packer/README.markdown

# EdgeX CI Packer

[Packer][1] is a tool for automatically creating VM and container images,
configuring them and post-processing them into standard output formats.

We build the CI images via Packer.

## Building

You'll need to [install Packer][2], of course.

The Packer configuration is divided into build-specific variables,
output-specific templates and a set of shared provisioning scripts. To do a
specific build, combine the template for the desired output artifact type with
a variable file. To build a new baseline instance the following would be done:

```
packer build -var-file=vars/cloud-env.json -var-file=vars/centos.json templates/baseline.json
```

**NOTE:** vars/cloud-env.json is a gitignored file as it contains private
information. There is a vars/cloud-env.json.example file that may be used as a
base for creating the one needed.

From a high level, the build process is:

* Boot a specified base image in any defined clouds.
* Run a set of shell scripts, listed in the template's shell provisioner
  section, to do any configuration required by the builder.
* Execute a shutdown of the running instance in the clouds.
* Execute the cloud specific method for creating a new image from the shutdown
  instance
* Perform the cloud specific method for deleting the shutdown instance

[1]: https://www.packer.io/
[2]: https://www.packer.io/intro/getting-started/setup.html