Agent skill

push-to-registry

Push Packer build metadata to HCP Packer registry for tracking and managing image lifecycle. Use when integrating Packer builds with HCP Packer for version control and governance.

View SKILL.md on GitHub Repository
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Forks 60

Install this agent skill to your Project

npx add-skill https://github.com/hashicorp/agent-skills/tree/main/packer/hcp/skills/push-to-registry

SKILL.md

Push to HCP Packer Registry

Configure Packer templates to push build metadata to HCP Packer registry.

Reference: HCP Packer Registry

Note: HCP Packer is free for basic use. Builds push metadata only (not actual images), adding minimal overhead (<1 minute).

Basic Registry Configuration

hcl
packer {
  required_version = ">= 1.7.7"
}

variable "image_name" {
  type    = string
  default = "web-server"
}

locals {
  timestamp = regex_replace(timestamp(), "[- TZ:]", "")
}

source "amazon-ebs" "ubuntu" {
  region        = "us-west-2"
  instance_type = "t3.micro"

  source_ami_filter {
    filters = {
      name = "ubuntu/images/*ubuntu-jammy-22.04-amd64-server-*"
    }
    most_recent = true
    owners      = ["099720109477"]
  }

  ssh_username = "ubuntu"
  ami_name     = "${var.image_name}-${local.timestamp}"
}

build {
  sources = ["source.amazon-ebs.ubuntu"]

  hcp_packer_registry {
    bucket_name = var.image_name
    description = "Ubuntu 22.04 base image for web servers"

    bucket_labels = {
      "os"   = "ubuntu"
      "team" = "platform"
    }

    build_labels = {
      "build-time" = local.timestamp
    }
  }

  provisioner "shell" {
    inline = [
      "sudo apt-get update",
      "sudo apt-get upgrade -y",
    ]
  }
}

Authentication

Set environment variables before building:

bash
export HCP_CLIENT_ID="your-service-principal-client-id"
export HCP_CLIENT_SECRET="your-service-principal-secret"
export HCP_ORGANIZATION_ID="your-org-id"
export HCP_PROJECT_ID="your-project-id"

packer build .

Create HCP Service Principal

  1. Navigate to HCP → Access Control (IAM)
  2. Create Service Principal
  3. Grant "Contributor" role on project
  4. Generate client secret
  5. Save client ID and secret

Registry Configuration Options

bucket_name (required)

The image identifier. Must stay consistent across builds!

hcl
bucket_name = "web-server"  # Keep this constant

bucket_labels (optional)

Metadata at bucket level. Updates with each build.

hcl
bucket_labels = {
  "os"        = "ubuntu"
  "team"      = "platform"
  "component" = "web"
}

build_labels (optional)

Metadata for each iteration. Immutable after build completes.

hcl
build_labels = {
  "build-time" = local.timestamp
  "git-commit" = var.git_commit
}

CI/CD Integration

GitHub Actions

yaml
name: Build and Push to HCP Packer

on:
  push:
    branches: [main]

env:
  HCP_CLIENT_ID: ${{ secrets.HCP_CLIENT_ID }}
  HCP_CLIENT_SECRET: ${{ secrets.HCP_CLIENT_SECRET }}
  HCP_ORGANIZATION_ID: ${{ secrets.HCP_ORGANIZATION_ID }}
  HCP_PROJECT_ID: ${{ secrets.HCP_PROJECT_ID }}

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: hashicorp/setup-packer@main

      - name: Build and push
        run: |
          packer init .
          packer build \
            -var "git_commit=${{ github.sha }}" \
            .

Querying in Terraform

hcl
data "hcp_packer_artifact" "ubuntu" {
  bucket_name  = "web-server"
  channel_name = "production"
  platform     = "aws"
  region       = "us-west-2"
}

resource "aws_instance" "web" {
  ami           = data.hcp_packer_artifact.ubuntu.external_identifier
  instance_type = "t3.micro"

  tags = {
    PackerBucket = data.hcp_packer_artifact.ubuntu.bucket_name
  }
}

Common Issues

Authentication Failed

  • Verify HCP_CLIENT_ID and HCP_CLIENT_SECRET
  • Ensure service principal has Contributor role
  • Check organization and project IDs

Bucket Name Mismatch

  • Keep bucket_name consistent across builds
  • Don't include timestamps in bucket_name
  • Creates new bucket if name changes

Build Fails

  • Packer fails immediately if can't push metadata
  • Prevents drift between artifacts and registry
  • Check network connectivity to HCP API

Best Practices

  • Consistent bucket names - Never change for same image type
  • Meaningful labels - Use for versions, teams, compliance
  • CI/CD automation - Automate builds and registry pushes
  • Immutable build labels - Put changing data (git SHA, date) in build_labels

References

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