190 lines
6.7 KiB
Markdown
190 lines
6.7 KiB
Markdown
# Services
|
|
|
|
Configuring How to Reach the Services
|
|
{: .subtitle }
|
|
|
|
![Services](../assets/img/services.png)
|
|
|
|
The `Services` are responsible for configuring how to reach the actual services that will eventually handle the incoming requests.
|
|
|
|
## Configuration Example
|
|
|
|
??? example "Declaring a Service with Two Servers (with Load Balancing) -- Using the [File Provider](../providers/file.md)"
|
|
|
|
```toml
|
|
[Services]
|
|
[Services.my-service.LoadBalancer]
|
|
method = "wrr" # Load Balancing based on weights
|
|
|
|
[[Services.my-service.LoadBalancer.servers]]
|
|
url = "http://private-ip-server-1/"
|
|
weight = 30 # 30% of the requests will go to that instance
|
|
[[Services.my-service.LoadBalancer.servers]]
|
|
url = "http://private-ip-server-2/"
|
|
weight = 70 # 70% of the requests will go to that instance
|
|
```
|
|
|
|
## Configuration
|
|
|
|
### General
|
|
|
|
Currently, the `LoadBalancer` service is the only supported kind of `Service` (see below).
|
|
However, since Traefik is an ever evolving project, other kind of Services will be available in the future,
|
|
reason why you have to specify what kind of service you declare.
|
|
|
|
### Load Balancer
|
|
|
|
The `LoadBalancer` service is able to load balance the requests between multiple instances of your programs.
|
|
|
|
??? example "Declaring a Service with Two Servers (with Load Balancing) -- Using the [File Provider](../providers/file.md)"
|
|
|
|
```toml
|
|
[Services]
|
|
[Services.my-service.LoadBalancer]
|
|
method = "wrr" # Load Balancing based on weights
|
|
|
|
[[Services.my-service.LoadBalancer.servers]]
|
|
url = "http://private-ip-server-1/"
|
|
weight = 50 # 50% of the requests will go to that instance
|
|
[[Services.my-service.LoadBalancer.servers]]
|
|
url = "http://private-ip-server-2/"
|
|
weight = 50 # 50% of the requests will go to that instance
|
|
```
|
|
|
|
#### Servers
|
|
|
|
Servers declare a single instance of your program.
|
|
The `url` option point to a specific instance.
|
|
The `weight` option defines the weight of the server for the load balancing algorithm.
|
|
|
|
!!! note
|
|
Paths in the servers' `url` have no effet.
|
|
If you want the requests to be sent to a specific path on your servers,
|
|
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.
|
|
|
|
??? example "A Service with One Server -- Using the [File Provider](../providers/file.md)"
|
|
|
|
```toml
|
|
[Services]
|
|
[Services.my-service.LoadBalancer]
|
|
[[Services.my-service.LoadBalancer.servers]]
|
|
url = "http://private-ip-server-1/"
|
|
```
|
|
|
|
#### Load-balancing
|
|
|
|
Various methods of load balancing are supported:
|
|
|
|
- `wrr`: Weighted Round Robin.
|
|
- `drr`: Dynamic Round Robin: increases weights on servers that perform better than others (rolls back to original weights when the server list is updated)
|
|
|
|
??? example "Load Balancing Using DRR -- Using the [File Provider](../providers/file.md)"
|
|
|
|
```toml
|
|
[Services]
|
|
[Services.my-service.LoadBalancer]
|
|
method = "drr"
|
|
[[Services.my-service.LoadBalancer.servers]]
|
|
url = "http://private-ip-server-1/"
|
|
[[Services.my-service.LoadBalancer.servers]]
|
|
url = "http://private-ip-server-1/"
|
|
```
|
|
|
|
#### Sticky sessions
|
|
|
|
When sticky sessions are enabled, a cookie is set on the initial request to track which server handles the first response.
|
|
On subsequent requests, the client is forwarded to the same server.
|
|
|
|
!!! note "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).
|
|
|
|
!!! note "Cookie Name"
|
|
|
|
The default cookie name is an abbreviation of a sha1 (ex: `_1d52e`).
|
|
|
|
??? example "Adding Stickiness"
|
|
|
|
```toml
|
|
[Services]
|
|
[Services.my-service]
|
|
[Services.my-service.LoadBalancer.stickiness]
|
|
```
|
|
|
|
??? example "Adding Stickiness with a Custom Cookie Name"
|
|
|
|
```toml
|
|
[Services]
|
|
[Services.my-service]
|
|
[Services.my-service.LoadBalancer.stickiness]
|
|
cookieName = "my_stickiness_cookie_name"
|
|
```
|
|
|
|
#### Health Check
|
|
|
|
Configure healthcheck 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`).
|
|
|
|
Below are the available options for the health check mechanism:
|
|
|
|
- `path` is appended to the server URL to set the healcheck endpoint.
|
|
- `scheme`, if defined, will replace the server URL `scheme` for the healthcheck endpoint
|
|
- `hostname`, if defined, will replace the server URL `hostname` for the healthcheck endpoint.
|
|
- `port`, if defined, will replace the server URL `port` for the healthcheck endpoint.
|
|
- `interval` defines the frequency of the healthcheck calls.
|
|
- `timeout` defines the maximum duration Traefik will wait for a healthcheck request before considering the server failed (unhealthy).
|
|
- `headers` defines custom headers to be sent to the healthcheck endpoint.
|
|
|
|
!!! note "Interval & Timeout Format"
|
|
|
|
Interval and timeout are to be given in a format understood by [time.ParseDuration](https://golang.org/pkg/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.
|
|
|
|
!!! note "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 balacer rotation pool.
|
|
|
|
??? example "Custom Interval & Timeout -- Using the File Provider"
|
|
|
|
```toml
|
|
[Services]
|
|
[Servicess.Service-1]
|
|
[Services.Service-1.healthcheck]
|
|
path = "/health"
|
|
interval = "10s"
|
|
timeout = "3s"
|
|
```
|
|
|
|
??? example "Custom Port -- Using the File Provider"
|
|
|
|
```toml
|
|
[Services]
|
|
[Services.Service-1]
|
|
[Services.Service-1.healthcheck]
|
|
path = "/health"
|
|
port = 8080
|
|
```
|
|
|
|
??? example "Custom Scheme -- Using the File Provider"
|
|
|
|
```toml
|
|
[Services]
|
|
[Services.Service-1]
|
|
[Services.Service-1.healthcheck]
|
|
path = "/health"
|
|
scheme = "http"
|
|
```
|
|
|
|
??? example "Additional HTTP Headers -- Using the File Provider"
|
|
|
|
```toml
|
|
[Services]
|
|
[Services.Service-1]
|
|
[Servicess.Service-1.healthcheck]
|
|
path = "/health"
|
|
|
|
[Service.Service-1.healthcheck.headers]
|
|
My-Custom-Header = "foo"
|
|
My-Header = "bar"
|
|
```
|