Merge branch '232831-check-redis-key-format' into 'master'

Validate Redis key format for same hash slot

Closes #232831

See merge request gitlab-org/gitlab!38782

lib/gitlab/redis/hll.rb

@@ -3,6 +3,9 @@
 module Gitlab
   module Redis
     class HLL
+      KEY_REGEX = %r{\A(\w|-|:)*\{\w*\}(\w|-|:)*\z}.freeze
+      KeyFormatError = Class.new(StandardError)
+
       def self.count(params)
         self.new.count(params)
       end
@@ -11,15 +14,25 @@ module Gitlab
         self.new.add(params)
       end
 
-      # NOTE: It is important to make sure the keys are in the same hash slot
-      # https://redis.io/topics/cluster-spec#keys-hash-tags
       def count(keys:)
         Gitlab::Redis::SharedState.with do |redis|
           redis.pfcount(*keys)
         end
       end
 
+      # Check a basic format for the Redis key in order to ensure the keys are in the same hash slot
+      #
+      # Examples of keys
+      #   project:{1}:set_a
+      #   project:{1}:set_b
+      #   project:{2}:set_c
+      #   2020-216-{project_action}
+      #   i_{analytics}_dev_ops_score-2020-32
       def add(key:, value:, expiry:)
+        unless KEY_REGEX.match?(key)
+          raise KeyFormatError.new("Invalid key format. #{key} key should have changeable parts in curly braces. See https://docs.gitlab.com/ee/development/redis.html#multi-key-commands")
+        end
+
         Gitlab::Redis::SharedState.with do |redis|
           redis.multi do |multi|
             multi.pfadd(key, value)

spec/lib/gitlab/redis/hll_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Redis::HLL, :clean_gitlab_redis_shared_state do
+  describe '.add' do
+    it 'raise an error when using an invalid key format' do
+      expect { described_class.add(key: 'test', value: 1, expiry: 1.day) }.to raise_error(Gitlab::Redis::HLL::KeyFormatError)
+      expect { described_class.add(key: 'test-{metric', value: 1, expiry: 1.day) }.to raise_error(Gitlab::Redis::HLL::KeyFormatError)
+      expect { described_class.add(key: 'test-{metric}}', value: 1, expiry: 1.day) }.to raise_error(Gitlab::Redis::HLL::KeyFormatError)
+    end
+
+    it "doesn't raise error when having correct format" do
+      expect { described_class.add(key: 'test-{metric}', value: 1, expiry: 1.day) }.not_to raise_error
+      expect { described_class.add(key: 'test-{metric}-1', value: 1, expiry: 1.day) }.not_to raise_error
+      expect { described_class.add(key: 'test:{metric}-1', value: 1, expiry: 1.day) }.not_to raise_error
+      expect { described_class.add(key: '2020-216-{project_action}', value: 1, expiry: 1.day) }.not_to raise_error
+      expect { described_class.add(key: 'i_{analytics}_dev_ops_score-2020-32', value: 1, expiry: 1.day) }.not_to raise_error
+    end
+  end
+end