Add a message to the logs indicating that RUST_LOG or APOLLO_ROUTER_L…

…OG must be configured to log entries from custom plugins.

Fixes #3526

apollo-router/src/executable.rs

@@ -28,6 +28,7 @@ use url::Url;
 use crate::configuration::generate_config_schema;
 use crate::configuration::generate_upgrade;
 use crate::configuration::Discussed;
+use crate::plugin::plugins;
 use crate::plugins::telemetry::reload::init_telemetry;
 use crate::router::ConfigurationSource;
 use crate::router::RouterHttpServer;
@@ -615,6 +616,17 @@ impl Executable {
             }
         };
 
+        // If there are custom plugins then if RUST_LOG hasn't been set and APOLLO_ROUTER_LOG contains one of the defaults.
+        let user_plugins_present = plugins().filter(|p| !p.is_apollo()).count() > 0;
+        let rust_log_set = std::env::var("RUST_LOG").is_ok();
+        let apollo_router_log = std::env::var("APOLLO_ROUTER_LOG").unwrap_or_default();
+        if user_plugins_present
+            && !rust_log_set
+            && ["", "off", "trace", "debug", "warn", "info"].contains(&apollo_router_log.as_str())
+        {
+            tracing::info!("Custom plugins are present. To see log messages from your plugins you must configure `RUST_LOG` or `APOLLO_ROUTER_LOG` environment variables. See the Router logging documentation for more details");
+        }
+
         let router = RouterHttpServer::builder()
             .configuration(configuration)
             .and_uplink(opt.uplink_config().ok())

apollo-router/src/plugin/mod.rs

@@ -184,6 +184,9 @@ impl fmt::Debug for PluginFactory {
 }
 
 impl PluginFactory {
+    pub(crate) fn is_apollo(&self) -> bool {
+        self.name.starts_with("apollo.") || self.name.starts_with("experimental.")
+    }
     /// Create a plugin factory.
     pub fn new<P: Plugin>(group: &str, name: &str) -> PluginFactory {
         let plugin_factory_name = if group.is_empty() {