diff --git a/changelogs/unreleased/pawel-ensure_temp_files_are_deleted_in_fs_metrics-35457.yml b/changelogs/unreleased/pawel-ensure_temp_files_are_deleted_in_fs_metrics-35457.yml
new file mode 100644
index 00000000000..1186dc59dc7
--- /dev/null
+++ b/changelogs/unreleased/pawel-ensure_temp_files_are_deleted_in_fs_metrics-35457.yml
@@ -0,0 +1,4 @@
+---
+title: Ensure filesystem metrics test files are deleted
+merge_request:
+author:
diff --git a/config/initializers/7_prometheus_metrics.rb b/config/initializers/7_prometheus_metrics.rb
index 987324a86c9..a2f8421f5d7 100644
--- a/config/initializers/7_prometheus_metrics.rb
+++ b/config/initializers/7_prometheus_metrics.rb
@@ -6,7 +6,7 @@ Prometheus::Client.configure do |config|
   config.initial_mmap_file_size = 4 * 1024
   config.multiprocess_files_dir = ENV['prometheus_multiproc_dir']
 
-  if Rails.env.development? && Rails.env.test?
+  if Rails.env.development? || Rails.env.test?
     config.multiprocess_files_dir ||= Rails.root.join('tmp/prometheus_multiproc_dir')
   end
 end
diff --git a/lib/gitlab/health_checks/base_abstract_check.rb b/lib/gitlab/health_checks/base_abstract_check.rb
index 7de6d4d9367..8b365dab185 100644
--- a/lib/gitlab/health_checks/base_abstract_check.rb
+++ b/lib/gitlab/health_checks/base_abstract_check.rb
@@ -27,10 +27,10 @@ module Gitlab
         Metric.new(name, value, labels)
       end
 
-      def with_timing(proc)
+      def with_timing
         start = Time.now
-        result = proc.call
-        yield result, Time.now.to_f - start.to_f
+        result = yield
+        [result, Time.now.to_f - start.to_f]
       end
 
       def catch_timeout(seconds, &block)
diff --git a/lib/gitlab/health_checks/fs_shards_check.rb b/lib/gitlab/health_checks/fs_shards_check.rb
index bebde857b16..9e91c135956 100644
--- a/lib/gitlab/health_checks/fs_shards_check.rb
+++ b/lib/gitlab/health_checks/fs_shards_check.rb
@@ -10,47 +10,45 @@ module Gitlab
         def readiness
           repository_storages.map do |storage_name|
             begin
-              tmp_file_path = tmp_file_path(storage_name)
-
               if !storage_stat_test(storage_name)
                 HealthChecks::Result.new(false, 'cannot stat storage', shard: storage_name)
-              elsif !storage_write_test(tmp_file_path)
-                HealthChecks::Result.new(false, 'cannot write to storage', shard: storage_name)
-              elsif !storage_read_test(tmp_file_path)
-                HealthChecks::Result.new(false, 'cannot read from storage', shard: storage_name)
               else
-                HealthChecks::Result.new(true, nil, shard: storage_name)
+                with_temp_file(storage_name) do |tmp_file_path|
+                  if !storage_write_test(tmp_file_path)
+                    HealthChecks::Result.new(false, 'cannot write to storage', shard: storage_name)
+                  elsif !storage_read_test(tmp_file_path)
+                    HealthChecks::Result.new(false, 'cannot read from storage', shard: storage_name)
+                  else
+                    HealthChecks::Result.new(true, nil, shard: storage_name)
+                  end
+                end
               end
             rescue RuntimeError => ex
               message = "unexpected error #{ex} when checking storage #{storage_name}"
               Rails.logger.error(message)
               HealthChecks::Result.new(false, message, shard: storage_name)
-            ensure
-              delete_test_file(tmp_file_path)
             end
           end
         end
 
         def metrics
           repository_storages.flat_map do |storage_name|
-            tmp_file_path = tmp_file_path(storage_name)
             [
-              operation_metrics(:filesystem_accessible, :filesystem_access_latency_seconds, -> { storage_stat_test(storage_name) }, shard: storage_name),
-              operation_metrics(:filesystem_writable, :filesystem_write_latency_seconds, -> { storage_write_test(tmp_file_path) }, shard: storage_name),
-              operation_metrics(:filesystem_readable, :filesystem_read_latency_seconds, -> { storage_read_test(tmp_file_path) }, shard: storage_name)
+              storage_stat_metrics(storage_name),
+              storage_write_metrics(storage_name),
+              storage_read_metrics(storage_name)
             ].flatten
           end
         end
 
         private
 
-        def operation_metrics(ok_metric, latency_metric, operation, **labels)
-          with_timing operation do |result, elapsed|
-            [
-              metric(latency_metric, elapsed, **labels),
-              metric(ok_metric, result ? 1 : 0, **labels)
-            ]
-          end
+        def operation_metrics(ok_metric, latency_metric, **labels)
+          result, elapsed = yield
+          [
+            metric(latency_metric, elapsed, **labels),
+            metric(ok_metric, result ? 1 : 0, **labels)
+          ]
         rescue RuntimeError => ex
           Rails.logger.error("unexpected error #{ex} when checking #{ok_metric}")
           [metric(ok_metric, 0, **labels)]
@@ -68,19 +66,36 @@ module Gitlab
           Gitlab::Popen.popen([TIMEOUT_EXECUTABLE, COMMAND_TIMEOUT].concat(cmd_args), *args, &block)
         end
 
-        def tmp_file_path(storage_name)
-          Dir::Tmpname.create(%w(fs_shards_check +deleted), path(storage_name)) { |path| path }
+        def with_temp_file(storage_name)
+          temp_file_path = Dir::Tmpname.create(%w(fs_shards_check +deleted), storage_path(storage_name)) { |path| path }
+          yield temp_file_path
+        ensure
+          delete_test_file(temp_file_path)
         end
 
-        def path(storage_name)
+        def storage_path(storage_name)
           storages_paths&.dig(storage_name, 'path')
         end
 
+        # All below test methods use shell commands to perform actions on storage volumes.
+        # In case a storage volume have connectivity problems causing pure Ruby IO operation to wait indefinitely,
+        # we can rely on shell commands to be terminated once `timeout` kills them.
+        #
+        # However we also fallback to pure Ruby file operations in case a specific shell command is missing
+        # so we are still able to perform healthchecks and gather metrics from such system.
+
+        def delete_test_file(tmp_path)
+          _, status = exec_with_timeout(%W{ rm -f #{tmp_path} })
+          status.zero?
+        rescue Errno::ENOENT
+          File.delete(tmp_path) rescue Errno::ENOENT
+        end
+
         def storage_stat_test(storage_name)
-          stat_path = File.join(path(storage_name), '.')
+          stat_path = File.join(storage_path(storage_name), '.')
           begin
             _, status = exec_with_timeout(%W{ stat #{stat_path} })
-            status == 0
+            status.zero?
           rescue Errno::ENOENT
             File.exist?(stat_path) && File::Stat.new(stat_path).readable?
           end
@@ -90,7 +105,7 @@ module Gitlab
           _, status = exec_with_timeout(%W{ tee #{tmp_path} }) do |stdin|
             stdin.write(RANDOM_STRING)
           end
-          status == 0
+          status.zero?
         rescue Errno::ENOENT
           written_bytes = File.write(tmp_path, RANDOM_STRING) rescue Errno::ENOENT
           written_bytes == RANDOM_STRING.length
@@ -100,17 +115,33 @@ module Gitlab
           _, status = exec_with_timeout(%W{ diff #{tmp_path} - }) do |stdin|
             stdin.write(RANDOM_STRING)
           end
-          status == 0
+          status.zero?
         rescue Errno::ENOENT
           file_contents = File.read(tmp_path) rescue Errno::ENOENT
           file_contents == RANDOM_STRING
         end
 
-        def delete_test_file(tmp_path)
-          _, status = exec_with_timeout(%W{ rm -f #{tmp_path} })
-          status == 0
-        rescue Errno::ENOENT
-          File.delete(tmp_path) rescue Errno::ENOENT
+        def storage_stat_metrics(storage_name)
+          operation_metrics(:filesystem_accessible, :filesystem_access_latency_seconds, shard: storage_name) do
+            with_timing { storage_stat_test(storage_name) }
+          end
+        end
+
+        def storage_write_metrics(storage_name)
+          operation_metrics(:filesystem_writable, :filesystem_write_latency_seconds, shard: storage_name) do
+            with_temp_file(storage_name) do |tmp_file_path|
+              with_timing { storage_write_test(tmp_file_path) }
+            end
+          end
+        end
+
+        def storage_read_metrics(storage_name)
+          operation_metrics(:filesystem_readable, :filesystem_read_latency_seconds, shard: storage_name) do
+            with_temp_file(storage_name) do |tmp_file_path|
+              storage_write_test(tmp_file_path) # writes data used by read test
+              with_timing { storage_read_test(tmp_file_path) }
+            end
+          end
         end
       end
     end
diff --git a/lib/gitlab/health_checks/simple_abstract_check.rb b/lib/gitlab/health_checks/simple_abstract_check.rb
index 3dcb28a193c..f5026171ba4 100644
--- a/lib/gitlab/health_checks/simple_abstract_check.rb
+++ b/lib/gitlab/health_checks/simple_abstract_check.rb
@@ -15,14 +15,13 @@ module Gitlab
       end
 
       def metrics
-        with_timing method(:check) do |result, elapsed|
-          Rails.logger.error("#{human_name} check returned unexpected result #{result}") unless is_successful?(result)
-          [
-            metric("#{metric_prefix}_timeout", result.is_a?(Timeout::Error) ? 1 : 0),
-            metric("#{metric_prefix}_success", is_successful?(result) ? 1 : 0),
-            metric("#{metric_prefix}_latency_seconds", elapsed)
-          ]
-        end
+        result, elapsed = with_timing(&method(:check))
+        Rails.logger.error("#{human_name} check returned unexpected result #{result}") unless is_successful?(result)
+        [
+          metric("#{metric_prefix}_timeout", result.is_a?(Timeout::Error) ? 1 : 0),
+          metric("#{metric_prefix}_success", is_successful?(result) ? 1 : 0),
+          metric("#{metric_prefix}_latency_seconds", elapsed)
+        ]
       end
 
       private
diff --git a/spec/lib/gitlab/health_checks/fs_shards_check_spec.rb b/spec/lib/gitlab/health_checks/fs_shards_check_spec.rb
index 3de73a9ff65..8abc4320c59 100644
--- a/spec/lib/gitlab/health_checks/fs_shards_check_spec.rb
+++ b/spec/lib/gitlab/health_checks/fs_shards_check_spec.rb
@@ -3,7 +3,7 @@ require 'spec_helper'
 describe Gitlab::HealthChecks::FsShardsCheck do
   def command_exists?(command)
     _, status = Gitlab::Popen.popen(%W{ #{command} 1 echo })
-    status == 0
+    status.zero?
   rescue Errno::ENOENT
     false
   end
@@ -64,9 +64,7 @@ describe Gitlab::HealthChecks::FsShardsCheck do
         it 'cleans up files used for testing' do
           expect(described_class).to receive(:storage_write_test).with(any_args).and_call_original
 
-          subject
-
-          expect(Dir.entries(tmp_dir).count).to eq(2)
+          expect { subject }.not_to change(Dir.entries(tmp_dir), :count)
         end
 
         context 'read test fails' do
@@ -88,8 +86,6 @@ describe Gitlab::HealthChecks::FsShardsCheck do
     end
 
     describe '#metrics' do
-      subject { described_class.metrics }
-
       context 'storage points to not existing folder' do
         let(:storages_paths) do
           {
@@ -104,14 +100,15 @@ describe Gitlab::HealthChecks::FsShardsCheck do
         end
 
         it 'provides metrics' do
-          expect(subject).to all(have_attributes(labels: { shard: :default }))
-          expect(subject).to include(an_object_having_attributes(name: :filesystem_accessible, value: 0))
-          expect(subject).to include(an_object_having_attributes(name: :filesystem_readable, value: 0))
-          expect(subject).to include(an_object_having_attributes(name: :filesystem_writable, value: 0))
+          metrics = described_class.metrics
 
-          expect(subject).to include(an_object_having_attributes(name: :filesystem_access_latency_seconds, value: be >= 0))
-          expect(subject).to include(an_object_having_attributes(name: :filesystem_read_latency_seconds, value: be >= 0))
-          expect(subject).to include(an_object_having_attributes(name: :filesystem_write_latency_seconds, value: be >= 0))
+          expect(metrics).to all(have_attributes(labels: { shard: :default }))
+          expect(metrics).to include(an_object_having_attributes(name: :filesystem_accessible, value: 0))
+          expect(metrics).to include(an_object_having_attributes(name: :filesystem_readable, value: 0))
+          expect(metrics).to include(an_object_having_attributes(name: :filesystem_writable, value: 0))
+          expect(metrics).to include(an_object_having_attributes(name: :filesystem_access_latency_seconds, value: be >= 0))
+          expect(metrics).to include(an_object_having_attributes(name: :filesystem_read_latency_seconds, value: be >= 0))
+          expect(metrics).to include(an_object_having_attributes(name: :filesystem_write_latency_seconds, value: be >= 0))
         end
       end
 
@@ -121,15 +118,19 @@ describe Gitlab::HealthChecks::FsShardsCheck do
         end
 
         it 'provides metrics' do
-          expect(subject).to all(have_attributes(labels: { shard: :default }))
+          metrics = described_class.metrics
 
-          expect(subject).to include(an_object_having_attributes(name: :filesystem_accessible, value: 1))
-          expect(subject).to include(an_object_having_attributes(name: :filesystem_readable, value: 1))
-          expect(subject).to include(an_object_having_attributes(name: :filesystem_writable, value: 1))
+          expect(metrics).to all(have_attributes(labels: { shard: :default }))
+          expect(metrics).to include(an_object_having_attributes(name: :filesystem_accessible, value: 1))
+          expect(metrics).to include(an_object_having_attributes(name: :filesystem_readable, value: 1))
+          expect(metrics).to include(an_object_having_attributes(name: :filesystem_writable, value: 1))
+          expect(metrics).to include(an_object_having_attributes(name: :filesystem_access_latency_seconds, value: be >= 0))
+          expect(metrics).to include(an_object_having_attributes(name: :filesystem_read_latency_seconds, value: be >= 0))
+          expect(metrics).to include(an_object_having_attributes(name: :filesystem_write_latency_seconds, value: be >= 0))
+        end
 
-          expect(subject).to include(an_object_having_attributes(name: :filesystem_access_latency_seconds, value: be >= 0))
-          expect(subject).to include(an_object_having_attributes(name: :filesystem_read_latency_seconds, value: be >= 0))
-          expect(subject).to include(an_object_having_attributes(name: :filesystem_write_latency_seconds, value: be >= 0))
+        it 'cleans up files used for metrics' do
+          expect { described_class.metrics }.not_to change(Dir.entries(tmp_dir), :count)
         end
       end
     end
@@ -150,18 +151,16 @@ describe Gitlab::HealthChecks::FsShardsCheck do
     end
 
     describe '#metrics' do
-      subject { described_class.metrics }
-
       it 'provides metrics' do
-        expect(subject).to all(have_attributes(labels: { shard: :default }))
+        metrics = described_class.metrics
 
-        expect(subject).to include(an_object_having_attributes(name: :filesystem_accessible, value: 0))
-        expect(subject).to include(an_object_having_attributes(name: :filesystem_readable, value: 0))
-        expect(subject).to include(an_object_having_attributes(name: :filesystem_writable, value: 0))
-
-        expect(subject).to include(an_object_having_attributes(name: :filesystem_access_latency_seconds, value: be >= 0))
-        expect(subject).to include(an_object_having_attributes(name: :filesystem_read_latency_seconds, value: be >= 0))
-        expect(subject).to include(an_object_having_attributes(name: :filesystem_write_latency_seconds, value: be >= 0))
+        expect(metrics).to all(have_attributes(labels: { shard: :default }))
+        expect(metrics).to include(an_object_having_attributes(name: :filesystem_accessible, value: 0))
+        expect(metrics).to include(an_object_having_attributes(name: :filesystem_readable, value: 0))
+        expect(metrics).to include(an_object_having_attributes(name: :filesystem_writable, value: 0))
+        expect(metrics).to include(an_object_having_attributes(name: :filesystem_access_latency_seconds, value: be >= 0))
+        expect(metrics).to include(an_object_having_attributes(name: :filesystem_read_latency_seconds, value: be >= 0))
+        expect(metrics).to include(an_object_having_attributes(name: :filesystem_write_latency_seconds, value: be >= 0))
       end
     end
   end