diff --git a/runtime/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/LogEntry.java b/runtime/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/LogEntry.java
new file mode 100644
index 0000000..4394033
--- /dev/null
+++ b/runtime/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/LogEntry.java
@@ -0,0 +1,103 @@
+package eu.mulk.quarkus.googlecloud.jsonlogging;
+
+import io.smallrye.common.constraint.Nullable;
+import java.time.Instant;
+import java.util.List;
+import java.util.Map;
+import javax.json.Json;
+import javax.json.JsonObject;
+import javax.json.JsonObjectBuilder;
+
+/**
+ * A JSON log entry compatible with Google Cloud Logging.
+ *
+ * <p>Roughly (but not quite) corresponds to Google Cloud Logging's <a
+ * href="https://cloud.google.com/logging/docs/reference/v2/rest/v2/LogEntry">LogEntry</a>
+ * structure.
+ *
+ * <p>A few of the fields are treated specially by the fluentd instance running in Google Kubernetes
+ * Engine. All other fields end up in the jsonPayload field on the Google Cloud Logging side.
+ */
+record LogEntry(
+    String message,
+    String severity,
+    Timestamp timestamp,
+    @Nullable String trace,
+    @Nullable String spanId,
+    SourceLocation sourceLocation,
+    Map<String, String> labels,
+    List<StructuredParameter> parameters,
+    Map<String, String> mappedDiagnosticContext,
+    @Nullable String nestedDiagnosticContext,
+    @Nullable String type) {
+
+  static record SourceLocation(
+      @Nullable String file, @Nullable String line, @Nullable String function) {
+
+    JsonObject json() {
+      return Json.createObjectBuilder()
+          .add("file", file)
+          .add("line", line)
+          .add("function", function)
+          .build();
+    }
+  }
+
+  static record Timestamp(long seconds, int nanos) {
+
+    Timestamp(Instant t) {
+      this(t.getEpochSecond(), t.getNano());
+    }
+
+    JsonObject json() {
+      return Json.createObjectBuilder().add("seconds", seconds).add("nanos", nanos).build();
+    }
+  }
+
+  JsonObjectBuilder json() {
+    var b = Json.createObjectBuilder();
+
+    if (trace != null) {
+      b.add("trace", trace);
+    }
+
+    if (spanId != null) {
+      b.add("spanId", spanId);
+    }
+
+    if (nestedDiagnosticContext != null && !nestedDiagnosticContext.isEmpty()) {
+      b.add("nestedDiagnosticContext", nestedDiagnosticContext);
+    }
+
+    if (!labels.isEmpty()) {
+      b.add("labels", jsonOfStringMap(labels));
+    }
+
+    if (type != null) {
+      b.add("@type", type);
+    }
+
+    return b.add("message", message)
+        .add("severity", severity)
+        .add("timestamp", timestamp.json())
+        .add("sourceLocation", sourceLocation.json())
+        .addAll(jsonOfStringMap(mappedDiagnosticContext))
+        .addAll(jsonOfParameterMap(parameters));
+  }
+
+  private static JsonObjectBuilder jsonOfStringMap(Map<String, String> stringMap) {
+    return stringMap.entrySet().stream()
+        .reduce(
+            Json.createObjectBuilder(),
+            (acc, x) -> acc.add(x.getKey(), x.getValue()),
+            JsonObjectBuilder::addAll);
+  }
+
+  private static JsonObjectBuilder jsonOfParameterMap(List<StructuredParameter> parameters) {
+    return parameters.stream()
+        .reduce(
+            Json.createObjectBuilder(),
+            (acc, p) -> acc.addAll(p.json()),
+            JsonObjectBuilder::addAll);
+  }
+}