Logging Client Libraries

This page shows how to get started with the Cloud Client Libraries for the Stackdriver Logging API. Read more about the client libraries for Cloud APIs, including the older Google APIs Client Libraries, in Client Libraries Explained.

Installing the client library

C#

For more information, see Setting Up a C# Development Environment. 
Install-Package Google.Cloud.Logging.V2

Go

go get -u cloud.google.com/go/logging

Java

For more information, see Setting Up a Java Development Environment. If you are using Maven with a BOM, add the following to your pom.xml file: 
<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>com.google.cloud</groupId>
      <artifactId>libraries-bom</artifactId>
      <version>4.1.0</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

<dependencies>
  <dependency>
    <groupId>com.google.cloud</groupId>
    <artifactId>google-cloud-logging</artifactId>
  </dependency>
</dependencies>
If you are using Maven without a BOM, add this to your dependencies: 
<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-logging</artifactId>
  <version>1.100.0</version>
</dependency>
If you are using Gradle, add the following to your dependencies: 
compile 'com.google.cloud:google-cloud-logging:1.100.0'
If you are using sbt, add the following to your dependencies: 
libraryDependencies += "com.google.cloud" % "google-cloud-logging" % "1.100.0"

If you're using IntelliJ or Eclipse, you can add client libraries to your project using the following IDE plugins:

The plugins provide additional functionality, such as key management for service accounts. Refer to each plugin's documentation for details.

Node.js

For more information, see Setting Up a Node.js Development Environment. 
npm install --save @google-cloud/logging

PHP

composer require google/cloud-logging

Python

For more information, see Setting Up a Python Development Environment. 
pip install --upgrade google-cloud-logging

Ruby

For more information, see Setting Up a Ruby Development Environment. 
gem install google-cloud-logging

Setting up authentication

To run the client library, you must first set up authentication by creating a service account and setting an environment variable. Complete the following steps to set up authentication. For other ways to authenticate, see the GCP authentication documentation.

Cloud Console

  1. In the Cloud Console, go to the Create service account key page.

    Go to the Create Service Account Key page
  2. From the Service account list, select New service account.
  3. In the Service account name field, enter a name.

  4. From the Role list, select Project > Owner.

    Note: The Role field authorizes your service account to access resources. You can view and change this field later by using the Cloud Console. If you are developing a production app, specify more granular permissions than Project > Owner. For more information, see granting roles to service accounts.
  5. Click Create. A JSON file that contains your key downloads to your computer.

Command line

You can run the following commands using the Cloud SDK on your local machine, or in Cloud Shell.

  1. Create the service account. Replace [NAME] with a name for the service account. 

    gcloud iam service-accounts create [NAME]

  2. Grant permissions to the service account. Replace [PROJECT_ID] with your project ID. 

    gcloud projects add-iam-policy-binding [PROJECT_ID] --member "serviceAccount:[NAME]@[PROJECT_ID].iam.gserviceaccount.com" --role "roles/owner"
    Note: The Role field authorizes your service account to access resources. You can view and change this field later by using Cloud Console. If you are developing a production app, specify more granular permissions than Project > Owner. For more information, see granting roles to service accounts.

  3. Generate the key file. Replace [FILE_NAME] with a name for the key file. 

    gcloud iam service-accounts keys create [FILE_NAME].json --iam-account [NAME]@[PROJECT_ID].iam.gserviceaccount.com

Provide authentication credentials to your application code by setting the environment variable GOOGLE_APPLICATION_CREDENTIALS. Replace [PATH] with the file path of the JSON file that contains your service account key, and [FILE_NAME] with the filename. This variable only applies to your current shell session, so if you open a new session, set the variable again.

Linux or macOS

export GOOGLE_APPLICATION_CREDENTIALS="[PATH]"

For example:

export GOOGLE_APPLICATION_CREDENTIALS="/home/user/Downloads/[FILE_NAME].json"

Windows

With PowerShell:

$env:GOOGLE_APPLICATION_CREDENTIALS="[PATH]"

For example:

$env:GOOGLE_APPLICATION_CREDENTIALS="C:\Users\username\Downloads\[FILE_NAME].json"

With command prompt:

set GOOGLE_APPLICATION_CREDENTIALS=[PATH]

Using the client library

The following example shows how to use the client library.

C#


using System;
// Imports the Google Cloud Logging client library
using Google.Cloud.Logging.V2;
using Google.Cloud.Logging.Type;
using System.Collections.Generic;
using Google.Api;

namespace GoogleCloudSamples
{
    public class QuickStart
    {
        public static void Main(string[] args)
        {
            // Your Google Cloud Platform project ID.
            string projectId = "YOUR-PROJECT-ID";

            // Instantiates a client.
            var client = LoggingServiceV2Client.Create();

            // Prepare new log entry.
            LogEntry logEntry = new LogEntry();
            string logId = "my-log";
            LogName logName = new LogName(projectId, logId);
            LogNameOneof logNameToWrite = LogNameOneof.From(logName);
            logEntry.LogName = logName.ToString();
            logEntry.Severity = LogSeverity.Info;

            // Create log entry message.
            string message = "Hello World!";
            string messageId = DateTime.Now.Millisecond.ToString();
            Type myType = typeof(QuickStart);
            string entrySeverity = logEntry.Severity.ToString().ToUpper();
            logEntry.TextPayload =
                $"{messageId} {entrySeverity} {myType.Namespace}.LoggingSample - {message}";

            // Set the resource type to control which GCP resource the log entry belongs to.
            // See the list of resource types at:
            // https://cloud.google.com/logging/docs/api/v2/resource-list
            // This sample uses resource type 'global' causing log entries to appear in the 
            // "Global" resource list of the Developers Console Logs Viewer:
            //  https://console.cloud.google.com/logs/viewer
            MonitoredResource resource = new MonitoredResource();
            resource.Type = "global";

            // Create dictionary object to add custom labels to the log entry.
            IDictionary<string, string> entryLabels = new Dictionary<string, string>();
            entryLabels.Add("size", "large");
            entryLabels.Add("color", "red");

            // Add log entry to collection for writing. Multiple log entries can be added.
            IEnumerable<LogEntry> logEntries = new LogEntry[] { logEntry };

            // Write new log entry.
            client.WriteLogEntries(logNameToWrite, resource, entryLabels, logEntries);

            Console.WriteLine("Log Entry created.");
        }
    }
}

Go


// Sample logging-quickstart writes a log entry to Stackdriver Logging.
package main

import (
	"context"
	"fmt"
	"log"

	"cloud.google.com/go/logging"
)

func main() {
	ctx := context.Background()

	// Sets your Google Cloud Platform project ID.
	projectID := "YOUR_PROJECT_ID"

	// Creates a client.
	client, err := logging.NewClient(ctx, projectID)
	if err != nil {
		log.Fatalf("Failed to create client: %v", err)
	}

	// Sets the name of the log to write to.
	logName := "my-log"

	// Selects the log to write to.
	logger := client.Logger(logName)

	// Sets the data to log.
	text := "Hello, world!"

	// Adds an entry to the log buffer.
	logger.Log(logging.Entry{Payload: text})

	// Closes the client and flushes the buffer to the Stackdriver Logging
	// service.
	if err := client.Close(); err != nil {
		log.Fatalf("Failed to close client: %v", err)
	}

	fmt.Printf("Logged: %v\n", text)
}

Java

import com.google.cloud.MonitoredResource;
import com.google.cloud.logging.LogEntry;
import com.google.cloud.logging.Logging;
import com.google.cloud.logging.LoggingOptions;
import com.google.cloud.logging.Payload.StringPayload;
import com.google.cloud.logging.Severity;
import java.util.Collections;

/**
 * This sample demonstrates writing logs using the Stackdriver Logging API.
 * The library also offers a java.util.logging Handler `com.google.cloud.logging.LoggingHandler`
 * Logback integration is also available : 
 * https://github.com/googleapis/google-cloud-java/tree/master/google-cloud-clients/google-cloud-contrib/google-cloud-logging-logback
 * Using the java.util.logging handler / Logback appender should be preferred to using the API
 * directly.
 */
public class QuickstartSample {

  /** Expects a new or existing Stackdriver log name as the first argument.*/
  public static void main(String... args) throws Exception {

    // Instantiates a client
    Logging logging = LoggingOptions.getDefaultInstance().getService();

    // The name of the log to write to
    String logName = args[0];  // "my-log";

    // The data to write to the log
    String text = "Hello, world!";

    LogEntry entry = LogEntry.newBuilder(StringPayload.of(text))
        .setSeverity(Severity.ERROR)
        .setLogName(logName)
        .setResource(MonitoredResource.newBuilder("global").build())
        .build();

    // Writes the log entry asynchronously
    logging.write(Collections.singleton(entry));

    System.out.printf("Logged: %s%n", text);
  }
}

Node.js

// Imports the Google Cloud client library
const {Logging} = require('@google-cloud/logging');

async function quickstart(
  projectId = 'YOUR_PROJECT_ID', // Your Google Cloud Platform project ID
  logName = 'my-log' // The name of the log to write to
) {
  // Creates a client
  const logging = new Logging({projectId});

  // Selects the log to write to
  const log = logging.log(logName);

  // The data to write to the log
  const text = 'Hello, world!';

  // The metadata associated with the entry
  const metadata = {
    resource: {type: 'global'},
  };

  // Prepares a log entry
  const entry = log.entry(metadata, text);

  async function writeLog() {
    // Writes the log entry
    await log.write(entry);
    console.log(`Logged: ${text}`);
  }
  writeLog();
}

PHP

# Includes the autoloader for libraries installed with composer
require __DIR__ . '/vendor/autoload.php';

# Imports the Google Cloud client library
use Google\Cloud\Logging\LoggingClient;

# Your Google Cloud Platform project ID
$projectId = 'YOUR_PROJECT_ID';

# Instantiates a client
$logging = new LoggingClient([
    'projectId' => $projectId
]);

# The name of the log to write to
$logName = 'my-log';

# Selects the log to write to
$logger = $logging->logger($logName);

# The data to log
$text = 'Hello, world!';

# Creates the log entry
$entry = $logger->entry($text);

# Writes the log entry
$logger->write($entry);

echo 'Logged ' . $text;

Python

# Imports the Google Cloud client library
from google.cloud import logging

# Instantiates a client
logging_client = logging.Client()

# The name of the log to write to
log_name = 'my-log'
# Selects the log to write to
logger = logging_client.logger(log_name)

# The data to log
text = 'Hello, world!'

# Writes the log entry
logger.log_text(text)

print('Logged: {}'.format(text))

Ruby

# Imports the Google Cloud client library
require "google/cloud/logging"

# Your Google Cloud Platform project ID
project_id = "YOUR_PROJECT_ID"

# Instantiates a client
logging = Google::Cloud::Logging.new project: project_id

# Prepares a log entry
entry = logging.entry
# The data to log
entry.payload = "Hello, world!"
# The name of the log to write to
entry.log_name = "my-log"
# The resource associated with the data
entry.resource.type = "global"

# Writes the log entry
logging.write_entries entry

puts "Logged #{entry.payload}"

Additional resources