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.

It is important that Envoy detects when a connection to a management server is unhealthy so that it can try to establish a new connection. Configuring either TCP keep-alives or HTTP/2 keepalives in the cluster that connects to the management server is recommended.

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

identifier

TextReadout

The identifier of the control plane instance that sent the last discovery response

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

update_time

Gauge

Timestamp of the last successful API fetch attempt as milliseconds since the epoch. Refreshed even after a trivial configuration reload that contained no configuration changes.

version

Gauge

Hash of the contents from the last successful API fetch

version_text

TextReadout

The version text 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