Add connector factory (#6611)

.chloggen/connector-factory.yaml

@@ -0,0 +1,16 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: connector
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add connector factory
+
+# One or more tracking issues or pull requests related to the change
+issues: [6611]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

component/config.go

@@ -28,6 +28,14 @@ type Config interface {
 	privateConfig()
 }
 
+// CreateDefaultConfigFunc is the equivalent of Factory.CreateDefaultConfig().
+type CreateDefaultConfigFunc func() Config
+
+// CreateDefaultConfig implements Factory.CreateDefaultConfig().
+func (f CreateDefaultConfigFunc) CreateDefaultConfig() Config {
+	return f()
+}
+
 // As interface types are only used for static typing, a common idiom to find the reflection Type
 // for an interface type Foo is to use a *Foo value.
 var configValidatorType = reflect.TypeOf((*ConfigValidator)(nil)).Elem()

connector/connector.go

@@ -35,3 +35,61 @@ type CreateSettings struct {
 	// BuildInfo can be used by components for informational purposes
 	BuildInfo component.BuildInfo
 }
+
+// Factory is factory interface for connectors.
+//
+// This interface cannot be directly implemented. Implementations must
+// use the NewFactory to implement it.
+type Factory interface {
+	component.Factory
+
+	// CreateDefaultConfig creates the default configuration for the Connector.
+	// This method can be called multiple times depending on the pipeline
+	// configuration and should not cause side-effects that prevent the creation
+	// of multiple instances of the Connector.
+	// The object returned by this method needs to pass the checks implemented by
+	// 'configtest.CheckConfigStruct'. It is recommended to have these checks in the
+	// tests of any implementation of the Factory interface.
+	CreateDefaultConfig() component.Config
+}
+
+// FactoryOption applies changes to Factory.
+type FactoryOption interface {
+	// apply applies the option.
+	apply(o *factory)
+}
+
+var _ FactoryOption = (*factoryOptionFunc)(nil)
+
+// factoryOptionFunc is an FactoryOption created through a function.
+type factoryOptionFunc func(*factory)
+
+func (f factoryOptionFunc) apply(o *factory) {
+	f(o)
+}
+
+// factory implements Factory.
+type factory struct {
+	component.Factory
+	cfgType component.Type
+	component.CreateDefaultConfigFunc
+}
+
+var _ Factory = (*factory)(nil)
+
+// Type returns the type of component.
+func (f *factory) Type() component.Type {
+	return f.cfgType
+}
+
+// NewFactory returns a Factory.
+func NewFactory(cfgType component.Type, createDefaultConfig component.CreateDefaultConfigFunc, options ...FactoryOption) Factory {
+	f := &factory{
+		cfgType:                 cfgType,
+		CreateDefaultConfigFunc: createDefaultConfig,
+	}
+	for _, opt := range options {
+		opt.apply(f)
+	}
+	return f
+}

connector/connector_test.go

@@ -0,0 +1,34 @@
+// Copyright The 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://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 connector // import "go.opentelemetry.io/collector/connector"
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/config"
+)
+
+func TestNewFactory_NoOptions(t *testing.T) {
+	const typeStr = "test"
+	defaultCfg := config.NewConnectorSettings(component.NewID(typeStr))
+	factory := NewFactory(
+		typeStr,
+		func() component.Config { return &defaultCfg })
+	assert.EqualValues(t, typeStr, factory.Type())
+	assert.EqualValues(t, &defaultCfg, factory.CreateDefaultConfig())
+}