lib-commons-logging-mdc

Helper methods to facilitate filling the Logging Mapped Diagnostics Context MDC with most used values

Available versions: see Releases

This lib consists of two modules:

• lib-commons-logging-mdc-api
  The API is a low-level wrapper around the MDC and also defines common values used by DV Bern applications.
• lib-commons-logging-mdc-jaxrs-filter
  The JAX-RS filter facilitates using JaxRS filters to fill the MDC with our common values.

Module: lib-commons-logging-mdc-api

Basic API to fill *and cleanup the MDC.

Workhorse is the class MDCDAOSlf4j which is used to fill the MDC with the most used values.

Usage

Maven-Dependency:

<dependency>
    <groupId>ch.dvbern.oss.commons-logging-mdc</groupId>
    <artifactId>commons-logging-mdc-api</artifactId>
    <version>see github releases for available versions</version>
</dependency>

import ch.dvbern.oss.commons.logging.mdc.MDCDAO;
import ch.dvbern.oss.commons.logging.mdc.MDCDAOSlf4j;
import ch.dvbern.oss.commons.logging.mdc.MDCValues;

public class MyClass {
	private final MDCDAO mdcDAO = new MDCDAOSlf4j();

    public void doSomethingWithMDC() {
        // fill MDC
        MDCValues values = MDCValues.empty()
            .with("foo", "The Foo")
            .with("bar", "The Bar");
        mdcDAO.applyToMDC(values);
		
        // call business logic
        doSomething();
        
        // clear MDC
        mdcDAO.clearMDC();
    }
}

Module: lib-commons-logging-mdc-jaxrs-filter

JAX-RS filter to fill the MDC with common values used by all DV Bern applications.

Usage

Maven-Dependency:

<dependency>
    <groupId>ch.dvbern.oss.commons-logging-mdc</groupId>
    <artifactId>commons-logging-mdc-jaxrs-filter</artifactId>
    <version>see github releases for available versions</version>
</dependency>

Initialize the MDC in a request filter:

@Provider
@PreMatching
// should be after any authentication filter, i.e. at least: jakarta.ws.rs.Priorities.AUTHENTICATION + 1
@Priority(jakarta.ws.rs.Priorities.AUTHENTICATION + 1)
@RequestScoped
@NoArgsConstructor
@AllArgsConstructor(
    access = AccessLevel.PACKAGE,
    onConstructor_ = @SuppressWarnings("rawtypes")
)
public class InitLoggingRequestFilter implements ContainerRequestFilter {

    private final CommonMDCFieldRequestFilterHelper helper = CommonMDCFieldRequestFilterHelper.usingDefaults();

	// roll your own deployment config
    @Inject
    DeploymentConfig deploymentConfig;
	// roll your own tenant provider
	@Inject
	TenantProvider tenantProvider;

    @Override
    public void filter(ContainerRequestContext requestContext) {
        var loggingPrincipal = Optional.ofNullable(requestContext.getSecurityContext().getUserPrincipal())
            .map(p -> new LoggingPrincipal(p.getName()))
            .orElse(null);
		
		var loggingTenant = Optional.ofNullable(tenantProvider.getTenant())
		    .map(t -> new LoggingTenant(t.getIdentifier()))
		    .orElse(null);

        helper.filter(
            requestContext,
            new LoggingApp(
                deploymentConfig.appProject(),
                deploymentConfig.appModule(),
                deploymentConfig.version(),
                deploymentConfig.instance()
            ),
            new LoggingSource(requestContext.getUriInfo().getRequestUri().getPath(), requestContext.getMethod()),
            loggingPrincipal,
            loggingTenant
        );

    }

}

Do not forget to register the response filter to cleanup the MDC:

@Provider
@PreMatching
@Priority(/* see Request Filter */)
@RequestScoped
@NoArgsConstructor
public class InitLoggingResponseFilter implements ContainerResponseFilter {

    private final CommonMDCFieldResponseFilterHelper helper = CommonMDCFieldResponseFilterHelper.usingDefaults();

    @Override
    public void filter(
        ContainerRequestContext requestContext,
        ContainerResponseContext responseContext
    ) {
        helper.filter(requestContext, responseContext);
    }

}