Add initial Packer definitions
Copy over the Packer definitions from ONOS since we've been asked to set
up the builders the same way initially.
Change-Id: I8c6e3cad05e4d4341ac58498d36810dac06f687f
Signed-off-by: Linux Foundation Administrators <collab-it+onlab@linuxfoundation.org>
diff --git a/packer/README.markdown b/packer/README.markdown
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+# 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