Configuration

Pedestal primarily is configured via the service map; however, there are sub-systems within Pedestal that can operate outside of a service, or before a service map is used to create and start a server.

These sub-systems are:

For all but Developer Mode[1], Pedestal operates in terms of a configuration function: The configuration function is specified in one of several ways, and this is resolved to a particular var in a namespace, which is invoked to return a needed value.

Configuration Order

Pedestal uses late binding to configure these values, so that it is possible to customize Pedestal’s behavior to the operating environment: anything from local developer to final production.

Pedestal will search a series of sources for a value that identifies the var; these are in a specific order, with an eye towards making it possible to override the value at runtime for testing or production, as that is often a need for these subsystems.

  • JVM system property name

  • Environment Variable

  • Entry in the pedestal-test-config.edn resource

  • Entry in the pedestal-config.edn resource

  • A hard-coded default, or nil

The intent is that a Pedestal application will typically include a pedestal-config.edn on the classpath (packaged with the application’s sources or compiled classes, typically stored in resources); the pedestal-test-config.edn will only be on the classpath during local testing (typically, stored in test-resources).

When necessary, these values can be overrridden when deployed to a staging or production deployment using environment variables or JVM system properties.

EDN Configuration Files

The contents of pedestal-config.edn (and pedestal-test-config.edn) are EDN maps.

The keys are the JVM property converted to a keyword (for example, :io.pedestal.log.overrideLogger).

The value can be either a qualified symbol, or a string that is converted to a qualified symbol.

Configuration Keys

Once a symbol is obtained from a configuration source, it is resolved to a Clojure Var. Each use of configuration has its own interpretation of the Var.

The following section list the current configuration values; each heading identifies the JVM system property, then the equivalent environment variable.

io.pedestal.log.overrideLogger / PEDESTAL_LOGGER

Used to create an LoggerSource instance from a logger name; If not specified, then org.slf4j.LoggerFactory.getLogger(java.lang.String) is used.

io.pedestal.log.formatter / PEDESTAL_LOG_FORMATTER

A function used to format a logged event map to a string prior to being passed to the LoggerSource. When not specified, pr-str is used.

io.pedestal.log.defaultMetricsRecorder / PEDESTAL_METRICS_RECORDER

Used to configure the now-deprecated support for metrics in the pedestal.log library. Supports the special string "nil" to indicate no metrics publishing. Does not check the EDN config files. Defaults to a registry built around jmx-recorder.

io.pedestal.telemetry.metric-source / PEDESTAL_METRICS_SOURCE

A function that returns an instance of MetricSource used to create metrics used by Pedestal or applications.

The default, metric-source, gets the value from io.opentelemetry.api.GlobalOpenTelemetry.getMeter(java.lang.String).

io.pedestal.telemetry.tracing-source/ PEDESTAL_TRACING_SOURCE

A function that returns an instance of TracingSource, used to emit tracing events.

The default, tracing-source, gets its value from io.opentelemetry.api.GlobalOpenTelemetry.getTracer(java.lang.String).

1. Developer mode is the exception, as it resolves to a boolean value, rather than a function to execute.