feat(config): Add relay configuration for detecting canary (#3938)

CHANGELOG.md

@@ -6,6 +6,10 @@
 
 - Keep frames from both ends of the stacktrace when trimming frames. ([#3905](https://github.com/getsentry/relay/pull/3905))
 
+**Features**:
+
+- Add configuration option to specify the instance type of Relay. ([#3938](https://github.com/getsentry/relay/pull/3938))
+
 ## 24.8.0
 
 **Bug Fixes**:

relay-config/src/config.rs

@@ -222,6 +222,8 @@ trait ConfigObject: DeserializeOwned + Serialize {
 pub struct OverridableConfig {
     /// The operation mode of this relay.
     pub mode: Option<String>,
+    /// The instance type of this relay.
+    pub instance: Option<String>,
     /// The log level of this relay.
     pub log_level: Option<String>,
     /// The upstream relay or sentry instance.
@@ -352,6 +354,44 @@ impl fmt::Display for RelayMode {
     }
 }
 
+/// The instance type of Relay.
+#[derive(Clone, Copy, Debug, Eq, PartialEq, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub enum RelayInstance {
+    /// This Relay is run as a default instance.
+    Default,
+
+    /// This Relay is run as a canary instance where experiments can be run.
+    Canary,
+}
+
+impl RelayInstance {
+    /// Returns `true` if the [`RelayInstance`] is of type [`RelayInstance::Canary`].
+    pub fn is_canary(&self) -> bool {
+        matches!(self, RelayInstance::Canary)
+    }
+}
+
+impl fmt::Display for RelayInstance {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            RelayInstance::Default => write!(f, "default"),
+            RelayInstance::Canary => write!(f, "canary"),
+        }
+    }
+}
+
+impl FromStr for RelayInstance {
+    type Err = fmt::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "canary" => Ok(RelayInstance::Canary),
+            _ => Ok(RelayInstance::Default),
+        }
+    }
+}
+
 /// Error returned when parsing an invalid [`RelayMode`].
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub struct ParseRelayModeError;
@@ -436,6 +476,8 @@ impl Default for ReadinessCondition {
 pub struct Relay {
     /// The operation mode of this relay.
     pub mode: RelayMode,
+    /// The instance type of this relay.
+    pub instance: RelayInstance,
     /// The upstream relay or sentry instance.
     pub upstream: UpstreamDescriptor<'static>,
     /// The host the relay should bind to (network interface).
@@ -463,6 +505,7 @@ impl Default for Relay {
     fn default() -> Self {
         Relay {
             mode: RelayMode::Managed,
+            instance: RelayInstance::Default,
             upstream: "https://sentry.io/".parse().unwrap(),
             host: default_host(),
             port: 3000,
@@ -1607,6 +1650,12 @@ impl Config {
                 .with_context(|| ConfigError::field("mode"))?;
         }
 
+        if let Some(deployment) = overrides.instance {
+            relay.instance = deployment
+                .parse::<RelayInstance>()
+                .with_context(|| ConfigError::field("deployment"))?;
+        }
+
         if let Some(log_level) = overrides.log_level {
             self.values.logging.level = log_level.parse()?;
         }
@@ -1820,6 +1869,11 @@ impl Config {
         self.values.relay.mode
     }
 
+    /// Returns the instance type of relay.
+    pub fn relay_instance(&self) -> RelayInstance {
+        self.values.relay.instance
+    }
+
     /// Returns the upstream target as descriptor.
     pub fn upstream_descriptor(&self) -> &UpstreamDescriptor<'_> {
         &self.values.relay.upstream

relay/src/cli.rs

@@ -97,6 +97,7 @@ pub fn extract_config_args(matches: &ArgMatches) -> OverridableConfig {
         secret_key: matches.get_one("secret_key").cloned(),
         outcome_source: matches.get_one("source_id").cloned(),
         shutdown_timeout: matches.get_one("shutdown_timeout").cloned(),
+        instance: matches.get_one("instance").cloned(),
     }
 }
 
@@ -117,6 +118,7 @@ pub fn extract_config_env_vars() -> OverridableConfig {
         secret_key: env::var("RELAY_SECRET_KEY").ok(),
         outcome_source: None, //already extracted in params
         shutdown_timeout: env::var("SHUTDOWN_TIMEOUT").ok(),
+        instance: env::var("RELAY_INSTANCE").ok(),
     }
 }
 

relay/src/cliapp.rs

@@ -141,6 +141,11 @@ pub fn make_app() -> Command {
                             "Maximum number of seconds to wait for pending envelopes on shutdown.",
                         ),
                 )
+                .arg(
+                    Arg::new("instance")
+                        .long("instance")
+                        .help("The instance type of this Relay.")
+                )
         )
         .subcommand(
             Command::new("credentials")