Change Deployment Replica Count

In this guide, we will create a self-service action in Port that executes a GitHub workflow to change the number of replica counts in a kubernetes deployment. The workflow involves updating the deployment manifest with the new replica count(s) and creating a Github pull request (PR) for it. The workflow can optionally merge the PR when enabled.

Prerequisites

1. Install Port's GitHub app by clicking here
2. This guide assumes the presence of a Service blueprint representing the repository where ArgoCD or Kubernetes workload lives
3. A repository to contain your deployment manifest and action resources i.e. the github workflow file

Below you can find the JSON for the Service blueprint required for the guide:

Service blueprint (click to expand)

{
  "identifier": "service",
  "title": "Service",
  "icon": "Github",
  "schema": {
    "properties": {
      "readme": {
        "title": "README",
        "type": "string",
        "format": "markdown",
        "icon": "Book"
      },
      "url": {
        "title": "URL",
        "format": "url",
        "type": "string",
        "icon": "Link"
      },
      "language": {
        "icon": "Git",
        "type": "string",
        "title": "Language",
        "enum": [
          "GO",
          "Python",
          "Node",
          "React"
        ],
        "enumColors": {
          "GO": "red",
          "Python": "green",
          "Node": "blue",
          "React": "yellow"
        }
      },
      "slack": {
        "icon": "Slack",
        "type": "string",
        "title": "Slack",
        "format": "url"
      },
      "code_owners": {
        "title": "Code owners",
        "description": "This service's code owners",
        "type": "string",
        "icon": "TwoUsers"
      },
      "type": {
        "title": "Type",
        "description": "This service's type",
        "type": "string",
        "enum": [
          "Backend",
          "Frontend",
          "Library"
        ],
        "enumColors": {
          "Backend": "purple",
          "Frontend": "pink",
          "Library": "green"
        },
        "icon": "DefaultProperty"
      },
      "lifecycle": {
        "title": "Lifecycle",
        "type": "string",
        "enum": [
          "Production",
          "Experimental",
          "Deprecated"
        ],
        "enumColors": {
          "Production": "green",
          "Experimental": "yellow",
          "Deprecated": "red"
        },
        "icon": "DefaultProperty"
      },
      "locked_in_prod": {
        "icon": "DefaultProperty",
        "title": "Locked in Prod",
        "type": "boolean",
        "default": false
      },
      "locked_reason_prod": {
        "icon": "DefaultProperty",
        "title": "Locked Reason Prod",
        "type": "string"
      }
    },
    "required": []
  },
  "mirrorProperties": {},
  "calculationProperties": {},
  "aggregationProperties": {},
  "relations": {}
}

Create Github workflow

Follow these steps to get started:

1. Create the following GitHub Action secrets:
   • PORT_CLIENT_ID - Port Client ID learn more
   • PORT_CLIENT_SECRET - Port Client Secret learn more
   • MY_GITHUB_TOKEN - a Classic Personal Access Token with the repo scope and the following permissions: pull_requests:write (to create PR) and contents:write (to merge PR)

2. Create a Port action in the self-service page on the Service blueprint with the following JSON definition:

Port Action: Change Replica Count

tip

• <GITHUB-ORG> - your GitHub organization or user name.
• <GITHUB-REPO-NAME> - your GitHub repository name.

{
  "identifier": "service_change_replica_count",
  "title": "Change Replica Count",
  "icon": "GithubActions",
  "trigger": {
    "type": "self-service",
    "operation": "DAY-2",
    "userInputs": {
      "properties": {
        "replica_count": {
          "icon": "DefaultProperty",
          "title": "Number of Replicas",
          "type": "number"
        },
        "auto_merge": {
          "title": "Auto Merge",
          "type": "boolean",
          "default": false,
          "description": "Whether the created PR should be merged or not"
        }
      },
      "required": [
        "replica_count"
      ],
      "order": [
        "replica_count",
        "auto_merge"
      ]
    },
    "blueprintIdentifier": "service"
  },
  "invocationMethod": {
    "type": "GITHUB",
    "org": "<GITHUB-ORG>",
    "repo": "<GITHUB-REPO-NAME>",
    "workflow": "change-replica-count.yaml",
    "workflowInputs": {
      "replica_count": "{{.inputs.\"replica_count\"}}",
      "auto_merge": "{{.inputs.\"auto_merge\"}}",
      "port_context": {
        "entity": "{{.entity.identifier}}",
        "blueprint": "{{.action.blueprint}}",
        "runId": "{{.run.id}}",
        "trigger": "{{.trigger}}"
      }
    },
    "reportWorkflowStatus": true
  },
  "requiredApproval": false,
  "publish": true
}

3. Create a workflow file under .github/workflows/change-replica-count.yml with the following content:

GitHub workflow script

Variable replacement

• <DEPLOYMENT-MANIFEST-PATH> - Path to the ArgoCD or K8s deployment manifest such as app/deployment.yaml.
• <REPLICA-PROPERTY-PATH> - Path to where the deployment replica count is specified in the deployment manifest such as spec.replicas.

change-replica-count.yml

name: Change Replica Count

on:
  workflow_dispatch:
    inputs:
      replica_count:
        description: The new replica count for the deployment
        required: true
        type: string
      auto_merge:
        description: Whether the created PR should be merged automatically
        required: true
        type: boolean
      port_context:
        required: true
        description: >-
          Port's payload, including details for who triggered the action and
          general context (blueprint, run id, etc...)
jobs:
  change-replica-count:
    runs-on: ubuntu-latest
    steps:
      - name: Inform execution of request to change replica count
        uses: port-labs/port-github-action@v1
        with:
          clientId: ${{ secrets.PORT_CLIENT_ID }}
          clientSecret: ${{ secrets.PORT_CLIENT_SECRET }}
          baseUrl: https://api.getport.io
          operation: PATCH_RUN
          runId: ${{fromJson(github.event.inputs.port_context).runId}}
          logMessage: "About to change replica count in deployment manifest..."

      - uses: actions/checkout@v4
      - name: Create PR
        id: create-pr
        uses: fjogeleit/yaml-update-action@main
        with:
          valueFile: '<DEPLOYMENT-MANIFEST-PATH>'  ## replace value
          propertyPath: '<REPLICA-PROPERTY-PATH>' ## replace value
          value: "!!int '${{ fromJson(github.event.inputs.replica_count) }}'"  ## using the yaml tag (!!int 'X') to convert the string to int
          commitChange: true
          token: ${{ secrets.MY_GITHUB_TOKEN }}
          targetBranch: main
          masterBranchName: main
          createPR: true
          branch: deployment/${{ fromJson(github.event.inputs.port_context).runId }}
          message: 'Update deployment replica to ${{ github.event.inputs.replica_count }}'
          
      - name: Inform Port about pull request creation status - Success
        if: steps.create-pr.outcome == 'success'
        uses: port-labs/port-github-action@v1
        with:
          clientId: ${{ secrets.PORT_CLIENT_ID }}
          clientSecret: ${{ secrets.PORT_CLIENT_SECRET }}
          baseUrl: https://api.getport.io
          operation: PATCH_RUN
          runId: ${{ fromJson(github.event.inputs.port_context).runId }}
          logMessage: |
            'The creation of PR was successful: ${{fromJson(steps.create-pr.outputs.pull_request).html_url}}'
          link: '["${{fromJson(steps.create-pr.outputs.pull_request).html_url}}"]'
      
      - name: Inform Port about pull request creation status - Failure
        if: steps.create-pr.outcome != 'success'
        uses: port-labs/port-github-action@v1
        with:
          clientId: ${{ secrets.PORT_CLIENT_ID }}
          clientSecret: ${{ secrets.PORT_CLIENT_SECRET }}
          baseUrl: https://api.getport.io
          operation: PATCH_RUN
          runId: ${{ fromJson(github.event.inputs.port_context).runId }}
          logMessage: |
            The creation of PR was not successful.
  
      - name: Merge Pull Request
        if: ${{ github.event.inputs.auto_merge == 'true' && steps.create-pr.outcome == 'success' }}
        env:
          GH_TOKEN: ${{ secrets.MY_GITHUB_TOKEN }}
          PR_URL: ${{ fromJson(steps.create-pr.outputs.pull_request).url }}
        run: |
          HTTP_STATUS=$(curl -s -o /dev/null -w "%{http_code}" \
            -X PUT \
            -H "Accept: application/vnd.github+json" \
            -H "Authorization: Bearer $GH_TOKEN" \
            "$PR_URL/merge")

          echo "HTTP Status: $HTTP_STATUS"

          if [ $HTTP_STATUS -eq 200 ]; then
            echo "Pull request merged successfully."
            echo "merge_status=successful" >> $GITHUB_ENV
          else
            echo "Failed to merge PR. HTTP Status: $HTTP_STATUS"
            echo "merge_status=unsuccessful" >> $GITHUB_ENV
          fi

      - name: Inform completion of replica update operation to Port
        if: ${{ github.event.inputs.auto_merge == 'true' }}
        uses: port-labs/port-github-action@v1
        with:
          clientId: ${{ secrets.PORT_CLIENT_ID }}
          clientSecret: ${{ secrets.PORT_CLIENT_SECRET }}
          baseUrl: https://api.getport.io
          operation: PATCH_RUN
          runId: ${{fromJson(github.event.inputs.port_context).runId}}
          logMessage: 'Pull request merge was ${{ env.merge_status }}'

4. Trigger the action from the self-service page of your Port application.

You should now be able to see a Github pull request created and merged for the deployment: