Multipurpose Packer Templates

What is a Multipurpose Packer Templates

We’ve now gotten to a point that I have probably the most experience with, and that is with Packer. After Terraform, Packer was the next HashiCorp tool that I picked up. Thankfully, the syntax moved from JSON to HCL a couple of years ago at this point.

Limitations

The downside with Packer are some of its limitations, specifically with meta-arguments.

Workarounds

So there are a couple of workarounds.

Dynamic Blocks

Dynamic blocks are similar to Terraform, where you can run a foreach against it, and it will loop through the input.

Shared Resources

When using shared scripts or files, I would recommend using environment_vars on the provisioners and have them specific for the build or source platform you will build on.

Additional Support

There are a couple of other ways I keep my templates generalized.

Tree Structure

The tree below is a work in progress, which I will later reference, but it is close to the final product.

└── packer
    ├── builds
    │   ├── app
    │   │   ├── build.pkr.hcl
    │   │   ├── hcp.pkr.hcl
    │   │   ├── locals.pkr.hcl
    │   │   ├── plugins.pkr.hcl
    │   │   ├── source_aws.pkr.hcl
    │   │   ├── source_azure.pkr.hcl
    │   │   ├── source_gce.pkr.hcl
    │   │   ├── variables_aws.pkr.hcl
    │   │   ├── variables_azure.pkr.hcl
    │   │   ├── variables_common.pkr.hcl
    │   │   └── variables_hcp.pkr.hcl
    │   └── base
    │       ├── build.pkr.hcl
    │       ├── locals.pkr.hcl
    │       ├── plugins.pkr.hcl
    │       ├── source_aws.pkr.hcl
    │       ├── source_azure.pkr.hcl
    │       ├── source_gce.pkr.hcl
    │       ├── variables_aws.pkr.hcl
    │       ├── variables_azure.pkr.hcl
    │       ├── variables_common.pkr.hcl
    │       └── variables_hcp.pkr.hcl
    ├── pkrvars
    │   ├── os
    │   │   ├── linux
    │   │   │   ├── debian
    │   │   │   │   ├── base.pkrvars.hcl
    │   │   │   │   ├── nomad.pkrvars.hcl
    │   │   │   │   ├── packer.pkrvars.hcl
    │   │   │   │   ├── terraform.pkrvars.hcl
    │   │   │   │   └── vault.pkrvars.hcl
    │   │   │   └── rhel
    │   │   └── windows
    │   │       └── base.pkrvars.hcl
    │   └── sources
    │       └── sources.pkrvars.hcl
    └── shared
        ├── README.MD
        ├── bootstrap
        │   └── bootstrap_win.txt
        ├── files
        ├── playbooks
        │   └── readme.md
        └── scripts
            ├── debian
            │   ├── base.sh
            │   ├── deprovision-aws.sh
            │   ├── deprovision-azure.sh
            │   ├── deprovision-google.sh
            │   ├── docker.sh
            │   └── nomad.sh
            ├── rhel
            └── windows
                ├── base.ps1
                ├── deprovision-aws.ps1
                ├── deprovision-azure.ps1
                └── deprovision-google.ps1

Conclusion

In this article, I have shown how to create a multipurpose Packer template that can be used for various cloud providers and on-premise hosting solutions. By using dynamic blocks and variables, you can create a template that can be easily customized for different use cases.

FAQs

Q: What are the limitations of Packer?
A: Packer has limitations with meta-arguments, which can make it difficult to create complex templates.

Q: How do I create a multipurpose Packer template?
A: You can create a multipurpose Packer template by using dynamic blocks and variables to customize the template for different use cases.

Q: What is the best way to organize my Packer templates?
A: The best way to organize your Packer templates is to use a structured directory layout, such as the one shown in this article.

Q: Can I use Packer to create images for multiple cloud providers?
A: Yes, Packer can be used to create images for multiple cloud providers, such as AWS, Azure, and GCP.