feat(metrics): Add platform tag (#1511)

This adds a configurable platform tag to metrics. If this is set, the platform (read from the SYMBOLICATOR_PLATFORM env variable) will be reported with every metric.

crates/symbolicator-service/src/config.rs

@@ -91,6 +91,11 @@ pub struct Metrics {
     pub hostname_tag: Option<String>,
     /// A tag name to report the environment to, for each metric. Defaults to not sending such a tag.
     pub environment_tag: Option<String>,
+    /// A tag name to report the platform to, for each metric. Defaults to not sending such a tag.
+    ///
+    /// If this is set, the platform will be read from the `SYMBOLICLATOR_PLATFORM`
+    /// environment variable.
+    pub platform_tag: Option<String>,
     /// A map containing custom tags and their values.
     ///
     /// These tags will be appended to every metric.
@@ -107,6 +112,7 @@ impl Default for Metrics {
             prefix: "symbolicator".into(),
             hostname_tag: None,
             environment_tag: None,
+            platform_tag: None,
             custom_tags: BTreeMap::new(),
         }
     }

crates/symbolicator/src/cli.rs

@@ -140,6 +140,20 @@ pub fn execute() -> Result<()> {
             }
         };
 
+        if let Some(platform_tag) = config.metrics.platform_tag.clone() {
+            if tags.contains_key(&platform_tag) {
+                tracing::warn!(
+                    "tag {} defined both as platform tag and as a custom tag",
+                    platform_tag
+                );
+            }
+            if let Ok(platform) = std::env::var("SYMBOLICATOR_PLATFORM") {
+                tags.insert(platform_tag, platform.to_string());
+            } else {
+                tracing::error!("platform not available");
+            }
+        };
+
         metrics::configure_statsd(&config.metrics.prefix, statsd, tags);
     }