README.md

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>16.1.0</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 BOM, add this to your dependencies:

<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-logging</artifactId>
  <version>2.0.1</version>
</dependency>

If you are using Gradle, add this to your dependencies

compile 'com.google.cloud:google-cloud-logging:2.0.1'

If you are using SBT, add this to your dependencies

libraryDependencies += "com.google.cloud" % "google-cloud-logging" % "2.0.1"

Authentication

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

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 authenticated requests to Cloud Logging, you must create a service object with credentials. You can then make API calls by calling methods on the Logging service object. The simplest way to authenticate is to use Application Default Credentials. These credentials are automatically inferred from your environment, so 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 authentication options, see the Authentication page.

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. The samples' README.md has instructions for running the samples.

Sample	Source Code	Try it
List Logs	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.

Java Versions

Java 7 or above is required for using this client.

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