Add http_forwarder skeleton (#979)

* Add http_forwarder skeleton

* Address feedback

* Address feedback

extension/httpforwarder/Makefile

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+include ../../Makefile.Common

extension/httpforwarder/README.md

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+# HTTP Forwarder Extension
+
+This extension accepts HTTP requests, optionally adds headers to them and forwards them.
+The RequestURIs of the original requests are preserved by the extension.
+
+## Configuration
+
+* `ingress`: HTTP config settings for HTTP server listening to requests.
+ * `endpoint` (default: `localhost:6060`): The host to which requests should be forwarded to.
+* `egress`: HTTP config settings to use for forwarding requests.
+ * `endpoint` (**required**): The target to which requests should be forwarded to.
+ * `headers` (default: `nil`): Additional headers to be added to all requests passing through the extension.
+ * `timeout` (default: `10s`): How long to wait for each request to complete.
+
+### Example
+
+```yaml
+ http_forwarder:
+ ingress:
+ endpoint: localhost:7070
+ egress:
+ endpoint: http:https://target/
+ headers:
+ otel_http_forwarder: dev
+ timeout: 5s
+```

extension/httpforwarder/config.go

@@ -0,0 +1,31 @@
+// 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: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 httpforwarder
+
+import (
+ "go.opentelemetry.io/collector/config/confighttp"
+ "go.opentelemetry.io/collector/config/configmodels"
+)
+
+// Config defines configuration for http forwarder extension.
+type Config struct {
+ configmodels.ExtensionSettings `mapstructure:",squash"`
+
+ // Ingress holds config settings for HTTP server listening for requests.
+ Ingress confighttp.HTTPServerSettings `mapstructure:"ingress"`
+
+ // Egress holds config settings to use for forwarded requests.
+ Egress confighttp.HTTPClientSettings `mapstructure:"egress"`
+}

extension/httpforwarder/extension.go

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+// 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: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 httpforwarder
+
+import (
+ "context"
+
+ "go.opentelemetry.io/collector/component"
+)
+
+type httpForwarder struct {
+}
+
+var _ component.ServiceExtension = (*httpForwarder)(nil)
+
+func (h httpForwarder) Start(_ context.Context, _ component.Host) error {
+ // TODO: Start HTTP server
+ return nil
+}
+
+func (h httpForwarder) Shutdown(_ context.Context) error {
+ // TODO: Shutdown HTTP server
+ return nil
+}

extension/httpforwarder/factory.go

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+// 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: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 httpforwarder
+
+import (
+ "context"
+ "time"
+
+ "go.opentelemetry.io/collector/component"
+ "go.opentelemetry.io/collector/config/confighttp"
+ "go.opentelemetry.io/collector/config/configmodels"
+ "go.opentelemetry.io/collector/extension/extensionhelper"
+)
+
+const (
+ // The value of extension "type" in configuration.
+ typeStr configmodels.Type = "http_forwarder"
+
+ // Default endpoints to bind to.
+ defaultEndpoint = ":6060"
+)
+
+// NewFactory creates a factory for HostObserver extension.
+func NewFactory() component.ExtensionFactory {
+ return extensionhelper.NewFactory(
+ typeStr,
+ createDefaultConfig,
+ createExtension)
+}
+
+func createDefaultConfig() configmodels.Extension {
+ return &Config{
+ ExtensionSettings: configmodels.ExtensionSettings{
+ TypeVal: typeStr,
+ NameVal: string(typeStr),
+ },
+ Ingress: confighttp.HTTPServerSettings{
+ Endpoint: defaultEndpoint,
+ },
+ Egress: confighttp.HTTPClientSettings{
+ Timeout: 10 * time.Second,
+ },
+ }
+}
+
+func createExtension(
+ _ context.Context,
+ _ component.ExtensionCreateParams,
+ _ configmodels.Extension,
+) (component.ServiceExtension, error) {
+ // TODO: Return httpForwarder
+ return nil, nil
+}

extension/httpforwarder/factory_test.go

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+// 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: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 httpforwarder
+
+import (
+ "testing"
+ "time"
+
+ "github.com/stretchr/testify/require"
+ "go.opentelemetry.io/collector/config/configmodels"
+)
+
+func TestFactory(t *testing.T) {
+ f := NewFactory()
+ expectType := "http_forwarder"
+ require.Equal(t, configmodels.Type(expectType), f.Type())
+
+ cfg := f.CreateDefaultConfig().(*Config)
+ require.Equal(t, expectType, cfg.Name())
+ require.Equal(t, configmodels.Type(expectType), cfg.Type())
+ require.Equal(t, ":6060", cfg.Ingress.Endpoint)
+ require.Equal(t, 10*time.Second, cfg.Egress.Timeout)
+}

extension/httpforwarder/go.mod

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+module github.com/open-telemetry/opentelemetry-collector-contrib/extension/httpforwarder
+
+go 1.14
+
+require (
+ github.com/stretchr/testify v1.6.1
+ go.opentelemetry.io/collector v0.9.1-0.20200903224024-3eb3b664a832
+ go.uber.org/zap v1.15.0
+)