190 lines
6.7 KiB
Markdown
190 lines
6.7 KiB
Markdown
# Services
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Configuring How to Reach the Services
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{: .subtitle }
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The `Services` are responsible for configuring how to reach the actual services that will eventually handle the incoming requests.
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## Configuration Example
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??? example "Declaring a Service with Two Servers (with Load Balancing) -- Using the [File Provider](../providers/file.md)"
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```toml
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[Services]
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[Services.my-service.LoadBalancer]
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method = "wrr" # Load Balancing based on weights
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[[Services.my-service.LoadBalancer.servers]]
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url = "http://private-ip-server-1/"
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weight = 30 # 30% of the requests will go to that instance
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[[Services.my-service.LoadBalancer.servers]]
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url = "http://private-ip-server-2/"
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weight = 70 # 70% of the requests will go to that instance
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```
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## Configuration
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### General
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Currently, the `LoadBalancer` service is the only supported kind of `Service` (see below).
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However, since Traefik is an ever evolving project, other kind of Services will be available in the future,
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reason why you have to specify what kind of service you declare.
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### Load Balancer
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The `LoadBalancer` service is able to load balance the requests between multiple instances of your programs.
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??? example "Declaring a Service with Two Servers (with Load Balancing) -- Using the [File Provider](../providers/file.md)"
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```toml
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[Services]
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[Services.my-service.LoadBalancer]
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method = "wrr" # Load Balancing based on weights
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[[Services.my-service.LoadBalancer.servers]]
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url = "http://private-ip-server-1/"
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weight = 50 # 50% of the requests will go to that instance
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[[Services.my-service.LoadBalancer.servers]]
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url = "http://private-ip-server-2/"
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weight = 50 # 50% of the requests will go to that instance
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```
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#### Servers
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Servers declare a single instance of your program.
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The `url` option point to a specific instance.
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The `weight` option defines the weight of the server for the load balancing algorithm.
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!!! note
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Paths in the servers' `url` have no effet.
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If you want the requests to be sent to a specific path on your servers,
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configure your [`routers`](./routers.md) to use a corresponding [Middleware](../middlewares/overview.md) (e.g. the [AddPrefix](../middlewares/addprefix.md) or [ReplacePath](../middlewares/replacepath.md)) middlewares.
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??? example "A Service with One Server -- Using the [File Provider](../providers/file.md)"
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```toml
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[Services]
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[Services.my-service.LoadBalancer]
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[[Services.my-service.LoadBalancer.servers]]
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url = "http://private-ip-server-1/"
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```
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#### Load-balancing
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Various methods of load balancing are supported:
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- `wrr`: Weighted Round Robin.
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- `drr`: Dynamic Round Robin: increases weights on servers that perform better than others (rolls back to original weights when the server list is updated)
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??? example "Load Balancing Using DRR -- Using the [File Provider](../providers/file.md)"
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```toml
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[Services]
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[Services.my-service.LoadBalancer]
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method = "drr"
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[[Services.my-service.LoadBalancer.servers]]
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url = "http://private-ip-server-1/"
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[[Services.my-service.LoadBalancer.servers]]
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url = "http://private-ip-server-1/"
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```
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#### Sticky sessions
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When sticky sessions are enabled, a cookie is set on the initial request to track which server handles the first response.
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On subsequent requests, the client is forwarded to the same server.
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!!! note "Stickiness & Unhealthy Servers"
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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).
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!!! note "Cookie Name"
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The default cookie name is an abbreviation of a sha1 (ex: `_1d52e`).
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??? example "Adding Stickiness"
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```toml
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[Services]
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[Services.my-service]
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[Services.my-service.LoadBalancer.stickiness]
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```
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??? example "Adding Stickiness with a Custom Cookie Name"
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```toml
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[Services]
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[Services.my-service]
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[Services.my-service.LoadBalancer.stickiness]
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cookieName = "my_stickiness_cookie_name"
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```
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#### Health Check
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Configure healthcheck to remove unhealthy servers from the load balancing rotation.
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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`).
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Below are the available options for the health check mechanism:
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- `path` is appended to the server URL to set the healcheck endpoint.
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- `scheme`, if defined, will replace the server URL `scheme` for the healthcheck endpoint
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- `hostname`, if defined, will replace the server URL `hostname` for the healthcheck endpoint.
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- `port`, if defined, will replace the server URL `port` for the healthcheck endpoint.
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- `interval` defines the frequency of the healthcheck calls.
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- `timeout` defines the maximum duration Traefik will wait for a healthcheck request before considering the server failed (unhealthy).
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- `headers` defines custom headers to be sent to the healthcheck endpoint.
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!!! note "Interval & Timeout Format"
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Interval and timeout are to be given in a format understood by [time.ParseDuration](https://golang.org/pkg/time/#ParseDuration).
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The interval must be greater than the timeout. If configuration doesn't reflect this, the interval will be set to timeout + 1 second.
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!!! note "Recovering Servers"
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Traefik keeps monitoring the health of unhealthy servers.
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If a server has recovered (returning `2xx` -> `3xx` responses again), it will be added back to the load balacer rotation pool.
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??? example "Custom Interval & Timeout -- Using the File Provider"
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```toml
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[Services]
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[Servicess.Service-1]
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[Services.Service-1.healthcheck]
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path = "/health"
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interval = "10s"
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timeout = "3s"
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```
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??? example "Custom Port -- Using the File Provider"
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```toml
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[Services]
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[Services.Service-1]
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[Services.Service-1.healthcheck]
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path = "/health"
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port = 8080
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```
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??? example "Custom Scheme -- Using the File Provider"
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```toml
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[Services]
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[Services.Service-1]
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[Services.Service-1.healthcheck]
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path = "/health"
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scheme = "http"
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```
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??? example "Additional HTTP Headers -- Using the File Provider"
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```toml
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[Services]
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[Services.Service-1]
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[Servicess.Service-1.healthcheck]
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path = "/health"
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[Service.Service-1.healthcheck.headers]
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My-Custom-Header = "foo"
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My-Header = "bar"
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```
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