Services

Configuring How to Reach the Services

The Services are responsible for configuring how to reach the actual services that will eventually handle the incoming requests.

Configuration Examples

Declaring an HTTP Service with Two Servers — Using the File Provider

YAML

## Dynamic configuration
http:
  services:
    my-service:
      loadBalancer:
        servers:
        - url: "http://<private-ip-server-1>:<private-port-server-1>/"
        - url: "http://<private-ip-server-2>:<private-port-server-2>/"

TOML

## Dynamic configuration
[http.services]
  [http.services.my-service.loadBalancer]
    [[http.services.my-service.loadBalancer.servers]]
      url = "http://<private-ip-server-1>:<private-port-server-1>/"
    [[http.services.my-service.loadBalancer.servers]]
      url = "http://<private-ip-server-2>:<private-port-server-2>/"

Declaring a TCP Service with Two Servers — Using the File Provider

YAML

tcp:
  services:
    my-service:
      loadBalancer:
        servers:
        - address: "<private-ip-server-1>:<private-port-server-1>"
        - address: "<private-ip-server-2>:<private-port-server-2>"

TOML

## Dynamic configuration
[tcp.services]
  [tcp.services.my-service.loadBalancer]
     [[tcp.services.my-service.loadBalancer.servers]]
       address = "<private-ip-server-1>:<private-port-server-1>"
     [[tcp.services.my-service.loadBalancer.servers]]
       address = "<private-ip-server-2>:<private-port-server-2>"

Declaring a UDP Service with Two Servers — Using the File Provider

YAML

udp:
  services:
    my-service:
      loadBalancer:
        servers:
        - address: "<private-ip-server-1>:<private-port-server-1>"
        - address: "<private-ip-server-2>:<private-port-server-2>"

TOML

## Dynamic configuration
[udp.services]
  [udp.services.my-service.loadBalancer]
     [[udp.services.my-service.loadBalancer.servers]]
       address = "<private-ip-server-1>:<private-port-server-1>"
     [[udp.services.my-service.loadBalancer.servers]]
       address = "<private-ip-server-2>:<private-port-server-2>"

Configuring HTTP Services

Servers Load Balancer

The load balancers are able to load balance the requests between multiple instances of your programs.

Each service has a load-balancer, even if there is only one server to forward traffic to.

Declaring a Service with Two Servers (with Load Balancing) — Using the File Provider

YAML

http:
  services:
    my-service:
      loadBalancer:
        servers:
        - url: "http://private-ip-server-1/"
        - url: "http://private-ip-server-2/"

TOML

## Dynamic configuration
[http.services]
  [http.services.my-service.loadBalancer]
    [[http.services.my-service.loadBalancer.servers]]
      url = "http://private-ip-server-1/"
    [[http.services.my-service.loadBalancer.servers]]
      url = "http://private-ip-server-2/"

Servers

Servers declare a single instance of your program. The url option point to a specific instance.

Paths in the servers’ url have no effect. If you want the requests to be sent to a specific path on your servers, configure your routers to use a corresponding middleware (e.g. the AddPrefix or ReplacePath) middlewares.

A Service with One Server — Using the File Provider

YAML

## Dynamic configuration
http:
  services:
    my-service:
      loadBalancer:
        servers:
          - url: "http://private-ip-server-1/"

TOML

## Dynamic configuration
[http.services]
  [http.services.my-service.loadBalancer]
    [[http.services.my-service.loadBalancer.servers]]
      url = "http://private-ip-server-1/"

Load-balancing

For now, only round robin load balancing is supported:

Load Balancing — Using the File Provider

YAML

## Dynamic configuration
http:
  services:
    my-service:
      loadBalancer:
        servers:
        - url: "http://private-ip-server-1/"
        - url: "http://private-ip-server-2/"

TOML

## Dynamic configuration
[http.services]
  [http.services.my-service.loadBalancer]
    [[http.services.my-service.loadBalancer.servers]]
      url = "http://private-ip-server-1/"
    [[http.services.my-service.loadBalancer.servers]]
      url = "http://private-ip-server-2/"

Sticky sessions

When sticky sessions are enabled, a Set-Cookie header is set on the initial response to let the client know which server handles the first response. On subsequent requests, to keep the session alive with the same server, the client should send the cookie with the value set.

Stickiness on multiple levels

When chaining or mixing load-balancers (e.g. a load-balancer of servers is one of the “children” of a load-balancer of services), for stickiness to work all the way, the option needs to be specified at all required levels. Which means the client needs to send a cookie with as many key/value pairs as there are sticky levels.

Stickiness & Unhealthy Servers

If the server specified in the cookie becomes unhealthy, the request will be forwarded to a new server (and the cookie will keep track of the new server).

Cookie Name

The default cookie name is an abbreviation of a sha1 (ex: _1d52e).

Secure & HTTPOnly & SameSite flags

By default, the affinity cookie is created without those flags. One however can change that through configuration.

SameSite can be none, lax, strict or empty.

Adding Stickiness — Using the File Provider

YAML

## Dynamic configuration
http:
  services:
    my-service:
      loadBalancer:
        sticky:
         cookie: {}

TOML

## Dynamic configuration
[http.services]
  [http.services.my-service]
    [http.services.my-service.loadBalancer.sticky.cookie]

Adding Stickiness with custom Options — Using the File Provider

YAML

## Dynamic configuration
http:
  services:
    my-service:
      loadBalancer:
        sticky:
          cookie:
            name: my_sticky_cookie_name
            secure: true
            httpOnly: true

TOML

## Dynamic configuration
[http.services]
  [http.services.my-service]
    [http.services.my-service.loadBalancer.sticky.cookie]
      name = "my_sticky_cookie_name"
      secure = true
      httpOnly = true
      sameSite = "none"

Setting Stickiness on all the required levels — Using the File Provider

YAML

## Dynamic configuration
http:
  services:
    wrr1:
      weighted:
        sticky:
          cookie:
            name: lvl1
        services:
          - name: whoami1
            weight: 1
          - name: whoami2
            weight: 1
    whoami1:
      loadBalancer:
        sticky:
          cookie:
            name: lvl2
        servers:
          - url: http://127.0.0.1:8081
          - url: http://127.0.0.1:8082
    whoami2:
      loadBalancer:
        sticky:
          cookie:
            name: lvl2
        servers:
          - url: http://127.0.0.1:8083
          - url: http://127.0.0.1:8084

TOML

## Dynamic configuration
[http.services]
  [http.services.wrr1]
    [http.services.wrr1.weighted.sticky.cookie]
      name = "lvl1"
    [[http.services.wrr1.weighted.services]]
      name = "whoami1"
      weight = 1
    [[http.services.wrr1.weighted.services]]
      name = "whoami2"
      weight = 1
  [http.services.whoami1]
    [http.services.whoami1.loadBalancer]
      [http.services.whoami1.loadBalancer.sticky.cookie]
        name = "lvl2"
      [[http.services.whoami1.loadBalancer.servers]]
        url = "http://127.0.0.1:8081"
      [[http.services.whoami1.loadBalancer.servers]]
        url = "http://127.0.0.1:8082"
  [http.services.whoami2]
    [http.services.whoami2.loadBalancer]
      [http.services.whoami2.loadBalancer.sticky.cookie]
        name = "lvl2"
      [[http.services.whoami2.loadBalancer.servers]]
        url = "http://127.0.0.1:8083"
      [[http.services.whoami2.loadBalancer.servers]]
        url = "http://127.0.0.1:8084"

To keep a session open with the same server, the client would then need to specify the two levels within the cookie for each request, e.g. with curl:

curl -b "lvl1=whoami1; lvl2=http://127.0.0.1:8081" http://localhost:8000

Health Check

Configure health check to remove unhealthy servers from the load balancing rotation. Traefik will consider your servers healthy as long as they return status codes between 2XX and 3XX to the health check requests (carried out every interval).

To propagate status changes (e.g. all servers of this service are down) upwards, HealthCheck must also be enabled on the parent(s) of this service.

Below are the available options for the health check mechanism:

• path (required), defines the server URL path for the health check endpoint .
• scheme (optional), replaces the server URL scheme for the health check endpoint.
• hostname (optional), sets the value of hostname in the Host header of the health check request.
• port (optional), replaces the server URL port for the health check endpoint.
• interval (default: 30s), defines the frequency of the health check calls.
• timeout (default: 5s), defines the maximum duration Traefik will wait for a health check request before considering the server unhealthy.
• headers (optional), defines custom headers to be sent to the health check endpoint.
• followRedirects (default: true), defines whether redirects should be followed during the health check calls.
• method (default: GET), defines the HTTP method that will be used while connecting to the endpoint.

Interval & Timeout Format

Interval and timeout are to be given in a format understood by time.ParseDuration. The interval must be greater than the timeout. If configuration doesn’t reflect this, the interval will be set to timeout + 1 second.

Recovering Servers

Traefik keeps monitoring the health of unhealthy servers. If a server has recovered (returning 2xx -> 3xx responses again), it will be added back to the load balancer rotation pool.

Health check with Kubernetes

Kubernetes has an health check mechanism to remove unhealthy pods from Kubernetes services (cf readiness probe). As unhealthy pods have no Kubernetes endpoints, Traefik will not forward traffic to them. Therefore, Traefik health check is not available for kubernetesCRD and kubernetesIngress providers.

Custom Interval & Timeout — Using the File Provider

YAML

## Dynamic configuration
http:
  services:
    Service-1:
      loadBalancer:
        healthCheck:
          path: /health
          interval: "10s"
          timeout: "3s"

TOML

## Dynamic configuration
[http.services]
  [http.services.Service-1]
    [http.services.Service-1.loadBalancer.healthCheck]
      path = "/health"
      interval = "10s"
      timeout = "3s"

Custom Port — Using the File Provider

YAML

## Dynamic configuration
http:
  services:
    Service-1:
      loadBalancer:
        healthCheck:
          path: /health
          port: 8080

TOML

## Dynamic configuration
[http.services]
  [http.services.Service-1]
    [http.services.Service-1.loadBalancer.healthCheck]
      path = "/health"
      port = 8080

Custom Scheme — Using the File Provider

YAML

## Dynamic configuration
http:
  services:
    Service-1:
      loadBalancer:
        healthCheck:
          path: /health
          scheme: http

TOML

## Dynamic configuration
[http.services]
  [http.services.Service-1]
    [http.services.Service-1.loadBalancer.healthCheck]
      path = "/health"
      scheme = "http"

Additional HTTP Headers — Using the File Provider

YAML

## Dynamic configuration
http:
  services:
    Service-1:
      loadBalancer:
        healthCheck:
          path: /health
          headers:
            My-Custom-Header: foo
            My-Header: bar

TOML

## Dynamic configuration
[http.services]
  [http.services.Service-1]
    [http.services.Service-1.loadBalancer.healthCheck]
      path = "/health"
      [http.services.Service-1.loadBalancer.healthCheck.headers]
        My-Custom-Header = "foo"
        My-Header = "bar"

Pass Host Header

The passHostHeader allows to forward client Host header to server.

By default, passHostHeader is true.

Don’t forward the host header — Using the File Provider

YAML

## Dynamic configuration
http:
  services:
    Service01:
      loadBalancer:
        passHostHeader: false

TOML

## Dynamic configuration
[http.services]
  [http.services.Service01]
    [http.services.Service01.loadBalancer]
      passHostHeader = false

ServersTransport

serversTransport allows to reference a ServersTransport configuration for the communication between Traefik and your servers.

Specify a transport — Using the File Provider

YAML

## Dynamic configuration
http:
  services:
    Service01:
      loadBalancer:
        serversTransport: mytransport

TOML

## Dynamic configuration
[http.services]
  [http.services.Service01]
    [http.services.Service01.loadBalancer]
      serversTransport = "mytransport"

Info

If no serversTransport is specified, the [[email protected]](https://doc.traefik.io/cdn-cgi/l/email-protection) will be used. The [[email protected]](https://doc.traefik.io/cdn-cgi/l/email-protection) serversTransport is created from the static configuration.

Response Forwarding

This section is about configuring how Traefik forwards the response from the backend server to the client.

Below are the available options for the Response Forwarding mechanism:

• FlushInterval specifies the interval in between flushes to the client while copying the response body. It is a duration in milliseconds, defaulting to 100. A negative value means to flush immediately after each write to the client. The FlushInterval is ignored when ReverseProxy recognizes a response as a streaming response; for such responses, writes are flushed to the client immediately.

Using a custom FlushInterval — Using the File Provider

YAML

## Dynamic configuration
http:
  services:
    Service-1:
      loadBalancer:
        responseForwarding:
          flushInterval: 1s

TOML

## Dynamic configuration
[http.services]
  [http.services.Service-1]
    [http.services.Service-1.loadBalancer.responseForwarding]
      flushInterval = "1s"

ServersTransport

ServersTransport allows to configure the transport between Traefik and your servers.

ServerName

Optional

serverName configure the server name that will be used for SNI.

File (YAML)

## Dynamic configuration
http:
  serversTransports:
    mytransport:
      serverName: "myhost"

File (TOML)

## Dynamic configuration
[http.serversTransports.mytransport]
  serverName = "myhost"

Kubernetes

apiVersion: traefik.containo.us/v1alpha1
kind: ServersTransport
metadata:
  name: mytransport
  namespace: default
spec:
    serverName: "test"

Certificates

Optional

certificates is the list of certificates (as file paths, or data bytes) that will be set as client certificates for mTLS.

File (YAML)

## Dynamic configuration
http:
  serversTransports:
    mytransport:
      certificates:
        - certFile: foo.crt
          keyFile: bar.crt

File (TOML)

## Dynamic configuration
[[http.serversTransports.mytransport.certificates]]
  certFile = "foo.crt"
  keyFile = "bar.crt"

Kubernetes

apiVersion: traefik.containo.us/v1alpha1
kind: ServersTransport
metadata:
  name: mytransport
  namespace: default
spec:
    certificatesSecrets:
    - mycert
---
apiVersion: v1
kind: Secret
metadata:
  name: mycert
  data:
    tls.crt: LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCi0tLS0tRU5EIENFUlRJRklDQVRFLS0tLS0=
    tls.key: LS0tLS1CRUdJTiBQUklWQVRFIEtFWS0tLS0tCi0tLS0tRU5EIFBSSVZBVEUgS0VZLS0tLS0=

insecureSkipVerify

Optional

insecureSkipVerify controls whether the server’s certificate chain and host name is verified.

File (YAML)

## Dynamic configuration
http:
  serversTransports:
    mytransport:
      insecureSkipVerify: true

File (TOML)

## Dynamic configuration
[http.serversTransports.mytransport]
  insecureSkipVerify = true

Kubernetes

apiVersion: traefik.containo.us/v1alpha1
kind: ServersTransport
metadata:
  name: mytransport
  namespace: default
spec:
    insecureSkipVerify: true

rootCAs

Optional

rootCAs defines the set of root certificate authorities (as file paths, or data bytes) to use when verifying server certificates.

File (YAML)

## Dynamic configuration
http:
  serversTransports:
    mytransport:
      rootCAs:
        - foo.crt
        - bar.crt

File (TOML)

## Dynamic configuration
[http.serversTransports.mytransport]
  rootCAs = ["foo.crt", "bar.crt"]

Kubernetes

apiVersion: traefik.containo.us/v1alpha1
kind: ServersTransport
metadata:
  name: mytransport
  namespace: default
spec:
    rootCAsSecrets:
    - myca
---
apiVersion: v1
kind: Secret
metadata:
  name: myca
  data:
    ca.crt: LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCi0tLS0tRU5EIENFUlRJRklDQVRFLS0tLS0=

maxIdleConnsPerHost

Optional, Default=2

If non-zero, maxIdleConnsPerHost controls the maximum idle (keep-alive) connections to keep per-host.

File (YAML)

## Dynamic configuration
http:
  serversTransports:
    mytransport:
      maxIdleConnsPerHost: 7

File (TOML)

## Dynamic configuration
[http.serversTransports.mytransport]
  maxIdleConnsPerHost = 7

Kubernetes

apiVersion: traefik.containo.us/v1alpha1
kind: ServersTransport
metadata:
  name: mytransport
  namespace: default
spec:
    maxIdleConnsPerHost: 7

disableHTTP2

Optional, Default=false

disableHTTP2 disables HTTP/2 for connections with servers.

File (TOML)

## Dynamic configuration
[http.serversTransports.mytransport]
  disableHTTP2 = true

File (YAML)

## Dynamic configuration
http:
  serversTransports:
    mytransport:
      disableHTTP2: true

Kubernetes

apiVersion: traefik.containo.us/v1alpha1
kind: ServersTransport
metadata:
  name: mytransport
  namespace: default
spec:
    disableHTTP2: true

peerCertURI

Optional, Default=false

peerCertURI defines the URI used to match against SAN URIs during the server’s certificate verification.

File (TOML)

## Dynamic configuration
[http.serversTransports.mytransport]
  peerCertURI = "foobar"

File (YAML)

## Dynamic configuration
http:
  serversTransports:
    mytransport:
      peerCertURI: foobar

Kubernetes

apiVersion: traefik.containo.us/v1alpha1
kind: ServersTransport
metadata:
  name: mytransport
  namespace: default
spec:
    peerCertURI: foobar

forwardingTimeouts

forwardingTimeouts are the timeouts applied when forwarding requests to the servers.

forwardingTimeouts.dialTimeout

Optional, Default=30s

dialTimeout is the maximum duration allowed for a connection to a backend server to be established. Zero means no timeout.

File (YAML)

## Dynamic configuration
http:
  serversTransports:
    mytransport:
      forwardingTimeouts:
        dialTimeout: "1s"

File (TOML)

## Dynamic configuration
[http.serversTransports.mytransport.forwardingTimeouts]
  dialTimeout = "1s"

Kubernetes

apiVersion: traefik.containo.us/v1alpha1
kind: ServersTransport
metadata:
  name: mytransport
  namespace: default
spec:
    forwardingTimeouts:
      dialTimeout: "1s"

forwardingTimeouts.responseHeaderTimeout

Optional, Default=0s

responseHeaderTimeout, if non-zero, specifies the amount of time to wait for a server’s response headers after fully writing the request (including its body, if any). This time does not include the time to read the response body. Zero means no timeout.

File (YAML)

## Dynamic configuration
http:
  serversTransports:
    mytransport:
      forwardingTimeouts:
        responseHeaderTimeout: "1s"

File (TOML)

## Dynamic configuration
[http.serversTransports.mytransport.forwardingTimeouts]
  responseHeaderTimeout = "1s"

Kubernetes

apiVersion: traefik.containo.us/v1alpha1
kind: ServersTransport
metadata:
  name: mytransport
  namespace: default
spec:
    forwardingTimeouts:
      responseHeaderTimeout: "1s"

forwardingTimeouts.idleConnTimeout

Optional, Default=90s

idleConnTimeout is the maximum amount of time an idle (keep-alive) connection will remain idle before closing itself. Zero means no limit.

File (YAML)

## Dynamic configuration
http:
  serversTransports:
    mytransport:
      forwardingTimeouts:
        idleConnTimeout: "1s"

File (TOML)

## Dynamic configuration
[http.serversTransports.mytransport.forwardingTimeouts]
  idleConnTimeout = "1s"

Kubernetes

apiVersion: traefik.containo.us/v1alpha1
kind: ServersTransport
metadata:
  name: mytransport
  namespace: default
spec:
    forwardingTimeouts:
      idleConnTimeout: "1s"

forwardingTimeouts.readIdleTimeout

Optional, Default=0s

readIdleTimeout is the timeout after which a health check using ping frame will be carried out if no frame is received on the HTTP/2 connection. Note that a ping response will be considered a received frame, so if there is no other traffic on the connection, the health check will be performed every readIdleTimeout interval. If zero, no health check is performed.

File (YAML)

## Dynamic configuration
http:
  serversTransports:
    mytransport:
      forwardingTimeouts:
        readIdleTimeout: "1s"

File (TOML)

## Dynamic configuration
[http.serversTransports.mytransport.forwardingTimeouts]
  readIdleTimeout = "1s"

Kubernetes

apiVersion: traefik.containo.us/v1alpha1
kind: ServersTransport
metadata:
  name: mytransport
  namespace: default
spec:
    forwardingTimeouts:
      readIdleTimeout: "1s"

forwardingTimeouts.pingTimeout

Optional, Default=15s

pingTimeout is the timeout after which the HTTP/2 connection will be closed if a response to ping is not received.

File (YAML)

## Dynamic configuration
http:
  serversTransports:
    mytransport:
      forwardingTimeouts:
        pingTimeout: "1s"

File (TOML)

## Dynamic configuration
[http.serversTransports.mytransport.forwardingTimeouts]
  pingTimeout = "1s"

Kubernetes

apiVersion: traefik.containo.us/v1alpha1
kind: ServersTransport
metadata:
  name: mytransport
  namespace: default
spec:
    forwardingTimeouts:
      pingTimeout: "1s"

Weighted Round Robin (service)

The WRR is able to load balance the requests between multiple services based on weights.

This strategy is only available to load balance between services and not between servers.

Supported Providers

This strategy can be defined currently with the File or IngressRoute providers.

YAML

## Dynamic configuration
http:
  services:
    app:
      weighted:
        services:
        - name: appv1
          weight: 3
        - name: appv2
          weight: 1
    appv1:
      loadBalancer:
        servers:
        - url: "http://private-ip-server-1/"
    appv2:
      loadBalancer:
        servers:
        - url: "http://private-ip-server-2/"

TOML

## Dynamic configuration
[http.services]
  [http.services.app]
    [[http.services.app.weighted.services]]
      name = "appv1"
      weight = 3
    [[http.services.app.weighted.services]]
      name = "appv2"
      weight = 1
  [http.services.appv1]
    [http.services.appv1.loadBalancer]
      [[http.services.appv1.loadBalancer.servers]]
        url = "http://private-ip-server-1/"
  [http.services.appv2]
    [http.services.appv2.loadBalancer]
      [[http.services.appv2.loadBalancer.servers]]
        url = "http://private-ip-server-2/"

Health Check

HealthCheck enables automatic self-healthcheck for this service, i.e. whenever one of its children is reported as down, this service becomes aware of it, and takes it into account (i.e. it ignores the down child) when running the load-balancing algorithm. In addition, if the parent of this service also has HealthCheck enabled, this service reports to its parent any status change.

All or nothing

If HealthCheck is enabled for a given service, but any of its descendants does not have it enabled, the creation of the service will fail.

HealthCheck on Weighted services can be defined currently only with the File provider.

YAML

## Dynamic configuration
http:
  services:
    app:
      weighted:
        healthCheck: {}
        services:
        - name: appv1
          weight: 3
        - name: appv2
          weight: 1
    appv1:
      loadBalancer:
        healthCheck:
          path: /status
          interval: 10s
          timeout: 3s
        servers:
        - url: "http://private-ip-server-1/"
    appv2:
      loadBalancer:
        healthCheck:
          path: /status
          interval: 10s
          timeout: 3s
        servers:
        - url: "http://private-ip-server-2/"

TOML

## Dynamic configuration
[http.services]
  [http.services.app]
    [http.services.app.weighted.healthCheck]
    [[http.services.app.weighted.services]]
      name = "appv1"
      weight = 3
    [[http.services.app.weighted.services]]
      name = "appv2"
      weight = 1
  [http.services.appv1]
    [http.services.appv1.loadBalancer]
      [http.services.appv1.loadBalancer.healthCheck]
        path = "/health"
        interval = "10s"
        timeout = "3s"
      [[http.services.appv1.loadBalancer.servers]]
        url = "http://private-ip-server-1/"
  [http.services.appv2]
    [http.services.appv2.loadBalancer]
      [http.services.appv2.loadBalancer.healthCheck]
        path = "/health"
        interval = "10s"
        timeout = "3s"
      [[http.services.appv2.loadBalancer.servers]]
        url = "http://private-ip-server-2/"

Mirroring (service)

The mirroring is able to mirror requests sent to a service to other services. Please note that by default the whole request is buffered in memory while it is being mirrored. See the maxBodySize option in the example below for how to modify this behaviour.

Supported Providers

This strategy can be defined currently with the File or IngressRoute providers.

YAML

## Dynamic configuration
http:
  services:
    mirrored-api:
      mirroring:
        service: appv1
        # maxBodySize is the maximum size allowed for the body of the request.
        # If the body is larger, the request is not mirrored.
        # Default value is -1, which means unlimited size.
        maxBodySize: 1024
        mirrors:
        - name: appv2
          percent: 10
    appv1:
      loadBalancer:
        servers:
        - url: "http://private-ip-server-1/"
    appv2:
      loadBalancer:
        servers:
        - url: "http://private-ip-server-2/"

TOML

## Dynamic configuration
[http.services]
  [http.services.mirrored-api]
    [http.services.mirrored-api.mirroring]
      service = "appv1"
      # maxBodySize is the maximum size in bytes allowed for the body of the request.
      # If the body is larger, the request is not mirrored.
      # Default value is -1, which means unlimited size.
      maxBodySize = 1024
    [[http.services.mirrored-api.mirroring.mirrors]]
      name = "appv2"
      percent = 10
  [http.services.appv1]
    [http.services.appv1.loadBalancer]
      [[http.services.appv1.loadBalancer.servers]]
        url = "http://private-ip-server-1/"
  [http.services.appv2]
    [http.services.appv2.loadBalancer]
      [[http.services.appv2.loadBalancer.servers]]
        url = "http://private-ip-server-2/"

Health Check

HealthCheck enables automatic self-healthcheck for this service, i.e. if the main handler of the service becomes unreachable, the information is propagated upwards to its parent.

All or nothing

If HealthCheck is enabled for a given service, but any of its descendants does not have it enabled, the creation of the service will fail.

HealthCheck on Mirroring services can be defined currently only with the File provider.

YAML

## Dynamic configuration
http:
  services:
    mirrored-api:
      mirroring:
        healthCheck: {}
        service: appv1
        mirrors:
        - name: appv2
          percent: 10
    appv1:
      loadBalancer:
        healthCheck:
          path: /status
          interval: 10s
          timeout: 3s
        servers:
        - url: "http://private-ip-server-1/"
    appv2:
      loadBalancer:
        servers:
        - url: "http://private-ip-server-2/"

TOML

## Dynamic configuration
[http.services]
  [http.services.mirrored-api]
    [http.services.mirrored-api.mirroring]
      [http.services.mirrored-api.mirroring.healthCheck]
      service = "appv1"
    [[http.services.mirrored-api.mirroring.mirrors]]
      name = "appv2"
      percent = 10
  [http.services.appv1]
    [http.services.appv1.loadBalancer]
      [http.services.appv1.loadBalancer.healthCheck]
        path = "/health"
        interval = "10s"
        timeout = "3s"
      [[http.services.appv1.loadBalancer.servers]]
        url = "http://private-ip-server-1/"
  [http.services.appv2]
    [http.services.appv2.loadBalancer]
      [http.services.appv1.loadBalancer.healthCheck]
        path = "/health"
        interval = "10s"
        timeout = "3s"
      [[http.services.appv2.loadBalancer.servers]]
        url = "http://private-ip-server-2/"

Failover (service)

A failover service job is to forward all requests to a fallback service when the main service becomes unreachable.

Relation to HealthCheck

The failover service relies on the HealthCheck system to get notified when its main service becomes unreachable, which means HealthCheck needs to be enabled and functional on the main service. However, HealthCheck does not need to be enabled on the failover service itself for it to be functional. It is only required in order to propagate upwards the information when the failover itself becomes down (i.e. both its main and its fallback are down too).

Supported Providers

This strategy can currently only be defined with the File provider.

YAML

## Dynamic configuration
http:
  services:
    app:
      failover:
        service: main
        fallback: backup
    main:
      loadBalancer:
        healthCheck:
          path: /status
          interval: 10s
          timeout: 3s
        servers:
        - url: "http://private-ip-server-1/"
    backup:
      loadBalancer:
        servers:
        - url: "http://private-ip-server-2/"

TOML

## Dynamic configuration
[http.services]
  [http.services.app]
    [http.services.app.failover]
      service = "main"
      fallback = "backup"
  [http.services.main]
    [http.services.main.loadBalancer]
      [http.services.main.loadBalancer.healthCheck]
        path = "/health"
        interval = "10s"
        timeout = "3s"
      [[http.services.main.loadBalancer.servers]]
        url = "http://private-ip-server-1/"
  [http.services.backup]
    [http.services.backup.loadBalancer]
      [[http.services.backup.loadBalancer.servers]]
        url = "http://private-ip-server-2/"

Health Check

HealthCheck enables automatic self-healthcheck for this service, i.e. if the main and the fallback services become unreachable, the information is propagated upwards to its parent.

All or nothing

If HealthCheck is enabled for a given service, but any of its descendants does not have it enabled, the creation of the service will fail.

HealthCheck on a Failover service can currently only be defined with the File provider.

YAML

## Dynamic configuration
http:
  services:
    app:
      failover:
        healthCheck: {}
        service: main
        fallback: backup
    main:
      loadBalancer:
        healthCheck:
          path: /status
          interval: 10s
          timeout: 3s
        servers:
        - url: "http://private-ip-server-1/"
    backup:
      loadBalancer:
        healthCheck:
          path: /status
          interval: 10s
          timeout: 3s
        servers:
        - url: "http://private-ip-server-2/"

TOML

## Dynamic configuration
[http.services]
  [http.services.app]
    [http.services.app.failover.healthCheck]
    [http.services.app.failover]
      service = "main"
      fallback = "backup"
  [http.services.main]
    [http.services.main.loadBalancer]
      [http.services.main.loadBalancer.healthCheck]
        path = "/health"
        interval = "10s"
        timeout = "3s"
      [[http.services.main.loadBalancer.servers]]
        url = "http://private-ip-server-1/"
  [http.services.backup]
    [http.services.backup.loadBalancer]
      [http.services.backup.loadBalancer.healthCheck]
        path = "/health"
        interval = "10s"
        timeout = "3s"
      [[http.services.backup.loadBalancer.servers]]
        url = "http://private-ip-server-2/"

Configuring TCP Services

General

Each of the fields of the service section represents a kind of service. Which means, that for each specified service, one of the fields, and only one, has to be enabled to define what kind of service is created. Currently, the two available kinds are LoadBalancer, and Weighted.

Servers Load Balancer

The servers load balancer is in charge of balancing the requests between the servers of the same service.

Declaring a Service with Two Servers — Using the File Provider

YAML

## Dynamic configuration
tcp:
  services:
    my-service:
      loadBalancer:
        servers:
        - address: "xx.xx.xx.xx:xx"
        - address: "xx.xx.xx.xx:xx"

TOML

## Dynamic configuration
[tcp.services]
  [tcp.services.my-service.loadBalancer]
    [[tcp.services.my-service.loadBalancer.servers]]
      address = "xx.xx.xx.xx:xx"
    [[tcp.services.my-service.loadBalancer.servers]]
       address = "xx.xx.xx.xx:xx"

Servers

Servers declare a single instance of your program. The address option (IP:Port) point to a specific instance.

A Service with One Server — Using the File Provider

YAML

## Dynamic configuration
tcp:
  services:
    my-service:
      loadBalancer:
        servers:
          - address: "xx.xx.xx.xx:xx"

TOML

## Dynamic configuration
[tcp.services]
  [tcp.services.my-service.loadBalancer]
    [[tcp.services.my-service.loadBalancer.servers]]
      address = "xx.xx.xx.xx:xx"

PROXY Protocol

Traefik supports PROXY Protocol version 1 and 2 on TCP Services. It can be enabled by setting proxyProtocol on the load balancer.

Below are the available options for the PROXY protocol:

• version specifies the version of the protocol to be used. Either 1 or 2.

Version

Specifying a version is optional. By default the version 2 will be used.

A Service with Proxy Protocol v1 — Using the File Provider

YAML

## Dynamic configuration
tcp:
  services:
    my-service:
      loadBalancer:
        proxyProtocol:
          version: 1

TOML

## Dynamic configuration
[tcp.services]
  [tcp.services.my-service.loadBalancer]
    [tcp.services.my-service.loadBalancer.proxyProtocol]
      version = 1

Termination Delay

As a proxy between a client and a server, it can happen that either side (e.g. client side) decides to terminate its writing capability on the connection (i.e. issuance of a FIN packet). The proxy needs to propagate that intent to the other side, and so when that happens, it also does the same on its connection with the other side (e.g. backend side).

However, if for some reason (bad implementation, or malicious intent) the other side does not eventually do the same as well, the connection would stay half-open, which would lock resources for however long.

To that end, as soon as the proxy enters this termination sequence, it sets a deadline on fully terminating the connections on both sides.

The termination delay controls that deadline. It is a duration in milliseconds, defaulting to 100. A negative value means an infinite deadline (i.e. the connection is never fully terminated by the proxy itself).

A Service with a termination delay — Using the File Provider

YAML

## Dynamic configuration
tcp:
  services:
    my-service:
      loadBalancer:
        terminationDelay: 200

TOML

## Dynamic configuration
[tcp.services]
  [tcp.services.my-service.loadBalancer]
    [[tcp.services.my-service.loadBalancer]]
      terminationDelay = 200

Weighted Round Robin

The Weighted Round Robin (alias WRR) load-balancer of services is in charge of balancing the requests between multiple services based on provided weights.

This strategy is only available to load balance between services and not between servers.

Supported Providers

This strategy can be defined currently with the File or IngressRoute providers.

YAML

## Dynamic configuration
tcp:
  services:
    app:
      weighted:
        services:
        - name: appv1
          weight: 3
        - name: appv2
          weight: 1
    appv1:
      loadBalancer:
        servers:
        - address: "xxx.xxx.xxx.xxx:8080"
    appv2:
      loadBalancer:
        servers:
        - address: "xxx.xxx.xxx.xxx:8080"

TOML

## Dynamic configuration
[tcp.services]
  [tcp.services.app]
    [[tcp.services.app.weighted.services]]
      name = "appv1"
      weight = 3
    [[tcp.services.app.weighted.services]]
      name = "appv2"
      weight = 1
  [tcp.services.appv1]
    [tcp.services.appv1.loadBalancer]
      [[tcp.services.appv1.loadBalancer.servers]]
        address = "private-ip-server-1:8080/"
  [tcp.services.appv2]
    [tcp.services.appv2.loadBalancer]
      [[tcp.services.appv2.loadBalancer.servers]]
        address = "private-ip-server-2:8080/"

Configuring UDP Services

General

Each of the fields of the service section represents a kind of service. Which means, that for each specified service, one of the fields, and only one, has to be enabled to define what kind of service is created. Currently, the two available kinds are LoadBalancer, and Weighted.

Servers Load Balancer

The servers load balancer is in charge of balancing the requests between the servers of the same service.

Declaring a Service with Two Servers — Using the File Provider

YAML

## Dynamic configuration
udp:
  services:
    my-service:
      loadBalancer:
        servers:
        - address: "xx.xx.xx.xx:xx"
        - address: "xx.xx.xx.xx:xx"

TOML

## Dynamic configuration
[udp.services]
  [udp.services.my-service.loadBalancer]
    [[udp.services.my-service.loadBalancer.servers]]
      address = "xx.xx.xx.xx:xx"
    [[udp.services.my-service.loadBalancer.servers]]
      address = "xx.xx.xx.xx:xx"

Servers

The Servers field defines all the servers that are part of this load-balancing group, i.e. each address (IP:Port) on which an instance of the service’s program is deployed.

A Service with One Server — Using the File Provider

YAML

## Dynamic configuration
udp:
  services:
    my-service:
      loadBalancer:
        servers:
          - address: "xx.xx.xx.xx:xx"

TOML

## Dynamic configuration
[udp.services]
  [udp.services.my-service.loadBalancer]
    [[udp.services.my-service.loadBalancer.servers]]
      address = "xx.xx.xx.xx:xx"

Weighted Round Robin

The Weighted Round Robin (alias WRR) load-balancer of services is in charge of balancing the requests between multiple services based on provided weights.

This strategy is only available to load balance between services and not between servers.

This strategy can only be defined with File.

YAML

## Dynamic configuration
udp:
  services:
    app:
      weighted:
        services:
        - name: appv1
          weight: 3
        - name: appv2
          weight: 1
    appv1:
      loadBalancer:
        servers:
        - address: "xxx.xxx.xxx.xxx:8080"
    appv2:
      loadBalancer:
        servers:
        - address: "xxx.xxx.xxx.xxx:8080"

TOML

## Dynamic configuration
[udp.services]
  [udp.services.app]
    [[udp.services.app.weighted.services]]
      name = "appv1"
      weight = 3
    [[udp.services.app.weighted.services]]
      name = "appv2"
      weight = 1
  [udp.services.appv1]
    [udp.services.appv1.loadBalancer]
      [[udp.services.appv1.loadBalancer.servers]]
        address = "private-ip-server-1:8080/"
  [udp.services.appv2]
    [udp.services.appv2.loadBalancer]
      [[udp.services.appv2.loadBalancer.servers]]
        address = "private-ip-server-2:8080/"

Using Traefik for Business Applications?

If you are using Traefik for commercial applications, consider the Enterprise Edition. You can use it as your:

• Kubernetes Ingress Controller
• Docker Swarm Ingress Controller
• API Gateway

Traefik Enterprise enables centralized access management, distributed Let’s Encrypt, and other advanced capabilities. Learn more in this 15-minute technical walkthrough.