Administration interface

Envoy exposes a local administration interface that can be used to query and modify different aspects of the server:

Attention

The administration interface in its current form both allows destructive operations to be performed (e.g., shutting down the server) as well as potentially exposes private information (e.g., stats, cluster names, cert info, etc.). It is critical that access to the administration interface is only allowed via a secure network. It is also critical that hosts that access the administration interface are only attached to the secure network (i.e., to avoid CSRF attacks). This involves setting up an appropriate firewall or optimally only allowing access to the administration listener via localhost. This can be accomplished with a v2 configuration like the following:

admin:
  access_log_path: /tmp/admin_access.log
  address:
    socket_address: { address: 127.0.0.1, port_value: 9901 }

In the future additional security options will be added to the administration interface. This work is tracked in this issue.

All mutations must be sent as HTTP POST operations. When a mutation is requested via GET, the request has no effect, and an HTTP 400 (Invalid Request) response is returned.

GET /

Render an HTML home page with a table of links to all available options.

GET /help

Print a textual table of all available options.

GET /certs

List out all loaded TLS certificates, including file name, serial number, and days until expiration.

GET /clusters

List out all configured cluster manager clusters. This information includes all discovered upstream hosts in each cluster along with per host statistics. This is useful for debugging service discovery issues.

Cluster manager information
  • version_info string – the version info string of the last loaded CDS update. If envoy does not have CDS setup, the output will read version_info::static.
Cluster wide information
Per host statistics
Name Type Description
cx_total Counter Total connections
cx_active Gauge Total active connections
cx_connect_fail Counter Total connection failures
rq_total Counter Total requests
rq_timeout Counter Total timed out requests
rq_success Counter Total requests with non-5xx responses
rq_error Counter Total requests with 5xx responses
rq_active Gauge Total active requests
healthy String The health status of the host. See below
weight Integer Load balancing weight (1-100)
zone String Service zone
canary Boolean Whether the host is a canary
success_rate Double Request success rate (0-100). -1 if there was not enough request volume in the interval to calculate it
Host health status

A host is either healthy or unhealthy because of one or more different failing health states. If the host is healthy the healthy output will be equal to healthy.

If the host is not healthy, the healthy output will be composed of one or more of the following strings:

/failed_active_hc: The host has failed an active health check.

/failed_eds_health: The host was marked unhealthy by EDS.

/failed_outlier_check: The host has failed an outlier detection check.

GET /clusters?format=json

Dump the /clusters output in a JSON-serialized proto. See the definition for more information.

GET /config_dump

Dump currently loaded configuration from various Envoy components as JSON-serialized proto messages. See the response definition for more information.

Warning

The underlying proto is marked v2alpha and hence its contents, including the JSON representation, are not guaranteed to be stable.

POST /cpuprofiler

Enable or disable the CPU profiler. Requires compiling with gperftools.

POST /healthcheck/fail

Fail inbound health checks. This requires the use of the HTTP health check filter. This is useful for draining a server prior to shutting it down or doing a full restart. Invoking this command will universally fail health check requests regardless of how the filter is configured (pass through, etc.).

POST /healthcheck/ok

Negate the effect of POST /healthcheck/fail. This requires the use of the HTTP health check filter.

GET /hot_restart_version

See --hot-restart-version.

POST /logging

Enable/disable different logging levels on different subcomponents. Generally only used during development.

POST /memory

Prints current memory allocation / heap usage, in bytes. Useful in lieu of printing all /stats and filtering to get the memory-related statistics.

POST /quitquitquit

Cleanly exit the server.

POST /reset_counters

Reset all counters to zero. This is useful along with GET /stats during debugging. Note that this does not drop any data sent to statsd. It just effects local output of the GET /stats command.

GET /server_info

Outputs information about the running server. Sample output looks like:

envoy 267724/RELEASE live 1571 1571 0

The fields are:

  • Process name
  • Compiled SHA and build type
  • Health check state (live or draining)
  • Current hot restart epoch uptime in seconds
  • Total uptime in seconds (across all hot restarts)
  • Current hot restart epoch
GET /stats

Outputs all statistics on demand. This command is very useful for local debugging. Histograms will output the computed quantiles i.e P0,P25,P50,P75,P90,P99,P99.9 and P100. The output for each quantile will be in the form of (interval,cumulative) where interval value represents the summary since last flush interval and cumulative value represents the summary since the start of envoy instance. “No recorded values” in the histogram output indicates that it has not been updated with a value. See here for more information.

GET /stats?usedonly

Outputs statistics that Envoy has updated (counters incremented at least once, gauges changed at least once, and histograms added to at least once).

GET /stats?filter=regex

Filters the returned stats to those with names matching the regular expression regex. Compatible with usedonly. Performs partial matching by default, so /stats?filter=server will return all stats containing the word server. Full-string matching can be specified with begin- and end-line anchors. (i.e. /stats?filter=^server.concurrency$)

GET /stats?format=json

Outputs /stats in JSON format. This can be used for programmatic access of stats. Counters and Gauges will be in the form of a set of (name,value) pairs. Histograms will be under the element “histograms”, that contains “supported_quantiles” which lists the quantiles supported and an array of computed_quantiles that has the computed quantile for each histogram.

If a histogram is not updated during an interval, the ouput will have null for all the quantiles.

Example histogram output:

{
  "histograms": {
    "supported_quantiles": [
      0, 25, 50, 75, 90, 95, 99, 99.9, 100
    ],
    "computed_quantiles": [
      {
        "name": "cluster.external_auth_cluster.upstream_cx_length_ms",
        "values": [
          {"interval": 0, "cumulative": 0},
          {"interval": 0, "cumulative": 0},
          {"interval": 1.0435787, "cumulative": 1.0435787},
          {"interval": 1.0941565, "cumulative": 1.0941565},
          {"interval": 2.0860023, "cumulative": 2.0860023},
          {"interval": 3.0665233, "cumulative": 3.0665233},
          {"interval": 6.046609, "cumulative": 6.046609},
          {"interval": 229.57333,"cumulative": 229.57333},
          {"interval": 260,"cumulative": 260}
        ]
      },
      {
        "name": "http.admin.downstream_rq_time",
        "values": [
          {"interval": null, "cumulative": 0},
          {"interval": null, "cumulative": 0},
          {"interval": null, "cumulative": 1.0435787},
          {"interval": null, "cumulative": 1.0941565},
          {"interval": null, "cumulative": 2.0860023},
          {"interval": null, "cumulative": 3.0665233},
          {"interval": null, "cumulative": 6.046609},
          {"interval": null, "cumulative": 229.57333},
          {"interval": null, "cumulative": 260}
        ]
      }
    ]
  }
}
GET /stats?format=json&usedonly

Outputs statistics that Envoy has updated (counters incremented at least once, gauges changed at least once, and histograms added to at least once) in JSON format.

GET /stats?format=prometheus

or alternatively,

GET /stats/prometheus

Outputs /stats in Prometheus v0.0.4 format. This can be used to integrate with a Prometheus server. Currently, only counters and gauges are output. Histograms will be output in a future update.

GET /runtime

Outputs all runtime values on demand in JSON format. See here for more information on how these values are configured and utilized. The output include the list of the active runtime override layers and the stack of layer values for each key. Empty strings indicate no value, and the final active value from the stack also is included in a separate key. Example output:

{
  "layers": [
    "disk",
    "override",
    "admin",
  ],
  "entries": {
    "my_key": {
      "layer_values": [
        "my_disk_value",
        "",
        ""
      ],
      "final_value": "my_disk_value"
    },
    "my_second_key": {
      "layer_values": [
        "my_second_disk_value",
        "my_disk_override_value",
        "my_admin_override_value"
      ],
      "final_value": "my_admin_override_value"
    }
  }
}
POST /runtime_modify?key1=value1&key2=value2&keyN=valueN

Adds or modifies runtime values as passed in query parameters. To delete a previously added key, use an empty string as the value. Note that deletion only applies to overrides added via this endpoint; values loaded from disk can be modified via override but not deleted.

Attention

Use the /runtime_modify endpoint with care. Changes are effectively immediately. It is critical that the admin interface is properly secured.

GET /hystrix_event_stream

This endpoint is intended to be used as the stream source for Hystrix dashboard. a GET to this endpoint will trriger a stream of statistics from envoy in text/event-stream format, as expected by the Hystrix dashboard.

If invoked from a browser or a terminal, the response will be shown as a continous stream, sent in intervals defined by the Bootstrap stats_flush_interval

This handler is enabled only when a Hystrix sink is enabled in the config file as documented here.

As Envoy’s and Hystrix resiliency mechanisms differ, some of the statistics shown in the dashboard had to be adapted:

  • Thread pool rejections - Generally similar to what’s called short circuited in Envoy, and counted by upstream_rq_pending_overflow, although the term thread pool is not accurate for Envoy. Both in Hystrix and Envoy, the result is rejected requests which are not passed upstream.
  • circuit breaker status (closed or open) - Since in Envoy, a circuit is opened based on the current number of connections/requests in queue, there is no sleeping window for circuit breaker, circuit open/closed is momentary. Hence, we set the circuit breaker status to “forced closed”.
  • Short-circuited (rejected) - The term exists in Envoy but refers to requests not sent because of passing a limit (queue or connections), while in Hystrix it refers to requests not sent because of high percentage of service unavailable responses during some time frame. In Envoy, service unavailable response will cause outlier detection - removing a node off the load balancer pool, but requests are not rejected as a result. Therefore, this counter is always set to ‘0’.
  • Latency information represents data since last flush. Mean latency is currently not available.