Observation

Observation

This section covers monitoring, logging, tracing, and health checks.

• Health Check

  Health Check

  The health check will answer with status 200 OK on every port with the configured health_path setting or the COUPER_HEALTH_PATH environment variable.

  As soon as the gateway instance receives a SIGINT or SIGTERM the check will return a status 500 Internal Server Error.

  A shutdown delay (environment variable COUPER_TIMING_SHUTDOWN_DELAY) allows the server to finish all running requests and gives a load balancer time to pick another gateway instance. After this delay the server goes into shutdown mode and no new requests will be accepted.

• Metrics

  Metrics

  • Metrics
    • Prometheus
    • Grafana Dashboard
  • Preview
    • Developers

  Our metrics feature is beta for now. However, we want to provide some core metrics which can be directly collected from Couper.

  Prometheus

  Couper provides a built-in Prometheus exporter. It is configurable with settings like port or service_name label. If enabled the default scrape target port is 9090.

  Grafana Dashboard

  Couper provides a maintained Grafana dashboard which you can find here: grafana.json and import this JSON model to your grafana instance. You may have to set your Datasource to your Prometheus one.

• Logging

  Logging

  Introduction

  Upon the execution of Couper all log events are sent to the standard output. You can adjust the appearance and verbosity of the logs with a variety of Settings. There are different Log Types and Fields containing useful information.

  We aspire to make Couper as stable as possible so these logs are still subject to change.

  Log Types

  Type	Description
  couper_access	Provides information about the frontend side of things. Compare Access Fields.
  couper_access_tls	Provides information about connections via configured https_dev_proxy. Compare Access Fields.
  couper_backend	Provides information about the backend side of things. Compare Backend Fields.
  couper_daemon	Provides background information about the execution of Couper. Each printed log of this type contains a message entry describing the current actions of Couper. Compare Daemon Fields.
  couper_job	Provides information about jobs. See Job Fields.

  Fields

  Given the large amount of information contained in some logs, it might come handy to change the format or log level (see Settings).

• Tracing

  Tracing

  Our tracing feature is beta for now. Couper supports distributed tracing using OpenTelemetry and the W3C Trace Context standard.

  Configuration

  Enable tracing with beta_traces = true in the settings block or the -beta-traces CLI flag. Couper exports trace spans via gRPC to an OpenTelemetry collector at beta_traces_endpoint (default localhost:4317).

  The beta_service_name setting is used as the service name in exported spans.

  Trace Propagation

  Couper supports W3C Trace Context propagation via the traceparent HTTP header. Two settings control how incoming trace context is handled: