Health Output Plugin

This plugin provides a HTTP health check endpoint that can be configured to return failure status codes based on the value of a metric.

When the plugin is healthy it will return a 200 response; when unhealthy it will return a 503 response. The default state is healthy, one or more checks must fail in order for the resource to enter the failed state.

Introduced in: Telegraf v1.11.0 Tags: applications OS support: all

Global configuration options

In addition to the plugin-specific configuration settings, plugins support additional global and plugin configuration settings. These settings are used to modify metrics, tags, and field or create aliases and configure ordering, etc. See the CONFIGURATION.md for more details.

Configuration

# Configurable HTTP health check resource based on metrics
[[outputs.health]]
  ## Address and port to listen on.
  ##   ex: service_address = "http://localhost:8080"
  ##       service_address = "unix:///var/run/telegraf-health.sock"
  # service_address = "http://:8080"

  ## The maximum duration for reading the entire request.
  # read_timeout = "5s"
  ## The maximum duration for writing the entire response.
  # write_timeout = "5s"

  ## Username and password to accept for HTTP basic authentication.
  # basic_username = "user1"
  # basic_password = "secret"

  ## Allowed CA certificates for client certificates.
  # tls_allowed_cacerts = ["/etc/telegraf/clientca.pem"]

  ## TLS server certificate and private key.
  # tls_cert = "/etc/telegraf/cert.pem"
  # tls_key = "/etc/telegraf/key.pem"

  ## Maximum expected time between metrics being written
  ## Enforces an unhealthy state if there was no new metric seen for at least
  ## the specified time. The check is disabled by default and only used if a
  ## positive time is specified.
  # max_time_between_metrics = "0s"

  ## NOTE: Due to the way TOML is parsed, tables must be at the END of the
  ## plugin definition, otherwise additional config options are read as part of
  ## the table

  ## One or more check sub-tables should be defined, it is also recommended to
  ## use metric filtering to limit the metrics that flow into this output.
  ##
  ## When using the default buffer sizes, this example will fail when the
  ## metric buffer is half full.
  ##
  ## namepass = ["internal_write"]
  ## tagpass = { output = ["influxdb"] }
  ##
  ## [[outputs.health.compares]]
  ##   field = "buffer_size"
  ##   lt = 5000.0
  ##
  ## [[outputs.health.contains]]
  ##   field = "buffer_size"

Maximum time between metrics

The health plugin can assert that metrics are being delivered to it at an expected rate when setting max_time_between_metrics to a positive number. The check measures the time between consecutive writes to the plugin and compares it to the defined max_time_between_metrics. When the time elapsed between writes is greater than the configured maximum time, the plugin will report an unhealthy status. As soon as metrics are written again to the plugin, the health status will reset to healthy.

Note that the metric timestamps are not taken into account, rather the time they are written to the plugin.

compares

The compares check is used to assert basic mathematical relationships. Use it by choosing a field key and one or more comparisons that must hold true. If the field is not found on a metric no comparison will be made.

Comparisons must be hold true on all metrics for the check to pass.

The available comparison operators are:

• gt greater than
• ge greater than or equal to
• lt less than
• le less than or equal to
• eq equal to
• ne not equal to

contains

The contains check can be used to require a field key to exist on at least one metric.

If the field is found on any metric the check passes.