# google-cloud-logging

[Stackdriver Logging](https://cloud.google.com/logging/) ([docs](https://cloud.google.com/logging/docs/)) allows you to store, search, analyze, monitor, and alert on log data and events from Google Cloud Platform and Amazon Web Services (AWS). It supports ingestion of any custom log data from any source. Stackdriver Logging is a fully-managed service that performs at scale and can ingest application and system log data from thousands of VMs. Even better, you can analyze all that log data in real-time.

- [google-cloud-logging API documentation](http://googlecloudplatform.github.io/google-cloud-ruby/#/docs/google-cloud-logging/latest)
- [google-cloud-logging on RubyGems](https://rubygems.org/gems/google-cloud-logging)
- [Stackdriver Logging documentation](https://cloud.google.com/logging/docs/)

## Quick Start

Install the gem directly:

```sh
$ gem install google-cloud-logging
```

Or install through Bundler:

1. Add the `google-cloud-logging` gem to your Gemfile:

```ruby
gem "google-cloud-logging"
```

2. Use Bundler to install the gem:

```sh
$ bundle install
```

Alternatively, check out the [`stackdriver`](../stackdriver) gem that includes
the `google-cloud-logging` gem.

## Logging using client library

You can directly read or write log entries through the client library:

```ruby
require "google/cloud/logging"

logging = Google::Cloud::Logging.new

# List all log entries
logging.entries.each do |e|
  puts "[#{e.timestamp}] #{e.log_name} #{e.payload.inspect}"
end

# List only entries from a single log
entries = logging.entries filter: "log:syslog"

# Write a log entry
entry = logging.entry
entry.payload = "Job started."
entry.log_name = "my_app_log"
entry.resource.type = "gae_app"
entry.resource.labels[:module_id] = "1"
entry.resource.labels[:version_id] = "20150925t173233"

logging.write_entries entry
```

## Using Stackdriver Logging in frameworks

The `google-cloud-logging` library provides framework integration for popular
Rack-based frameworks, such as Ruby on Rails and Sinatra, which sets the default
Rack logger to an instance of the Stackdriver Logging logger.

### With Ruby on Rails

You can load the Railtie that comes with the library into your Ruby
on Rails application by explicitly requiring it during the application startup:

```ruby
# In config/application.rb
require "google/cloud/logging/rails"
```

If you're using the `stackdriver` gem, it automatically loads the Railtie into
your application when it starts.

You'll be able to use Stackdriver logger through the standard Rails logger:

```ruby
Rails.logger.info "Hello World"
# Or just...
logger.warn "Hola Mundo"
```

### With other Rack-based frameworks

Other Rack-based applications can use the Rack Middleware to replace the Rack
logger with the Stackdriver Logging logger:

```ruby
require "google/cloud/logging"
use Google::Cloud::Logging::Middleware
```

Once the Rack logger is set, some Rack-based frameworks, such as Ruby on Rails
and Sinatra, automatically initialize the default application logger to use the
Rack logger:

```ruby
logger.info "Hello World"
logger.warn "Hola Mundo"
logger.error "Bonjour Monde"
```

For other frameworks, consult the documentations on how to utilize the Rack
logger.

### Configuring the framework integration

You can customize the behavior of the Stackdriver Logging framework integration
for Ruby. See the [configuration guide](../stackdriver/configuration.md) for a
list of possible configuration options.

## Authentication

This library uses Service Account credentials to connect to Google Cloud
services. When running on Compute Engine the credentials will be discovered
automatically. When running on other environments the Service Account
credentials can be specified by providing in several ways.

If you're using Ruby on Rails and the library's Rails integration feature, you
can provide the authentication parameters through the Rails configuration
interface:

```ruby
# Add this to config/environments/*.rb
Rails.application.configure do |config|
  # Shared parameters
  config.google_cloud.project_id = "your-project-id"
  config.google_cloud.keyfile = "/path/to/key.json"
  # Stackdriver Logging specific parameters
  config.google_cloud.logging.project_id = "your-project-id"
  config.google_cloud.logging.keyfile    = "/path/to/key.json"
end
```
Other Rack-based applications that are loading the Rack Middleware directly can
use the configration interface:

```ruby
require "google/cloud/logging"
Google::Cloud.configure do |config|
  # Shared parameters
  config.project_id = "your-project-id"
  config.keyfile = "/path/to/key.json"
  # Or Stackdriver logging specific parameters
  config.logging.project_id = "your-project-id"
  config.logging.keyfile = "/path/to/key.json"
end
```

See the [Authentication
Guide](https://googlecloudplatform.github.io/google-cloud-ruby/#/docs/google-cloud-logging/guides/authentication).
for more ways to authenticate the client library.

## Enabling Logging

To enable logging for this library, set the logger for the underlying [gRPC](https://github.com/grpc/grpc/tree/master/src/ruby) library. The logger that you set may be a Ruby stdlib [`Logger`](https://ruby-doc.org/stdlib-2.5.0/libdoc/logger/rdoc/Logger.html) as shown below, or a [`Google::Cloud::Logging::Logger`](https://googlecloudplatform.github.io/google-cloud-ruby/#/docs/google-cloud-logging/latest/google/cloud/logging/logger) that will write logs to [Stackdriver Logging](https://cloud.google.com/logging/). See [grpc/logconfig.rb](https://github.com/grpc/grpc/blob/master/src/ruby/lib/grpc/logconfig.rb) and the gRPC [spec_helper.rb](https://github.com/grpc/grpc/blob/master/src/ruby/spec/spec_helper.rb) for additional information.

Configuring a Ruby stdlib logger:

```ruby
require "logger"

module MyLogger
  LOGGER = Logger.new $stderr, level: Logger::WARN
  def logger
    LOGGER
  end
end

# Define a gRPC module-level logger method before grpc/logconfig.rb loads.
module GRPC
  extend MyLogger
end
```

## Supported Ruby Versions

This library is supported on Ruby 2.0+.

However, Ruby 2.3 or later is strongly recommended, as earlier releases have
reached or are nearing end-of-life. After June 1, 2018, Google will provide
official support only for Ruby versions that are considered current and
supported by Ruby Core (that is, Ruby versions that are either in normal
maintenance or in security maintenance).
See https://www.ruby-lang.org/en/downloads/branches/ for further details.

## Versioning

This library follows [Semantic Versioning](http://semver.org/).

## Contributing

Contributions to this library are always welcome and highly encouraged.

See the [Contributing Guide](https://googlecloudplatform.github.io/google-cloud-ruby/#/docs/guides/contributing) for more information on 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](../CODE_OF_CONDUCT.md) for more information.

## License

This library is licensed under Apache 2.0. Full license text is available in [LICENSE](LICENSE).

## Support

Please [report bugs at the project on Github](https://github.com/GoogleCloudPlatform/google-cloud-ruby/issues).
Don't hesitate to [ask questions](http://stackoverflow.com/questions/tagged/google-cloud-platform+ruby) about the client or APIs on [StackOverflow](http://stackoverflow.com).
