Build triggers configuration in GCP - Mini Project: Build & Apply

Build triggers configuration

📖 Scenario: You are setting up an automated build process in Google Cloud Platform (GCP). This process will start a build whenever code is pushed to a specific branch in your repository.

🎯 Goal: Create a build trigger configuration that listens to pushes on the main branch of a GitHub repository and starts a build using a specified build configuration file.

📋 What You'll Learn

Create a dictionary named trigger_config with the exact keys and values for the build trigger.

Add a branch_name variable set to main to specify which branch triggers the build.

Use the trigger_config dictionary to set the trigger's branch filter using the branch_name variable.

Complete the build trigger configuration with the required fields for GitHub repository and build configuration file.

💡 Why This Matters

🌍 Real World

Automating builds on code changes helps teams deliver software faster and with fewer errors.

💼 Career

Understanding build triggers is essential for roles in DevOps, cloud engineering, and software development automation.

1

Create initial build trigger dictionary

Create a dictionary called trigger_config with these exact keys and values: 'name' set to 'my-build-trigger', 'description' set to 'Trigger for main branch builds', and 'github' set to an empty dictionary {}.

GCP

# Create the initial build trigger dictionary
# Your code here

Hint

Use a dictionary with keys 'name', 'description', and 'github'. Set 'github' to an empty dictionary.

2

Add branch name variable

Create a variable called branch_name and set it to the string 'main'.

GCP

trigger_config = {
    'name': 'my-build-trigger',
    'description': 'Trigger for main branch builds',
    'github': {}
}
# Create a variable called branch_name and set it to 'main'
# Your code here

Hint

Assign the string 'main' to the variable named branch_name.

3

Set branch filter in trigger configuration

Inside the trigger_config dictionary, set the github key to a dictionary with a key 'push' that contains another dictionary with the key 'branch' set to the variable branch_name.

GCP

trigger_config = {
    'name': 'my-build-trigger',
    'description': 'Trigger for main branch builds',
    'github': {}
}
branch_name = 'main'
# Set the branch filter inside trigger_config['github'] using branch_name
# Your code here

Hint

Update the 'github' key to include a nested dictionary for 'push' with 'branch' set to branch_name.

4

Complete build trigger with repo and build config

Add to trigger_config['github'] the keys 'owner' set to 'example-owner', 'name' set to 'example-repo', and add a key 'build' with a dictionary containing 'build_config' set to 'cloudbuild.yaml'.

GCP

branch_name = 'main'
trigger_config = {
    'name': 'my-build-trigger',
    'description': 'Trigger for main branch builds',
    'github': {
        'push': {
            'branch': branch_name
        }
    }
}
# Add 'owner', 'name', and 'build' keys to trigger_config['github']
# Your code here

Hint

Add the repository owner and name, and specify the build configuration file inside the 'github' dictionary.

Practice

1. What is the main purpose of a build trigger in Google Cloud Build?

easy

A. To monitor server health

B. To manually deploy an application

C. To automatically start a build when code changes occur

D. To create a new repository

Solution

1. Step 1: Understand build triggers role

   Build triggers watch for code changes and start builds automatically.

2. Step 2: Compare options with purpose

   Only To automatically start a build when code changes occur describes automatic build start on code changes.

3. Final Answer:

   To automatically start a build when code changes occur -> Option C

4. Quick Check:

   Build trigger = auto build start [OK]

Hint: Build triggers start builds automatically on code changes [OK]

Common Mistakes:

• Confusing triggers with manual deployment
• Thinking triggers monitor servers
• Assuming triggers create repositories

2. Which of the following is the correct syntax to specify a branch filter in a Cloud Build trigger YAML?

easy

A. trigger:
branchName: "^main$"

B. trigger:
branchName: "main"

C. trigger:
branch: "main"

D. trigger:
branchFilter: "main"

Solution

1. Step 1: Identify correct branch filter syntax

   Cloud Build uses regex in branchName to filter branches.

2. Step 2: Match regex syntax for main branch

   "^main$" matches exactly the main branch name.

3. Final Answer:

   trigger: branchName: "^main$" -> Option A

4. Quick Check:

   branchName uses regex = trigger: branchName: "^main$" [OK]

Hint: Use regex in branchName to filter branches [OK]

Common Mistakes:

• Using branch instead of branchName
• Not using regex anchors ^ and $
• Using incorrect field like branchFilter

3. Given this trigger configuration snippet:

trigger:
  branchName: "^release-.*$"
  build:
    steps:
    - name: "gcr.io/cloud-builders/docker"
      args: ["build", "-t", "gcr.io/my-project/my-app:$SHORT_SHA", "."]

What happens when a commit is pushed to branch release-v1.2?

medium

A. The build fails due to syntax error

B. The build starts and tags the image with the commit SHA

C. The build starts but tags the image with 'latest'

D. The build does not start because branch name does not match

Solution

1. Step 1: Check branchName regex against branch

   Regex "^release-.*$" matches any branch starting with 'release-', so 'release-v1.2' matches.

2. Step 2: Understand build step and tagging

   The build uses $SHORT_SHA to tag the image, so image is tagged with commit SHA.

3. Final Answer:

   The build starts and tags the image with the commit SHA -> Option B

4. Quick Check:

   Branch matches regex and tags with SHA = The build starts and tags the image with the commit SHA [OK]

Hint: Regex matches branch, build tags image with commit SHA [OK]

Common Mistakes:

• Assuming branch does not match regex
• Thinking image tags as 'latest'
• Confusing syntax error with correct YAML

4. You configured a build trigger with this YAML snippet:

trigger:
  branchName: "main"
  build:
    steps:
    - name: "gcr.io/cloud-builders/gcloud"
      args: ["app", "deploy"]

But the build never starts when you push to main. What is the likely error?

medium

A. The build steps are missing the Docker build command

B. The trigger YAML is missing the substitutions field

C. The trigger must specify a tagName instead of branchName

D. branchName should be a regex like "^main$"

Solution

1. Step 1: Check branchName format in trigger

   Cloud Build expects branchName as a regex pattern, not plain string.

2. Step 2: Correct branchName to regex

   Changing branchName to "^main$" matches exactly the main branch and triggers build.

3. Final Answer:

   branchName should be a regex like "^main$" -> Option D

4. Quick Check:

   branchName needs regex = branchName should be a regex like "^main$" [OK]

Hint: branchName must be regex, not plain text [OK]

Common Mistakes:

• Using plain branch name without regex anchors
• Confusing branchName with tagName
• Thinking substitutions are mandatory

5. You want to create a build trigger that starts only when a tag matching v* is pushed, and the build should run two steps: first build a Docker image, then deploy it. Which YAML snippet correctly configures this trigger?

hard

A. trigger:
tagName: "^v.*$"
build:
steps:
- name: "gcr.io/cloud-builders/docker"
args: ["build", "-t", "gcr.io/my-project/my-app:$TAG_NAME", "."]
- name: "gcr.io/cloud-builders/gcloud"
args: ["app", "deploy"]

B. trigger:
branchName: "^v.*$"
build:
steps:
- name: "gcr.io/cloud-builders/docker"
args: ["build", "-t", "gcr.io/my-project/my-app:$TAG_NAME", "."]
- name: "gcr.io/cloud-builders/gcloud"
args: ["app", "deploy"]

C. trigger:
tagName: "v*"
build:
steps:
- name: "gcr.io/cloud-builders/gcloud"
args: ["app", "deploy"]

D. trigger:
tagName: "^v.*$"
build:
steps:
- name: "gcr.io/cloud-builders/docker"
args: ["build", "-t", "gcr.io/my-project/my-app:latest", "."]

Solution

1. Step 1: Identify correct tag filter syntax

   Use tagName with regex "^v.*$" to match tags starting with 'v'.

2. Step 2: Verify build steps order and commands

   First step builds Docker image tagged with $TAG_NAME, second step deploys app.

3. Step 3: Check for errors in other options

   trigger: branchName: "^v.*$" build: steps: - name: "gcr.io/cloud-builders/docker" args: ["build", "-t", "gcr.io/my-project/my-app:$TAG_NAME", "."] - name: "gcr.io/cloud-builders/gcloud" args: ["app", "deploy"] uses branchName instead of tagName, C misses Docker build step, D tags image as latest without deploy step.

4. Final Answer:

   trigger: tagName: "^v.*$" build: steps: - name: "gcr.io/cloud-builders/docker" args: ["build", "-t", "gcr.io/my-project/my-app:$TAG_NAME", "."] - name: "gcr.io/cloud-builders/gcloud" args: ["app", "deploy"] -> Option A

5. Quick Check:

   tagName regex and two steps build+deploy = trigger: tagName: "^v.*$" build: steps: - name: "gcr.io/cloud-builders/docker" args: ["build", "-t", "gcr.io/my-project/my-app:$TAG_NAME", "."] - name: "gcr.io/cloud-builders/gcloud" args: ["app", "deploy"] [OK]

Hint: Use tagName regex and list all build steps in order [OK]

Common Mistakes:

• Using branchName instead of tagName for tags
• Missing one of the required build steps
• Incorrect tagName regex syntax