CI/CD pipeline setup in Deno

Introduction

A CI/CD pipeline helps automatically test and deliver your code changes fast and safely.

You want to automatically check your code for errors when you save changes.

You want to deploy your app to a server or cloud without doing it manually.

You want to run tests every time you add new features to catch bugs early.

You want to speed up your team's work by automating repetitive steps.

You want to make sure your app is always up-to-date with the latest code.

Syntax

Deno

steps:
  - name: Run tests
    run: deno test
  - name: Build app
    run: deno bundle main.ts bundle.js
  - name: Deploy
    run: ./deploy.sh

Each step runs a command or script in order.

Use deno test to run tests and deno bundle to prepare code for deployment.

Examples

This step runs all tests in your Deno project.

Deno

steps:
  - name: Run tests
    run: deno test

This step bundles your Deno app into a single JavaScript file.

Deno

steps:
  - name: Build app
    run: deno bundle main.ts bundle.js

This step runs a deployment script to update your live app.

Deno

steps:
  - name: Deploy
    run: ./deploy.sh

Sample Program

This simple CI/CD pipeline runs tests, builds the app, and deploys it automatically.

Deno

steps:
  - name: Run tests
    run: deno test
  - name: Build app
    run: deno bundle main.ts bundle.js
  - name: Deploy
    run: ./deploy.sh

Important Notes

Make sure your deploy.sh script has execute permission (chmod +x deploy.sh).

Keep your tests fast and reliable to avoid slowing down the pipeline.

Use environment variables to keep secrets safe during deployment.

Summary

CI/CD pipelines automate testing and deployment to save time and reduce errors.

Use deno test to check your code and deno bundle to prepare it for deployment.

Write simple steps that run commands in order to build your pipeline.

Practice

1. What is the main purpose of setting up a CI/CD pipeline for a Deno project?

easy

A. To automate testing and deployment processes

B. To write code faster manually

C. To increase the size of the project files

D. To disable automatic updates

Solution

1. Step 1: Understand CI/CD pipeline purpose

   A CI/CD pipeline automates repetitive tasks like testing and deployment to save time and reduce errors.

2. Step 2: Match purpose to options

   Only To automate testing and deployment processes describes automation of testing and deployment, which is the main goal.

3. Final Answer:

   To automate testing and deployment processes -> Option A

4. Quick Check:

   CI/CD automates testing and deployment = A [OK]

Hint: CI/CD means automating build, test, and deploy steps [OK]

Common Mistakes:

• Thinking CI/CD is about writing code manually
• Confusing CI/CD with increasing file size
• Believing CI/CD disables updates

2. Which of the following is the correct command to run tests in a Deno CI/CD pipeline?

easy

A. deno test

B. deno run test

C. deno build test

D. deno deploy test

Solution

1. Step 1: Recall Deno test command

   The official command to run tests in Deno is deno test.

2. Step 2: Compare options with correct syntax

   Only deno test matches the correct command syntax for running tests.

3. Final Answer:

   deno test -> Option A

4. Quick Check:

   Run tests with 'deno test' = A [OK]

Hint: Use 'deno test' to run tests, not 'deno run test' [OK]

Common Mistakes:

• Using 'deno run test' which runs a script, not tests
• Confusing build or deploy commands with test command
• Adding extra words like 'build' or 'deploy' incorrectly

3. Given this CI step in a Deno pipeline:

steps:
  - name: Run tests
    run: deno test --unstable
  - name: Bundle code
    run: deno bundle mod.ts bundle.js

What will be the result if tests fail?

medium

A. The pipeline skips tests and bundles code

B. The pipeline stops and does not bundle the code

C. The pipeline continues and bundles the code anyway

D. The pipeline deletes the bundle.js file

Solution

1. Step 1: Understand default pipeline behavior on failure

   In most CI/CD systems, if a test step fails, the pipeline stops to prevent deploying broken code.

2. Step 2: Apply to given steps

   If deno test --unstable fails, the next step to bundle code will not run.

3. Final Answer:

   The pipeline stops and does not bundle the code -> Option B

4. Quick Check:

   Failed tests stop pipeline = C [OK]

Hint: Failed tests usually stop pipeline to avoid bad deploys [OK]

Common Mistakes:

• Assuming pipeline continues after test failure
• Thinking tests are skipped automatically
• Believing files get deleted on test failure

4. You wrote this pipeline step:

steps:
  - name: Bundle code
    run: deno bundle mod.ts -o bundle.js

But the pipeline fails with an error. What is the likely cause?

medium

A. The pipeline requires 'deno test' before bundling

B. The file 'mod.ts' does not exist

C. The 'run' keyword is misspelled

D. The '-o' flag is not valid for 'deno bundle'

Solution

1. Step 1: Check 'deno bundle' syntax

   The correct syntax to specify output file is: deno bundle input.ts output.js without '-o' flag.

2. Step 2: Identify error cause

   Using '-o' causes an error because 'deno bundle' does not support it.

3. Final Answer:

   The '-o' flag is not valid for 'deno bundle' -> Option D

4. Quick Check:

   Output file is positional, no '-o' flag = D [OK]

Hint: Use positional output filename, not '-o', with deno bundle [OK]

Common Mistakes:

• Adding '-o' flag like other bundlers
• Assuming file existence without checking
• Thinking 'run' keyword is wrong
• Believing tests must run before bundling always

5. You want to create a CI/CD pipeline that runs tests, bundles code, and then deploys only if tests pass. Which YAML snippet correctly represents this sequence?

hard

A. steps:
- run: deno bundle mod.ts bundle.js
- run: deno test
- run: deploy.sh

B. steps:
- run: deploy.sh
- run: deno test
- run: deno bundle mod.ts bundle.js

C. steps:
- run: deno test
- run: deno bundle mod.ts bundle.js
- run: deploy.sh

D. steps:
- run: deno test
- run: deploy.sh
- run: deno bundle mod.ts bundle.js

Solution

1. Step 1: Determine correct order for CI/CD steps

   Tests must run first to verify code, then bundle code, then deploy if tests pass.

2. Step 2: Match order with options

   Only steps: - run: deno test - run: deno bundle mod.ts bundle.js - run: deploy.sh runs tests first, then bundles, then deploys.

3. Final Answer:

   Tests first, then bundle, then deploy -> Option C

4. Quick Check:

   Test -> Bundle -> Deploy = B [OK]

Hint: Test first, then bundle, then deploy in pipeline steps [OK]

Common Mistakes:

• Deploying before tests run
• Bundling before tests
• Changing step order incorrectly