Metric Reporters

Flink allows reporting metrics to external systems. For more information about Flink’s metric system go to the metric system documentation.

Metrics can be exposed to an external system by configuring one or several reporters in conf/flink-conf.yaml. These reporters will be instantiated on each job and task manager when they are started.

Below is a list of parameters that are generally applicable to all reporters. All properties are configured by setting metrics.reporter.<reporter_name>.<property> in the configuration. Reporters may additionally offer implementation-specific parameters, which are documented in the respective reporter’s section.

All reporter configurations must contain the factory.class property. Some reporters (referred to as Scheduled) allow specifying a reporting interval.

Example reporter configuration that specifies multiple reporters:

metrics.reporters: my_jmx_reporter,my_other_reporter
metrics.reporter.my_jmx_reporter.factory.class: org.apache.flink.metrics.jmx.JMXReporterFactory
metrics.reporter.my_jmx_reporter.port: 9020-9040
metrics.reporter.my_jmx_reporter.scope.variables.excludes: job_id;task_attempt_num
metrics.reporter.my_jmx_reporter.scope.variables.additional: cluster_name:my_test_cluster,tag_name:tag_value
metrics.reporter.my_other_reporter.factory.class: org.apache.flink.metrics.graphite.GraphiteReporterFactory
metrics.reporter.my_other_reporter.host: 192.168.1.1
metrics.reporter.my_other_reporter.port: 10000

Important: The jar containing the reporter must be accessible when Flink is started. Reporters are loaded as plugins. All reporters documented on this page are available by default.

You can write your own Reporter by implementing the org.apache.flink.metrics.reporter.MetricReporter interface. If the Reporter should send out reports regularly you have to implement the Scheduled interface as well. Be careful that report() method must not block for a significant amount of time, and any reporter needing more time should instead run the operation asynchronously. By additionally implementing a MetricReporterFactory your reporter can also be loaded as a plugin.

Identifiers vs. tags

There are generally 2 formats for how reporters export metrics.

Identifier-based reporters assemble a flat string containing all scope information and the metric name. An example could be job.MyJobName.numRestarts.

Tag-based reporters on the other hand define a generic class of metrics consisting of a logical scope and metric name (e.g., job.numRestarts), and report a particular instance of said metric as a set of key-value pairs, so called “tags” or “variables” (e.g., “jobName=MyJobName”).

Push vs. Pull

Metrics are exported either via pushes or pulls.

Push-based reporters usually implement the Scheduled interface and periodically send a summary of current metrics to an external system.

Pull-based reporters are queried from an external system instead.

Reporters

The following sections list the supported reporters.

JMX

(org.apache.flink.metrics.jmx.JMXReporter)

Type: pull/tags

Parameters:

• port - (optional) the port on which JMX listens for connections. In order to be able to run several instances of the reporter on one host (e.g. when one TaskManager is colocated with the JobManager) it is advisable to use a port range like 9250-9260. When a range is specified the actual port is shown in the relevant job or task manager log. If this setting is set Flink will start an extra JMX connector for the given port/range. Metrics are always available on the default local JMX interface.

Example configuration:

metrics.reporter.jmx.factory.class: org.apache.flink.metrics.jmx.JMXReporterFactory
metrics.reporter.jmx.port: 8789

Metrics exposed through JMX are identified by a domain and a list of key-properties, which together form the object name.

The domain always begins with org.apache.flink followed by a generalized metric identifier. In contrast to the usual identifier it is not affected by scope-formats, does not contain any variables and is constant across jobs. An example for such a domain would be org.apache.flink.job.task.numBytesOut.

The key-property list contains the values for all variables, regardless of configured scope formats, that are associated with a given metric. An example for such a list would be host=localhost,job_name=MyJob,task_name=MyTask.

The domain thus identifies a metric class, while the key-property list identifies one (or multiple) instances of that metric.

Graphite

(org.apache.flink.metrics.graphite.GraphiteReporter)

Type: push/identifier

Parameters:

• host - the Graphite server host
• port - the Graphite server port
• protocol - protocol to use (TCP/UDP)

Example configuration:

metrics.reporter.grph.factory.class: org.apache.flink.metrics.graphite.GraphiteReporterFactory
metrics.reporter.grph.host: localhost
metrics.reporter.grph.port: 2003
metrics.reporter.grph.protocol: TCP
metrics.reporter.grph.interval: 60 SECONDS

InfluxDB

(org.apache.flink.metrics.influxdb.InfluxdbReporter)

Type: push/tags

Parameters:

Example configuration:

metrics.reporter.influxdb.factory.class: org.apache.flink.metrics.influxdb.InfluxdbReporterFactory
metrics.reporter.influxdb.scheme: http
metrics.reporter.influxdb.host: localhost
metrics.reporter.influxdb.port: 8086
metrics.reporter.influxdb.db: flink
metrics.reporter.influxdb.username: flink-metrics
metrics.reporter.influxdb.password: qwerty
metrics.reporter.influxdb.retentionPolicy: one_hour
metrics.reporter.influxdb.consistency: ANY
metrics.reporter.influxdb.connectTimeout: 60000
metrics.reporter.influxdb.writeTimeout: 60000
metrics.reporter.influxdb.interval: 60 SECONDS

The reporter would send metrics using http protocol to the InfluxDB server with the specified retention policy (or the default policy specified on the server). All Flink metrics variables (see List of all Variables) are exported as InfluxDB tags.

Prometheus

(org.apache.flink.metrics.prometheus.PrometheusReporter)

Type: pull/tags

Parameters:

• port - (optional) the port the Prometheus exporter listens on, defaults to 9249. In order to be able to run several instances of the reporter on one host (e.g. when one TaskManager is colocated with the JobManager) it is advisable to use a port range like 9250-9260.
• filterLabelValueCharacters - (optional) Specifies whether to filter label value characters. If enabled, all characters not matching [a-zA-Z0-9:_] will be removed, otherwise no characters will be removed. Before disabling this option please ensure that your label values meet the Prometheus requirements.

Example configuration:

metrics.reporter.prom.factory.class: org.apache.flink.metrics.prometheus.PrometheusReporterFactory

Flink metric types are mapped to Prometheus metric types as follows:

All Flink metrics variables (see List of all Variables) are exported to Prometheus as labels.

PrometheusPushGateway

(org.apache.flink.metrics.prometheus.PrometheusPushGatewayReporter)

Type: push/tags

Parameters:

Example configuration:

metrics.reporter.promgateway.factory.class: org.apache.flink.metrics.prometheus.PrometheusPushGatewayReporterFactory
metrics.reporter.promgateway.hostUrl: http://localhost:9091
metrics.reporter.promgateway.jobName: myJob
metrics.reporter.promgateway.randomJobNameSuffix: true
metrics.reporter.promgateway.deleteOnShutdown: false
metrics.reporter.promgateway.groupingKey: k1=v1;k2=v2
metrics.reporter.promgateway.interval: 60 SECONDS

The PrometheusPushGatewayReporter pushes metrics to a Pushgateway, which can be scraped by Prometheus.

Please see the Prometheus documentation for use-cases.

StatsD

(org.apache.flink.metrics.statsd.StatsDReporter)

Type: push/identifier

Parameters:

• host - the StatsD server host
• port - the StatsD server port

Example configuration:

metrics.reporter.stsd.factory.class: org.apache.flink.metrics.statsd.StatsDReporterFactory
metrics.reporter.stsd.host: localhost
metrics.reporter.stsd.port: 8125
metrics.reporter.stsd.interval: 60 SECONDS

Datadog

(org.apache.flink.metrics.datadog.DatadogHttpReporter)

Type: push/tags

Note any variables in Flink metrics, such as <host>, <job_name>, <tm_id>, <subtask_index>, <task_name>, and <operator_name>, will be sent to Datadog as tags. Tags will look like host:localhost and job_name:myjobname.

Note For legacy reasons the reporter uses both the metric identifier and tags. This redundancy can be avoided by enabling useLogicalIdentifier.

Note Histograms are exposed as a series of gauges following the naming convention of Datadog histograms (<metric_name>.<aggregation>). The min aggregation is reported by default, whereas sum is not available. In contrast to Datadog-provided Histograms the reported aggregations are not computed for a specific reporting interval.

Parameters:

• apikey - the Datadog API key
• proxyHost - (optional) The proxy host to use when sending to Datadog.
• proxyPort - (optional) The proxy port to use when sending to Datadog, defaults to 8080.
• dataCenter - (optional) The data center (EU/US) to connect to, defaults to US.
• maxMetricsPerRequest - (optional) The maximum number of metrics to include in each request, defaults to 2000.
• useLogicalIdentifier -> (optional) Whether the reporter uses a logical metric identifier, defaults to false.

Example configuration:

metrics.reporter.dghttp.factory.class: org.apache.flink.metrics.datadog.DatadogHttpReporterFactory
metrics.reporter.dghttp.apikey: xxx
metrics.reporter.dghttp.proxyHost: my.web.proxy.com
metrics.reporter.dghttp.proxyPort: 8080
metrics.reporter.dghttp.dataCenter: US
metrics.reporter.dghttp.maxMetricsPerRequest: 2000
metrics.reporter.dghttp.interval: 60 SECONDS
metrics.reporter.dghttp.useLogicalIdentifier: true

Slf4j

(org.apache.flink.metrics.slf4j.Slf4jReporter)

Type: push/identifier

Example configuration:

metrics.reporter.slf4j.factory.class: org.apache.flink.metrics.slf4j.Slf4jReporterFactory
metrics.reporter.slf4j.interval: 60 SECONDS