feat: add GrafanaConfig struct with a couple of useful keys

CHANGELOG.md

@@ -12,6 +12,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Add `AppInstanceSettings::api_version` and `DataSourceInstanceSettings::api_version` fields.
+- Add `PluginContext::grafana_config` field. This can be used to access a new struct,
+  `GrafanaConfig`, which contains the configuration passed to the plugin from Grafana.
+  Use the methods on `GrafanaConfig` to access the configuration.
 
 ### Changed
 

crates/grafana-plugin-sdk/src/backend/grafana_config.rs

@@ -0,0 +1,71 @@
+use std::collections::HashMap;
+
+/// The error returned when Grafana does not provide a requested configuration option.
+#[derive(Debug, Clone, thiserror::Error)]
+#[error("key {key} not found in Grafana config; a more recent version of Grafana may be required")]
+pub struct ConfigError {
+    key: String,
+}
+
+impl ConfigError {
+    fn from_key(key: String) -> Self {
+        Self { key }
+    }
+}
+
+type ConfigResult<T> = std::result::Result<T, ConfigError>;
+
+/// Configuration passed to the plugin from Grafana.
+#[derive(Clone)]
+pub struct GrafanaConfig {
+    config: HashMap<String, String>,
+}
+
+impl GrafanaConfig {
+    const APP_URL: &'static str = "GF_APP_URL";
+    const APP_CLIENT_SECRET: &'static str = "GF_PLUGIN_APP_CLIENT_SECRET";
+    // const CONCURRENT_QUERY_COUNT: &'static str = "GF_CONCURRENT_QUERY_COUNT";
+    // const USER_FACING_DEFAULT_ERROR: &'static str = "GF_USER_FACING_DEFAULT_ERROR";
+    // const SQL_ROW_LIMIT: &'static str = "GF_SQL_ROW_LIMIT";
+    // const SQL_MAX_OPEN_CONNS_DEFAULT: &'static str = "GF_SQL_MAX_OPEN_CONNS_DEFAULT";
+    // const SQL_MAX_IDLE_CONNS_DEFAULT: &'static str = "GF_SQL_MAX_IDLE_CONNS_DEFAULT";
+    // const SQL_MAX_CONN_LIFETIME_SECONDS_DEFAULT: &'static str =
+    //     "GF_SQL_MAX_CONN_LIFETIME_SECONDS_DEFAULT";
+    // const RESPONSE_LIMIT: &'static str = "GF_RESPONSE_LIMIT";
+
+    pub(crate) fn new(config: HashMap<String, String>) -> Self {
+        Self { config }
+    }
+
+    /// Get the value of a configuration option, if it was provided by Grafana.
+    fn get(&self, key: &str) -> ConfigResult<&String> {
+        self.config
+            .get(key)
+            .ok_or_else(|| ConfigError::from_key(key.to_string()))
+    }
+
+    /// Return the URL of the Grafana instance.
+    pub fn app_url(&self) -> ConfigResult<&String> {
+        self.get(Self::APP_URL)
+    }
+
+    /// Return the client secret for the app plugin's service account, if set.
+    ///
+    /// Plugins can request a service account be created by Grafana at startup
+    /// time by using the `iam` field of their `plugin.json` file. This method
+    /// will then return the client secret for that service account, which can
+    /// be used to authenticate with the Grafana API.
+    ///
+    /// See [this example plugin][example] for a full example of how to use this.
+    ///
+    /// [example]: https://github.com/grafana/grafana-plugin-examples/tree/main/examples/app-with-service-account
+    pub fn plugin_app_client_secret(&self) -> ConfigResult<&String> {
+        self.get(Self::APP_CLIENT_SECRET)
+    }
+}
+
+impl std::fmt::Debug for GrafanaConfig {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("GrafanaConfig").finish()
+    }
+}

crates/grafana-plugin-sdk/src/backend/mod.rs

@@ -158,6 +158,7 @@ pub use tonic::async_trait;
 mod data;
 mod diagnostics;
 mod error_source;
+mod grafana_config;
 mod noop;
 mod resource;
 mod stream;
@@ -172,6 +173,7 @@ pub use diagnostics::{
     DiagnosticsService, HealthStatus, Payload as MetricsPayload,
 };
 pub use error_source::ErrorSource;
+pub use grafana_config::{ConfigError, GrafanaConfig};
 pub use resource::{
     BoxResourceFuture, BoxResourceStream, CallResourceRequest, ErrIntoHttpResponse,
     IntoHttpResponse, ResourceService,
@@ -1109,6 +1111,9 @@ where
     pub instance_settings: Option<IS>,
     _json_data: PhantomData<JsonData>,
     _secure_json_data: PhantomData<SecureJsonData>,
+
+    /// Configuration passed to the plugin from Grafana.
+    pub grafana_config: GrafanaConfig,
 }
 
 impl<IS, JsonData, SecureJsonData> TryFrom<pluginv2::PluginContext>
@@ -1132,6 +1137,7 @@ where
             instance_settings,
             _json_data: PhantomData,
             _secure_json_data: PhantomData,
+            grafana_config: GrafanaConfig::new(other.grafana_config),
         })
     }
 }