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Aisalkyn Aidarova
Aisalkyn Aidarova

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Install Jenkins

#docker #devops #cicd #tutorial

Jenkins on macOS using Docker — full DevOps setup

Image

Image

Image

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This is the BEST + industry-standard way for DevOps engineers.

PHASE 1 — Install prerequisites (once)

1. Install Docker Desktop for Mac

Download:

https://www.docker.com/products/docker-desktop/
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After install:

  • Open Docker Desktop
  • Make sure Docker is running
  • Verify: 
docker --version
docker ps
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PHASE 2 — Run Jenkins using Docker (clean & correct)

2. Create Jenkins container

Run this exact command:

docker run -d \
  --name jenkins \
  -p 8080:8080 \
  -p 50000:50000 \
  -v jenkins_home:/var/jenkins_home \
  jenkins/jenkins:lts
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Why this matters (DevOps mindset):

  • -v jenkins_home → persistent data
  • LTS → stable for production
  • No Java install on Mac needed

Check:

docker ps
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PHASE 3 — Unlock & login Jenkins

3. Get admin password 

docker exec jenkins cat /var/jenkins_home/secrets/initialAdminPassword
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Copy the password.

4. Open Jenkins UI

Browser:

http://localhost:8080
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Steps:

  1. Paste admin password
  2. Click Install suggested plugins
  3. Create admin user
  4. Finish setup

You are now logged in as Jenkins admin.

PHASE 4 — Jenkins basics every DevOps must know

Jenkins UI essentials

  • Dashboard → all pipelines/jobs
  • Manage Jenkins → configuration
  • Manage Plugins → DevOps tools
  • Credentials → secrets management
  • Nodes → agents/workers

PHASE 5 — First DevOps job (hands-on)

5. Create your first job

  1. Click New Item
  2. Name: devops-demo-job
  3. Type: Freestyle project
  4. Click OK

6. Add build step

Scroll → Build → Add build step → Execute shell

Paste:

echo "Hello DevOps"
date
whoami
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Save.

7. Run job

Click Build Now

Check:

  • Console Output
  • Job status (blue = success)

This proves:

  • Jenkins works
  • Linux shell runs inside container

PHASE 6 — Real DevOps workflow (what matters)

Typical DevOps CI pipeline 

Git → Jenkins → Build → Test → Artifact → Deploy
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You will now build toward:

  • GitHub / GitLab integration
  • Maven / Gradle / Node builds
  • Docker image builds
  • AWS deployment
  • Kubernetes pipelines

PHASE 7 — Must-install plugins (DevOps standard)

Go to:
Manage Jenkins → Manage Plugins → Available

Install:

  • Git
  • Pipeline
  • Docker Pipeline
  • Credentials Binding
  • Blue Ocean
  • Maven Integration

Restart Jenkins when asked.

PHASE 8 — Jenkins + Git (real CI)

Example: clone Git repo

In job config:

  • Source Code Management → Git
  • Repo URL: 
https://github.com/spring-projects/spring-petclinic.git
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Build step:

ls -la
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Build → see repo files → CI working.

PHASE 9 — Jenkins container access (important)

Enter Jenkins container 

docker exec -it jenkins bash
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Inside container:

  • Jenkins workspace
  • Linux commands
  • Java available

Exit:

exit
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PHASE 10 — DevOps mindset (very important)

You are NOT “installing Jenkins”.
You are building automation.

As a DevOps engineer, Jenkins is used to:

  • Enforce CI
  • Catch bugs early
  • Automate deployments
  • Replace manual work
  • Integrate tools (Git, Docker, AWS, K8s)

A) Verify Jenkins is running locally (Mac)

1) Confirm process + port 

ps aux | grep jenkins
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2) Open Jenkins in browser

Open:

  • http://127.0.0.1:9090

If this doesn’t open, Jenkins is not running (stop here and fix Jenkins start).

B) Install ngrok on Mac (2 options)

Option 1: Homebrew (recommended) 

brew install ngrok/ngrok/ngrok
ngrok version
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Option 2: Download from ngrok website

  1. Go to ngrok downloads (Mac)
  2. Download zip, unzip
  3. Move binary: 
sudo mv ~/Downloads/ngrok /usr/local/bin/ngrok
ngrok version
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C) Connect ngrok to your ngrok account (required)

ngrok requires auth token.

1) Login to ngrok dashboard

  • Go to your ngrok account → “Your Authtoken”

2) Copy token and paste this command (exact) 

ngrok config add-authtoken YOUR_TOKEN_HERE
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Check config:

cat ~/.config/ngrok/ngrok.yml
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D) Start ngrok tunnel for Jenkins

1) Start tunnel (Jenkins port 9090) 

ngrok http 9090
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You will see something like:

  • Forwarding https://temple-deontic-ansley.ngrok-free.dev -> http://localhost:9090
  • Web Interface http://127.0.0.1:4040

2) Copy ONLY this URL

Copy the https forwarding URL, example:

  • https://temple-deontic-ansley.ngrok-free.dev

E) Prepare Jenkins for GitHub webhooks

1) Install required plugins (Jenkins UI)

Go to:

  • Manage Jenkins → Plugins → Available

Install:

  • GitHub
  • Git
  • Pipeline
  • Multibranch Pipeline (optional, but recommended)
  • GitHub Branch Source (recommended)

Restart Jenkins if asked.

2) Set Jenkins URL (important)

Go to:

  • Manage Jenkins → System

Find Jenkins Location → Jenkins URL
Set it to your ngrok public URL:

  • https://temple-deontic-ansley.ngrok-free.dev

Save.

Why DevOps does this:

  • Jenkins generates correct callback URLs (links in webhook, notifications, etc.)

F) Create GitHub token (DevOps standard, secure)

You should NOT use GitHub password.

1) In GitHub

Go:

  • GitHub → Settings → Developer settings → Personal access tokens → Tokens (classic)

Create token with scopes:

  • repo
  • admin:repo_hook (needed to manage webhooks)
  • read:org (if repo is org)

Copy the token (save it).

2) Add token to Jenkins as credential

In Jenkins:

  • Manage Jenkins → Credentials
  • Domain: (global)

  • Add Credentials

    • Kind: Secret text
    • Secret: paste GitHub token
    • ID: github-token Save.

G) Create Jenkins Pipeline job that reads Jenkinsfile from GitHub

1) Create job

  • Jenkins → New Item
  • Name: eks-text (example)
  • Type: Pipeline
  • OK

2) Configure “Pipeline script from SCM”

In job config:

Pipeline section

  • Definition: Pipeline script from SCM
  • SCM: Git

  • Repository URL:

    • https://github.com/jumptotechschooldevops/cloud-guardrails.git

  • Credentials:

    • choose your GitHub token credential (github-token) if Jenkins asks

  • Branches to build:

    • */main (or */master)

  • Script Path:

    • 01-eks-gatekeeper/Jenkinsfile

Save.

3) Enable webhook trigger

In the same job config:

  • Build Triggers

    • ✅ Check GitHub hook trigger for GITScm polling Save.

DevOps reason:

  • This tells Jenkins: “Start build when GitHub webhook arrives.”

H) Add GitHub Webhook (this is the KEY part)

Go to your GitHub repo:

  • Repo → Settings → Webhooks → Add webhook

Fill:

1) Payload URL (copy/paste exact)

Use your ngrok URL + Jenkins GitHub endpoint:

https://temple-deontic-ansley.ngrok-free.dev/github-webhook/
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Important:

  • Must end with /github-webhook/

2) Content type

  • application/json

3) Which events

  • Choose: Just the push event (That’s enough for auto-build on push.)

4) Active

  • ✅ Active

Click: Add webhook

I) Test (DevOps validation checklist)

1) Check webhook delivery

In GitHub webhook page:

  • Click the webhook
  • Go to Recent Deliveries
  • You want Status: 200 OK

If you see 404/500 → Jenkins didn’t receive it.

2) Make a test commit + push

From your repo:

git pull
echo "webhook test $(date)" >> webhook-test.txt
git add webhook-test.txt
git commit -m "test webhook trigger"
git push
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Expected:

  • GitHub webhook shows 200
  • Jenkins job starts automatically: “Started by GitHub push …”

J) If webhook triggers but job doesn’t run (common fixes)

Fix 1: Wrong webhook URL

Must be:

  • https://YOUR-NGROK-DOMAIN/github-webhook/

Fix 2: Jenkins is only listening on 127.0.0.1

That’s OK with ngrok, because ngrok forwards to localhost.

Fix 3: ngrok is running but Jenkins not reachable

Open in browser:

  • https://YOUR-NGROK-DOMAIN If you don’t see Jenkins login page, ngrok isn’t forwarding to correct port.

Fix 4: ngrok changes URL

Free ngrok changes domain each time.
If you restart ngrok → you MUST update GitHub webhook payload URL.

K) What DevOps engineers do in real companies

  • Use a real public DNS + TLS (not ngrok)

  • Put Jenkins behind:

    • Reverse proxy (Nginx)
    • HTTPS cert (Let’s Encrypt)
    • Auth (SSO)

  • Lock down webhook security:

    • GitHub “Secret” header validation
    • IP allowlist (GitHub webhook IPs)

  • Use Multibranch Pipeline + PR builds

1) Confirm Jenkins is running on your Mac

You already confirmed with:

ps aux | grep jenkins
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You saw Jenkins running like:

  • jenkins.war
  • listening on 127.0.0.1
  • port like 9090

So locally Jenkins works.

Open in browser:

  • http://127.0.0.1:9090

2) Problem: GitHub cannot reach localhost Jenkins

Because Jenkins was on 127.0.0.1, GitHub webhook cannot call it.

So we used ngrok to expose Jenkins.

3) Start ngrok to expose Jenkins

Run (example if Jenkins on 9090):

ngrok http 9090
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ngrok gave you a public URL like:

  • https://temple-deontic-ansley.ngrok-free.dev

That URL forwards internet traffic → your local Jenkins.

4) Create a Pipeline job in Jenkins (GitHub Jenkinsfile)

In Jenkins UI:

  1. New Item
  2. Name: for example eks-text (your job name)
  3. Choose: Pipeline
  4. Click OK

Then configure:

Pipeline section

  • Definition: Pipeline script from SCM

  • SCM: Git

  • Repository URL:
    https://github.com/jumptotechschooldevops/cloud-guardrails.git

  • Branches to build:
    */main (or */master depending on your repo)

  • Script Path:
    01-eks-gatekeeper/Jenkinsfile

Save.

5) Fix #1 you hit: “Unable to find Jenkinsfile”

Reason: Jenkins was looking in wrong place.

Fix:

  • Ensure the Script Path matches exactly where Jenkinsfile is.
  • You confirmed correct path when Jenkins log showed:

Obtained 01-eks-gatekeeper/Jenkinsfile from git ...

So that part became correct.

6) Commit Jenkinsfile + required folders to GitHub

Inside your repo you created/edited:

cd cloud-guardrails/01-eks-gatekeeper
vim Jenkinsfile
tree
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You had:

  • Jenkinsfile

  • tests/

  • policies_backup/ (yaml)
    Later you added the real conftest policies folder:

  • policies/ (rego files)

Final working structure:

01-eks-gatekeeper/
  Jenkinsfile
  policies/
    deny-hostpath.rego
    deny-privileged.rego
  tests/
    bad-pod.yaml
    good-deployment.yaml
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Then push:

git add .
git commit -m "Add Jenkinsfile + policies + tests"
git push
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7) Fix #2 you hit: sudo password issue

Your pipeline originally did:

sudo mv conftest /usr/local/bin
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Jenkins cannot type sudo password → fails.

Fix:

  • Install conftest without sudo
  • Put it in workspace, mark executable, run from there.

8) Fix #3 you hit: “cannot execute binary file”

That happened because you downloaded the wrong conftest build for your platform/architecture.

Fix:

  • Download correct conftest for the machine running Jenkins.
  • You’re running Jenkins on Mac, so use Darwin build when running locally.

(When you later ran with correct binary + chmod, that error was gone.)

9) Fix #4 you hit: “no policies found in [policies_backup]”

Reason:

  • policies_backup/ had YAML constraints, not .rego policies.
  • conftest requires OPA Rego policies.

Fix:

  • Create a policies/ directory with .rego files:

Example (you created):

policies/
  deny-hostpath.rego
  deny-privileged.rego
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Then update Jenkinsfile to point to:

  • --policy policies

10) Final working Jenkinsfile approach (what made it succeed)

Key things your successful Jenkinsfile did:

  1. Run inside repo folder:

  • dir("01-eks-gatekeeper") { ... }

    1. Install conftest locally (no sudo)
    2. Run conftest against:

  • tests/

  • using policies from policies/

11) Configure GitHub Webhook to auto-trigger Jenkins on push

In GitHub repo:

  1. Settings → Webhooks → Add webhook
  2. Payload URL: 
https://temple-deontic-ansley.ngrok-free.dev/github-webhook/
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Important:

  • Must end with /github-webhook/
  1. Content type: application/json
  2. Events: Just the push event
  3. Add webhook

12) Enable Jenkins trigger for GitHub webhook

In Jenkins job config:

  • Build Triggers ✅ check GitHub hook trigger for GITScm polling

Save.

13) Verify it works

Test by pushing a commit

Make a small change:

echo "# test" >> 01-eks-gatekeeper/tests/bad-pod.yaml
git add .
git commit -m "trigger webhook test"
git push
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Expected result:

  • GitHub webhook shows 200 OK
  • Jenkins job starts automatically: “Started by GitHub push…”

14) What “success” looks like

In Jenkins console output, you should see:

  • Repo checked out
  • conftest installed (without sudo)
  • conftest test tests --policy policies

  • One of:

    • ✅ Policies passed
    • or ❌ failed (if bad yaml triggers deny)

Important notes (DevOps engineer best practice)

  • If ngrok URL changes (free plan does), you must update webhook URL in GitHub.
  • For production, don’t use ngrok — use a real public Jenkins endpoint behind TLS.
  • Keep Jenkins credentials secure (GitHub tokens, etc.).

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