Configuring per-route options

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By default, communication between Gorouter and backends is configured through the general settings at the platform level.

This topic describes how to specify per-route Gorouter options scoped at the application level. This greater granularity lets developers tailor optimal routing behavior for applications’ unique load profiles or other requirements.

Gorouter supports the following per-route option, described in the section below:

• loadbalancing: Configures the load balancing algorithm used by Gorouter for this particular route.
  • Settings: round-robin, least-connection.

Configure Gorouter’s Load Balancing Algorithm

The per-route option loadbalancing allows configuring the load balancing algorithm, which defines how the load is distributed between Gorouters and backends.

This option supports two settings for load balancing:

• round-robin distributes the load evenly across all available backends
• least-connection directs traffic to the backend with the fewest active connections at any given time, optimizing resource utilization

Configure Load Balancing in an App Manifest

To configure per-route load balancing for an application that has not yet been pushed:

1. In the application manifest, include a route definition with an options: loadbalancing attribute set to round-robin or least-connection. For example:

   ---
   applications:
   - name: MY-APP
     routes:
       - route: MY-HOST.EXAMPLE.COM
          options:
            loadbalancing: least-connection
   

   Where MY-APP is the name of your app and MY-HOST.EXAMPLE.COM is the route you want to map to your app.

2. Push the app with the manifest:

   cf push -f manifest.yml
   

Change Load Balancing Algorithm of an Existing Route

To change the per-route loadbalancing option of an existing route, you can use the cli command, update-route.

For example, to change an app route’s algorithm from least-connection to round-robin, you can run the update-route command:

```console
cf update-route EXAMPLE.COM --host MY-HOST --option loadbalancing=round-robin
```

Alternatively, it is also possible to update the per-route load balancing option via the /v3/routes API.

Run the PATCH request to the targeted API endpoint:

```console
cf curl /v3/routes/GUID -X PATCH -H "Content-type: application/json" \
  -d '{
    "options": {
      "loadbalancing": "round-robin"
    }
  }'
```

Where `GUID` is the unique identifier for the route.

Create a Route with a specific Load Balancing Algorithm

To create a route with a per-route loadbalancing option, you can use the cli command create-route. For example:

```console
cf create-route EXAMPLE.COM --host MY-HOST --option loadbalancing=round-robin
```

Alternatively, it is also possible to create a route with a per-route load balancing option via the /v3/routes API:

```console
cf curl /v3/routes -X POST -H "Content-type: application/json" \
  -d '{
    "host": "MY-HOST",
    "path": "MY-PATH",
    ...
    "options": {
      "loadbalancing": "round-robin"
    }
  }'
```

Map a Route to an Existing App with specific Load Balancing Algorithm

To create and map a new route to an existing application with the per-route loadbalancing option, you can use the cli command map-route.

For example:

```console
cf map-route MY-APP EXAMPLE.COM --hostname MY-HOST --option loadbalancing=round-robin
```

The command map-route supports the --option flag only for new routes. To update an existing route, the command update-route must be used as described before.

Retrieve Route Options

To read route options, you can query the route using the route command:

```console
cf route EXAMPLE.COM --hostname MY-HOST
```

The response lists the chosen loadbalancing algorithm option, e.g. least-connection:

```console
options: {loadbalancing=least-connection}
```

Alternatively, you can query the routes API endpoint for a route:

```console
cf curl /v3/routes/?hosts=MY-HOST
```

Where `MY-HOST` is the host attribute of the route. The response lists the chosen `loadbalancing` algorithm option as well:

```console
   "options": {"loadbalancing": "least-connection"}
```

To retrieve all the routes with the corresponding options in a space of an organization, you can use the routes command.