Commit 204af2e1 authored by Stan Hu's avatar Stan Hu

Support resetting of Prometheus metrics between test runs

Adding the :prometheus tag to an rspec test will clear out
memory-mapped files and reset the registry.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/39968
parent 5b0e96d0
......@@ -297,7 +297,7 @@ group :metrics do
gem 'influxdb', '~> 0.2', require: false
# Prometheus
gem 'prometheus-client-mmap', '~> 0.9.1'
gem 'prometheus-client-mmap', '~> 0.9.2'
gem 'raindrops', '~> 0.18'
end
......
......@@ -634,7 +634,7 @@ GEM
parser
unparser
procto (0.0.3)
prometheus-client-mmap (0.9.1)
prometheus-client-mmap (0.9.2)
pry (0.10.4)
coderay (~> 1.1.0)
method_source (~> 0.8.1)
......@@ -1133,7 +1133,7 @@ DEPENDENCIES
peek-sidekiq (~> 1.0.3)
pg (~> 0.18.2)
premailer-rails (~> 1.9.7)
prometheus-client-mmap (~> 0.9.1)
prometheus-client-mmap (~> 0.9.2)
pry-byebug (~> 3.4.1)
pry-rails (~> 0.3.4)
rack-attack (~> 4.4.1)
......
......@@ -230,6 +230,11 @@ describe "#==" do
end
```
### Prometheus tests
Prometheus metrics may be preserved from one test run to another. To ensure that metrics are
reset before each example, add the `:prometheus` tag to the Rspec test.
### Matchers
Custom matchers should be created to clarify the intent and/or hide the
......
......@@ -25,6 +25,14 @@ module Gitlab
end
end
def reset_registry!
clear_memoization(:registry)
REGISTRY_MUTEX.synchronize do
::Prometheus::Client.reset!
end
end
def registry
strong_memoize(:registry) do
REGISTRY_MUTEX.synchronize do
......
require 'spec_helper'
describe Gitlab::Metrics::Prometheus, :prometheus do
let(:all_metrics) { Gitlab::Metrics }
let(:registry) { all_metrics.registry }
describe '#reset_registry!' do
it 'clears existing metrics' do
registry.counter(:test, 'test metric')
expect(registry.metrics.count).to eq(1)
all_metrics.reset_registry!
expect(all_metrics.registry.metrics.count).to eq(0)
end
end
end
......@@ -137,6 +137,13 @@ RSpec.configure do |config|
reset_delivered_emails!
end
config.before(:example, :prometheus) do
matching_files = File.join(::Prometheus::Client.configuration.multiprocess_files_dir, "*.db")
Dir[matching_files].map { |filename| File.delete(filename) if File.file?(filename) }
Gitlab::Metrics.reset_registry!
end
config.around(:each, :use_clean_rails_memory_store_caching) do |example|
caching_store = Rails.cache
Rails.cache = ActiveSupport::Cache::MemoryStore.new
......
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