Merge #109: feat: Add centralized variables template infrastructure for Ansible playbooks (#105)

e162cf1 fix: [#105] improve error mapping for context creation failures (copilot-swe-agent[bot])
b61ffea fix: [#105] remove Tera variables from comments in template (copilot-swe-agent[bot])
57c357d fix: [#105] fix clippy warnings and formatting (copilot-swe-agent[bot])
dae5fa0 feat: [#105] integrate variables rendering into AnsibleTemplateRenderer (copilot-swe-agent[bot])
5976b7c feat: [#105] add VariablesTemplateRenderer (copilot-swe-agent[bot])
b411b6d feat: [#105] add AnsibleVariablesTemplate wrapper (copilot-swe-agent[bot])
a033f0d feat: [#105] add AnsibleVariablesContext with validation (copilot-swe-agent[bot])
8759e57 feat: [#105] add centralized variables template file (copilot-swe-agent[bot])
bff5db0 Initial plan (copilot-swe-agent[bot])

Pull request description:

  Implements the foundational infrastructure for consolidating Ansible playbook variables into a centralized `variables.yml` file, following the same pattern as OpenTofu's `variables.tfvars.tera`.

  ## Implementation

  ### Template & Context
  - **Template**: `templates/ansible/variables.yml.tera` - Centralized variable definitions with SSH port
  - **Context**: `AnsibleVariablesContext` - Validates SSH port using existing `AnsiblePort` validation

  ### Wrapper & Renderer
  - **Wrapper**: `AnsibleVariablesTemplate` - Renders template with domain `TemplateEngine`
  - **Renderer**: `VariablesTemplateRenderer` - Orchestrates template loading, context processing, and file output
  - **Integration**: Hooked into `AnsibleTemplateRenderer::render()` workflow after firewall playbook rendering

  ### Error Handling
  - Added `ContextCreationFailed` error variant for SSH port validation failures
  - Updated both `create_firewall_context()` and `create_variables_context()` to use semantically correct error types

  ## Output

  Generated `variables.yml` contains runtime SSH port configuration:

  ```yaml
  ---
  # Centralized Ansible Variables
  ssh_port: 22
  # Future service variables can be added here when needed
  ```

  ## Architecture

  Follows existing three-layer template pattern:
  1. **Context Layer** - Validates input data (SSH port)
  2. **Wrapper Layer** - Renders Tera template with validated context
  3. **Renderer Layer** - Orchestrates file I/O and template management

  Future service variables (MySQL, Tracker, Prometheus, Grafana) can be added to the template without additional Rust infrastructure per service.

  <!-- START COPILOT CODING AGENT SUFFIX -->

  <details>

  <summary>Original prompt</summary>

  >
  > ----
  >
  > *This section details on the original issue you should resolve*
  >
  > <issue_title>Create Variables Template Infrastructure</issue_title>
  > <issue_description>**Parent Epic**: #19 - Refactor Ansible Templates to Variables Pattern
  >
  > ## Overview
  >
  > Create the centralized `variables.yml.tera` template and supporting Rust infrastructure (context, wrapper, renderer) to consolidate Ansible playbook variables into a single file. This establishes the foundation for the variables pattern that will simplify future playbook additions.
  >
  > ## Goals
  >
  > - [ ] **Variables Template**: Create `templates/ansible/variables.yml.tera` with system configuration variables
  > - [ ] **Context Layer**: Implement `AnsibleVariablesContext` with validation
  > - [ ] **Wrapper Layer**: Implement `AnsibleVariablesTemplate` for rendering
  > - [ ] **Renderer Layer**: Implement `VariablesTemplateRenderer` for orchestration
  > - [ ] **Integration**: Hook into `AnsibleTemplateRenderer::render()` workflow
  > - [ ] **Test Coverage**: Comprehensive unit tests for all components
  >
  > ## 🏗️ Architecture Requirements
  >
  > **DDD Layer**: Infrastructure
  > **Module Path**: `src/infrastructure/external_tools/ansible/template/`
  > **Pattern**: Template Wrapper + Context + Renderer (existing pattern)
  >
  > ## Time Estimate
  >
  > **2.5 days** - Complete vertical slice including implementation, testing, and documentation
  >
  > ## Documentation
  >
  > Full implementation details: [`docs/issues/19.1-create-variables-template.md`](https://github.com/torrust/torrust-tracker-deployer/blob/copilot/configure-ufw-firewall/docs/issues/19.1-create-variables-template.md)
  >
  > ## Acceptance Criteria
  >
  > ### Template File
  > - [ ] `templates/ansible/variables.yml.tera` exists with SSH port variable
  > - [ ] Template has correct Tera syntax: `{{ ssh_port }}`
  > - [ ] YAML linting passes
  >
  > ### Implementation
  > - [ ] `AnsibleVariablesContext` with SSH port validation
  > - [ ] `AnsibleVariablesTemplate` wrapper implementation
  > - [ ] `VariablesTemplateRenderer` orchestrator
  > - [ ] Integration into `AnsibleTemplateRenderer`
  >
  > ### Testing
  > - [ ] Unit tests pass: `cargo test`
  > - [ ] Config tests pass: `cargo run --bin e2e-config-tests`
  > - [ ] Linters pass: `cargo run --bin linter all`
  > - [ ] `variables.yml` generated in build directory
  >
  > ### Documentation
  > - [ ] Rustdoc comments for all public types
  > - [ ] Template file includes descriptive comments
  > - [ ] Error types have clear descriptions
  >
  > ## Related
  >
  > - Parent Epic: #19
  > - Next Task: #19.2 (depends on this task)
  > - [Template System Architecture](https://github.com/torrust/torrust-tracker-deployer/blob/main/docs/technical/template-system-architecture.md)</issue_description>
  >
  > ## Comments on the Issue (you are @copilot in this section)
  >
  > <comments>
  > </comments>
  >

  </details>

  - Fixes #105

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  ---

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ACKs for top commit:
  josecelano:
    ACK e162cf1

Tree-SHA512: 7dc3c0b1e16a99eb0ada7881c0f047289f2a50524a4014ced1c5bae3085edbe30a079cca8aff8ecd13481f07987ab06ad7a559ac8ee93b82c2732367bf84daba

Author: josecelano

src/infrastructure/external_tools/ansible/template/renderer/mod.rs

@@ -55,9 +55,11 @@ use crate::infrastructure::external_tools::ansible::template::wrappers::inventor
 
 pub mod firewall_playbook;
 pub mod inventory;
+pub mod variables;
 
 pub use firewall_playbook::FirewallPlaybookTemplateRenderer;
 pub use inventory::InventoryTemplateRenderer;
+pub use variables::VariablesTemplateRenderer;
 
 /// Errors that can occur during configuration template rendering
 #[derive(Error, Debug)]
@@ -129,6 +131,20 @@ pub enum ConfigurationTemplateError {
         #[source]
         source: firewall_playbook::FirewallPlaybookTemplateError,
     },
+
+    /// Failed to render variables template using collaborator
+    #[error("Failed to render variables template: {source}")]
+    VariablesRenderingFailed {
+        #[source]
+        source: variables::VariablesTemplateError,
+    },
+
+    /// Failed to create context from inventory data
+    #[error("Failed to create {context_type} context: {message}")]
+    ContextCreationFailed {
+        context_type: String,
+        message: String,
+    },
 }
 
 /// Renders `Ansible` configuration templates to a build directory
@@ -141,6 +157,7 @@ pub struct AnsibleTemplateRenderer {
     template_manager: Arc<TemplateManager>,
     inventory_renderer: InventoryTemplateRenderer,
     firewall_playbook_renderer: FirewallPlaybookTemplateRenderer,
+    variables_renderer: VariablesTemplateRenderer,
 }
 
 impl AnsibleTemplateRenderer {
@@ -161,12 +178,14 @@ impl AnsibleTemplateRenderer {
         let inventory_renderer = InventoryTemplateRenderer::new(template_manager.clone());
         let firewall_playbook_renderer =
             FirewallPlaybookTemplateRenderer::new(template_manager.clone());
+        let variables_renderer = VariablesTemplateRenderer::new(template_manager.clone());
 
         Self {
             build_dir: build_dir.as_ref().to_path_buf(),
             template_manager,
             inventory_renderer,
             firewall_playbook_renderer,
+            variables_renderer,
         }
     }
 
@@ -219,6 +238,12 @@ impl AnsibleTemplateRenderer {
                 |source| ConfigurationTemplateError::FirewallPlaybookRenderingFailed { source },
             )?;
 
+        // Render dynamic variables template with system configuration using collaborator
+        let variables_context = Self::create_variables_context(inventory_context)?;
+        self.variables_renderer
+            .render(&variables_context, &build_ansible_dir)
+            .map_err(|source| ConfigurationTemplateError::VariablesRenderingFailed { source })?;
+
         // Copy static Ansible files (config and playbooks)
         self.copy_static_templates(&self.template_manager, &build_ansible_dir)
             .await?;
@@ -421,21 +446,50 @@ impl AnsibleTemplateRenderer {
 
         // Extract SSH port from inventory context
         let ssh_port = AnsiblePort::new(inventory_context.ansible_port()).map_err(|e| {
-            ConfigurationTemplateError::TemplatePathFailed {
-                file_name: "configure-firewall.yml.tera".to_string(),
-                source: TemplateManagerError::TemplateNotFound {
-                    relative_path: format!("Invalid SSH port: {e}"),
-                },
+            ConfigurationTemplateError::ContextCreationFailed {
+                context_type: "FirewallPlaybook".to_string(),
+                message: format!("Invalid SSH port: {e}"),
             }
         })?;
 
         // Create firewall context
         FirewallPlaybookContext::new(ssh_port).map_err(|e| {
-            ConfigurationTemplateError::TemplatePathFailed {
-                file_name: "configure-firewall.yml.tera".to_string(),
-                source: TemplateManagerError::TemplateNotFound {
-                    relative_path: format!("Failed to create firewall context: {e}"),
-                },
+            ConfigurationTemplateError::ContextCreationFailed {
+                context_type: "FirewallPlaybook".to_string(),
+                message: format!("Failed to create firewall context: {e}"),
+            }
+        })
+    }
+
+    /// Creates an `AnsibleVariablesContext` from an `InventoryContext`
+    ///
+    /// Extracts the SSH port from the inventory context to create
+    /// a variables context for template rendering.
+    ///
+    /// # Arguments
+    ///
+    /// * `inventory_context` - The inventory context containing SSH port information
+    ///
+    /// # Returns
+    ///
+    /// * `Result<AnsibleVariablesContext, ConfigurationTemplateError>` - The variables context or an error
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the SSH port cannot be extracted or validated
+    fn create_variables_context(
+        inventory_context: &InventoryContext,
+    ) -> Result<
+        crate::infrastructure::external_tools::ansible::template::wrappers::variables::AnsibleVariablesContext,
+        ConfigurationTemplateError,
+    >{
+        use crate::infrastructure::external_tools::ansible::template::wrappers::variables::AnsibleVariablesContext;
+
+        // Extract SSH port from inventory context and create variables context
+        AnsibleVariablesContext::new(inventory_context.ansible_port()).map_err(|e| {
+            ConfigurationTemplateError::ContextCreationFailed {
+                context_type: "AnsibleVariables".to_string(),
+                message: format!("Failed to create variables context: {e}"),
             }
         })
     }