With config mappings it is possible to group multiple configuration properties in a single interface that share the same prefix.
1. @ConfigMapping
A config mapping requires an interface with minimal metadata configuration and annotated with the
@io.smallrye.config.ConfigMapping
annotation.
@ConfigMapping(prefix = "server")
interface Server {
String host();
int port();
}
The Server
interface is able to map configuration properties with the name server.host
into the Server.host()
method and server.port
into Server.port()
method. The configuration property name to look up is built from the
prefix, and the method name with .
(dot) as the separator.
If a mapping fails to match a configuration property a NoSuchElementException is thrown, unless the mapped
element is an Optional .
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1.1. Registration
When a Quarkus application starts, a config mapping can be registered twice. One time for STATIC INIT and a second time for RUNTIME INIT:
1.1.1. STATIC INIT
Quarkus starts some of its services during static initialization, and Config
is usually one of the first things that
is created. In certain situations it may not be possible to correctly initialize a config mapping. For instance, if the
mapping requires values from a custom ConfigSource
. For this reason, any config mapping requires the annotation
@io.quarkus.runtime.configuration.StaticInitSafe
to mark the mapping as safe to be used at this stage. Learn more
about registration of a custom ConfigSource
.
1.2. Retrieval
A config mapping interface can be injected into any CDI aware bean:
class BusinessBean {
@Inject
Server server;
public void businessMethod() {
String host = server.host();
}
}
In non-CDI contexts, use the API io.smallrye.config.SmallRyeConfig#getConfigMapping
to retrieve the config mapping
instance:
SmallRyeConfig config = ConfigProvider.getConfig().unwrap(SmallRyeConfig.class);
Server server = config.getConfigMapping(Server.class);
1.3. Nested groups
A nested mapping provides a way to subgroup other config properties:
@ConfigMapping(prefix = "server")
public interface Server {
String host();
int port();
Log log();
interface Log {
boolean enabled();
String suffix();
boolean rotate();
}
}
server.host=localhost
server.port=8080
server.log.enabled=true
server.log.suffix=.log
server.log.rotate=false
The method name of a mapping group acts as sub-namespace to the configurations properties.
1.4. Overriding property names
1.4.1. @WithName
If a method name, or a property name do not match with each other, the @WithName
annotation can override the method
name mapping and use the name supplied in the annotation:
@ConfigMapping(prefix = "server")
interface Server {
@WithName("name")
String host();
int port();
}
server.name=localhost
server.port=8080
1.4.2. @WithParentName
The @WithParent
annotation allows to configurations mapping to inherit its container name, simplifying the
configuration property name required to match the mapping:
interface Server {
@WithParentName
ServerHostAndPort hostAndPort();
@WithParentName
ServerInfo info();
}
interface ServerHostAndPort {
String host();
int port();
}
interface ServerInfo {
String name();
}
server.host=localhost
server.port=8080
server.name=konoha
Without the @WithParentName
the method name()
requires the configuration property server.info.name
. Because we use
@WithParentName
, the info()
mapping will inherit the parent name from Server
and name()
maps to server.name
instead.
1.4.3. NamingStrategy
Method names in camelCase map to kebab-case property names:
@ConfigMapping(prefix = "server")
interface Server {
String theHost();
int thePort();
}
server.the-host=localhost
server.the-port=8080
The mapping strategy can be adjusted by setting namingStrategy
value in the @ConfigMapping
annotation:
@ConfigMapping(prefix = "server", namingStrategy = ConfigMapping.NamingStrategy.VERBATIM)
public interface ServerVerbatimNamingStrategy {
String theHost();
int thePort();
}
server.theHost=localhost
server.thePort=8080
The @ConfigMapping
annotation support the following naming stategies:
-
KEBAB_CASE
(default) - The method name is derived by replacing case changes with a dash to map the configuration property. -
VERBATIM
- The method name is used as is to map the configuration property. -
SNAKE_CASE
- The method name is derived by replacing case changes with an underscore to map the configuration property.
1.5. Conversions
A config mapping class support automatic conversions of all types available for conversion in Config
:
@ConfigMapping
public interface SomeTypes {
@WithName("int")
int intPrimitive();
@WithName("int")
Integer intWrapper();
@WithName("long")
long longPrimitive();
@WithName("long")
Long longWrapper();
@WithName("float")
float floatPrimitive();
@WithName("float")
Float floatWrapper();
@WithName("double")
double doublePrimitive();
@WithName("double")
Double doubleWrapper();
@WithName("char")
char charPrimitive();
@WithName("char")
Character charWrapper();
@WithName("boolean")
boolean booleanPrimitive();
@WithName("boolean")
Boolean booleanWrapper();
}
int=9
long=9999999999
float=99.9
double=99.99
char=c
boolean=true
This is also valid for Optional
and friends:
@ConfigMapping
public interface Optionals {
Optional<Server> server();
Optional<String> optional();
@WithName("optional.int")
OptionalInt optionalInt();
interface Server {
String host();
int port();
}
}
In this case, the mapping won’t fail if there are not configuration properties to match the mapping.
1.5.1. @WithConverter
The @WithConverter
annotation provides a way to set a Converter
to use in a specific mapping:
@ConfigMapping
public interface Converters {
@WithConverter(FooBarConverter.class)
String foo();
}
public static class FooBarConverter implements Converter<String> {
@Override
public String convert(final String value) {
return "bar";
}
}
foo=foo
A call to Converters.foo()
results in the value bar
.
1.5.2. Collections
A config mapping is also able to map collections types List
and Set
:
@ConfigMapping(prefix = "server")
public interface ServerCollections {
Set<Environment> environments();
interface Environment {
String name();
List<App> apps();
interface App {
String name();
List<String> services();
Optional<List<String>> databases();
}
}
}
server.environments[0].name=dev
server.environments[0].apps[0].name=rest
server.environments[0].apps[0].services=bookstore,registration
server.environments[0].apps[0].databases=pg,h2
server.environments[0].apps[1].name=batch
server.environments[0].apps[1].services=stock,warehouse
The List
or Set
mappings can use indexed properties to map
configuration values in mapping groups. For collection with simple element types like String
, their configuration
value is a comma separated string.
1.5.3. Maps
A config mapping is also able to map a Map
:
@ConfigMapping(prefix = "server")
public interface Server {
String host();
int port();
Map<String, String> form();
}
server.host=localhost
server.port=8080
server.form.login-page=login.html
server.form.error-page=error.html
server.form.landing-page=index.html
The configuration property needs to specify an additional name to act as the key. In this case the form()
Map
will
contain three elements with the keys login-page
, error-page
and landing-page
.
1.6. Defaults
The @WithDefault
annotation allows to set a default property into a mapping (and prevent and error if the
configuration value is not available in any ConfigSource
):
public interface Defaults {
@WithDefault("foo")
String foo();
@WithDefault("bar")
String bar();
}
No configuration properties required. The Defaults.foo()
will return the value foo
and Defaults.bar()
will return
thevalue bar
.
1.7. Validation
A config mapping may combine annotations from Bean Validation to validate configuration values:
@ConfigMapping(prefix = "server")
interface Server {
@Size(min = 2, max = 20)
String host();
@Max(10000)
int port();
}
For validation to work, the quarkus-hibernate-validator extension is required, and it is performed
automatically.
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1.8. Mocking
A mapping interface implementation is not a proxy, so it cannot be mocked directly with @InjectMock
like other CDI
beans. One trick is to make it proxyable with a producer method:
public class ServerMockProducer {
@Inject
Config config;
@Produces
@ApplicationScoped
@io.quarkus.test.Mock
Server server() {
return config.unwrap(SmallRyeConfig.class).getConfigMapping(Server.class);
}
}
The Server
can be injected as a mock into a Quarkus test class with @InjectMock
:
@QuarkusTest
class ServerMockTest {
@InjectMock
Server server;
@Test
void localhost() {
Mockito.when(server.host()).thenReturn("localhost");
assertEquals("localhost", server.host());
}
}
The mock is just an empty shell without any actual configuration values. |
If the goal is to only mock certain configuration values and retain the original configuration, the mocking instance requires a spy:
@ConfigMapping(prefix = "app")
public interface AppConfig {
@WithDefault("app")
String name();
Info info();
interface Info {
@WithDefault("alias")
String alias();
@WithDefault("10")
Integer count();
}
}
public static class AppConfigProducer {
@Inject
Config config;
@Produces
@ApplicationScoped
@io.quarkus.test.Mock
AppConfig appConfig() {
AppConfig appConfig = config.unwrap(SmallRyeConfig.class).getConfigMapping(AppConfig.class);
AppConfig appConfigSpy = Mockito.spy(appConfig);
AppConfig.Info infoSpy = Mockito.spy(appConfig.info());
Mockito.when(appConfigSpy.info()).thenReturn(infoSpy);
return appConfigSpy;
}
}
The AppConfig
can be injected as a mock into a Quarkus test class with @Inject
:
@QuarkusTest
class AppConfigTest {
@Inject
AppConfig appConfig;
@Test
void localhost() {
Mockito.when(appConfig.name()).thenReturn("mocked-app");
assertEquals("mocked-app", server.host());
Mockito.when(appConfig.info().alias()).thenReturn("mocked-alias");
assertEquals("mocked-alias", server.info().alias());
}
}
Nested elements need to be spied individually by Mockito. |
2. @ConfigProperties
(Deprecated)
This feature will be removed soon, please update your code base and use @ConfigMapping instead.
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The @io.quarkus.arc.config.ConfigProperties
annotation is able to group multiple related configuration values in its
own class:
package org.acme.config;
import io.quarkus.arc.config.ConfigProperties;
import java.util.Optional;
@ConfigProperties(prefix = "greeting") (1)
public class GreetingConfiguration {
private String message;
private String suffix = "!"; (2)
private Optional<String> name;
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public String getSuffix() {
return suffix;
}
public void setSuffix(String suffix) {
this.suffix = suffix;
}
public Optional<String> getName() {
return name;
}
public void setName(Optional<String> name) {
this.name = name;
}
}
1 | prefix is optional. If not set then the prefix to be used will be determined by the class name. In this case it
would still be greeting (since the Configuration suffix is removed). If the class were named
GreetingExtraConfiguration then the resulting default prefix would be greeting-extra . |
2 | ! will be the default value if greeting.suffix is not set. |
Inject the GreetingResource
with CDI @Inject
:
@Inject
GreetingConfiguration greetingConfiguration;
Another alternative style provided by Quarkus is to create GreetingConfiguration
as an interface:
package org.acme.config;
import io.quarkus.arc.config.ConfigProperties;
import org.eclipse.microprofile.config.inject.ConfigProperty;
import java.util.Optional;
@ConfigProperties(prefix = "greeting")
public interface GreetingConfiguration {
@ConfigProperty(name = "message") (1)
String message();
@ConfigProperty(defaultValue = "!")
String getSuffix(); (2)
Optional<String> getName(); (3)
}
1 | The @ConfigProperty annotation is needed because the name of the configuration property that the method
corresponds does not follow the getter method naming conventions. |
2 | In this case since name is not set, the corresponding property will be greeting.suffix . |
3 | It is unnecessary to specify the @ConfigProperty annotation because the method name follows the getter method
naming conventions (greeting.name being the corresponding property) and no default value is required. |
When using @ConfigProperties
on a class or an interface, if the value of one of its fields is not provided, the
application startup will fail, and a javax.enterprise.inject.spi.DeploymentException
will be thrown. This does not
apply to Optional
fields and fields with a default value.
2.1. Additional notes on @ConfigProperties
When using a regular class annotated with @ConfigProperties
the class doesn’t necessarily have to declare getters and
setters. Having simple public non-final fields is valid as well.
Furthermore, the configuration classes support nested object configuration. Suppose there was a need to have an extra
layer of greeting configuration named content
that would contain a few fields:
@ConfigProperties(prefix = "greeting")
public class GreetingConfiguration {
public String message;
public String suffix = "!";
public Optional<String> name;
public ContentConfig content; (1)
public static class ContentConfig {
public Integer prizeAmount;
public List<String> recipients;
}
}
1 | The name of the field (not the class name) will determine the name of the properties that are bound to the object. |
Setting the properties would occur in the normal manner:
greeting.message = hello
greeting.name = quarkus
greeting.content.prize-amount=10
greeting.content.recipients=Jane,John
Furthermore, classes annotated with @ConfigProperties
can be annotated with Bean Validation annotations:
@ConfigProperties(prefix = "greeting")
public class GreetingConfiguration {
@Size(min = 20)
public String message;
public String suffix = "!";
}
For validation to work, the quarkus-hibernate-validator extension is required.
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2.2. Using same ConfigProperties with different prefixes
Quarkus also supports the use of the same @ConfigProperties
object with different prefixes for each injection point
using the io.quarkus.arc.config.@ConfigPrefix
annotation. If GreetingConfiguration
from above needs to be used for
both the greeting
prefix and the other
prefix:
@ConfigProperties(prefix = "greeting")
public class GreetingConfiguration {
@Size(min = 20)
public String message;
public String suffix = "!";
}
@ApplicationScoped
public class SomeBean {
@Inject (1)
GreetingConfiguration greetingConfiguration;
@ConfigPrefix("other") (2)
GreetingConfiguration otherConfiguration;
}
1 | At this injection point greetingConfiguration will use the greeting prefix since that is what has been defined
on @ConfigProperties . |
2 | At this injection point otherConfiguration will use the other prefix from @ConfigPrefix instead of the
greeting prefix. Notice that in this case @Inject is not required. |
2.3. Combining ConfigProperties with build time conditions
Quarkus allows you to define conditions evaluated at build time (@IfBuildProfile
, @UnlessBuildProfile
,
@IfBuildProperty
and @UnlessBuildProperty
) to enable or not the annotations @ConfigProperties
and @ConfigPrefix
which gives you a very flexible way to map your configuration.
Let’s assume that the configuration of a service is mapped thanks to a @ConfigProperties
and you don’t need this part
of the configuration for your tests as it will be mocked, in that case you can define a build time condition like in
the next example:
ServiceConfiguration.java
@UnlessBuildProfile("test") (1)
@ConfigProperties
public class ServiceConfiguration {
public String user;
public String password;
}
1 | The annotation @ConfigProperties is considered if and only if the active profile is not test . |
SomeBean.java
@ApplicationScoped
public class SomeBean {
@Inject
Instance<ServiceConfiguration> serviceConfiguration; (1)
}
1 | As the configuration of the service could be missing, we need to use Instance<ServiceConfiguration> as type at
the injection point. |