Servers (“runners”)

Servers (“runners”)

• Much smaller/slower than SALMO/LOTA/ARION, BUT

Parts of a GH Action

• Workflow
  • May contain multiple jobs
  • Contains information of what events trigger the workflow to start
• Jobs
  • May contain multiple steps
  • Most steps involve downloading/installing the necessary programs (R, R packages, etc.)
• Steps
  • The meat of the process

Environments

• Environments are:
  • shared between steps
  • NOT shared between jobs
  • NOT shared between workflows.
• Environment in a step takes precedence over that of the bigger job, which takes precedence over that of the workflow.

Location

• Stored in a special “.github” directory in your repository
• And then within a “workflows” directory
• Saved in a yaml (or yml) file

YAML

• GH Actions are coded in YAML
  • “Yet Another Markup Language”
  • “YAML Ain’t Markup Language”
• Spacing is VERY important in YAML
• Unfortunately, I haven’t really figured out the rules, but GitHub will yell at you if something is incorrect
• https://learnxinyminutes.com/docs/yaml/

Workflow info

• Name of the workflow (useful to keep track of things)

name: my_workflow

• Event triggers (there are a quite a few; these are my favorites)

on:
  workflow_dispatch:
  push:
    branches: [main, my_feature_branch]
  schedule:
    - cron: "30  9,17 * * 1-5" 

Workflow: Event triggers

Jobs

• Name of the job
• OS to run the job
  • runs-on; usually ubuntu-latest
• Environmental variables
  • usually always a GH token
  • other secrets

jobs:
  my-super-neat-job:
    runs-on: ubuntu-latest
    env:
      GITHUB_PAT: ${{ secrets.GITHUB_TOKEN}}
      MY_SECRET_PASSWORD: ${{ secrets.MIKES_PW }}

Steps: Setting it up

• Nested under jobs
• Can run your own program (run), or call others that have been developed (uses)
  • https://github.com/r-lib/actions/tree/v2
  • https://github.com/marketplace?type=actions
• First few are usually:
  1. Check out repository
  2. Install R
  3. Install packages

Steps: Setting it up

steps:
  - name: Check out repository
    uses: actions/checkout@v3
    
  - name: Set up R
    uses: r-lib/actions/setup-r@v2
    with:
      use-public-rspm: true
      
  - name: Install packages
    uses: r-lib/actions/setup-r-dependencies@v2
    with:
      packages: |
        any::dplyr
        any::lubridate

Steps: Getting it done

The next few are usually where all of the fun stuff happens

  - name: My first R script
    run: Rscript "do_the_thing.R"
    
  - name: My next R commands
    run: |
      my_addition <- 2 + 2
    shell: Rscript {0}
    
  - name: Show my variable
    run: my_addition
    shell: Rscript {0}

Steps: Saving the result

We usually want to do something with the result. If we want to save things, we need to commit it to the repository.

  - name: Commit files
    run: |
      git config --local user.name actions-user
      git config --local user.email "[email protected]"
      git add .
      git commit -am "GH ACTION did something on $(date)"
      git push origin main

Permissions

• Likely need to allow write permissions
  • Settings > Actions > General > Worflow permissions > Read and write permissions
• Could also possibly do this in the Workflow, but I haven’t checked
• https://docs.github.com/en/actions/using-jobs/assigning-permissions-to-jobs

Permissions: allow writing

Workflow level

on:
  workflow_dispatch:

permissions:
  contents: write

Job level

job:
  my_awesome_job:
    permissions:
      contents:
        write

Artifacts

• Allow sharing of data between jobs/workflows
• Need to be uploaded/downloaded
• If you want to keep things free:
  • Last 90 days, at most
  • Are 500 MB, at most

Secrets

• Information you’d like to use in your script, but don’t want others to see
  • Usernames/passwords needed to access certain information
• Secrets are encrypted
• Can be accessed as an environmental variable

Secrets (in R)

env:
  SUPERSECRET: ${{ secrets.my_saved_secret_on_GH }}