Cloud Logging API - Class Google::Cloud::Logging::Middleware (v2.3.1)

Reference documentation and code samples for the Cloud Logging API class Google::Cloud::Logging::Middleware.


  • Object



def self.build_monitored_resource(type = nil, labels = nil) -> Google::Cloud::Logging::Resource

Construct a monitored resource based on the given type and label if both are provided. Otherwise, construct a default monitored resource based on the current environment.

  • type (String) — Type of Google::Cloud::Logging::Resource
  • labels (Hash<String, String>) — Metadata lebels of Google::Cloud::Logging::Resource

If both type and labels are provided, it returns resource:

rc = Google::Cloud::Logging::Middleware.build_monitored_resource(
         instance_id: "ec2-id",
         aws_account: "aws-id"
rc.type   #=> "aws_ec2_instance"
rc.labels #=> { instance_id: "ec2-id", aws_account: "aws-id" }

If running from GAE, returns default resource:

rc = Google::Cloud::Logging::Middleware.build_monitored_resource
rc.type   #=> "gae_app"
rc.labels # { module_id: [GAE module name],
          #   version_id: [GAE module version] }

If running from GKE, returns default resource:

rc = Google::Cloud::Logging::Middleware.build_monitored_resource
rc.type   #=> "container"
rc.labels # { cluster_name: [GKE cluster name],
          #   namespace_id: [GKE namespace_id] }

If running from GCE, return default resource:

rc = Google::Cloud::Logging::Middleware.build_monitored_resource
rc.type   #=> "gce_instance"
rc.labels # { instance_id: [GCE VM instance id],
          #   zone: [GCE vm group zone] }

Otherwise default to generic "global" type:

rc = Google::Cloud::Logging::Middleware.build_monitored_resource
rc.type   #=> "global"
rc.labels #=> {}


def call(env) -> Rack::Response

Rack middleware entry point. In most Rack based frameworks, a request is served by one thread. So entry point, we associate the GCP request trace_id with the current thread's object_id in logger. All the logs written by logger beyond this point will carry this request's trace_id. Untrack the trace_id with this thread upon exiting.

  • env (Hash) — Rack environment hash
  • (Rack::Response) — The response from downstream Rack app


def initialize(app, logger: nil, on_init: nil, **kwargs) -> Google::Cloud::Logging::Middleware

Create a new AppEngine logging Middleware.

  • app (Rack Application) — Rack application
  • logger (Google::Cloud::Logging::Logger) (defaults to: nil) — A logger to be used by this middleware. The middleware will be interacting with the logger to track Stackdriver request trace ID. It also properly sets env["rack.logger"] to this assigned logger for accessing. If not specified, a default logger with be used.
  • on_init (Proc) (defaults to: nil) — A callback to be invoked when the middleware is initialized. The callback takes no arguments. Optional.
  • kwargs (Hash) — Hash of configuration settings. Used for backward API compatibility. See the Configuration Guide for the prefered way to set configuration parameters.


def logger()

The Google::Cloud::Logging::Logger instance



value: "ruby_app_log".freeze
The default log name used to instantiate the default logger if one isn't provided.


value: { "/_ah/health" => "ruby_health_check_log", "/healthz" => "ruby_health_check_log" }.freeze
A default value for the log_name_map argument. Directs health check logs to a separate log name so they don't spam the main log.