/
factory.go
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/
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://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 healthcheckextension
import (
"context"
"errors"
"sync/atomic"
"go.opentelemetry.io/collector/component"
"go.opentelemetry.io/collector/config/configmodels"
"go.opentelemetry.io/collector/extension/extensionhelper"
)
const (
// The value of extension "type" in configuration.
typeStr = "health_check"
)
// NewFactory creates a factory for HealthCheck extension.
func NewFactory() component.ExtensionFactory {
return extensionhelper.NewFactory(
typeStr,
createDefaultConfig,
createExtension)
}
func createDefaultConfig() configmodels.Extension {
return &Config{
ExtensionSettings: configmodels.ExtensionSettings{
TypeVal: typeStr,
NameVal: typeStr,
},
Port: 13133,
}
}
func createExtension(_ context.Context, params component.ExtensionCreateParams, cfg configmodels.Extension) (component.ServiceExtension, error) {
config := cfg.(*Config)
// The runtime settings are global to the application, so while in principle it
// is possible to have more than one instance, running multiple does not bring
// any value to the service.
// In order to avoid this issue we will allow the creation of a single
// instance once per process while keeping the private function that allow
// the creation of multiple instances for unit tests. Summary: only a single
// instance can be created via the factory.
if !atomic.CompareAndSwapInt32(&instanceState, instanceNotCreated, instanceCreated) {
return nil, errors.New("only a single health check extension instance can be created per process")
}
return newServer(*config, params.Logger), nil
}
// See comment in createExtension how these are used.
var instanceState int32
const (
instanceNotCreated int32 = 0
instanceCreated int32 = 1
)