Process Cloud Audit Logs with Cloud Functions

This sample demonstrates how to process Cloud Audit Logs using Cloud Functions. It extracts and prints the method name, resource name, and initiator email from each log entry.

Code sample

Go

To authenticate to Cloud Run functions, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

// Package log contains examples for handling Cloud Functions logs.
package log

import (
	"context"
	"fmt"
	"log"

	"github.com/GoogleCloudPlatform/functions-framework-go/functions"
	"github.com/cloudevents/sdk-go/v2/event"
)

func init() {
	functions.CloudEvent("ProcessLogEntry", ProcessLogEntry)
}

// MessagePublishedData contains the full Pub/Sub message
// See the documentation for more details:
// https://cloud.google.com/eventarc/docs/cloudevents#pubsub
type MessagePublishedData struct {
	Message PubSubMessage
}

// PubSubMessage is the payload of a Pub/Sub event.
// See the documentation for more details:
// https://cloud.google.com/pubsub/docs/reference/rest/v1/PubsubMessage
type PubSubMessage struct {
	Data []byte `json:"data"`
}

// ProcessLogEntry processes a Pub/Sub message from Cloud Logging.
func ProcessLogEntry(ctx context.Context, e event.Event) error {
	var msg MessagePublishedData
	if err := e.DataAs(&msg); err != nil {
		return fmt.Errorf("event.DataAs: %w", err)
	}

	log.Printf("Log entry data: %s", string(msg.Message.Data)) // Automatically decoded from base64.
	return nil
}

Java

To authenticate to Cloud Run functions, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

import com.google.cloud.functions.CloudEventsFunction;
import com.google.gson.Gson;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import functions.eventpojos.PubSubBody;
import io.cloudevents.CloudEvent;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
import java.util.logging.Logger;

public class StackdriverLogging implements CloudEventsFunction {
  private static final Logger logger = Logger.getLogger(StackdriverLogging.class.getName());
  // Use Gson (https://github.com/google/gson) to parse JSON content.
  private static final Gson gson = new Gson();

  @Override
  public void accept(CloudEvent event) throws Exception {
    if (event.getData() == null) {
      logger.info("Hello, World!");
      return;
    }

    // Extract Cloud Event data and convert to PubSubBody
    String cloudEventData = new String(event.getData().toBytes(), StandardCharsets.UTF_8);
    PubSubBody body = gson.fromJson(cloudEventData, PubSubBody.class);

    String encodedData = body.getMessage().getData();
    String decodedData = new String(Base64
        .getDecoder().decode(encodedData), StandardCharsets.UTF_8);

    // Retrieve and decode PubSubMessage data into a JsonElement.
    // Function is expecting a user-supplied JSON message which contains what
    // name to log.
    JsonElement jsonPubSubMessageElement = gson.fromJson(decodedData, JsonElement.class);

    // Extract name if present or default to World
    String name = "World";
    if (jsonPubSubMessageElement != null && jsonPubSubMessageElement.isJsonObject()) {
      JsonObject jsonPubSubMessageObject = jsonPubSubMessageElement.getAsJsonObject();

      if (jsonPubSubMessageObject.has("name")
          && jsonPubSubMessageObject.get("name").isJsonPrimitive()
          && jsonPubSubMessageObject.get("name").getAsJsonPrimitive().isString()) {
        name = jsonPubSubMessageObject.get("name").getAsString();
      }
    }

    String res = String.format("Hello, %s!", name);
    logger.info(res);
  }
}

Node.js

To authenticate to Cloud Run functions, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

const functions = require('@google-cloud/functions-framework');

functions.cloudEvent('processLogEntry', async event => {
  const dataBuffer = Buffer.from(event.data.message.data, 'base64');

  const logEntry = JSON.parse(dataBuffer.toString()).protoPayload;
  console.log(`Method: ${logEntry.methodName}`);
  console.log(`Resource: ${logEntry.resourceName}`);
  console.log(`Initiator: ${logEntry.authenticationInfo.principalEmail}`);
});

Python

To authenticate to Cloud Run functions, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

import base64
import json

import functions_framework


@functions_framework.cloud_event
def process_log_entry(event):
    data_buffer = base64.b64decode(event.data["message"]["data"])
    log_entry = json.loads(data_buffer)["protoPayload"]

    print(f"Method: {log_entry['methodName']}")
    print(f"Resource: {log_entry['resourceName']}")
    print(f"Initiator: {log_entry['authenticationInfo']['principalEmail']}")

What's next

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