ENH - os_builders: Update build.pkr.hcl with env

Using an input variable and conditional check we can set either the dev
or prod network ID at runtime. Rather than the user edit the file or
input it on the command line.

Before users had to edit build.pkr.hcl and update the network ID and set
it to either prod or dev.

Now users can just provide the flag --var env=prod when running packer
build and it will use the dev or prod ID depending on the value of the
variable.

The variable defaults to dev if not specified as a saftey catch.

Author: khalford

os_builders/README.md

@@ -91,21 +91,21 @@ The following steps assume you have set up your VM correctly as in the previous
 
 2. Initiate Packer image build for all images
    ```shell
-   packer build build.pkr.hcl
+   packer build --var env=dev build.pkr.hcl
    ```
 3. Intiate Packer image build for multiple images
    ```shell
    # Replace image-name with the actual image name. "openstack." is required
-   packer build -only <openstack.image-name>,<openstack.image-name>... build.pkr.hcl
+   packer build --var env=dev -only <openstack.image-name>,<openstack.image-name>... build.pkr.hcl
    # e.g.
-   packer build -only openstack.ubuntu-jammy-22.04-nogui,openstack.rocky-8-nogui build.pkr.hcl
+   packer build --var env=dev -only openstack.ubuntu-jammy-22.04-nogui,openstack.rocky-8-nogui build.pkr.hcl
    ```
 4. Initiate Packer image build for a single image
    ```shell
    # Replace image-name with the actual image name. "openstack." is required
-   packer build -only <openstack.image-name> build.pkr.hcl
+   packer build --var env=dev -only <openstack.image-name> build.pkr.hcl
    # e.g.
-   packer build -only openstack.ubuntu-jammy-22.04-nogui build.pkr.hcl
+   packer build --var env=dev -only openstack.ubuntu-jammy-22.04-nogui build.pkr.hcl
    ```
 5. Once the build completes successfully you should get a UUID of the new image
 

os_builders/build.pkr.hcl

@@ -11,7 +11,13 @@ packer {
   }
 }
 
+variable "env" {
+  type    = string
+  default = "dev"
+}
+
 locals {
+  env_network_id = var.env == "prod" ? "5be315b7-7ebd-4254-97fe-18c1df501538" : "fa2f5ebe-d0e0-4465-9637-e9461de443f1"
   date_suffix = "${formatdate("YYYY-MM-DD", timestamp())}"
   metadata = {
     "hw_machine_type" : "q35",
@@ -43,7 +49,7 @@ source "openstack" "builder" {
   domain_name       = "Default"
   flavor            = "l3.imagecreate"
   security_groups   = ["default"]
-  networks          = ["fa2f5ebe-d0e0-4465-9637-e9461de443f1"]  # Dev OpenStack Network ID
+  networks          = ["${local.env_network_id}"]  
   image_visibility  = "private"
   ssh_timeout       = "20m"
   image_min_disk    = "20"