role: heat_stack - compress user data support

Add support for passing user data as a compressed archive.

Assisted-By: Claude Code/claude-4.5-sonnet
Signed-off-by: Harald Jensås <hjensas@redhat.com>

Author: hjensas

roles/heat_stack/README.md

@@ -6,6 +6,16 @@ input.
 When the stack has been successfully created/updated the stack output is stored
 in the `stack_outputs` fact, and also written to file.
 
+## Role Variables
+
+- `os_cloud`: OpenStack cloud name from clouds.yaml
+- `stack_name`: Name of the Heat stack to create/update
+- `stack_template_path`: Path to the Heat template file
+- `stack_parameters`: Dictionary of parameters to pass to the Heat template
+- `compress_heat_files`: (Optional) List of file archives to compress for use as user data. Each item should define:
+  - `archive`: Base name for the archive (without extension)
+  - `files`: List of files to include in the tar.gz archive
+
 ## Example playbook
 
 ```yaml
@@ -21,3 +31,57 @@ in the `stack_outputs` fact, and also written to file.
         stack_template_path: "{{ stack_template_path }}"
         stack_parameters: "{{ stack_parameters }}"
 ```
+
+## Compressing files for user data
+
+When you need to pass multiple files as user data to instances, you can use the
+`compress_heat_files` variable to create compressed tar archives that are base64
+encoded. This is useful for passing scripts, configuration files, or other data
+that instances need at boot time.
+
+```yaml
+- name: Deploy stack with compressed user data
+  hosts: localhost
+  roles:
+    - role: heat_stack
+      vars:
+        ...
+        compress_heat_files:
+          - archive: "data"
+            files:
+              - "script.sh"
+              - "config.yaml"
+              - "setup.py"
+```
+
+The role will create `data.tar.gz` and `data.tar.gz.b64` files in the same
+directory as the stack template. The base64-encoded version can then be referenced
+in your Heat template using `get_file`.
+
+### Heat template example
+
+```yaml
+resources:
+  server-write-files:
+    type: OS::Heat::CloudConfig
+    properties:
+      cloud_config:
+        write_files:
+          - path: /tmp/data.tar.gz
+            encoding: b64
+            content: {get_file: archive.tar.gz.b64}
+            owner: root:root
+            permissions: '0644'
+
+  server-runcmd:
+    type: OS::Heat::CloudConfig
+    properties:
+      cloud_config:
+        runcmd:
+          - ['tar', '-xzf', '/tmp/data.tar.gz', '-C', '/opt/']
+          - ['chmod', '+x', '/opt/script.sh']
+          - ['/opt/script.sh']
+```
+
+This example writes the compressed archive to the instance, then extracts it and
+runs a script from the archive during instance initialization.

roles/heat_stack/defaults/main.yml

@@ -17,3 +17,7 @@
 hotstack_work_dir: "{{ playbook_dir }}"
 os_cloud: "{{ lookup('ansible.builtin.env', 'OS_CLOUD') }}"
 hotstack_revive_snapshot: false
+# List of file archives to compress and base64 encode for user data.
+# Creates tar.gz and tar.gz.b64 files that can be referenced in Heat
+# template using get_file. See README.md for complete usage examples.
+compress_heat_files: []

roles/heat_stack/tasks/main.yml

@@ -36,6 +36,18 @@
     msg:
       "{{ _latest_snapset.output }}"
 
+- name: Compress files for user data
+  when: compress_heat_files | default([]) | length > 0
+  block:
+    - name: Create tar archives and compress
+      ansible.builtin.shell: |
+        tar -czf "{{ item.archive }}.tar.gz" {{ item.files | join(' ') }}
+        base64 -w0 "{{ item.archive }}.tar.gz" > "{{ item.archive }}.tar.gz.b64"
+      args:
+        chdir: "{{ stack_template_path | dirname }}"
+      loop: "{{ compress_heat_files }}"
+      changed_when: true
+
 - name: Create stack
   openstack.cloud.stack:
     cloud: "{{ os_cloud }}"