Allow to configure log level of Gitlab:Logger (by env variable)

Changelog: added

config/environments/production.rb

@@ -36,7 +36,9 @@ Rails.application.configure do
   # Force all access to the app over SSL, use Strict-Transport-Security, and use secure cookies.
   # config.force_ssl = true
 
-  # See everything in the log (default is :info)
+  # Include generic and useful information about system operation, but avoid logging too much
+  # information to avoid inadvertent exposure of personally identifiable information (PII).
+  # Note: This configuration does not affect the log level of `Gitlab::Logger` and its subclasses.
   config.log_level = :info
 
   # Suppress 'Rendered template ...' messages in the log

doc/administration/logs.md

@@ -20,6 +20,54 @@ including adjusting log retention, log forwarding,
 switching logs from JSON to plain text logging, and more.
 - [How to parse and analyze JSON logs](troubleshooting/log_parsing.md).
 
+## Log Levels
+ 
+Each log message has an assigned log level that indicates its importance and verbosity.
+Each logger has an assigned minimum log level.
+A logger emits a log message only if its log level is equal to or above the minimum log level.
+
+The following log levels are supported:
+
+| Level | Name    |
+|-------|---------|
+| 0     | DEBUG   |
+| 1     | INFO    |
+| 2     | WARN    |
+| 3     | ERROR   |
+| 4     | FATAL   |
+| 5     | UNKNOWN |
+
+GitLab loggers emit all log messages because they are set to `DEBUG` by default.
+
+### Override default log level
+
+You can override the minimum log level for GitLab loggers using the `GITLAB_LOG_LEVEL` environment variable.
+Valid values are either a value of `0` to `5`, or the name of the log level.
+
+Example:
+
+```shell
+GITLAB_LOG_LEVEL=info
+```
+
+For some services, other log levels are in place that are not affected by this setting.
+Some of these services have their own environment variables to override the log level. For example:
+
+| Service              | Log Level | Environment variable |
+|----------------------|-----------|----------------------|
+| GitLab API           | `INFO`    |                      |
+| GitLab Cleanup       | `INFO`    | `DEBUG`              |
+| GitLab Doctor        | `INFO`    | `VERBOSE`            |
+| GitLab Export        | `INFO`    | `EXPORT_DEBUG`       |
+| GitLab Geo           | `INFO`    |                      |
+| GitLab Import        | `INFO`    | `IMPORT_DEBUG`       |
+| GitLab QA Runtime    | `ERROR`   | `QA_DEBUG`           |
+| Google APIs          | `INFO`    |                      |
+| Rack Timeout         | `ERROR`   |                      |
+| Sidekiq (server)     | `INFO`    |                      |
+| Snowplow Tracker     | `FATAL`   |                      |
+| gRPC Client (Gitaly) | `WARN`    | `GRPC_LOG_LEVEL`     |
+
 ## Log Rotation
 
 The logs for a given service may be managed and rotated by:

lib/gitlab/logger.rb

@@ -33,7 +33,11 @@ module Gitlab
 
     def self.build
       Gitlab::SafeRequestStore[self.cache_key] ||=
-        new(self.full_log_path, level: ::Logger::DEBUG)
+        new(self.full_log_path, level: log_level)
+    end
+
+    def self.log_level(fallback: ::Logger::DEBUG)
+      ENV.fetch('GITLAB_LOG_LEVEL', fallback)
     end
 
     def self.full_log_path

spec/lib/gitlab/logger_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Logger do
+  describe '.build' do
+    before do
+      allow(described_class).to receive(:file_name_noext).and_return('log')
+    end
+
+    subject { described_class.build }
+
+    it 'builds logger using Gitlab::Logger.log_level' do
+      expect(described_class).to receive(:log_level).and_return(:warn)
+
+      expect(subject.level).to eq(described_class::WARN)
+    end
+
+    it 'raises ArgumentError if invalid log level' do
+      allow(described_class).to receive(:log_level).and_return(:invalid)
+
+      expect { subject.level }.to raise_error(ArgumentError, 'invalid log level: invalid')
+    end
+
+    using RSpec::Parameterized::TableSyntax
+
+    where(:env_value, :resulting_level) do
+      0         | described_class::DEBUG
+      :debug    | described_class::DEBUG
+      'debug'   | described_class::DEBUG
+      'DEBUG'   | described_class::DEBUG
+      'DeBuG'   | described_class::DEBUG
+      1         | described_class::INFO
+      :info     | described_class::INFO
+      'info'    | described_class::INFO
+      'INFO'    | described_class::INFO
+      'InFo'    | described_class::INFO
+      2         | described_class::WARN
+      :warn     | described_class::WARN
+      'warn'    | described_class::WARN
+      'WARN'    | described_class::WARN
+      'WaRn'    | described_class::WARN
+      3         | described_class::ERROR
+      :error    | described_class::ERROR
+      'error'   | described_class::ERROR
+      'ERROR'   | described_class::ERROR
+      'ErRoR'   | described_class::ERROR
+      4         | described_class::FATAL
+      :fatal    | described_class::FATAL
+      'fatal'   | described_class::FATAL
+      'FATAL'   | described_class::FATAL
+      'FaTaL'   | described_class::FATAL
+      5         | described_class::UNKNOWN
+      :unknown  | described_class::UNKNOWN
+      'unknown' | described_class::UNKNOWN
+      'UNKNOWN' | described_class::UNKNOWN
+      'UnKnOwN' | described_class::UNKNOWN
+    end
+
+    with_them do
+      it 'builds logger if valid log level' do
+        stub_env('GITLAB_LOG_LEVEL', env_value)
+
+        expect(subject.level).to eq(resulting_level)
+      end
+    end
+  end
+
+  describe '.log_level' do
+    context 'if GITLAB_LOG_LEVEL is set' do
+      before do
+        stub_env('GITLAB_LOG_LEVEL', described_class::ERROR)
+      end
+
+      it 'returns value of GITLAB_LOG_LEVEL' do
+        expect(described_class.log_level).to eq(described_class::ERROR)
+      end
+
+      it 'ignores fallback' do
+        expect(described_class.log_level(fallback: described_class::FATAL)).to eq(described_class::ERROR)
+      end
+    end
+
+    context 'if GITLAB_LOG_LEVEL is not set' do
+      it 'returns default fallback DEBUG' do
+        expect(described_class.log_level).to eq(described_class::DEBUG)
+      end
+
+      it 'returns passed fallback' do
+        expect(described_class.log_level(fallback: described_class::FATAL)).to eq(described_class::FATAL)
+      end
+    end
+  end
+end