Hello World

Creating a Workflow

Now that you have Scaffold up and running and your CLI configured, let’s build a basic workflow to take you through working with Scaffold

Scaffold workflows use inputs and tasks to define the execution steps

Inputs are objects which allow you to setup ui-managed configuration values. For example, you may want to clone a specific branch so you might create a branch input that defaults to main, but allows you to change the branch you’re going to pull from as needed
Tasks are the actual execution steps which make up the workflow logic

To get started on your workflow, we first need to setup the basic structure

version: v1
name: hello_world
groups: 
  - foo
inputs: []
tasks: []

In this example, we’ve created an empty workflow with the name hello_world which the foo group has access too

Adding an Input

Now that we have our workflow, let’s add an input to allow us to control who we’re saying hello to

version: v1
name: hello_world
groups:
- foo
inputs:
- name: name
  description: "Who to say hello to"
  default: "World"
  type: plaintext
tasks: []

Now we have the ability to change who we say hello to, with World being the default name

Adding tasks

So we’ve created an input, now we just need to setup the tasks to actually use it and do some work

Let’s add a task to take in that input and craft our greeting message

version: v1
name: hello_world
groups:
- foo
inputs:
- name: greeting_name
  description: "Who to say hello to"
  default: "World"
  type: plaintext
tasks:
- name: setup_message
  kind: local
  run: |
    export message="Hello ${greeting_name}"
    echo "message stored"
  store:
    env:
      - message
  inputs:
    greeting_name: greeting_name

We’ve now added our first task, which we can breakdown as follows:

Our task is named as setup_message and is used to create the greeting we will display. We are running locally on the worker, no need to deal with containers at this point. Additionally, we will load in the value from the greeting_name input we created earlier and export the environment variable message to be equal to Hello ${greeting_name}

NOTE: To store environment variable values they must be exported After doing this, we store the message variable to our context to be used later

So we have one task, but it just stores our message it doesn’t really do anything with it, so let’s add another task to change that

version: v1
name: hello_world
groups:
- foo
inputs:
- name: greeting_name
  description: "Who to say hello to"
  default: "World"
  type: plaintext
tasks:
- name: setup_message
  kind: local
  run: |
    export message="Hello ${greeting_name}"
    echo "message stored"
  store:
    env:
      - message
  inputs:
    greeting_name: greeting_name
- name: echo_message
  kind: local
  auto_execute: true
  depends_on:
    success:
      - setup_message
  run: |
    echo "${message}"
  load:
    env:
      - message

Here we’ve added our second step with similar configuration but with a few key differences:

echo_message depends on the success of the setup_message and with auto-execute enabled it will run once setup_message passes
We don’t persist anything to our context, instead we’re loading in the message variable from it
We don’t use any inputs, since that’s already been used in the setup_message step there’s no point

Save this workflow at hello-world.yaml and we can move on to the next step

Applying The Workflow

We’re written a workflow with two tasks, so now what?

Next we need to apply our workflow so that we can use it in Scaffold:

scaffold apply workflow -f hello-world.yaml

Once this has been applied, go to http://localhost:2997 and login with the username admin and password admin

Once you’re logged in, click on the link icon corresponding to our workflow to take you to the workflow page

Next, double click the setup_message step and click on the play button on the top right of the box that appears

Close out of that box and you should see the setup_message step either running (blue) or finished (green)

Once it finishes, you’ll see the echo_message step run automatically. Double click its box and you can expand the context section to view the stored context that was passed down from the previous step. Additionally, view the output section to see your message

So what next? Try clicking to the Inputs button on the top right and changing who you want to say hello to. Click on the save icon and you can now re-run your setup_message step to see the greeting change to whoever you decided