guicedee/guicedee-config

GuicedEE Config

MicroProfile Config implementation for GuicedEE using SmallRye Config and Google Guice.

Core Concept

Inject configuration values with @ConfigProperty, resolve from environment variables, system properties, and META-INF/microprofile-config.properties — all wired automatically through SPI discovery and Guice bindings.

Required Flow

1. Add com.guicedee.microprofile:config dependency.
2. Add a microprofile-config.properties file:

   # src/main/resources/META-INF/microprofile-config.properties
   messaging.enabled=true
   messaging.bootstrap.servers=localhost:9092
   liveness.port=8081
   

3. Inject configuration values:

   public class MessagingService {
       @ConfigProperty(name = "messaging.enabled", defaultValue = "true")
       boolean enabled;
   
       @ConfigProperty(name = "messaging.bootstrap.servers")
       String bootstrapServers;
   }
   

4. Configure module-info.java:

   module my.app {
       requires com.guicedee.microprofile.config;
       opens my.app.services to com.google.guice;
   }
   

Configuration Sources

| Source | Ordinal | Example | |---|---|---| | Environment variables | 300 (highest) | MESSAGING_ENABLED=true | | System properties | 200 | -Dmessaging.enabled=true | | META-INF/microprofile-config.properties | 100 (lowest) | messaging.enabled=true |

Key mapping

Environment variable names follow MicroProfile Config rules:

• Dots and hyphens → underscores
• Uppercased
• e.g. messaging.bootstrap.servers → MESSAGING_BOOTSTRAP_SERVERS

Profiles

SmallRye Config supports profile-specific properties using %profile. prefix:

db.url=jdbc:postgresql://prod-host:5432/mydb
%dev.db.url=jdbc:postgresql://localhost:5432/mydb

Activate with mp.config.profile=dev.

Supported Injection Types

| Type | Binding | |---|---| | String | Direct value | | boolean / Boolean | Parsed | | int / Integer | Parsed | | long / Long | Parsed | | double / Double | Parsed | | float / Float | Parsed | | Optional<T> | Wrapped optional (all above types) |

Default values via @ConfigProperty(defaultValue = "...").

Programmatic Access

@Inject
SmallRyeConfig config;

int port = config.getOptionalValue("liveness.port", Integer.class).orElse(8081);

Custom Converters

Register Converter<T> implementations via ServiceLoader for application-specific types.

Startup Flow

IGuiceContext.instance().inject()
 └─ MicroProfileConfigContext (builds SmallRyeConfig on Vert.x worker thread)
     ├─ addDefaultSources() (env vars, system props, microprofile-config.properties)
     ├─ addDiscoveredSources() (ServiceLoader-discovered ConfigSource SPIs)
     └─ addDiscoveredConverters()
 └─ MicroProfileConfigBinder (scans @ConfigProperty fields, creates Guice bindings)

Non-Negotiable Constraints

• Module must requires com.guicedee.microprofile.config;.
• Classes with @ConfigProperty fields must be in packages opened to com.google.guice.
• The config module is registered automatically — no provides needed.
• Config is built on a Vert.x worker thread to avoid blocking the event loop.