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Command Function Invoker

Command functions are invoked using a Command Function Invoker that is provided by riff when building the function.

The command function invoker provides a host for functions implemented as a single executable command (be it a shell script or a binary). It accepts HTTP requests and invokes the command for each request.

Communication with the function is done via stdin and stdout. Functions can log by writing to stderr.

For each invocation, functions are expected to read stdin until the end of the stream (EOF) and provide a result on stdout.

Correct function execution is assumed if the exit code is zero. Any other value indicates an error.

Authoring a function

This example uses the sample command-wordcount function from projectriff-samples on GitHub. It consists of a single executable file named wordcount.sh with the following content:

#!/bin/bash

tr [:punct:] ' ' | tr -s ' ' '\n' | tr [:upper:] [:lower:] | sort | uniq -c | sort -n

Then set the execute bit to make the function executable.

chmod +x wordcount.sh

NOTE: If creating a command function on Windows then the the execute bit cannot be set on the local file. Before committing the function file to a Git repository it must have the execute bit set using the following Git command: git update-index --chmod=+x wordcount.sh.

Creating a function

Function can either be built from local source or from source committed to a Git repository.

build from local source

NOTE: The --local-path builds option is disabled on Windows.

For local build use:

riff function create wordcount --artifact wordcount.sh --local-path .

build from git repository

When building from a Git repo use something like the example below and replace the --git-repo value with the new repository URL.

For building from a Git repository use:

riff function create wordcount --artifact wordcount.sh --git-repo https://github.com/projectriff-samples/command-wordcount

Deploying a function

Please see the runtime documentation for how to deploy and invoke the function.

Cleanup

When done with the function, delete the function resource to stop creating new builds.

NOTE: Images built by the function continue to exist in the container registry and may continue to be consumed by a runtime.

riff function delete wordcount

Deleted function "wordcount"
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