ["http", "https"]

[entryPoints]
  [entryPoints.http]
  address = ":80"
  [entryPoints.https]
  address = ":443"
    [entryPoints.https.tls]
      [[entryPoints.https.tls.certificates]]
      certFile = "integration/fixtures/https/snitest.com.cert"
      keyFile = "integration/fixtures/https/snitest.com.key"
      [[entryPoints.https.tls.certificates]]
      certFile = """-----BEGIN CERTIFICATE-----
                      <cert file content>
                      -----END CERTIFICATE-----"""
      keyFile = """-----BEGIN CERTIFICATE-----
                      <key file content>
                      -----END CERTIFICATE-----"""
    [entryPoints.other-https]
    address = ":4443"
      [entryPoints.other-https.tls]

[consul]
  endpoint = "127.0.0.1:8500"
  watch = true
  prefix = "traefik"

[web]
  address = ":8081"

And there, the same global configuration in the Key-value Store (using prefix = "traefik"):

Key Value
/traefik/loglevel DEBUG
/traefik/defaultentrypoints/0 http
/traefik/defaultentrypoints/1 https
/traefik/entrypoints/http/address :80
/traefik/entrypoints/https/address :443
/traefik/entrypoints/https/tls/certificates/0/certfile integration/fixtures/https/snitest.com.cert
/traefik/entrypoints/https/tls/certificates/0/keyfile integration/fixtures/https/snitest.com.key
/traefik/entrypoints/https/tls/certificates/1/certfile --BEGIN CERTIFICATE--<cert file content>--END CERTIFICATE--
/traefik/entrypoints/https/tls/certificates/1/keyfile --BEGIN CERTIFICATE--<key file content>--END CERTIFICATE--
/traefik/entrypoints/other-https/address :4443
/traefik/consul/endpoint 127.0.0.1:8500
/traefik/consul/watch true
/traefik/consul/prefix traefik
/traefik/web/address :8081

In case you are setting key values manually:

  • Remember to specify the indexes (0,1, 2, ... ) under prefixes /traefik/defaultentrypoints/ and /traefik/entrypoints/https/tls/certificates/ in order to match the global configuration structure.
  • Be careful to give the correct IP address and port on the key /traefik/consul/endpoint.

Note that we can either give path to certificate file or directly the file content itself.

Launch Træfik

We will now launch Træfik in a container.

We use CLI flags to setup the connection between Træfik and Consul. All the rest of the global configuration is stored in Consul.

Here is the docker-compose file :

traefik:
  image: traefik
  command: --consul --consul.endpoint=127.0.0.1:8500
  ports:
    - "80:80"
    - "8080:8080"

!!! warning Be careful to give the correct IP address and port in the flag --consul.endpoint.

Consul ACL Token support

To specify a Consul ACL token for Traefik, we have to set a System Environment variable named CONSUL_HTTP_TOKEN prior to starting Traefik. This variable must be initialized with the ACL token value.

If Traefik is launched into a Docker container, the variable CONSUL_HTTP_TOKEN can be initialized with the -e Docker option : -e "CONSUL_HTTP_TOKEN=[consul-acl-token-value]"

If a Consul ACL is used to restrict Træfik read/write access, one of the following configurations is needed.

  • HCL format :
    key "traefik" {
        policy = "write"
    },
    
    session "" {
        policy = "write"
    }
  • JSON format :
{
    "key": {
        "traefik": {
          "policy": "write"
        }
    },
    "session": {
        "": {
        "policy": "write"
        }
    }
}

TLS support

To connect to a Consul endpoint using SSL, simply specify https:// in the consul.endpoint property

  • --consul.endpoint=https://[consul-host]:[consul-ssl-port]

TLS support with client certificates

So far, only Consul and etcd support TLS connections with client certificates.

To set it up, we should enable consul security (or etcd security).

Then, we have to provide CA, Cert and Key to Træfik using consul flags :

  • --consul.tls
  • --consul.tls.ca=path/to/the/file
  • --consul.tls.cert=path/to/the/file
  • --consul.tls.key=path/to/the/file

Or etcd flags :

  • --etcd.tls
  • --etcd.tls.ca=path/to/the/file
  • --etcd.tls.cert=path/to/the/file
  • --etcd.tls.key=path/to/the/file

!! note We can either give directly directly the file content itself (instead of the path to certificate) in a TOML file configuration.

Remember the command traefik --help to display the updated list of flags.

Dynamic configuration in Key-value store

Following our example, we will provide backends/frontends rules and HTTPS certificates to Træfik.

!!! note This section is independent of the way Træfik got its static configuration. It means that the static configuration can either come from the same Key-value store or from any other sources.

Key-value storage structure

Here is the toml configuration we would like to store in the store :

[file]

# rules
[backends]
  [backends.backend1]
    [backends.backend1.circuitbreaker]
    expression = "NetworkErrorRatio() > 0.5"
    [backends.backend1.servers.server1]
    url = "http://172.17.0.2:80"
    weight = 10
    [backends.backend1.servers.server2]
    url = "http://172.17.0.3:80"
    weight = 1
  [backends.backend2]
    [backends.backend1.maxconn]
    amount = 10
    extractorfunc = "request.host"
    [backends.backend2.LoadBalancer]
    method = "drr"
    [backends.backend2.servers.server1]
    url = "http://172.17.0.4:80"
    weight = 1
    [backends.backend2.servers.server2]
    url = "http://172.17.0.5:80"
    weight = 2

[frontends]
  [frontends.frontend1]
  backend = "backend2"
    [frontends.frontend1.routes.test_1]
    rule = "Host:test.localhost"
  [frontends.frontend2]
  backend = "backend1"
  passHostHeader = true
  priority = 10
  entrypoints = ["https"] # overrides defaultEntryPoints
    [frontends.frontend2.routes.test_1]
    rule = "Host:{subdomain:[a-z]+}.localhost"
  [frontends.frontend3]
  entrypoints = ["http", "https"] # overrides defaultEntryPoints
  backend = "backend2"
  rule = "Path:/test"

[[tlsConfiguration]]
  [tlsConfiguration.certificate]
    certFile = "path/to/your.cert"
    keyFile = "path/to/your.key"
[[tlsConfiguration]]
entryPoints = ["https","other-https"]
  [tlsConfiguration.certificate]
    certFile = """-----BEGIN CERTIFICATE-----
                      <cert file content>
                      -----END CERTIFICATE-----"""
    keyFile = """-----BEGIN CERTIFICATE-----
                      <key file content>
                      -----END CERTIFICATE-----"""

And there, the same dynamic configuration in a KV Store (using prefix = "traefik"):

  • backend 1
Key Value
/traefik/backends/backend1/circuitbreaker/expression NetworkErrorRatio() > 0.5
/traefik/backends/backend1/servers/server1/url http://172.17.0.2:80
/traefik/backends/backend1/servers/server1/weight 10
/traefik/backends/backend1/servers/server2/url http://172.17.0.3:80
/traefik/backends/backend1/servers/server2/weight 1
/traefik/backends/backend1/servers/server2/tags api,helloworld
  • backend 2
Key Value
/traefik/backends/backend2/maxconn/amount 10
/traefik/backends/backend2/maxconn/extractorfunc request.host
/traefik/backends/backend2/loadbalancer/method drr
/traefik/backends/backend2/servers/server1/url http://172.17.0.4:80
/traefik/backends/backend2/servers/server1/weight 1
/traefik/backends/backend2/servers/server2/url http://172.17.0.5:80
/traefik/backends/backend2/servers/server2/weight 2
/traefik/backends/backend2/servers/server2/tags web
  • frontend 1
Key Value
/traefik/frontends/frontend1/backend backend2
/traefik/frontends/frontend1/routes/test_1/rule Host:test.localhost
  • frontend 2
Key Value
/traefik/frontends/frontend2/backend backend1
/traefik/frontends/frontend2/passHostHeader true
/traefik/frontends/frontend2/priority 10
/traefik/frontends/frontend2/entrypoints http,https
/traefik/frontends/frontend2/routes/test_2/rule PathPrefix:/test
  • certificate 1
Key Value
/traefik/tlsconfiguration/1/certificate/certfile path/to/your.cert
/traefik/tlsconfiguration/1/certificate/keyfile path/to/your.key

!!! note As /traefik/tlsconfiguration/1/entrypoints is not defined, the certificate will be attached to all defaulEntryPoints with a TLS configuration (in the example, the entryPoint https)

  • certificate 2
Key Value
/traefik/tlsconfiguration/2/entrypoints https,other-https
/traefik/tlsconfiguration/2/certificate/certfile <cert file content>
/traefik/tlsconfiguration/2/certificate/certfile <key file content>

Atomic configuration changes

Træfik can watch the backends/frontends configuration changes and generate its configuration automatically.

!!! note Only backends/frontends rules are dynamic, the rest of the Træfik configuration stay static.

The Etcd and Consul backends do not support updating multiple keys atomically.
As a result, it may be possible for Træfik to read an intermediate configuration state despite judicious use of the --providersThrottleDuration flag.
To solve this problem, Træfik supports a special key called /traefik/alias. If set, Træfik use the value as an alternative key prefix.

!!! note The field useAPIV3 allows using Etcd V3 API which should support updating multiple keys atomically with Etcd. Etcd API V2 is deprecated and, in the future, Træfik will support API V3 by default.

Given the key structure below, Træfik will use the http://172.17.0.2:80 as its only backend (frontend keys have been omitted for brevity).

Key Value
/traefik/alias /traefik_configurations/1
/traefik_configurations/1/backends/backend1/servers/server1/url http://172.17.0.2:80
/traefik_configurations/1/backends/backend1/servers/server1/weight 10

When an atomic configuration change is required, you may write a new configuration at an alternative prefix.

Here, although the /traefik_configurations/2/... keys have been set, the old configuration is still active because the /traefik/alias key still points to /traefik_configurations/1:

Key Value
/traefik/alias /traefik_configurations/1
/traefik_configurations/1/backends/backend1/servers/server1/url http://172.17.0.2:80
/traefik_configurations/1/backends/backend1/servers/server1/weight 10
/traefik_configurations/2/backends/backend1/servers/server1/url http://172.17.0.2:80
/traefik_configurations/2/backends/backend1/servers/server1/weight 5
/traefik_configurations/2/backends/backend1/servers/server2/url http://172.17.0.3:80
/traefik_configurations/2/backends/backend1/servers/server2/weight 5

Once the /traefik/alias key is updated, the new /traefik_configurations/2 configuration becomes active atomically.

Here, we have a 50% balance between the http://172.17.0.3:80 and the http://172.17.0.4:80 hosts while no traffic is sent to the 172.17.0.2:80 host:

Key Value
/traefik/alias /traefik_configurations/2
/traefik_configurations/1/backends/backend1/servers/server1/url http://172.17.0.2:80
/traefik_configurations/1/backends/backend1/servers/server1/weight 10
/traefik_configurations/2/backends/backend1/servers/server1/url http://172.17.0.3:80
/traefik_configurations/2/backends/backend1/servers/server1/weight 5
/traefik_configurations/2/backends/backend1/servers/server2/url http://172.17.0.4:80
/traefik_configurations/2/backends/backend1/servers/server2/weight 5

!!! note Træfik will not watch for key changes in the /traefik_configurations prefix. It will only watch for changes in the /traefik/alias.
Further, if the /traefik/alias key is set, all other configuration with /traefik/backends or /traefik/frontends prefix are ignored.

Store configuration in Key-value store

!!! note Don't forget to setup the connection between Træfik and Key-value store.

The static Træfik configuration in a key-value store can be automatically created and updated, using the storeconfig subcommand.

traefik storeconfig [flags] ...

This command is here only to automate the process which upload the configuration into the Key-value store. Træfik will not start but the static configuration will be uploaded into the Key-value store.

If you configured ACME (Let's Encrypt), your registration account and your certificates will also be uploaded.

If you configured a file backend [file], all your dynamic configuration (backends, frontends...) will be uploaded to the Key-value store.

To upload your ACME certificates to the KV store, get your Traefik TOML file and add the new storage option in the acme section:

[acme]
email = "test@traefik.io"
storage = "traefik/acme/account" # the key where to store your certificates in the KV store
storageFile = "acme.json" # your old certificates store

Call traefik storeconfig to upload your config in the KV store. Then remove the line storageFile = "acme.json" from your TOML config file.

That's it!