Management Server

Management Server Unreachability

When an Envoy instance loses connectivity with the management server, Envoy will latch on to the previous configuration while actively retrying in the background to reestablish the connection with the management server.

Envoy debug logs the fact that it is not able to establish a connection with the management server every time it attempts a connection.

connected_state statistic provides a signal for monitoring this behavior.

Statistics

Management Server has a statistics tree rooted at control_plane. with the following statistics:

Name	Type	Description
connected_state	Gauge	A boolean (1 for connected and 0 for disconnected) that indicates the current connection state with management server
rate_limit_enforced	Counter	Total number of times rate limit was enforced for management server requests
pending_requests	Gauge	Total number of pending requests when the rate limit was enforced

xDS subscription statistics

Envoy discovers its various dynamic resources via discovery services referred to as xDS. Resources are requested via subscriptions, by specifying a filesystem path to watch, initiating gRPC streams or polling a REST-JSON URL.

The following statistics are generated for all subscriptions.

Name	Type	Description
config_reload	Counter	Total API fetches that resulted in a config reload due to a different config
init_fetch_timeout	Counter	Total initial fetch timeouts
update_attempt	Counter	Total API fetches attempted
update_success	Counter	Total API fetches completed successfully
update_failure	Counter	Total API fetches that failed because of network errors
update_rejected	Counter	Total API fetches that failed because of schema/validation errors
version	Gauge	Hash of the contents from the last successful API fetch
control_plane.connected_state	Gauge	A boolean (1 for connected and 0 for disconnected) that indicates the current connection state with management server