Google Cloud Logging Client for Java

Java idiomatic client for Cloud Logging.

• Product Documentation
• Client Library Documentation

Quickstart

If you are using Maven with BOM, add this to your pom.xml file

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>com.google.cloud</groupId>
      <artifactId>libraries-bom</artifactId>
      <version>21.0.0</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 BOM, add this to your dependencies:

<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-logging</artifactId>
  <version>3.0.1</version>
</dependency>

If you are using Gradle 5.x or later, add this to your dependencies

implementation platform('com.google.cloud:libraries-bom:21.0.0')

compile 'com.google.cloud:google-cloud-logging'

If you are using Gradle without BOM, add this to your dependencies

compile 'com.google.cloud:google-cloud-logging:3.0.1'

If you are using SBT, add this to your dependencies

libraryDependencies += "com.google.cloud" % "google-cloud-logging" % "3.0.1"

Authentication

See the Authentication section in the base directory's README.

Authorization

The client application making API calls must be granted authorization scopes required for the desired Cloud Logging APIs, and the authenticated principal must have the IAM role(s) required to access GCP resources using the Cloud Logging API calls.

Getting Started

Prerequisites

You will need a Google Cloud Platform Console project with the Cloud Logging API enabled.

Follow these instructions to get your project set up. You will also need to set up the local development environment by installing the Google Cloud SDK and running the following commands in command line: gcloud auth login and gcloud config set project [YOUR PROJECT ID].

Installation and setup

You'll need to obtain the google-cloud-logging library. See the Quickstart section to add google-cloud-logging as a dependency in your code.

About Cloud Logging

Cloud Logging allows you to store, search, analyze, monitor, and alert on log data and events from Google Cloud and Amazon Web Services. Using the BindPlane service, you can also collect this data from over 150 common application components, on-premises systems, and hybrid cloud systems. BindPlane is included with your Google Cloud project at no additional cost.

See the Cloud Logging client library docs to learn how to use this Cloud Logging Client Library.

Creating an authorized service object

To make requests to Cloud Logging, you must create a service object with valid credentials. You can then make API calls by calling methods on the Logging service object. You can obtain credentials by using Application Default Credentials. Or you can use a Service Account which is a recommended way to obtain credentials. The credentials can be automatically inferred from your environment. Then you only need the following code to create your service object:

import com.google.cloud.logging.Logging;
import com.google.cloud.logging.LoggingOptions;

LoggingOptions options = LoggingOptions.getDefaultInstance();
try(Logging logging = options.getService()) {
  // use logging here
}

For other options, see the Authentication page. The service object should be granted permissions to make API calls. Each API call describes the permissions under Authorized Scopes section. See Logging API to find the required list of permissions or consult with Access control guide for predefined IAM roles that can be granted to the Logging service object.

Creating a metric

With Logging you can create logs-based metrics. Logs-based metrics allow to keep track of the number of log messages associated to specific events. Add the following imports at the top of your file:

import com.google.cloud.logging.Metric;
import com.google.cloud.logging.MetricInfo;

Then, to create the metric, use the following code:

MetricInfo metricInfo = MetricInfo.newBuilder("test-metric", "severity >= ERROR")
    .setDescription("Log entries with severity higher or equal to ERROR")
    .build();
logging.create(metricInfo);

Writing log entries

With Logging you can also write custom log entries. Add the following imports at the top of your file:

import com.google.cloud.MonitoredResource;
import com.google.cloud.logging.LogEntry;
import com.google.cloud.logging.Logging;
import com.google.cloud.logging.Payload.StringPayload;

import java.util.Collections;

Then, to write the log entries, use the following code:

LogEntry firstEntry = LogEntry.newBuilder(StringPayload.of("message"))
    .setLogName("test-log")
    .setResource(MonitoredResource.newBuilder("global")
        .addLabel("project_id", options.getProjectId())
        .build())
    .build();
logging.write(Collections.singleton(firstEntry));

Listing log entries

With Logging you can also list log entries that have been previously written. Add the following imports at the top of your file:

import com.google.cloud.Page;
import com.google.cloud.logging.LogEntry;
import com.google.cloud.logging.Logging.EntryListOption;

Then, to list the log entries, use the following code:

Page<LogEntry> entries = logging.listLogEntries(
    EntryListOption.filter("logName=projects/" + options.getProjectId() + "/logs/test-log"));
Iterator<LogEntry> entryIterator = entries.iterateAll().iterator();
while (entryIterator.hasNext()) {
  System.out.println(entryIterator.next());
}

Add a Cloud Logging handler to a logger

You can also register a LoggingHandler to a java.util.logging.Logger that publishes log entries to Cloud Logging. Given the following logger:

private final static Logger LOGGER = Logger.getLogger(MyClass.class.getName());

You can register a LoggingHandler with the code:

LoggingHandler.addHandler(LOGGER, new LoggingHandler());

After that, logs generated using LOGGER will be also directed to Cloud Logging.

Notice that you can also register a LoggingHandler via the logging.properties configuration file. Adding, for instance, the following line:

com.google.cloud.examples.logging.snippets.AddLoggingHandler.handlers=com.google.cloud.logging.LoggingHandler

Complete source code

In CreateAndListMetrics.java, WriteAndListLogEntries.java and AddLoggingHandler.java we put together all the code shown above into three programs. The programs assume that you are running on Compute Engine or from your own desktop.

Samples

Samples are in the samples/ directory.

Sample	Source Code	Try it
Get Sink Metadata	source code
List Log Entries	source code
List Logs	source code
Log Entry Write Http Request	source code
Quickstart Sample	source code
Quickstart	source code
Example Enhancer	source code

Troubleshooting

To get help, follow the instructions in the shared Troubleshooting document.

Transport

Cloud Logging uses gRPC for the transport layer.

Supported Java Versions

Java 7 or above is required for using this client.

Google's Java client libraries, Google Cloud Client Libraries and Google Cloud API Libraries, follow the Oracle Java SE support roadmap (see the Oracle Java SE Product Releases section).

For new development

In general, new feature development occurs with support for the lowest Java LTS version covered by Oracle's Premier Support (which typically lasts 5 years from initial General Availability). If the minimum required JVM for a given library is changed, it is accompanied by a semver major release.

Java 11 and (in September 2021) Java 17 are the best choices for new development.

Keeping production systems current

Google tests its client libraries with all current LTS versions covered by Oracle's Extended Support (which typically lasts 8 years from initial General Availability).

Legacy support

Google's client libraries support legacy versions of Java runtimes with long term stable libraries that don't receive feature updates on a best efforts basis as it may not be possible to backport all patches.

Google provides updates on a best efforts basis to apps that continue to use Java 7, though apps might need to upgrade to current versions of the library that supports their JVM.

Where to find specific information

The latest versions and the supported Java versions are identified on the individual GitHub repository github.com/GoogleAPIs/java-SERVICENAME and on google-cloud-java.

Versioning

This library follows Semantic Versioning.

Contributing

Contributions to this library are always welcome and highly encouraged.

See CONTRIBUTING for more information how to get started.

Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms. See Code of Conduct for more information.

License

Apache 2.0 - See LICENSE for more information.

CI Status

Java Version	Status
Java 7
Java 8
Java 8 OSX
Java 8 Windows
Java 11

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