OpenFaaS Clojure Template

For a more in-depth walkthrough, please see my introductory post.

Installation

To install this template, run the following command:

faas-cli template pull https://github.com/tessellator/openfaas-clojure-template

If you ever need to update the template, simply run the the command above with the --overwrite flag.

This command will create (if necessary) a new folder template and add this template to it.

You can read more about how templates work in the faas-cli documentation.

Usage

Create a new function with the following command:

faas-cli new my-function --lang=clojure

A new project using deps.edn will be created. It will contain a function.core namespace that is required for the template to work properly. The requirement for this namespace is to have a ring handler defined as app. The app will be run in a jetty server in production.

You may add and use ring middleware and other libraries per usual.

Using compojure

If you would like your function to support subroutes of your main function route, you can use compojure to specify the subroutes. It is important to note that you only need to specify the subroute in your route definitions.

For example, in order to handle a call to /function/my-function/subroute/1234, the my-function function might contain the following definition:

(GET "/subroute/:id" [id]
  ...)

Adding items to the uberjar manifest

It can occasionally be useful to add properties to the uberjar, such as specifying the Implementation-Version. This template will apply the properties defined in a manifest.mf file in the top-level function folder (alongside the deps.edn file).

Running a server during local development

The template provides development tools for running a Jetty server locally during development. The additional features are associated with the dev alias, so to access them you must use the following command to launch a REPL.

clj -A:dev

The REPL will now have access to the function.server namespace located in the dev folder. You can start the server with the following commands:

(require '[function.server :as server])
(server/start!)

You can provide Jetty options to the start! function. For convenience, the options are stored between calls and are not necessary for subsequent calls to start!.

You can stop the server by calling the stop! function.

License

Copyright © 2019-2021 Thomas C. Taylor and contributors.

Distributed under the MIT License, the same as OpenFaaS.