Setting Up Cloud Logging for Ruby

You can write logs to Cloud Logging from Ruby applications by using the Cloud Logging library for Ruby, or by using the Cloud Logging Cloud client library for Ruby directly.

The Cloud Logging agent does not have to be installed to use the Cloud Logging library for Ruby on a Compute Engine VM instance.

Before you begin

Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Go to project selector

Make sure that billing is enabled for your Google Cloud project.

Enable the Cloud Logging API.

Enable the API

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Go to project selector

Make sure that billing is enabled for your Google Cloud project.

Enable the Cloud Logging API.

Enable the API

Install Ruby 2.2+ or greater.

Installing the library

We provide a Cloud Logging library for Ruby, which provides an easy-to-use logger implementation for Rack-based Ruby web frameworks:

Add the Google Cloud Observability gem to your Gemfile:
```
gem "stackdriver"
```
Use Bundler to install the gem:
```
bundle install
```

Enabling the library

If you're using Ruby on Rails, Bundler automatically loads the library into your application when it starts, which sets the default Rails.logger to an instance of Cloud Logging logger.

Other Rack-based applications can use the Rack Middleware to replace the Rack logger with the Cloud Logging logger if your web framework supports Rack logger:

require "google/cloud/logging"

use Google::Cloud::Logging::Middleware

Configuring the library

You can customize the behavior of the Cloud Logging library for Ruby. See the library's configuration for a list of possible configuration options.

Using the Cloud Logging Logger

Once the Cloud Logging library for Ruby is enabled, you can use the logger in your application:

logger.info "Hello World!"
logger.error "Oh No!"

For more information on installation, see the documentation for the Cloud Logging library for Ruby. You can also report issues using the issue tracker.

Write logs with the Cloud Logging client library

For information on using the Cloud Logging client library for Ruby directly, see Cloud Logging Client Libraries.

Run on Google Cloud

For an application to write logs by using the Cloud Logging library for Ruby, the service account for the underlying resource must have the Logs Writer (roles/logging.logWriter) IAM role. Most Google Cloud environments automatically configure the default service account to have this role.

App Engine

Cloud Logging is automatically enabled for App Engine, and your app's default service account has the IAM permissions by default to write log entries.

For more information, see Writing and viewing logs.

Google Kubernetes Engine (GKE)

GKE automatically grants the default service account the Logs Writer (roles/logging.logWriter) IAM role. If you use Workload Identity Federation for GKE with this default service account to let workloads access specific Google Cloud APIs, then no additional configuration is required. However, if you use Workload Identity Federation for GKE with a custom IAM service account, then ensure that the custom service account has the role of Logs Writer (roles/logging.logWriter).

If needed, you can also use the following command to add the logging.write access scope when creating the cluster:

gcloud container clusters create example-cluster-name \
    --scopes https://www.googleapis.com/auth/logging.write

Compute Engine

When using Compute Engine VM instances, add the cloud-platform access scope to each instance. When creating a new instance through the Google Cloud console, you can do this in the Identity and API access section of the Create Instance panel. Use the Compute Engine default service account or another service account of your choice, and select Allow full access to all Cloud APIs in the Identity and API access section. Whichever service account you select, ensure that it has been granted the Logs Writer role in the IAM & Admin section of the Google Cloud console.

Run locally and elsewhere

To use the Cloud Logging library for Ruby outside of Google Cloud, including running the library on your own workstation, on your data center's computers, or on the VM instances of another cloud provider, you must supply your Google Cloud project ID and appropriate service account credentials directly to the Cloud Logging library for Ruby.

For existing service accounts, do the following:

Grant the service account the IAM the Logs Writer (roles/logging.logWriter) IAM role. For more information on IAM roles, see Access control.
Set up Application Default Credentials.

If you don't have a service account, then create one. For information about this process, see Create service accounts.

For general information about the methods that you can use to authenticate, see Terminology: service accounts.

Using Ruby on Rails configuration interface:

Provide the parameters through the Ruby on Rails configuration interface if you are using Ruby on Rails framework:

# Add this to config/environments/*.rb
Rails.application.configure do |config|
  # Stackdriver Logging specific parameters
  config.google_cloud.logging.project_id = "YOUR-PROJECT-ID"
  config.google_cloud.logging.keyfile    = "/path/to/service-account.json"
end

You can also set shared configuration for all Google Cloud Observability gems using:

# Add this to config/environments/*.rb
Rails.application.configure do |config|
  # Stackdriver Shared parameters
  config.google_cloud.project_id = "YOUR-PROJECT-ID"
  config.google_cloud.keyfile    = "/path/to/service-account.json"
end

Logging is enabled by default when Rails is running in production mode. To enable Logging in development mode, add the following add:

# Add this to config/environments/development.rb
Rails.application.configure do |config|
  config.google_cloud.use_logging = true
end

Using instrumentation configuration interface:

Provide the parameters through the configuration interface when used in other Rack-based applications:

require "google/cloud/logging"

Google::Cloud.configure do |config|
  # Stackdriver Logging specific parameters
  config.logging.project_id = "YOUR-PROJECT-ID"
  config.logging.keyfile    = "/path/to/service-account.json"
end

You can also set shared configuration for all Google Cloud Observability gems using:

require "stackdriver"

Google::Cloud.configure do |config|
  # Stackdriver Shared parameters
  config.project_id = "YOUR-PROJECT-ID"
  config.keyfile    = "/path/to/service-account.json"
end

View the logs

In the Google Cloud console, go to the Logs Explorer page:

Go to Logs Explorer

If you use the search bar to find this page, then select the result whose subheading is Logging.

In the Logs Explorer, you must specify one or more resources, but the resource selection might not be obvious. Here are some tips to help you get started:

If you are deploying your application to App Engine or using the App Engine-specific libraries, set your resource to GAE Application.
If you are deploying your application on Compute Engine, set the resource to GCE VM Instance.
If you are deploying your application on Google Kubernetes Engine, your cluster's logging configuration determines the resource type of the log entries. For a detailed discussion on the Legacy Google Cloud Observability and the Google Cloud Observability Kubernetes Monitoring solutions, and how those options affect the resource type, see Migrating to Google Cloud Observability Kubernetes Monitoring.
If your application is using the Cloud Logging API directly, the resource is dependent on the API and your configuration. For example, in your application, you can specify a resource or use a default resource.
If you don't see any logs in the Logs Explorer, to see all log entries, switch to the advanced query mode and use an empty query.
1. To switch to the advanced query mode, click menu (▾) at the top of the Logs Explorer and then select Convert to advanced filter.
2. Clear the content that appears in the filter box.
3. Click Submit Filter.
You can examine the individual entries to identify your resources.

For additional information, see Using the Logs Explorer.