feat(redis): default timeout bumped to 10s

.changesets/fix_low_redis_timeout.md

@@ -0,0 +1,5 @@
+### Update internal redis timeout ([PR #8863](https://github.com/apollographql/router/pull/8863))
+Because mTLS handshakes can be slow in some environments, we’ve doubled our internal Redis timeout from 5s to 10s. This also increases the connection "unresponsive" threshold from 5s to 10s.
+
+
+By [@aaronarinder](https://github.com/aaronarinder) in https://github.com/apollographql/router/pull/8863

apollo-router/src/cache/redis.rs

@@ -56,7 +56,8 @@ const SUPPORTED_REDIS_SCHEMES: [&str; 6] = [
 ];
 
 /// Timeout applied to internal Redis operations, such as TCP connection initialization, TLS handshakes, AUTH or HELLO, cluster health checks, etc.
-const DEFAULT_INTERNAL_REDIS_TIMEOUT: Duration = Duration::from_secs(5);
+// NOTE: In practice we've found that 5s is too low, so we've set it to 10s. Do some sanity checking before tweaking it to a lower value
+const DEFAULT_INTERNAL_REDIS_TIMEOUT: Duration = Duration::from_secs(10);
 /// Interval on which we send PING commands to the Redis servers.
 const REDIS_HEARTBEAT_INTERVAL: Duration = Duration::from_secs(10);
 
@@ -362,6 +363,9 @@ impl RedisCacheStorage {
                 }
             })
             .with_connection_config(|config| {
+                // NOTE: the default internal_command_timeout is 10s, so this line is just to make
+                // it explicit that we're using that default (at the time of writing, this const is
+                // set to 10s)
                 config.internal_command_timeout = DEFAULT_INTERNAL_REDIS_TIMEOUT;
                 config.max_command_buffer_len = 10_000;
                 config.reconnect_on_auth_error = true;