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Define a CI Build Infrastructure in Google Cloud Platform


Currently, this feature is behind the Feature Flag CI_VM_INFRASTRUCTURE. Contact Harness Support to enable the feature.

This topic describes how to set up a CI build infrastructure in Google Cloud Platform. You will create an Ubuntu VM and install a CI Delegate and Drone Runner on it. The Delegate creates VMs dynamically in response to CI build requests.

Running builds in your infrastructure, rather than in a vendor's cloud, has significant benefits. Vendor clouds often experience outages that can result in backlogs and delayed builds. You can build software and run tests, repeatedly and automatically, on a scalable platform with no outages or backlogs.

For information on using Kubernetes as a build farm, see Define Kubernetes Cluster Build Infrastructure.

The following diagram illustrates a build farm. The ​Harness Docker Delegate communicates directly with your Harness instance. The VM Runner maintains a pool of VMs for running builds. When the Delegate receives a build request, it forwards the request to the Runner, which runs the build on an available VM.

CI build infrastructure in Google Cloud Platform

Important Notes

  • Google Cloud VM configuration:
    • For the Delegate VM, use a machine type with 4 vCPU and 16 GB memory or more.
    • Harness recommends the Ubuntu 18.04 LTS (Bionic) machine image.
    • The VM must allow ingress access on ports 22 and 9079.

To find images to use on google compute engine, use the following command:

gcloud compute images list

A valid image reference looks like this: projects/{PROJECT}/global/images/{IMAGE} 

For example: projects/docs-test/global/images/ubuntu-pro-1804-bionic-v20220131

Step 1: Set up the delegate VM

  1. Log into the Google Cloud Console and launch the VM that will host your Harness delegate.

  2. Install Docker on the VM.

  3. Install Docker Compose on the VM. You must have Docker Compose version 3.7 or higher installed.

  4. Run this command on the VM:

    gcloud auth application-default login

    This creates the following credentials file:


  5. Create a /runner folder on your VM and cd into it:

    mkdir /runner  
    cd /runner

Step 2: Configure the Drone pool on the Google VM

The .drone_pool.yml file defines the VM spec and pool size for the VM instances used to run the Pipeline. A pool is a group of instantiated VMs that are immediately available to build CI Pipelines.

  1. In the /runner folder, create a new .drone_pool.yml file.
  2. Set up the file as described in the following example. Note the following:
    1. To avoid latency issues between delegate and build VMs, specify the same zone where your delegate is running in the spec: zone: field.
    2. Set up spec: account: with your Google project ID and your JSON credentials file.
    3. See pool.yml Settings Reference below for details on specific settings. See also Drone Pool) and Google in the Drone docs.
Example pool.yaml
version: "1"  
- name: ubuntu-gcp
default: true
type: google
pool: 1
os: linux
arch: amd64
project_id: docs-play
key: /path/to/application_default_credentials.json
image: projects/ubuntu-os-pro-cloud/global/images/ubuntu-pro-1804-bionic-v20220510
machine_type: e2-small
- us-west1-a

Later in this workflow, you'll reference the pool identifier in Harness Manager to map the pool with a Stage Infrastructure in a CI Pipeline. This is described later in this topic.

Step 3: Create the Docker-Compose YAML

  1. Navigate to the Delegates page for your Harness account, organization, or project.
  2. Click New Delegate and select Docker.
  3. Follow the steps in Install the Docker Delegate and download the docker-compose.yaml file to your local machine.

Step 4: Configure the 'docker-compose.yml' file

The runner and delegate are both hosted on the same VM. The Runner communicates with the Harness Delegate on localhost and port 3000 of your VM. 

In this step, you'll add the Runner spec to the new Delegate definition. 

  1. Copy your local docker-compose.yaml to the /runner folder on the VM. This folder should now have docker-compose.yaml and .drone_pool.yml.

  2. Append the following to docker-compose.yaml.

    restart: unless-stopped
    image: drone/drone-runner-aws:latest
    - /runner:/runner
    - /path/to/google/credentials/file/:/key
    # example: /home/jsmith/.config/gcloud/:/key
    entrypoint: ["/bin/drone-runner-aws", "delegate", "--pool", "pool.yml"]
    working_dir: /runner
    - "3000:3000"
  3. In the docker-compose.yaml file, add the following under services: harness-ng-delegate: restart: unless-stopped:

    network_mode: "host"

Your Docker Compose file now looks something like this:

Updated docker-compose.yml
version: "3.7"  
restart: unless-stopped
network_mode: "host"
cpus: "0.5"
memory: 2048M
image: harness/delegate:latest
- WATCHER_CHECK_LOCATION=current.version
- USE_CDN=true
- NEXT_GEN=true
- INIT_SCRIPT=echo "Docker delegate init script executed."
restart: unless-stopped
image: drone/drone-runner-aws:latest
- /runner:/runner
- /home/jsmith/.config/gcloud/:/key
entrypoint: ["/bin/drone-runner-aws", "delegate", "--pool", "pool.yml"]
working_dir: /runner
- "3000:3000"

Step 5: Install the Delegate and Runner

  1. SSH into the Delegate VM and cd to /runner.

  2. Confirm that the folder has both setup files:

    $ ls -a  
    .  ..  docker-compose.yml  .drone_pool.yml 
  3. Install the Delegate and Runner:

    $ docker-compose -f docker-compose.yml up -d
  4. Verify that both containers are running correctly. You might need to wait a few minutes for both processes to start.

    $ docker ps  
    $ docker logs <delegate-container-id>
    $ docker logs <runner-container-id>
  5. In the Harness UI, verify that the delegate appears in the delegates list. This might take two or three minutes. You should see Connected next to the Delegate listing.

  6. If you see Not Connected, make sure the Docker host can connect to

    The Delegate and Runner have now been successfully installed, registered, and connected.

    To configure the Harness Docker Delegate, see Harness Docker Delegate Environment Variables.

Step 6: Run a CI build

  1. In the Harness CI Stage, in Infrastructure, select VMs.

  2. In the Pool ID, enter the pool name <pool_id> that you added in Step 2: Configure the Drone Pool on the Google VM.

You can now run builds in your GCP build infrastructure.

Pool Settings Reference

You can configure the following settings in your pool.yml file.

name (String)NAname: windows_pool
pool (Integer)NApool: 1
limit (Integer)NAlimit: 3
platformos (String) platform: os: windowsarch (String)
specConfigure the settings of your build VMs as described in Build VM Settings.

Build VM Settings

  • account  — Specify your GCP project Id and the full path and filename of your local Google credentials file.
  • image  — The image type to use for the build VM.
  • machine_type  — The google machine type. See About Machine Families in the Google Cloud docs.
  • zone  —  To minimize latency, specify the zone where the Delegate is running.

Troubleshooting (Advanced)

If you have problems running the delegate, runner, or VMs, you can collect debug and trace information in your container logs.

  1. Create a .env file with the following options in your /runner folder:
  2. Shut down the delegate and runner: docker-compose down
  3. In your docker-compose.yml file, update the drone-runner-aws: entrypoint to include the .env file:
    restart: unless-stopped
    image: drone/drone-runner-aws:1.0.0-rc.9
    - /runner:/runner
    - /home/jsmith/.config/gcloud/:/key
    entrypoint: ["/bin/drone-runner-aws", "delegate", "--envfile", ".env", "--pool", "pool.yml"]
    working_dir: /runner
    - "3000:3000"
  4. Restart the delegate and runner: docker-compose up

See Also