traefik/docs/content/middlewares/overview.md

Middlewares

Tweaking the Request {: .subtitle }

Attached to the routers, pieces of middleware are a mean of tweaking the requests before they are sent to your service (or before the answer from the services are sent to the clients).

There are many different available middlewares in Traefik, some can modify the request, the headers, some are in charge of redirections, some add authentication, and so on.

Pieces of middleware can be combined in chains to fit every scenario.

Configuration Example

??? example "As Toml Configuration File"

```toml
[providers]
   [providers.file]

[Routers]
  [Routers.router1]
    Service = "myService"
    Middlewares = ["foo-add-prefix"]
    Rule = "Host: example.com"
  
[Middlewares]
 [Middlewares.foo-add-prefix.AddPrefix]
    prefix = "/foo"

[Services]
 [Services.service1]
   [Services.service1.LoadBalancer]

     [[Services.service1.LoadBalancer.Servers]]
       URL = "http://127.0.0.1:80"
       Weight = 1
```

??? example "As a Docker Label"

```yaml
# A container that exposes a simple API
whoami:
  image: containous/whoami  # A container that exposes an API to show its IP address
    labels:
      - "traefik.middlewares.foo-add-prefix.addprefix.prefix=/foo",
```

Advanced Configuration

When you declare a middleware, it lives in its provider namespace. For example, if you declare a middleware using a Docker label, under the hoods, it will reside in the docker provider namespace.

If you use multiple providers and wish to reference a middleware declared in another provider, then you'll have to prefix the middleware name with the provider name.

??? abstract "Referencing a Middleware from Another Provider"

Declaring the add-foo-prefix in the file provider.
    
```toml
[providers]
   [providers.file]
      
[middlewares]
 [middlewares.add-foo-prefix.AddPrefix]
    prefix = "/foo"
```

Using the add-foo-prefix middleware from docker.

```yaml
your-container: #
    image: your-docker-image  
    
    labels:
      # Attach file.add-foo-prefix middleware (declared in file)
      - "traefik.routers.middlewares=file.add-foo-prefix",
```

Available Middlewares

Middleware	Purpose	Area
AddPrefix	Add a Path Prefix	Path Modifier
BasicAuth	Basic auth mechanism	Security, Authentication
Buffering	Buffers the request/response	Request Lifecycle
Chain	Combine multiple pieces of middleware	Middleware tool
CircuitBreaker	Stop calling unhealthy services	Request Lifecycle
Compress	Compress the response	Content Modifier
DigestAuth	Adds Digest Authentication	Security, Authentication
Errors	Define custom error pages	Request Lifecycle
ForwardAuth	Authentication delegation	Security, Authentication
Headers	Add / Update headers	Security
IPWhiteList	Limit the allowed client IPs	Security, Request lifecycle
MaxConnection	Limit the number of simultaneous connections	Security, Request lifecycle
PassTLSClientCert	TODO	Security
RateLimit	Limit the call frequency	Security, Request lifecycle
RedirectScheme	Redirect easily the client elsewhere	Request lifecycle
RedirectRegex	Redirect the client elsewhere	Request lifecycle
ReplacePath	Change the path of the request	Path Modifier
ReplacePathRegex	Change the path of the request	Path Modifier
Retry	Automatically retry the request in case of errors	Request lifecycle
StripPrefix	Change the path of the request	Path Modifier
StripPrefixRegex	Change the path of the request	Path Modifier