Workflows

Workflows were introduced as a major new feature in Ansible Tower 3.1. The basic idea of a workflow is to link multiple Job Templates together. They may or may not share inventory, Playbooks or even permissions. The links can be conditional:

  • if job template A succeeds, job template B is automatically executed afterwards

  • but in case of failure, job template C will be run.

And the workflows are not even limited to Job Templates, but can also include project or inventory updates.

This enables new applications for Tower: different Job Templates can build upon each other. E.g. the networking team creates playbooks with their own content, in their own Git repository and even targeting their own inventory, while the operations team also has their own repos, playbooks and inventory.

In this lab you’ll learn how to setup a workflow.

Lab Scenario

You have two departments in your organization:

  • The web operations team that is developing Playbooks for deploying web infrastructures in their own Git repository.

  • The web applications team, that develops JavaScript web applications for NodeJS in their Git repository.

When there is a new NodeJS-based website to deploy, two main steps need to happen:

The web operations team has to:

  • Install and configure NodeJS to run as a service.

  • An Apache instance needs to be installed and configured as proxy to pass requests for the NodeJS content to the NodeJS backend. And a lot of other steps might be needed, too. Like SELinux, firewall… you know the drill.

The web developer team has to:

  • Deploy the most recent version of the JavaScript web application.

    • Make sure stuff like making sure the directory structure is fine and service restarts happen.

To make things somewhat easier for you, everything needed already exists in a Github repository: Playbooks, JavaScript files etc. You just need to glue it together.

In this example we use two different tags (each on its specific branch) of the same repository for the content of the separate teams. In reality the structure of your SCM repositories depends on a lot of factors and could be different.

Set up Projects

First you have to set up the Git repo as Projects like you normally would. You have done this before, try to do this on your own. Detailed instructions can be found below.

If you are still logged in as user wweb, log out of and log in as user admin again.

  • Create the project for web operations:

    • It should be named Webops Git Repo

    • The URL to access the repo is https://github.com/ansible/workshop-examples.git

    • The SCM BRANCH/TAG/COMMIT is webops_summit_2020

    • Do not allow branch overrides

  • Create the project for the application developers:

    • It should be named Webdev Git Repo

    • The URL to access the repo is https://github.com/ansible/workshop-examples.git

    • The SCM BRANCH/TAG/COMMIT is webdev_summit_2020

    • Do not allow branch overrides

Click here for Solution

  • Create the project for web operations. In the Projects view click the green us button and fill in:

    • NAME: Webops Git Repo

    • ORGANIZATION: Default

    • SCM TYPE: Git

    • SCM URL: https://github.com/ansible/workshop-examples.git

    • SCM BRANCH/TAG/COMMIT: webops_summit_2020

    • SCM UPDATE OPTIONS: Tick the first three boxes.

  • Click SAVE

  • Create the project for the application developers. In the Projects view click the green plus button and fill in:

    • NAME: Webdev Git Repo

    • ORGANIZATION: Default

    • SCM TYPE: Git

    • SCM URL: https://github.com/ansible/workshop-examples.git

    • SCM BRANCH/TAG/COMMIT: webdev_summit_2020

    • SCM UPDATE OPTIONS: Tick the first three boxes.

  • Click SAVE

Set up Job Templates

Now you have to create Job Templates like you would for “normal” Jobs.

We want to install the NodeJS app on node3 only. The Inventory Workshop Inventory contains all nodes, but we can limit the nodes using the LIMIT field!

  • Go to the Templates view, click the green plus button and choose Job Template:

    • NAME: Web Infra Deploy

    • JOB TYPE: Run

    • INVENTORY: Workshop Inventory

    • PROJECT: Webops Git Repo

    • PLAYBOOK: rhel/webops/web_infrastructure.yml

    • CREDENTIAL: Workshop Credentials

    • LIMIT: node3

    • OPTIONS: Enable privilege escalation

  • Click SAVE

  • Go to the Templates view, click the green plus button and choose Job Template:

    • NAME: Web App Deploy

    • JOB TYPE: Run

    • INVENTORY: Workshop Inventory

    • PROJECT: Webdev Git Repo

    • PLAYBOOK: rhel/webdev/install_node_app.yml

    • CREDENTIALS: Workshop Credentials

    • LIMIT: node3

    • OPTIONS: Enable privilege escalation

  • Click SAVE

If you want to know what the Playbooks look like, check out the Github URL and switch to the appropriate branches.

Set up the Workflow

And now you finally set up the Workflow. Workflows are configured in the Templates view, you might have noticed you can choose between Job Template and Workflow Template when adding a template so this is finally making sense.

  • Go to the Templates view and click the the green plus button. This time choose Workflow Template

    • NAME: Deploy Webapplication

    • ORGANIZATION: Default

  • Click SAVE

  • After saving the template the Workflow Visualizer opens to allow you to build a workflow. You can later open the Workflow Visualizer again by using the button on the template details page.

  • Click on the START button, a new node opens. To the right under ADD A NODE you can assign an action to the node, you can choose between Template, Project Sync, Inventory Sync and Approval.

  • In this lab we’ll link Templates together, so select the Web Infra Deploy Template and click SELECT.

  • The node gets annotated with the name of the job. Hover the mouse pointer over the node, you’ll see a red x, a green + and a blue chain-symbol appear.

Using the red “x” allows you to remove the node, the green plus lets you add the next node and the chain-symbol links to another node.

  • Click the green + sign

  • Choose Web App Deploy as the next Job (you might have to switch to the next page)

  • Leave Run set to On Success

The type allows for more complex workflows. You could lay out different execution paths for successful and for failed Playbook runs.

  • Click SELECT

  • Click SAVE in the WORKFLOW VISUALIZER view

  • Click SAVE in the Workflow Template view

The Workflow Visualizer has options for setting up more advanced workflows, please refer to the documentation.

And Action

Your Deploy Webapplication workflow is ready to go, launch it.

  • Click the blue LAUNCH button directly or go to the the Templates view and launch the Deploy Webapplication workflow by clicking the rocket icon.

jobs view of workflow

Note how the workflow run is shown in the job view. In contrast to a normal job template job execution this time there is no Playbook output on the right, but a visual representation of the different workflow steps. If you want to look at the actual Jobs behind that, click DETAILS in each step. If you want to get back from a details view to the corresponding workflow, just hit your browsers back button.

After the job has finished, check if everything worked fine. In your code-server terminal, run:

[student@ansible-1 ~]$ curl http://node3/nodejs

You should be greeted with a friendly Hello World