CorrelationIdFilter.java

import io.arleigh.gantry.util.UuidGenerator;
import lombok.RequiredArgsConstructor;
import org.slf4j.MDC;
import org.springframework.context.annotation.Profile;
import org.springframework.lang.NonNull;
import org.springframework.stereotype.Component;
import org.springframework.web.filter.OncePerRequestFilter;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.UUID;

@Profile("!prod") // infrastructure does it for us in production
@Component
@RequiredArgsConstructor
class CorrelationIdFilter extends OncePerRequestFilter {
    public static final String REQUEST_HEADER_NAME = "X-Request-Id";

    public static final String ATTRIBUTE_NAME = "RequestCorrelation.ATTRIBUTE";

    public static final String LOG_VARIABLE_NAME = "correlationId";

    @Override
    protected void doFilterInternal(
        @NonNull HttpServletRequest request, @NonNull HttpServletResponse response, @NonNull FilterChain filterChain) throws ServletException, IOException {
        String correlationId = request.getHeader(REQUEST_HEADER_NAME);

        if (correlationId == null || !UuidGenerator.isValidUUID(correlationId)) {
            correlationId = UUID.randomUUID().toString();
        }

        request.setAttribute(ATTRIBUTE_NAME, correlationId);

        try (MDC.MDCCloseable ignored = MDC.putCloseable(LOG_VARIABLE_NAME, correlationId)) {
            response.setHeader(REQUEST_HEADER_NAME, correlationId);
            filterChain.doFilter(request, response);
        }
    }
}