fn-serverless/docs/operating/routes.md

Fn Routes

Routes have a many-to-one mapping to an app.

A good practice to get the best performance on your Fn API is define the required memory as well as CPU limits for each function.

Route level configuration

When creating a route, you can configure it to tweak its behavior, the possible choices are: memory, cpus, type and config.

memory is number of usable MiB for this function. If during the execution it exceeds this maximum threshold, it will halt and return an error in the logs. It expects to be an integer. Default: 128.

cpus is the amount of available CPU cores for this function. For example, 100m or 0.1 will allow the function to consume at most 1/10 of a CPU core on the running machine. It expects to be a string in MilliCPUs format ('100m') or floating-point number ('0.5'). Default: "" or unset, which is unlimited.

type is the type of the function. Either sync, in which the client waits until the request is successfully completed, or async, in which the clients dispatches a new request, gets a call ID back and closes the HTTP connection. Default: sync.

config is a map of values passed to the route runtime in the form of environment variables.

Note: Route level configuration overrides app level configuration.

TODO: link to swagger doc on swaggerhub after it's updated.

Understanding Fn memory and CPU management

When Fn starts it registers the total available memory and CPU cores in your system in order to know during its runtime if the system has the required amount of free memory and CPU to run each function. Every function starts the runner reduces the amount of memory and CPU used by that function from the available memory and CPU register. When the function finishes the runner returns the used memory and CPU to the available memory and CPU register.

Creating function

curl -H "Content-Type: application/json" -X POST -d '{
    "route": {
        "path":"<route name>",
        "image":"<route image>",
        "memory": <memory mb number>,
        "cpus": "<cpus MilliCPUs or floating-point number>",
        "type": "<route type>",
        "config": {"<unique key>": <value>}
    }
}' http://localhost:8080/v1/apps/<app name>/routes

Eg. Creating /myapp/hello with required memory as 100mb, cpus as 200m, type sync and some container configuration values.

curl -H "Content-Type: application/json" -X POST -d '{
    "route": {
        "path":"/hello",
        "image":"fnproject/hello",
        "memory": 100,
        "cpus": "200m",
        "type": "sync",
        "config": {"APPLOG": "stderr"}
    }
}' http://localhost:8080/v1/apps/myapp/routes

Updating function

curl -H "Content-Type: application/json" -X POST -d '{
    "route": {
        "memory": <memory mb number>,
        "cpus": "<cpus MilliCPUs or floating-point number>",
        "type": "<route type>",
        "config": {"<unique key>": <value>}
    }
}' http://localhost:8080/v1/apps/<app name>/routes/<route name>

Eg. Updating /myapp/hello required memory as 100mb, cpus as 0.2, type async and changed container configuration values.

curl -H "Content-Type: application/json" -X POST -d '{
    "route": {
        "memory": 100,
        "cpus": "0.2",
        "type": "async",
        "config": {"APPLOG": "stdout"}
    }
}' http://localhost:8080/v1/apps/myapp/routes/hello