K8X Developer Guide

Ferris K8X Developer Guide.

Ferris K8X aims to make it easy to build event-driven microservices in polyglot environments. As such it gives you complete freedom in selecting the language of your choice.

In order to ’event-enable’ a service K8X requires 3 artefacts to be created.

  • The manifest.json file: Which describes your service to the platform.
  • The deployment.yaml: A standard kubernetes deployment file which defines your Kubernetes deployment.

Optional Files

  • The parameters.json file: Which can be used to define UI Forms attached to the service for manaully trigerred runs. Please read the section on parameters.json to understand the structure of this file.
  • The configs.json file: Defines configurations of the service.
  • The secrets.json file: Any secrets that are to be associated with the service. These will be injected to the container on launch.

The manifest.json

The following is a sample manifest.json file.

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{
  "name": "k8s_test_job",
  "type": "k8s_job",
  "description": "Deploying k8 job",
  "allow_manual_triggering": true,
  "active": true,
  "trigger_events": ["ferris.apps.minio.file_uploaded"],
  "tags": ["k8s"]
}

The following table describes the attributes of the manifest.json file.

Attribute Description
name Name of the service. Spaces will be replaced by underscores.
type The type of the service must always be ‘k8x_job’
description Description of the service which will be displayed in the UI.
allow_manual_triggering Values are either ’true’ or ‘false’ . Defines whether the service may be trigerred manually from the UI. Which normally means the service is either trigerred from a micro-ui or does not expect any event parameters.
active Values are either ’true’ or ‘false’ . Can be used to selectively deactivate the service.
trigger_events An array of trigger events. The service will be trigerred when any of these events arrive on the platform.
tags An array of tags. Tags are used for organising and finding related services easily.

The deployment.yaml file

The following is a sample deployment.yaml file

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apiVersion: batch/v1
kind: Job
metadata:
  name: hello-world
spec:
  template:
    spec:
      containers:
        - name: hello-alpine
          image: frolvlad/alpine-bash
          command: [ "/bin/bash", "-c" ]
          args: [ "echo BEGIN; env; sleep 5; ls -la /usr/bin; echo DONE!" ]
          env:
            - name: SERVICE_PORT
              value: "80"
      restartPolicy: Never

The above is a standard kubernetes job deployment yaml file. As you will note there is nothing special about it. When the above file is processed by K8X it will add the incoming parameters, service secrets and configs into the environment.


Last modified November 24, 2023: update (f4bc5ea)