> For the complete documentation index, see [llms.txt](https://developer.harness.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.harness.io/continuous-delivery/use-continuous-delivery/deploy-services-on-different-platforms/google-cloud-functions/mig/step-references/deploy-mig.md).

# 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.

{% hint style="info" %}
**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.

  <figure><img src="/files/VLp1hRHXSePZdV89ESOm" alt=""><figcaption><p>Click to view full size image</p></figcaption></figure>

{% endhint %}

## Deployment flow <a href="#deployment-flow" id="deployment-flow"></a>

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.

<figure><img src="/files/UeIwtAmzS8arUR2ZAfkJ" alt=""><figcaption><p>Click to view full size image</p></figcaption></figure>

## What this step does <a href="#what-this-step-does" id="what-this-step-does"></a>

* 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 <a href="#required-manifests" id="required-manifests"></a>

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 <a href="#step-parameters" id="step-parameters"></a>

| 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 <a href="#container-configuration" id="container-configuration"></a>

| 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`](https://hub.docker.com/r/harness/google-mig-deploy/tags) |

## Stepgroup YAML <a href="#stepgroup-yaml" id="stepgroup-yaml"></a>

```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
```