traefik/docs/content/routing/overview.md

# Overview

What's Happening to the Requests?
{: .subtitle }

Let's zoom in on Traefik's architecture and talk about the components that enable the routes to be created.

First, when you start Traefik, you define [entrypoints](../entrypoints) (in their most basic forms, they are port numbers).
Then, connected to these entrypoints, [routers](../routers) analyze the incoming requests to see if they match a set of [rules](../routers#rule).
If they do, the router might transform the request using pieces of [middleware](../middlewares/overview.md) before forwarding them to your [services](./services/index.md).

![Architecture](../assets/img/architecture-overview.png)

## Clear Responsibilities

- [_Providers_](../providers/overview.md) discover the services that live on your infrastructure (their IP, health, ...)
- [_Entrypoints_](./entrypoints.md) listen for incoming traffic (ports, ...)
- [_Routers_](./routers/index.md) analyse the requests (host, path, headers, SSL, ...)
- [_Services_](./services/index.md) forward the request to your services (load balancing, ...)
- [_Middlewares_](../middlewares/overview.md) may update the request or make decisions based on the request (authentication, rate limiting, headers, ...)

## Example with a File Provider

Below is an example of a full configuration file for the [file provider](../providers/file.md) that forwards `http://domain/whoami/` requests to a service reachable on `http://private/whoami-service/`.
In the process, Traefik will make sure that the user is authenticated (using the [BasicAuth middleware](../middlewares/basicauth.md)).

Static configuration:

```toml tab="TOML"
[entryPoints]
  [entryPoints.web]
    # Listen on port 8081 for incoming requests
    address = ":8081"

[providers]
  # Enable the file provider to define routers / middlewares / services in a file
  [providers.file]
```

```yaml tab="YAML"
entryPoints:
  web:
    # Listen on port 8081 for incoming requests
    address: :8081

providers:
  # Enable the file provider to define routers / middlewares / services in a file
  file: {}
```

Dynamic configuration:

```toml tab="TOML"
# http routing section
[http]
  [http.routers]
     # Define a connection between requests and services
     [http.routers.to-whoami]
      rule = "Host(`domain`) && PathPrefix(`/whoami/`)"
      # If the rule matches, applies the middleware
      middlewares = ["test-user"]
      # If the rule matches, forward to the whoami service (declared below)
      service = "whoami"

  [http.middlewares]
    # Define an authentication mechanism
    [http.middlewares.test-user.basicAuth]
      users = ["test:$apr1$H6uskkkW$IgXLP6ewTrSuBkTrqE8wj/"]

  [http.services]
    # Define how to reach an existing service on our infrastructure
    [http.services.whoami.loadBalancer]
      [[http.services.whoami.loadBalancer.servers]]
        url = "http://private/whoami-service"
```

```yaml tab="YAML"
# http routing section
http:
  routers:
    # Define a connection between requests and services
    to-whoami:
      rule: "Host(`domain`) && PathPrefix(`/whoami/`)"
       # If the rule matches, applies the middleware
      middlewares:
      - test-user
      # If the rule matches, forward to the whoami service (declared below)
      service: whoami

  middlewares:
    # Define an authentication mechanism
    test-user:
      basicAuth:
        users:
        - test:$apr1$H6uskkkW$IgXLP6ewTrSuBkTrqE8wj/

  services:
    # Define how to reach an existing service on our infrastructure
    whoami:
      loadBalancer:
        servers:
        - url: http://private/whoami-service
```

!!! note "The File Provider"

    In this example, we use the [file provider](../providers/file.md).
    Even if it is one of the least magical way of configuring Traefik, it explicitly describes every available notion.

!!! note "HTTP / TCP"

    In this example, we've defined routing rules for http requests only.
    Traefik also supports TCP requests. To add [TCP routers](./routers/index.md) and [TCP services](./services/index.md), declare them in a TCP section like in the following.

    ??? example "Adding a TCP route for TLS requests on whoami.traefik.io"

        Static configuration:
        
        ```toml tab="TOML"
        [entryPoints]
          [entryPoints.web]
            # Listen on port 8081 for incoming requests
            address = ":8081"

        [providers]
          # Enable the file provider to define routers / middlewares / services in a file
          [providers.file]
        ```
        
        ```yaml tab="YAML"
        entryPoints:
          web:
            # Listen on port 8081 for incoming requests
            address: :8081
        providers:
          # Enable the file provider to define routers / middlewares / services in a file
          file: {}
        ```
        
        Dynamic configuration:

        ```toml tab="TOML"
        # http routing section
        [http]
          [http.routers]
            # Define a connection between requests and services
            [http.routers.to-whoami]
              rule = "Host(`domain`) && PathPrefix(`/whoami/`)"
              # If the rule matches, applies the middleware
              middlewares = ["test-user"]
              # If the rule matches, forward to the whoami service (declared below)
              service = "whoami"

          [http.middlewares]
             # Define an authentication mechanism
             [http.middlewares.test-user.basicAuth]
               users = ["test:$apr1$H6uskkkW$IgXLP6ewTrSuBkTrqE8wj/"]

          [http.services]
             # Define how to reach an existing service on our infrastructure
             [http.services.whoami.loadBalancer]
               [[http.services.whoami.loadBalancer.servers]]
                 url = "http://private/whoami-service"

        [tcp]
          [tcp.routers]
            [tcp.routers.to-whoami-tcp]
              rule = "HostSNI(`whoami-tcp.traefik.io`)"
              service = "whoami-tcp"
              [tcp.routers.to-whoami-tcp.tls]

          [tcp.services]
            [tcp.services.whoami-tcp.loadBalancer]
              [[tcp.services.whoami-tcp.loadBalancer.servers]]
                address = "xx.xx.xx.xx:xx"
        ```
        
        ```yaml tab="YAML"
        # http routing section
        http:

          routers:
            # Define a connection between requests and services
            to-whoami:
              rule: Host(`domain`) && PathPrefix(`/whoami/`)
              # If the rule matches, applies the middleware
              middlewares:
              - test-user
              # If the rule matches, forward to the whoami service (declared below)
              service: whoami

          middlewares:
            # Define an authentication mechanism
            test-user:
              basicAuth:
                users:
                - test:$apr1$H6uskkkW$IgXLP6ewTrSuBkTrqE8wj/

          services:
            # Define how to reach an existing service on our infrastructure
            whoami:
              loadBalancer:
                servers:
                - url: http://private/whoami-service
        tcp:

          routers:
            to-whoami-tcp:
              service: whoami-tcp
              rule: HostSNI(`whoami-tcp.traefik.io`)

          services:
            whoami-tcp:
              loadBalancer:
                servers:
                - address: xx.xx.xx.xx:xx
        ```