Google MIG Deploy

The Google MIG Deploy step creates a new version of the instance template and, if the instance group doesn't exist, creates the instance group.

Prerequisites

• This step must be added within a Container Step Group. The step runs as a containerized task and requires the container infrastructure configuration provided by the step group.
• A Download Manifests step must be added before this step to fetch the required manifest files (instance template, MIG manifest, etc.) from your configured manifest store.

Deployment flow

1. Download Manifests: Fetches all manifest files (instance template, MIG configuration, autoscaler, health check) from your configured manifest store and makes them available for subsequent steps.

2. Google MIG Deploy: Reads the downloaded manifests and executes the deployment by creating the instance template version and provisioning the MIG in GCP.

What this step does

• Creates a new version of the instance template based on your manifest configuration
• Creates the instance group if it doesn't exist
• Applies the target size configuration to the MIG

Required manifests

This step requires the following manifest files configured in your service:

• Instance template: Defines the VM configuration (machine type, boot disk, network interfaces, startup scripts, metadata, labels)
• MIG manifest: Defines the Managed Instance Group configuration (distribution policy, update policy, constraints)
• Autoscaler manifest (optional): Defines autoscaling rules based on metrics
• Health check configuration (optional): Defines health check settings for instance monitoring

Step parameters

Parameter	Description	Required
MIG Name	The name of the Managed Instance Group to deploy. This should be a unique identifier for your MIG (e.g., basic-deploy-testing-2).	Yes
Target Size	The desired number of instances to maintain in the MIG (e.g., 1, 3, 5).	Yes
Timeout	Maximum time allowed for the step to complete (default: 10m).	No

Container configuration

Parameter	Description
Container Registry	Harness connector for authenticating to your container registry. This connector pulls the deployment plugin image.
Image	The deployment plugin container image. Use the official Harness image: harness/google-mig-deploy:0.0.1-linux-amd64

Stepgroup YAML

- stepGroup:
    name: Deployment MIG
    identifier: blueGreenDeployment
    steps:
      - step:
          type: DownloadManifests
          name: Download Manifests
          identifier: DownloadManifests
          spec: {}
          failureStrategies: []
      - step:
          type: GoogleMigDeploy
          name: GoogleMigDeploy
          identifier: GoogleMigDeploy
          spec:
            connectorRef: account.harnessImage
            mig: mig-pool-1
            image: harness/google-mig-deploy:0.0.1-linux-amd64
            targetSize: 4
          timeout: 10m
    stepGroupInfra:
      type: KubernetesDirect
      spec:
        connectorRef: k8s-connector
        namespace: default