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Fan-out-fan-in Pipeline

Use parallel mode to fan-in and fan-out your step dependencies

In pipelines, the concept of fan-in/fan-out is depicted in the diagram below. This pipeline offers parallel sub-flows in a single pipeline. Fan-out refers to spreading a task to multiple destinations in parallel, and fan-in is the opposite, where we spread multiple different tasks to the same destination.

parallel pipeline diagraam

Parallel Mode Diagram

As you can see by the diagram, Step1 fans out to Step2 and Step4 (which run in parallel), while Step3 and Step4 fan-in to Step5.

You can achieve parallelism in your Codefresh pipelines by using the following:

Prerequisites

The Example Project

You can find the example Spring boot application on GitHub. It is a simple Hello World application that has several different types of tests we will be using to run using Codefresh’s parallel mode.

Create the Pipeline

Our pipeline will have five stages: setup, start, web-tests, smoke, and end:

fan-in-fan-out UI pipeline view

Codefresh UI Pipeline View

You should be able to copy and paste this YAML in the in-line editor of the Codefresh UI. It will automatically clone the project for you.

codefresh.yml

version: "1.0"
mode: parallel
stages:
- setup
- start
- web-tests
- smoke
- end
steps:
  Clone: 
    title: Cloning main repository...
    stage: setup
    type: git-clone
    arguments:
      repo: codefresh-contrib/fan-out-fan-in-sample-app
      git: github
      revision: master
  Build_image:
    title: Building Docker Image...
    type: build
    stage: setup
    working_directory: ${{Clone}}
    arguments:
      image_name: spring-backend
      tag: latest
      dockerfile: Dockerfile 
      when:
        steps:
        - name: Clone
          on:
          - success 
  Step1:
    title: Running unit tests...
    stage: start
    working_directory: ${{Clone}}/complete
    arguments:
      image: maven:3.5.2-jdk-8-alpine
      commands:
        - mvn -Dmaven.repo.local=/codefresh/volume/m2_repository -Dgroups="unit" test
      when:
        steps:
        - name: Build_image
          on:
          - success
    services:
      composition:
        spring_backend:
          image: ${{Build_image}}
          ports:
            - 8080
  Step2:
    title: Running web mock test...
    stage: web-tests
    working_directory: ${{Clone}}/complete
    arguments:
      image: maven:3.5.2-jdk-8-alpine
      commands:
        - mvn -Dmaven.repo.local=/codefresh/volume/m2_repository -Dgroups="web-mock" test
      when:
            steps:
            - name: Step1
              on:
              - success
      services:
          composition:
            spring_backend:
              image: ${{Build_image}}
              ports:
                - 8080
  Step3:
    title: Running smoke test...
    stage: smoke
    working_directory: ${{Clone}}/complete
    arguments:
      image: maven:3.5.2-jdk-8-alpine
      commands:
        - mvn -Dmaven.repo.local=/codefresh/volume/m2_repository -Dgroups="smoke" test
      when:
        steps:
          - name: Step2
            on:
            - success
      services:
          composition:
            spring_backend:
              image: ${{Build_image}}
              ports:
                - 8080           
  Step4:
    title: Running web layer tests...
    stage: web-tests
    working_directory: ${{Clone}}/complete
    arguments:
      image: maven:3.5.2-jdk-8-alpine
      commands:
        - mvn -Dmaven.repo.local=/codefresh/volume/m2_repository -Dgroups="web-layer" test
      when:
        steps:
          - name: Step1
            on:
            - success
      services:
          composition:
            spring_backend:
              image: ${{Build_image}}
              ports:
                - 8080
  Step5:
    title: Running integration tests...
    stage: end
    working_directory: ${{Clone}}/complete
    arguments:
      image: maven:3.5.2-jdk-8-alpine
      commands:
        - mvn -Dmaven.repo.local=/codefresh/volume/m2_repository -Dgroups="integration" test
      when:
        steps:
          - name: Step3
            on:
            - success
          - name: Step4
            on:
            - success
      services:
          composition:
            spring_backend:
              image: ${{Build_image}}
              ports:
                - 8080

Note the special use of mode: parallel declared at the root of our yaml. This syntax makes the pipeline use the full parallel mode. The order of your build steps doesn’t matter in this case, each step is executed according to its conditionals.

  • Step1 (unit tests) fans out to Step2 and Step4 (web tests), which run in parallel
  • Step3 (smoke tests) does not execute until Step2 is completed
  • Step3 and Step4 fan in to the final step, Step5 (integration tests)

This pipeline consists of the following:

  1. A git-clone step that clones the main repository
  2. A build step that builds the cloned source code into a Docker image
  3. 5 freestyle steps that:
    • Runs unit tests according to their respective @Tags
    • Uses the image built in the second step as a Service container