Add Prometheus metrics reader factory and config (#3049)

* Add metrics reader factory and config

Signed-off-by: albertteoh <albert.teoh@logz.io>

* Address review comments

Signed-off-by: albertteoh <albert.teoh@logz.io>

pkg/prometheus/config/config.go

@@ -0,0 +1,23 @@
+// Copyright (c) 2021 The Jaeger 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://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 config
+
+import "time"
+
+// Configuration describes the options to customize the storage behavior.
+type Configuration struct {
+	HostPort       string        `validate:"nonzero" mapstructure:"server"`
+	ConnectTimeout time.Duration `validate:"nonzero" mapstructure:"timeout"`
+}

pkg/prometheus/config/empty_test.go

@@ -0,0 +1,15 @@
+// Copyright (c) 2021 The Jaeger 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://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 config

plugin/metrics/factory.go

@@ -0,0 +1,101 @@
+// Copyright (c) 2021 The Jaeger 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://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 metrics
+
+import (
+	"flag"
+	"fmt"
+
+	"github.com/spf13/viper"
+	"go.uber.org/zap"
+
+	"github.com/jaegertracing/jaeger/plugin"
+	"github.com/jaegertracing/jaeger/plugin/metrics/prometheus"
+	"github.com/jaegertracing/jaeger/storage"
+	"github.com/jaegertracing/jaeger/storage/metricsstore"
+)
+
+const (
+	prometheusStorageType = "prometheus"
+)
+
+// AllStorageTypes defines all available storage backends.
+var AllStorageTypes = []string{prometheusStorageType}
+
+// Factory implements storage.Factory interface as a meta-factory for storage components.
+type Factory struct {
+	FactoryConfig
+	factories map[string]storage.MetricsFactory
+}
+
+// NewFactory creates the meta-factory.
+func NewFactory(config FactoryConfig) (*Factory, error) {
+	f := &Factory{FactoryConfig: config}
+	uniqueTypes := map[string]struct{}{
+		f.MetricsStorageType: {},
+	}
+	f.factories = make(map[string]storage.MetricsFactory)
+	for t := range uniqueTypes {
+		ff, err := f.getFactoryOfType(t)
+		if err != nil {
+			return nil, err
+		}
+		f.factories[t] = ff
+	}
+	return f, nil
+}
+
+func (f *Factory) getFactoryOfType(factoryType string) (storage.MetricsFactory, error) {
+	switch factoryType {
+	case prometheusStorageType:
+		return prometheus.NewFactory(), nil
+	}
+	return nil, fmt.Errorf("unknown metrics type %q. Valid types are %v", factoryType, AllStorageTypes)
+}
+
+// Initialize implements storage.MetricsFactory.
+func (f *Factory) Initialize(logger *zap.Logger) error {
+	for _, factory := range f.factories {
+		factory.Initialize(logger)
+	}
+	return nil
+}
+
+// CreateMetricsReader implements storage.MetricsFactory.
+func (f *Factory) CreateMetricsReader() (metricsstore.Reader, error) {
+	factory, ok := f.factories[f.MetricsStorageType]
+	if !ok {
+		return nil, fmt.Errorf("no %q backend registered for metrics store", f.MetricsStorageType)
+	}
+	return factory.CreateMetricsReader()
+}
+
+// AddFlags implements plugin.Configurable.
+func (f *Factory) AddFlags(flagSet *flag.FlagSet) {
+	for _, factory := range f.factories {
+		if conf, ok := factory.(plugin.Configurable); ok {
+			conf.AddFlags(flagSet)
+		}
+	}
+}
+
+// InitFromViper implements plugin.Configurable.
+func (f *Factory) InitFromViper(v *viper.Viper) {
+	for _, factory := range f.factories {
+		if conf, ok := factory.(plugin.Configurable); ok {
+			conf.InitFromViper(v)
+		}
+	}
+}

plugin/metrics/factory_config.go

@@ -0,0 +1,36 @@
+// Copyright (c) 2021 The Jaeger 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://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 metrics
+
+import (
+	"os"
+)
+
+const (
+	// StorageTypeEnvVar is the name of the env var that defines the type of backend used for metrics storage.
+	StorageTypeEnvVar = "METRICS_STORAGE_TYPE"
+)
+
+// FactoryConfig tells the Factory which types of backends it needs to create for different storage types.
+type FactoryConfig struct {
+	MetricsStorageType string
+}
+
+// FactoryConfigFromEnv reads the desired types of storage backends from METRICS_STORAGE_TYPE.
+func FactoryConfigFromEnv() FactoryConfig {
+	return FactoryConfig{
+		MetricsStorageType: os.Getenv(StorageTypeEnvVar),
+	}
+}

plugin/metrics/factory_config_test.go

@@ -0,0 +1,42 @@
+// Copyright (c) 2021 The Jaeger 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://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 metrics
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func clearEnv(t *testing.T) {
+	err := os.Setenv(StorageTypeEnvVar, "")
+	require.NoError(t, err)
+}
+
+func TestFactoryConfigFromEnv(t *testing.T) {
+	clearEnv(t)
+	defer clearEnv(t)
+
+	fc := FactoryConfigFromEnv()
+	assert.Empty(t, fc.MetricsStorageType)
+
+	err := os.Setenv(StorageTypeEnvVar, prometheusStorageType)
+	require.NoError(t, err)
+
+	fc = FactoryConfigFromEnv()
+	assert.Equal(t, prometheusStorageType, fc.MetricsStorageType)
+}

plugin/metrics/factory_test.go

@@ -0,0 +1,108 @@
+// Copyright (c) 2021 The Jaeger 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://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 metrics
+
+import (
+	"flag"
+	"testing"
+
+	"github.com/spf13/viper"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.uber.org/zap"
+
+	"github.com/jaegertracing/jaeger/storage"
+	"github.com/jaegertracing/jaeger/storage/mocks"
+)
+
+var _ storage.MetricsFactory = new(Factory)
+
+func defaultCfg() FactoryConfig {
+	return FactoryConfig{
+		MetricsStorageType: prometheusStorageType,
+	}
+}
+
+func TestNewFactory(t *testing.T) {
+	f, err := NewFactory(defaultCfg())
+	require.NoError(t, err)
+	assert.NotEmpty(t, f.factories)
+	assert.NotEmpty(t, f.factories[prometheusStorageType])
+	assert.Equal(t, prometheusStorageType, f.MetricsStorageType)
+}
+
+func TestUnsupportedMetricsStorageType(t *testing.T) {
+	f, err := NewFactory(FactoryConfig{MetricsStorageType: "foo"})
+	require.Error(t, err)
+	assert.Nil(t, f)
+	assert.EqualError(t, err, `unknown metrics type "foo". Valid types are [prometheus]`)
+}
+
+func TestCreateMetricsReader(t *testing.T) {
+	f, err := NewFactory(defaultCfg())
+	require.NoError(t, err)
+	require.NotNil(t, f)
+
+	require.NoError(t, f.Initialize(zap.NewNop()))
+
+	reader, err := f.CreateMetricsReader()
+	require.NoError(t, err)
+	require.NotNil(t, reader)
+
+	f.MetricsStorageType = "foo"
+	reader, err = f.CreateMetricsReader()
+	require.Error(t, err)
+	require.Nil(t, reader)
+
+	assert.EqualError(t, err, `no "foo" backend registered for metrics store`)
+}
+
+type configurable struct {
+	mocks.MetricsFactory
+	flagSet *flag.FlagSet
+	viper   *viper.Viper
+}
+
+// AddFlags implements plugin.Configurable.
+func (f *configurable) AddFlags(flagSet *flag.FlagSet) {
+	f.flagSet = flagSet
+}
+
+// InitFromViper implements plugin.Configurable.
+func (f *configurable) InitFromViper(v *viper.Viper) {
+	f.viper = v
+}
+
+func TestConfigurable(t *testing.T) {
+	clearEnv(t)
+	defer clearEnv(t)
+
+	f, err := NewFactory(defaultCfg())
+	require.NoError(t, err)
+	assert.NotEmpty(t, f.factories)
+	assert.NotEmpty(t, f.factories[prometheusStorageType])
+
+	mock := new(configurable)
+	f.factories[prometheusStorageType] = mock
+
+	fs := new(flag.FlagSet)
+	v := viper.New()
+
+	f.AddFlags(fs)
+	f.InitFromViper(v)
+
+	assert.Equal(t, fs, mock.flagSet)
+	assert.Equal(t, v, mock.viper)
+}

plugin/metrics/prometheus/factory.go

@@ -0,0 +1,59 @@
+// Copyright (c) 2021 The Jaeger 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://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 prometheus
+
+import (
+	"flag"
+
+	"github.com/spf13/viper"
+	"go.uber.org/zap"
+
+	prometheusstore "github.com/jaegertracing/jaeger/plugin/metrics/prometheus/metricsstore"
+	"github.com/jaegertracing/jaeger/storage/metricsstore"
+)
+
+// Factory implements storage.Factory and creates storage components backed by memory store.
+type Factory struct {
+	options *Options
+	logger  *zap.Logger
+}
+
+// NewFactory creates a new Factory.
+func NewFactory() *Factory {
+	return &Factory{
+		options: NewOptions("prometheus"),
+	}
+}
+
+// AddFlags implements plugin.Configurable.
+func (f *Factory) AddFlags(flagSet *flag.FlagSet) {
+	f.options.AddFlags(flagSet)
+}
+
+// InitFromViper implements plugin.Configurable.
+func (f *Factory) InitFromViper(v *viper.Viper) {
+	f.options.InitFromViper(v)
+}
+
+// Initialize implements storage.MetricsFactory.
+func (f *Factory) Initialize(logger *zap.Logger) error {
+	f.logger = logger
+	return nil
+}
+
+// CreateMetricsReader implements storage.MetricsFactory.
+func (f *Factory) CreateMetricsReader() (metricsstore.Reader, error) {
+	return prometheusstore.NewMetricsReader(f.logger, f.options.Primary.HostPort, f.options.Primary.ConnectTimeout)
+}