Add path mdc filter.

src/main/java/io/kokuwa/micronaut/logging/http/mdc/PathMdcFilter.java

@@ -0,0 +1,88 @@
+package io.kokuwa.micronaut.logging.http.mdc;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.regex.Pattern;
+import java.util.regex.PatternSyntaxException;
+
+import org.reactivestreams.Publisher;
+
+import io.kokuwa.micronaut.logging.http.AbstractMdcFilter;
+import io.micronaut.context.annotation.Requires;
+import io.micronaut.context.annotation.Value;
+import io.micronaut.core.util.StringUtils;
+import io.micronaut.http.HttpRequest;
+import io.micronaut.http.MutableHttpResponse;
+import io.micronaut.http.annotation.Filter;
+import io.micronaut.http.filter.ServerFilterChain;
+import io.micronaut.http.filter.ServerFilterPhase;
+import io.micronaut.runtime.context.scope.Refreshable;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * Filter to add request path parts to MDC.
+ *
+ * @author Stephan Schnabel
+ */
+@Refreshable
+@Requires(property = PathMdcFilter.PREFIX + ".enabled", notEquals = StringUtils.FALSE)
+@Requires(property = PathMdcFilter.PREFIX + ".patterns")
+@Filter("${" + PathMdcFilter.PREFIX + ".path:/**}")
+@Slf4j
+public class PathMdcFilter extends AbstractMdcFilter {
+
+	public static final String PREFIX = "logger.http.path";
+	public static final int DEFAULT_ORDER = ServerFilterPhase.FIRST.before();
+	public static final Pattern PATTERN_GROUPS = Pattern.compile("\\(\\?<([a-zA-Z][a-zA-Z0-9]+)>");
+
+	private final Map<Pattern, Set<String>> patternsWithGroups;
+
+	public PathMdcFilter(
+			@Value("${" + PREFIX + ".patterns}") List<String> patterns,
+			@Value("${" + PREFIX + ".prefix}") Optional<String> prefix,
+			@Value("${" + PREFIX + ".order}") Optional<Integer> order) {
+		super(order.orElse(DEFAULT_ORDER), prefix.orElse(null));
+		this.patternsWithGroups = new HashMap<>();
+		for (var patternString : patterns) {
+			try {
+				var pattern = Pattern.compile(patternString);
+				var groupMatcher = PATTERN_GROUPS.matcher(pattern.toString());
+				var groups = new HashSet<String>();
+				while (groupMatcher.find()) {
+					groups.add(groupMatcher.group(1));
+				}
+
+				if (groups.isEmpty()) {
+					log.warn("Path {} is missing groups.", patternString);
+				} else {
+					log.info("Added path {} with groups {}.", patternString, groups);
+					patternsWithGroups.put(pattern, groups);
+				}
+			} catch (PatternSyntaxException e) {
+				log.warn("Path {} is invalid.", patternString);
+			}
+		}
+	}
+
+	@Override
+	public Publisher<MutableHttpResponse<?>> doFilter(HttpRequest<?> request, ServerFilterChain chain) {
+
+		var mdc = new HashMap<String, String>();
+		var path = request.getPath();
+
+		for (var patternWithGroup : patternsWithGroups.entrySet()) {
+			var matcher = patternWithGroup.getKey().matcher(path);
+			if (matcher.matches()) {
+				for (var group : patternWithGroup.getValue()) {
+					mdc.put(group, matcher.group(group));
+				}
+			}
+		}
+
+		return doFilter(request, chain, mdc);
+	}
+}