Memcached Receiver Skeleton (#1414)

This is the start of a basic memcached receiver.  It scrapes some basic
metrics from a memcached instance and sends them along.  The primary
test of the metric generation logic is in the integration test due to
the relative opacity of the memcached protocol and the lack of any
preexisting mock (the integration test uses a real memcached instance
via Docker containers).

There are only five basic metrics to start with but this can be easily
expanded with this framework.

go.mod

@@ -41,6 +41,7 @@ require (
  github.com/open-telemetry/opentelemetry-collector-contrib/receiver/dockerstatsreceiver v0.0.0-00010101000000-000000000000
  github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver v0.0.0-00010101000000-000000000000
  github.com/open-telemetry/opentelemetry-collector-contrib/receiver/kubeletstatsreceiver v0.0.0-00010101000000-000000000000
+ github.com/open-telemetry/opentelemetry-collector-contrib/receiver/memcachedreceiver v0.0.0-00010101000000-000000000000
  github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusexecreceiver v0.0.0-00010101000000-000000000000
  github.com/open-telemetry/opentelemetry-collector-contrib/receiver/receivercreator v0.0.0-00010101000000-000000000000
  github.com/open-telemetry/opentelemetry-collector-contrib/receiver/redisreceiver v0.0.0-00010101000000-000000000000
@@ -157,6 +158,8 @@ replace github.com/open-telemetry/opentelemetry-collector-contrib/processor/grou
 
 replace github.com/open-telemetry/opentelemetry-collector-contrib/receiver/stanzareceiver => ./receiver/stanzareceiver/
 
+replace github.com/open-telemetry/opentelemetry-collector-contrib/receiver/memcachedreceiver => ./receiver/memcachedreceiver
+
 replace github.com/open-telemetry/opentelemetry-collector-contrib/processor/k8sprocessor => ./processor/k8sprocessor/
 
 replace github.com/open-telemetry/opentelemetry-collector-contrib/processor/resourcedetectionprocessor => ./processor/resourcedetectionprocessor/

receiver/memcachedreceiver/Makefile

@@ -0,0 +1 @@
+include ../../Makefile.Common

receiver/memcachedreceiver/README.md

@@ -0,0 +1,39 @@
+# Memcached Receiver
+
+This receiver can fetch stats from a Memcached instance using the [stats
+command](https://github.com/memcached/memcached/wiki/Commands#statistics). A
+detailed description of all the stats available is at
+https://github.com/memcached/memcached/blob/master/doc/protocol.txt#L1159.
+
+> :construction: This receiver is currently in **BETA**.
+
+## Details
+
+## Configuration
+
+> :information_source: This receiver is in beta and configuration fields are subject to change.
+
+The following settings are required:
+
+- `endpoint` (default: `localhost:11211`): The hostname/IP address and port of the memcached instance
+
+The following settings are optional:
+
+- `collection_interval` (default = `10s`): This receiver runs on an interval.
+Each time it runs, it queries memcached, creates metrics, and sends them to the
+next consumer. The `collection_interval` configuration option tells this
+receiver the duration between runs. This value must be a string readable by
+Golang's `ParseDuration` function (example: `1h30m`). Valid time units are
+`ns`, `us` (or `µs`), `ms`, `s`, `m`, `h`.
+
+Example:
+
+```yaml
+receivers:
+ memcached:
+ endpoint: "localhost:11211"
+ collection_interval: 10s
+```
+
+The full list of settings exposed for this receiver are documented [here](./config.go)
+with detailed sample configurations [here](./testdata/config.yaml).

receiver/memcachedreceiver/config.go

@@ -0,0 +1,32 @@
+// Copyright 2020, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http:https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package memcachedreceiver
+
+import (
+ "time"
+
+ "go.opentelemetry.io/collector/config/configmodels"
+ "go.opentelemetry.io/collector/config/confignet"
+ "go.opentelemetry.io/collector/receiver/receiverhelper"
+)
+
+type config struct {
+ configmodels.ReceiverSettings `mapstructure:",squash"`
+ receiverhelper.ScraperControllerSettings `mapstructure:",squash"`
+ confignet.TCPAddr `mapstructure:",squash"`
+
+ // Timeout for the memcache stats request
+ Timeout time.Duration `mapstructure:"timeout"`
+}

receiver/memcachedreceiver/factory.go

@@ -0,0 +1,72 @@
+// Copyright 2020, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http:https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package memcachedreceiver
+
+//go:generate mdatagen metadata.yaml
+
+import (
+ "context"
+ "time"
+
+ "go.opentelemetry.io/collector/component"
+ "go.opentelemetry.io/collector/config/configmodels"
+ "go.opentelemetry.io/collector/config/confignet"
+ "go.opentelemetry.io/collector/consumer"
+ "go.opentelemetry.io/collector/receiver/receiverhelper"
+)
+
+const (
+ typeStr = "memcached"
+)
+
+// NewFactory creates a factory for memcached receiver.
+func NewFactory() component.ReceiverFactory {
+ return receiverhelper.NewFactory(
+ typeStr,
+ createDefaultConfig,
+ receiverhelper.WithMetrics(createMetricsReceiver))
+}
+
+func createDefaultConfig() configmodels.Receiver {
+ return &config{
+ ReceiverSettings: configmodels.ReceiverSettings{
+ TypeVal: typeStr,
+ NameVal: typeStr,
+ },
+ ScraperControllerSettings: receiverhelper.ScraperControllerSettings{
+ CollectionInterval: 10 * time.Second,
+ },
+ Timeout: 10 * time.Second,
+ TCPAddr: confignet.TCPAddr{
+ Endpoint: "localhost:11211",
+ },
+ }
+}
+
+func createMetricsReceiver(
+ ctx context.Context,
+ params component.ReceiverCreateParams,
+ rConf configmodels.Receiver,
+ consumer consumer.MetricsConsumer,
+) (component.MetricsReceiver, error) {
+ cfg := rConf.(*config)
+
+ scraper := newMemcachedScraper(params.Logger, cfg)
+
+ return receiverhelper.NewScraperControllerReceiver(
+ &cfg.ScraperControllerSettings, consumer,
+ receiverhelper.AddResourceMetricsScraper(scraper),
+ )
+}

receiver/memcachedreceiver/factory_test.go

@@ -0,0 +1,56 @@
+// Copyright 2020, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http:https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package memcachedreceiver
+
+import (
+ "context"
+ "testing"
+ "time"
+
+ "github.com/stretchr/testify/require"
+ "go.opentelemetry.io/collector/component"
+ "go.opentelemetry.io/collector/config/configcheck"
+ "go.opentelemetry.io/collector/receiver/receiverhelper"
+ "go.opentelemetry.io/collector/testbed/testbed"
+ "go.uber.org/zap"
+)
+
+func TestType(t *testing.T) {
+ factory := NewFactory()
+ ft := factory.Type()
+ require.EqualValues(t, "memcached", ft)
+}
+
+func TestValidConfig(t *testing.T) {
+ factory := NewFactory()
+ err := configcheck.ValidateConfig(factory.CreateDefaultConfig())
+ require.NoError(t, err)
+}
+
+func TestCreateMetricsReceiver(t *testing.T) {
+ factory := NewFactory()
+ metricsReceiver, err := factory.CreateMetricsReceiver(
+ context.Background(),
+ component.ReceiverCreateParams{Logger: zap.NewNop()},
+ &config{
+ ScraperControllerSettings: receiverhelper.ScraperControllerSettings{
+ CollectionInterval: 10 * time.Second,
+ },
+ },
+ &testbed.MockMetricConsumer{},
+ )
+ require.NoError(t, err)
+ require.NotNil(t, metricsReceiver)
+}

receiver/memcachedreceiver/go.mod

@@ -0,0 +1,18 @@
+module github.com/open-telemetry/opentelemetry-collector-contrib/receiver/memcachedreceiver
+
+go 1.14
+
+require (
+ github.com/census-instrumentation/opencensus-proto v0.3.0
+ github.com/davecgh/go-spew v1.1.1
+ github.com/go-redis/redis/v7 v7.4.0
+ github.com/grobie/gomemcache v0.0.0-20180201122607-1f779c573665
+ github.com/open-telemetry/opentelemetry-collector-contrib/internal/common v0.0.0-00010101000000-000000000000
+ github.com/stretchr/testify v1.6.1
+ go.opentelemetry.io/collector v0.13.1-0.20201027215027-6ae66159741d
+ go.uber.org/zap v1.16.0
+ google.golang.org/api v0.32.0
+ google.golang.org/protobuf v1.25.0
+)
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/common => ../../internal/common