clojure-base-image

Clojure (on JVM) support for Dispatch

Latest image on Docker Hub

Usage

You need a recent version of Dispatch installed in your Kubernetes cluster, Dispatch CLI configured to use it.

Adding the Base Image

To add the base-image to Dispatch:

$ dispatch create base-image clj dispatchframework/clojure-base:<tag>

Make sure the base-image status is READY (it normally goes from INITIALIZED to READY):

$ dispatch get base-image clj

Adding Runtime Dependencies

Library dependencies listed in deps.edn (Clojure dependency manifest) need to be wrapped into a Dispatch image. For example, suppose we need a YAML parser and an image processing library:

$ cat ./deps.edn

{:deps
 {exoscale/clj-yaml {:mvn/version "0.5.6"}
  net.mikera/imagez {:mvn/version "0.12.0"}}}

$ dispatch create image clj-mylibs clj --runtime-deps ./deps.edn

Make sure the image status is READY (it normally goes from INITIALIZED to READY):

$ dispatch get image clj-mylibs

Creating Functions

Using the Clojure base-image, you can create Dispatch functions from Clojure project directories (source files are in src sub-dir):

$ cat ./src/func_demo.clj

(ns func-demo
  (:require [clj-yaml.core :as yaml]))

(defn parse-yaml [contextpayload]
  (yaml/parse-string payload))

$ dispatch create function --image=clj-mylibs parse-yaml . --handler=func-demo/parse-yaml

You can also use a single source file to create a simple function. The only requirement is: the entry point (handler) function must be a public function named handle that accepts 2 arguments (context and payload), for example:

$ cat ./src/func_demo.clj

(ns func-demo
  (:require [clj-yaml.core :as yaml]))

(defn handle [context payload]
  (yaml/parse-string payload))

$ dispatch create function --image=clj-mylibs parse-yaml ./src/func_demo.clj

Make sure the function status is READY (it normally goes from INITIALIZED to READY):

$ dispatch get function parse-yaml

Running Functions

As usual:

$ dispatch exec --json --input '"{name: VMware, place: Palo Alto}"' --wait parse-yaml

{
    "blocking": true,
    "executedTime": 1524535747,
    "faasId": "5e6dde4a-9ac8-4b4e-80c0-5166f0a3b3c3",
    "finishedTime": 1524535756,
    "functionId": "486de3c7-b428-400e-8cc8-483f1955b627",
    "functionName": "parse-yaml",
    "input": "{name: VMware, place: Palo Alto}",
    "logs": null,
    "name": "7a8e76ab-d3c3-4a83-ba69-735d984c50af",
    "output": {
        "name": "VMware",
        "place": "Palo Alto"
    },
    "reason": null,
    "secrets": [],
    "services": null,
    "status": "READY",
    "tags": []
}

Running Tests

To run tests for func-server:

$ pwd
/clojure-base-image/func-server
$ lein test