Configuration Reference Guide

The content of this guide has been revised and split into additional topics. Please check the Additional Information section.

In this reference guide we’re going to describe various aspects of Quarkus configuration. A Quarkus application and Quarkus itself (core and extensions) are both configured via the same mechanism that leverages the SmallRye Config API an implementation of the MicroProfile Config specification.

If you’re looking for information how to make a Quarkus extension configurable then see the Writing Your Own Extension guide.

1. Config Sources

By default, Quarkus reads configuration properties from multiple sources (by descending ordinal):

  1. (400) System properties

  2. (300) Environment variables

  3. (295) .env file in the current working directory

  4. (260) Quarkus Application configuration file in $PWD/config/application.properties

  5. (250) Quarkus Application configuration file application.properties in classpath

  6. (100) MicroProfile Config configuration file META-INF/microprofile-config.properties in classpath

The final configuration is the aggregation of the properties defined by all these sources. A configuration property lookup starts by the highest ordinal configuration source available and works it way down to other sources until a match is found. This means that any configuration property may override a value just by setting a different value in a higher ordinal config source. For example, a property configured using an environment property overrides the value provided using the application.properties file.

config sources

1.1. System properties

System properties can be handed to the application through the -D flag during startup. The following examples assign the value youshallnotpass to the attribute quarkus.datasource.password.

  • For Quarkus dev mode: ./mvnw quarkus:dev -Dquarkus.datasource.password=youshallnotpass

  • For a runner jar: java -Dquarkus.datasource.password=youshallnotpass -jar target/quarkus-app/quarkus-run.jar

  • For a native executable: ./target/myapp-runner -Dquarkus.datasource.password=youshallnotpass

1.2. Environment variables

  • For a runner jar: export QUARKUS_DATASOURCE_PASSWORD=youshallnotpass ; java -jar target/quarkus-app/quarkus-run.jar

  • For a native executable: export QUARKUS_DATASOURCE_PASSWORD=youshallnotpass ; ./target/myapp-runner

Environment variables names follow the conversion rules specified by MicroProfile Config.

1.3. .env file in the current working directory

.env
QUARKUS_DATASOURCE_PASSWORD=youshallnotpass (1)
1 The name QUARKUS_DATASOURCE_PASSWORD the same conversion rules used for Environment variables.

For dev mode, this file can be placed in the root of the project, but it is advised to not check it in to version control.

Environment variables in the .env file are not available via the System.getenv(String) API.

1.4. Quarkus Application configuration file

The Quarkus Application configuration file is loaded from the classpath resources, for instance src/main/resources/application.properties, src/test/resources/application.properties or from a jar dependency that contains an application.properties entry. Additionally, the configuration file may also reside in $PWD/config/application.properties. The loading starts from the config folder and then classpath order (application.properties files in the application sources will have priority on the classloader loading order).

application.properties
greeting.message=hello (1)
quarkus.http.port=9090 (2)
1 This is a user-defined configuration property.
2 This is a configuration property consumed by the quarkus-vertx-http extension.
The config/application.properties is also available in dev mode. The file needs to be placed inside the build tool output directory (target for Maven and build/classes/java/main for Gradle). Keep in mind however that any cleaning operation from the build tool like mvn clean or gradle clean will remove the config directory as well.

1.5. MicroProfile Config configuration file

The MicroProfile Config configuration file in src/main/resources/META-INF/microprofile-config.properties.

microprofile-config.properties
greeting.message=hello (1)
quarkus.http.port=9090 (2)
1 This is a user-defined configuration property.
2 This is a configuration property consumed by the quarkus-vertx-http extension.
It works in the exact same way as Quarkus Application configuration file application.properties. Recommendation is to use Quarkus application.properties.

1.6. Additional Config Sources

Quarkus provides additional extensions which cover other configuration formats and stores:

It is also possible to create a Custom Config Source.

2. Inject

Quarkus uses MicroProfile Config annotations to inject the configuration properties in the application.

@ConfigProperty(name = "greeting.message") (1)
String message;
1 You can use @Inject @ConfigProperty or just @ConfigProperty. The @Inject annotation is not necessary for members annotated with @ConfigProperty.
If the application attempts to inject a configuration property that is not set, an error is thrown.
@ConfigProperty(name = "greeting.message") (1)
String message;

@ConfigProperty(name = "greeting.suffix", defaultValue="!") (2)
String suffix;

@ConfigProperty(name = "greeting.name")
Optional<String> name; (3)
1 If you do not provide a value for this property, the application startup fails with javax.enterprise.inject.spi.DeploymentException: No config value of type [class java.lang.String] exists for: greeting.message.
2 The default value is injected if the configuration does not provide a value for greeting.suffix.
3 This property is optional - an empty Optional is injected if the configuration does not provide a value for greeting.name.
Use Config Mappings to group similar configuration properties.

3. Programmatically access

The org.eclipse.microprofile.config.ConfigProvider.getConfig() API allows to access the Config API programmatically. This API is mostly useful in situations where CDI injection is not available.

String databaseName = ConfigProvider.getConfig().getValue("database.name", String.class);
Optional<String> maybeDatabaseName = ConfigProvider.getConfig().getOptionalValue("database.name", String.class);
Do not use System.getProperty(String) or System.getEnv(String) to retrieve configuration values. These APIs are not configuration aware and do not support the features described in this guide.

4. Profiles

We often need to configure differently our application depending on the target environment. For example, the local development environment may be different from the production environment.

Configuration Profiles allow for multiple configurations in the same file or separate files and select between them via a profile name.

4.1. Profile in the property name

To be able to set properties with the same name, each property needs to be prefixed with a percentage sign % followed by the profile name and a dot . in the syntax %{profile-name}.config.name:

application.properties
quarkus.http.port=9090
%dev.quarkus.http.port=8181

The Quarkus HTTP port will be 9090. If the dev profile is active it will be 8181.

Profiles in the .env file follow the syntax _{PROFILE}_CONFIG_KEY=value:

.env
QUARKUS_HTTP_PORT=9090
_DEV_QUARKUS_HTTP_PORT=8181

If a profile does not define a value for a specific attribute, the default (no profile) value is used:

application.properties
bar=”hello”
baz=”bonjour”
%dev.bar=”hallo”

With the dev profile enabled, the property bar has the value hallo, but the property baz has the value bonjour. If the prod profile is enabled, bar has the value hello (as there is no specific value for the prod profile), and baz the value bonjour.

4.2. Default Profiles

By default, Quarkus provides three profiles, that activate automatically in certain conditions:

  • dev - Activated when in development mode (i.e. quarkus:dev)

  • test - Activated when running tests

  • prod - The default profile when not running in development or test mode

4.3. Custom Profiles

It is also possible to create additional profiles and activate them with the quarkus.profile configuration property. A single config property with the new profile name is the only requirement:

application.properties
quarkus.http.port=9090
%staging.quarkus.http.port=9999

Setting quarkus.profile to staging will activate the staging profile.

Only a single profile may be active at a time.

The io.quarkus.runtime.configuration.ProfileManager#getActiveProfile API provides a way to retrieve the active profile programmatically.

Using @ConfigProperty("quarkus.profile") will not work properly.

4.4. Profile aware files

In this case, properties for a specific profile may reside in an application-{profile}.properties named file. The previous example may be expressed as:

application.properties
quarkus.http.port=9090
%staging.quarkus.http.test-port=9091
application-staging.properties
quarkus.http.port=9190
quarkus.http.test-port=9191

In this style, the configuration names in the profile aware file do not need to be prefixed with the profile name.

Properties in the profile aware file have priority over profile aware properties defined in the main file.

4.5. Parent Profile

A Parent Profile adds one level of hierarchy to the current profile. The configuration quarkus.config.profile.parent accepts a single profile name.

When the Parent Profile is active, if a property cannot be found in the current active Profile, the config lookup fallbacks to the Parent Profile. Consider:

quarkus.profile=dev
quarkus.config.profile.parent=common

%common.quarkus.http.port=9090
%dev.quarkus.http.ssl-port=9443

quarkus.http.port=8080
quarkus.http.ssl-port=8443

Then

  • The active profile is dev

  • The parent profile is common

  • quarkus.http.port is 9090

  • quarkus.http.ssl-port is 9443

4.6. Default Runtime Profile

The default Quarkus runtime profile is set to the profile used to build the application:

./mvnw package -Pnative -Dquarkus.profile=prod-aws
./target/my-app-1.0-runner (1)
1 The command will run with the prod-aws profile. This can be overridden using the quarkus.profile configuration.

5. Property Expressions

Quarkus provides property expressions expansion on configuration values. An expression string is a mix of plain strings and expression segments, which are wrapped by the sequence ${ …​ }.

These expressions are resolved when the property is read. So if the configuration property is build time the property expression will be resolved at build time. If the configuration property is overridable at runtime it will be resolved at runtime.

Consider:

application.properties
remote.host=quarkus.io
callable.url=https://${remote.host}/

The resolved value of the callable.url property is https://quarkus.io/.

Another example would be defining different database servers by profile:

application.properties
%dev.quarkus.datasource.jdbc.url=jdbc:mysql://localhost:3306/mydatabase?useSSL=false
quarkus.datasource.jdbc.url=jdbc:mysql://remotehost:3306/mydatabase?useSSL=false

can be simplified to:

application.properties
%dev.application.server=localhost
application.server=remotehost

quarkus.datasource.jdbc.url=jdbc:mysql://${application.server}:3306/mydatabase?useSSL=false

Additionally, the Expression Expansion engine supports the following segments:

  • ${expression:value} - Provides a default value after the : if the expansion doesn’t find a value.

  • ${my.prop${compose}} - Composed expressions. Inner expressions are resolved first.

  • ${my.prop}${my.prop} - Multiple expressions.

If an expression cannot be expanded and no default is supplied a NoSuchElementException is thrown.

Expressions lookups are performed in all config sources. The expression values and expansion values may reside in different config sources.

5.1. With Environment Variables

Property Expressions also work with Environment Variables.

application.properties
remote.host=quarkus.io
application.host=${HOST:${remote.host}}

This will expand the HOST environment variable and use the value of the property remote.host as the default value if HOST is not set.

6. Accessing a generating UUID

The default config source from Quarkus provides a random UUID value. It generates the UUID at startup time. So, the value changes between startups, including reloads in dev mode.

You can access the generated value using the quarkus.uuid property. Use expressions to access it: ${quarkus.uuid}. For example, it can be useful to configure a Kafka client with a unique consumer group:

mp.messaging.incoming.prices.group.id=${quarkus.uuid}

7. Clearing properties

Run time properties which are optional, and which have had values set at build time or which have a default value, may be explicitly cleared by assigning an empty string to the property. Note that this will only affect runtime properties, and will only work with properties whose values are not required.

application.properties
remote.host=quarkus.io

A lookup to remote.host with -Dremote.host= will throw an Exception, because the system property cleared the value.

8. Indexed Properties

A config value which contains unescaped commas may be converted to Collection. This works for simple cases, but it becomes cumbersome and limited for more advanced cases.

Indexed Properties provide a way to use indexes in config property names to map specific elements in a Collection type. Since the indexed element is part of the property name and not contained in the value, this can also be used to map complex object types as `Collectionª elements. Consider:

application.properties
my.collection=dog,cat,turtle

my.indexed.collection[0]=dog
my.indexed.collection[1]=cat
my.indexed.collection[2]=turtle

The indexed property syntax uses the property name and square brackets `[ ] with an index in between.

A call to Config#getValues("my.collection", String.class), will automatically create and convert a List<String> that contains the values dog, cat and turtle. A call to Config#getValues("my.indexed.collection", String.class) returns the exact same result. If the same property name exists in both froms (regular and indexed), the regular value has priority.

The indexed property is sorted by their index before being added to the target Collection. Any gaps contained in the indexes do not resolve to the target Collection, which means that the Collection result will store all values without any gaps.

Indexed Properties are not supported in Environment Variables.

9. Generate Configuration

It is also possible to generate an example application.properties with all known configuration properties:

./mvnw quarkus:generate-config

This creates a src/main/resources/application.properties.example file that contains all the config options exposed via the extensions currently present in the application. These options are commented out, and have their value set to defaults when applicable. For example this HTTP port config entry will appear as:

application.properties
#
# The HTTP port
#
#quarkus.http.port=8080

Rather than generating an example config file, you can also add these to you actual config file by setting the -Dfile parameter:

./mvnw quarkus:generate-config -Dfile=application.properties

If a config option is already present it will not be added, so it is safe to run this after adding an extension to see which configurations are available.

10. Configuring Quarkus

Quarkus itself is configured via the same mechanism as your application. Quarkus reserves the quarkus. namespace for its own configuration. For example to configure the HTTP server port you can set quarkus.http.port in application.properties. All the Quarkus configuration properties are documented and searchable.

As mentioned above, properties prefixed with quarkus. are effectively reserved for configuring Quarkus itself and its extensions. Therefore, the quarkus. prefix should never be used for application specific properties.

10.1. Build Time configuration

Some Quarkus configurations only take effect during build time, meaning is not possible to change them at runtime. These configurations are still available at runtime but as read-only and have no effect in Quarkus behaviour. A change to any of these configurations requires a rebuild of the application itself to reflect changes of such properties.

The properties fixed at build time are marked with a lock icon () in the list of all configuration options.

However, some extensions do define properties overridable at runtime. A simple example is the database URL, username and password which is only known specifically in your target environment, so they can be set and influence the application behaviour at runtime.

11. Change build time properties after your application has been published

If you are in the rare situation that you need to change the build time configuration after your application is built, then check out how re-augmentation can be used to rebuild the augmentation output for a different build time configuration.

12. Additional Information

Quarkus relies on SmallRye Config and inherits its features:

  • Additional ConfigSources

  • Additional Converters

  • Indexed properties

  • Parent profile

  • Interceptors for configuration value resolution

  • Relocate configuration properties

  • Fallback configuration properties

  • Logging

  • Hide secrets

For more information, please check the SmallRye Config documentation.

13. Configuration Reference

Configuration property fixed at build time - All other configuration properties are overridable at runtime

Configuration property

Type

Default

Additional config locations to be loaded with the Config. The configuration support multiple locations separated by a comma and each must represent a valid java.net.URI.

list of string

Accepts a single configuration profile name. If a configuration property cannot be found in the current active profile, the config performs the same lookup in the profile set by this configuration.

string

A property that allows accessing a generated UUID. It generates that UUID at startup time. So it changes between two starts including in dev mode. Access this generated UUID using expressions: ${quarkus.uuid}.

string