feat: [#246] add GrafanaConfig domain model

Author: josecelano

src/domain/grafana/config.rs

@@ -0,0 +1,109 @@
+//! Grafana configuration domain type
+
+use serde::{Deserialize, Serialize};
+
+use crate::shared::secrets::Password;
+
+/// Grafana metrics visualization configuration
+///
+/// Configures Grafana service for displaying tracker metrics.
+/// Grafana requires Prometheus to be enabled for metrics visualization.
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+pub struct GrafanaConfig {
+    /// Grafana admin username
+    pub admin_user: String,
+
+    /// Grafana admin password (should be changed in production)
+    ///
+    /// Uses `Password` wrapper from secrecy crate for secure handling:
+    /// - Automatic redaction in debug output (shows `[REDACTED]`)
+    /// - Memory zeroing when the value is dropped
+    /// - Explicit `.expose_secret()` calls required to access plaintext
+    pub admin_password: Password,
+}
+
+impl Default for GrafanaConfig {
+    fn default() -> Self {
+        Self {
+            admin_user: "admin".to_string(),
+            admin_password: Password::new("admin"),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_should_create_grafana_config_with_default_values() {
+        let config = GrafanaConfig::default();
+
+        assert_eq!(config.admin_user, "admin");
+        assert_eq!(config.admin_password.expose_secret(), "admin");
+    }
+
+    #[test]
+    fn it_should_create_grafana_config_with_custom_values() {
+        let config = GrafanaConfig {
+            admin_user: "custom_admin".to_string(),
+            admin_password: Password::new("custom_pass"),
+        };
+
+        assert_eq!(config.admin_user, "custom_admin");
+        assert_eq!(config.admin_password.expose_secret(), "custom_pass");
+    }
+
+    #[test]
+    fn it_should_serialize_grafana_config_to_json() {
+        let config = GrafanaConfig {
+            admin_user: "admin".to_string(),
+            admin_password: Password::new("secret123"),
+        };
+
+        let json = serde_json::to_string(&config).expect("Failed to serialize");
+
+        assert!(json.contains("\"admin_user\":\"admin\""));
+        assert!(json.contains("\"admin_password\":\"secret123\""));
+    }
+
+    #[test]
+    fn it_should_deserialize_grafana_config_from_json() {
+        let json = r#"{"admin_user":"admin","admin_password":"secret123"}"#;
+
+        let config: GrafanaConfig = serde_json::from_str(json).expect("Failed to deserialize");
+
+        assert_eq!(config.admin_user, "admin");
+        assert_eq!(config.admin_password.expose_secret(), "secret123");
+    }
+
+    #[test]
+    fn it_should_redact_password_in_debug_output() {
+        let config = GrafanaConfig {
+            admin_user: "admin".to_string(),
+            admin_password: Password::new("super_secret"),
+        };
+
+        let debug_output = format!("{config:?}");
+
+        assert!(debug_output.contains("admin_user: \"admin\""));
+        assert!(debug_output.contains("Password(SecretBox<str>([REDACTED]"));
+        assert!(!debug_output.contains("super_secret"));
+    }
+
+    #[test]
+    fn it_should_clone_grafana_config() {
+        let config = GrafanaConfig {
+            admin_user: "admin".to_string(),
+            admin_password: Password::new("password"),
+        };
+
+        let cloned = config.clone();
+
+        assert_eq!(cloned.admin_user, config.admin_user);
+        assert_eq!(
+            cloned.admin_password.expose_secret(),
+            config.admin_password.expose_secret()
+        );
+    }
+}

src/domain/grafana/mod.rs

@@ -0,0 +1,5 @@
+//! Grafana metrics visualization service domain types
+
+pub mod config;
+
+pub use config::GrafanaConfig;

src/domain/mod.rs

@@ -14,6 +14,7 @@
 //! - `template` - Core template domain models and business logic
 
 pub mod environment;
+pub mod grafana;
 pub mod instance_name;
 pub mod profile_name;
 pub mod prometheus;