chore: enable partial auth as a feature flag (#5711)

crates/router/src/configs/defaults.rs

@@ -11225,6 +11225,9 @@ impl Default for super::settings::ApiKeys {
             // context used for blake3
             #[cfg(feature = "partial-auth")]
             checksum_auth_context: String::new().into(),
+
+            #[cfg(feature = "partial-auth")]
+            enable_partial_auth: false,
         }
     }
 }

crates/router/src/configs/secrets_transformers.rs

@@ -123,6 +123,9 @@ impl SecretsHandler for settings::ApiKeys {
             .get_secret(api_keys.checksum_auth_key.clone())
             .await?;
 
+        #[cfg(feature = "partial-auth")]
+        let enable_partial_auth = api_keys.enable_partial_auth;
+
         Ok(value.transition_state(|_| Self {
             hash_key,
             #[cfg(feature = "email")]
@@ -132,6 +135,8 @@ impl SecretsHandler for settings::ApiKeys {
             checksum_auth_key,
             #[cfg(feature = "partial-auth")]
             checksum_auth_context,
+            #[cfg(feature = "partial-auth")]
+            enable_partial_auth,
         }))
     }
 }

crates/router/src/configs/settings.rs

@@ -669,6 +669,9 @@ pub struct ApiKeys {
 
     #[cfg(feature = "partial-auth")]
     pub checksum_auth_key: Secret<String>,
+
+    #[cfg(feature = "partial-auth")]
+    pub enable_partial_auth: bool,
 }
 
 #[derive(Debug, Deserialize, Clone, Default)]

crates/router/src/services/authentication.rs

@@ -443,6 +443,14 @@ where
         request_headers: &HeaderMap,
         state: &A,
     ) -> RouterResult<(AuthenticationData, AuthenticationType)> {
+        let enable_partial_auth = state.conf().api_keys.get_inner().enable_partial_auth;
+
+        // This is a early return if partial auth is disabled
+        // Preventing the need to go through the header extraction process
+        if !enable_partial_auth {
+            return self.0.authenticate_and_fetch(request_headers, state).await;
+        }
+
         let report_failure = || {
             metrics::PARTIAL_AUTH_FAILURE.add(&metrics::CONTEXT, 1, &[]);
         };