Introduction to GitHub Actions – How to easily automate and integrate with GitHub

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© 2021 Brent C. Laster &
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Tech Skills Transformations & Brent Laster
Introduction to GitHub Actions

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About me
• R&D Director, DevOps
• Global trainer – training (Git,
Jenkins, Gradle, CI/CD,
pipelines, Kubernetes,
Helm, ArgoCD, operators)
• Author -
§ OpenSource.com
§ Professional Git book
§ Jenkins 2 – Up and
Running book
§ Mini-books on O'Reilly
§ GitHub Actions book
(coming in 2023 - early
preview on O'Reilly)
techskillstransformations.com
getskillsnow.com
https://www.linkedin.com/in/brentlaster
@BrentCLaster
GitHub: brentlaster

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Book – Professional Git
• Extensive Git reference,
explanations, and examples
• First part for non-technical
• Beginner and advanced
reference
• Hands-on labs

@techupskills
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Jenkins 2 Book
• Jenkins 2 – Up and Running
• “It’s an ideal book for those who are
new to CI/CD, as well as those who
have been using Jenkins for many
years. This book will help you discover
and rediscover Jenkins.” By Kohsuke
Kawaguchi, Creator of Jenkins

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Learning GitHub Actions - Early Release
• Early release - Chapters 1 & 2 on learning.oreilly.com

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ATO 2022
Session: Cloud-native CI/CD in Kubernetes with Tekton
Tekton is a newer entry in the CI/CD tooling space that allows you to implement CI/CD
pipelines through custom Kubernetes objects. Because of that, you can utilize the
same Kubernetes knowledge you already have without learning another application
and take advantage of your existing Kubernetes infrastructure and features such as
scaling that are built in. Join author and trainer and DevOps Director Brent Laster to
learn how to easily and quickly get up to speed with Tekton and the supporting pieces
around it including its dashboard and CLI.

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O’Reilly Training

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NFJS Training

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What are GitHub Actions?
• Way to create custom, automated workflows in GitHub
• Executed based on repository operations
• Building blocks - can be combined & shared
• Used for usual SDLC tasks
• Can be used for CI/CD as alternatives to other apps

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Example use cases (starter workflows)

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What's interesting about it?
• Direct integration with GitHub

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What else is interesting about it?
• Lots of events can trigger an action workflow -
automate practically anything!
on: project
on: watch
on: repository_dispatch
on: delete
on: check_run
on: page_build
on: scheduled
on: pull_request
on: public
on: pull_request_review_comment
on: pull_push
on: fork
https://docs.github.com/en/actions/learn-github-actions/events-that-trigger-workflows

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Types of triggers for events
• single event - on: push
• list of events - on: [push, pull_request]
• specify activity types or configuration - on:
push:
branches:
- main
• scheduled events - on:
scheduled:
- cron: '30 5,15 * * *'
• manual events - on: workflow-dispatch
on: repository-dispatch
[opened, deleted]
• workflow reuse events - on: workflow-call
(can be called from another workflow)
• webhook events - on: issue_comment
on: pull_request

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How Actions work (events)
• Events occur
§ Example: pull request
triggers build for
validation
§ Example: push for
commit
• Repository Dispatch
Events
§ Endpoint that can be
used to trigger webhook
event
§ Can be used for activity
that is not in GitHub
§ Can trigger a GitHub
Actions workflow or
GitHub App webhook
• ref
https://docs.github.com
/en/rest/reference/repo
s#create-a-repository-
dispatch-event
Event

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How Actions work (workflows)
• Events trigger workflows
workflow
Event
§ Procedure to run
automatically
§ Added to your repository
§ Composed of one+ jobs
§ Can be triggered/scheduled
by event
§ Useful for doing CI/CD
actions such as building,
testing, packaging, etc.

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How actions work (jobs, steps, actions, shell cmds)
Workflows contain jobs
§ Set of steps
§ Workflow with multiple jobs runs them in parallel
Jobs contain steps
§ A task that can execute commands in a job
§ Can be either
» action
» shell command
workflow
Job 1
Job 2
Event
Step 1
Step 1
Step 2
action or
shell cmd
action
§ Independent
commands
§ Based off repository
in GitHub
§ Used in steps to
form a job
§ Smallest unit in a
workflow
§ Can be created or
pulled in from the
community
§ Only usable if
included as a step
action or
shell cmd
action or
shell cmd

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How Actions work (runner)
Runner
• A server with GitHub
Actions runner app
on it
• Can use runner
provided by/hosted
via GitHub or use
your own
• Runner listens for
available jobs
• Steps in a job execute
on the same runner
workflow
Job 1
Job 2
Event
Step 1
Step 1
Step 2
Runner 1
action or cmd
runs
Runner 2
action or cmd
runs
logs results
logs results
action or
shell cmd
action or
shell cmd
action or
shell cmd

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How actions work
GitHub Repository
.github
workflows
workflow1.yml
Job 1
Step 1
Step 2
Job 2
Step 1
workflow2.yml
Job 1
Step 1
Job 2
Step 1
Step 2
Runner 1
Runner 2
Event
• Resides in
.github/workflows
• Can have multiple
workflows
action or
shell cmd
action or
shell cmd
action or
shell cmd
action or
shell cmd
action or
shell cmd
action or
shell cmd
action or cmd
runs
logs results
action or cmd
runs
logs results

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GitHub-hosted vs Self-hosted Runners
GitHub-hosted Self-hosted
Definition Hosted by GitHub Any system/configuration
you want to use
Prereqs Running GitHub actions
runner application
GitHub actions self-hosted
runner application
Platforms Windows, Linux, MacOS Any that can be made to
work
Advantages Quicker and simpler Highly configurable
Management/Ownership GitHub As defined
Clean instance For every job execution Optional
Cost Free minutes on GitHub
plan with cost for overages
Free to use with actions,
but owner is responsible
for any other cost
Automatic updates For OS, installed packages,
tools, and hosted runner
application
Only for self-hosted runner
application
Implementation Virtual Virtual or physical

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GitHub Actions Runners
• Virtual
environments for
GitHub actions
hosted runners
• New VM for each
job run
• VM images of
Microsoft-hosted
agents used for
Azure Pipelines
• Updated
periodically by
GitHub

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Self-hosted Runners
• Useful when you need more configurability
and control
• Allows you to choose and customize
configuration, system resources, available
software, etc.
• Can be physical systems, VMs, containers, on-
prem or cloud
• Runner system connects to GitHub via GitHub
Actions self-hosted runner
• Automatically kicked off of GitHub if no
connection to GitHub Actions after 30 days
• Recommended to use only with private repos
§ Forks of repos could run dangerous code on self-
hosted runner machine (via PR that executes code
in workflow)

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GitHub Actions Storage - Artifacts
• Actions allow you to persist data after job has completed - as artifacts
• Artifact - file or collection of files produced during workflow run
§ build and test output
§ log files
§ binary files
• Artifacts are uploaded during workflow run
§ can be shared between jobs in same workflow
§ visible in the UI
• Default retention period is 90 days

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How much does it cost? (part 1)
• Free for public repos and/or self-hosted runners
• For private repos, each GitHub account gets
designated amount of free minutes and storage
§ above that, usage is controlled by spending limits
§ minutes reset every month, but not storage
Product Storage Minutes (per month)
GitHub Free 500 MB 2,000
GitHub Pro 1 GB 3,000
GitHub Free for
organizations
500 MB 2,000
GitHub Team 2 GB 3,000
GitHub Enterprise
Cloud
50 GB 50,000

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How much does it cost? (part 2)
• Total storage is Actions artifacts and GitHub Packages
§ GitHub Packages = platform for hosting and managing packages, such as containers or
dependencies
• Storage usage is calculated for each month based on hourly usage during the month
• Per-minute rates
• If jobs run on Windows or macOS on runners hosted by GitHub, multiplier comes into play
Operating system Minute multiplier
Linux 1
macOS 10
Windows 2
Operating system Per-minute rate
(USD)
Linux $0.008
macOS $0.08
Windows $0.016

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Integration with GitHub Interface

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Viewing Logs

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Viewing the Workflow Run history

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Filtering workflows
• Enter text in search bar
• Click on "x" at end to
clear
• Click on category in
"workflow run results"
bar
• Select from the list

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Viewing a Specific Workflow Run

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Job Graph

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Drilling into logs

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Editing Workflows

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Editing with VSCode
• Hit "." when in file

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Updating workflows with Pull Requests #1

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Running your workflow manually
• Add a "workflow dispatch event" trigger
• Merge changes
• Afterwards will have "Run workflow" button in
workflow list

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Public Actions

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Searching for a Public Action

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Actions use Workflows

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Action Metadata File
• action.yml or
action.yaml
• defines inputs,
outputs, runtime
env, config, branding
• must be present to
have an action

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Custom Actions
• Can be created by you
• Can result from customizing community actions
• Can be put on Marketplace and shared
• repository must be public
• Can integrate with any public API
• Can run directly on a machine or in Docker
container
• Can define inputs, outputs, and environment
variables
• Require metadata file
• defines inputs, outputs, and entrypoint
• must be named either action.yaml or
action.yml
• Should be tagged with a label and then pushed to
GitHub
• To use:
• In file in .github/workflows/main.yml
• In steps
• "uses: <github path to action>@<label>
$ <create GitHub repo>
$ <clone repo>
$ <create files>
$ git add action.yml <other files>
$ git commit -m "action files"
$ git tag -a -m "first release of action" v1
$ git push --follow-tags
on: [push]
jobs:
example_job:
runs on: ubuntu-latest
name: An example job
steps:
- name: Example step
id: example_step
uses: <repo name>/<action name>@<tag>
...
.github/workflows/example.yml

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Custom Action Types
• Docker
• Packages env with actions code
• Env can include specific OS versions,
config, tools, etc.
• Well suited for specific env needs
• Runs only on Linux runners with
Docker installed
• Slower due to cost of building and
retrieving container
• GitHub builds image from Dockerfile
and runs comands in a new
container based on image
• Javascript
• Run directly on runner for any of
macOS, Linux, or Windows
• Separates action from env
• Fast than Docker
• Needs to be pure JavaScript (no
other binaries)
• Can use binaries already on runner
• Composite
• Combines multiple workflow steps
in one action
Runner
FROM <base> ....
COPY <entry script>
ENTRYPOINT <script>
Dockerfile
...
runs:
using: 'docker'
image: 'Dockerfile'
args:
....
action.yml
+ +
Runner
+ +
...
runs:
using: 'node12'
main: 'index.js'
action.yml
npm install @actions/core
npm install @actions/github
const core =
require('@actions/core');
const github =
require('@actions/github);
try{
...
} catch (error) {
...
}
index.js
Runner
...
runs:
using: 'composite'
- run: echo ...
- run: ${{ github.action.path
}}/shell-script.sh
action.yml
+
echo ...
...
shell-script.sh

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Workflow commands
• Used to communicate with the runner machine to
§ Set environment variables
§ Set output values used by other actions
§ Add debug messages to logs
• Typically use "echo" command with certain format
• Also can be used to execute some commands in
Actions Toolkit

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Actions Toolkit
• Provides packages for more
easily creating/working with
actions
• Functions in packages can be
run in code as in
core.setOutput('SELECTED_COLOR
', 'red');
or (in many cases)
• run as workflow commands
- name: Set selected color run:
echo '::set-output
name=SELECTED_COLOR::green'

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Actions Toolkit packages
• Collections of
related
functions
• Can be
imported into
code for actions

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Monitoring and Troubleshooting
• Use "default" information
§ Visualization graph of a workflow
§ Workflow run history
§ Workflow logs
§ Dump out the runner context
§ Enable debug logging
» can use core.debug or "echo
"::debug:: <message>"
» must be enabled via setting up
secrets
» ACTIONS_RUNNER_DEBUG
» ACTIONS_STEP_DEBUG

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Enabling/Creating Secrets for Actions
• Create in same repo, so same permissions needed
1
2
3

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Defining Secrets for Actions
• Provide secret name
• Provide value
• Add secret

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GitHub Personal Access Token
• Provides specific accesses
• Replaces passwords
• Can be done through https://github.com/settings/tokens
• Or can be setup via Settings->Profile->Developer Settings->Personal Access Tokens
• Generate new token and save it

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Workflows invoking GitHub
• Workflows can
invoke GitHub or
other
functionality via
techniques such
as curl

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Chaining Workflows Together
• Can be done via GitHub API calls
• Requires API Token saved as a secret
• One workflow then invokes the other via API call
create-issue-on-failure:
runs-on: ubuntu-latest
needs: [test-run, count-args]
if: always() && failure()
steps:
- name: invoke workflow to create issue
run: >
curl -X POST
-H "authorization: Bearer ${{ secrets.WORKFLOW_USE }}"
-H "Accept: application/vnd.github.v3+json"
"https://api.github.com/repos/${{ github.repository }}/actions/workflows/create-failure-issue.yml/dispatches"
-d '{"ref":"main",
"inputs":
{"title":"Automated workflow failure issue for commit ${{ github.sha }}",
"body":"This issue was automatically created by the GitHub Action workflow ** ${{ github.workflow }} **"}
}'

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That’s all - thanks!
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getskillsnow.com

Introduction to GitHub Actions – How to easily automate and integrate with GitHub

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