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config_server.go
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config_server.go
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// Copyright Splunk, Inc.
// 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 configconverter
import (
"context"
"errors"
"fmt"
"log"
"net"
"net/http"
"os"
"strings"
"sync"
"sync/atomic"
"syscall"
"time"
"github.com/spf13/cast"
"go.opentelemetry.io/collector/confmap"
"gopkg.in/yaml.v2"
"github.com/signalfx/splunk-otel-collector/internal/confmapprovider/configsource"
)
const (
configServerEnabledEnvVar = "SPLUNK_DEBUG_CONFIG_SERVER"
configServerPortEnvVar = "SPLUNK_DEBUG_CONFIG_SERVER_PORT"
defaultConfigServerPort = "55554"
defaultConfigServerEndpoint = "localhost:" + defaultConfigServerPort
effectivePath = "/debug/configz/effective"
initialPath = "/debug/configz/initial"
)
type ConfigType int
const (
initialConfig ConfigType = 1
effectiveConfig ConfigType = 2
)
var _ confmap.Converter = (*ConfigServer)(nil)
var _ configsource.Hook = (*ConfigServer)(nil)
type ConfigServer struct {
// Use get/set methods instead of direct usage
initial map[string]any
effective map[string]any
server *http.Server
serverCount atomic.Int64
serverShutdown sync.WaitGroup
initialMutex sync.RWMutex
effectiveMutex sync.RWMutex
once sync.Once
}
func NewConfigServer() *ConfigServer {
cs := &ConfigServer{
initial: map[string]any{},
effective: map[string]any{},
initialMutex: sync.RWMutex{},
effectiveMutex: sync.RWMutex{},
serverCount: atomic.Int64{},
serverShutdown: sync.WaitGroup{},
once: sync.Once{},
}
mux := http.NewServeMux()
initialHandleFunc := cs.muxHandleFunc(initialConfig)
mux.HandleFunc(initialPath, initialHandleFunc)
effectiveHandleFunc := cs.muxHandleFunc(effectiveConfig)
mux.HandleFunc(effectivePath, effectiveHandleFunc)
cs.server = &http.Server{
ReadHeaderTimeout: 20 * time.Second,
Handler: mux,
}
return cs
}
// Convert is intended to be called as the final service confmap.Converter,
// which registers the service config before being finally resolved and unmarshalled.
func (cs *ConfigServer) Convert(_ context.Context, conf *confmap.Conf) error {
cs.start()
cs.setEffective(conf.ToStringMap())
return nil
}
func (cs *ConfigServer) OnNew() {
cs.serverCount.Add(1)
}
func (cs *ConfigServer) OnRetrieve(scheme string, retrieved map[string]any) {
cs.initialMutex.Lock()
defer cs.initialMutex.Unlock()
cs.initial[scheme] = retrieved
}
func (cs *ConfigServer) getInitial() map[string]any {
cs.initialMutex.RLock()
defer cs.initialMutex.RUnlock()
return cs.initial
}
func (cs *ConfigServer) setEffective(config map[string]any) {
cs.effectiveMutex.Lock()
defer cs.effectiveMutex.Unlock()
cs.effective = config
}
func (cs *ConfigServer) getEffective() map[string]any {
cs.effectiveMutex.RLock()
defer cs.effectiveMutex.RUnlock()
return cs.effective
}
// start will create and start the singleton http server. It presumes cs.OnNew() has been
// called at least once and will tear down the moment the final cs.OnShutdown() call is made.
func (cs *ConfigServer) start() {
if enabled := os.Getenv(configServerEnabledEnvVar); enabled != "true" {
// The config server needs to be explicitly enabled for the time being.
return
}
cs.once.Do(
func() {
endpoint := defaultConfigServerEndpoint
if portOverride, ok := os.LookupEnv(configServerPortEnvVar); ok {
if portOverride == "" {
// If explicitly set to empty do not start the server.
return
}
endpoint = "localhost:" + portOverride
}
listener, err := net.Listen("tcp", endpoint)
if err != nil {
if errors.Is(err, syscall.EADDRINUSE) {
err = fmt.Errorf("%w: please set %q environment variable to nonconflicting port", err, configServerPortEnvVar)
}
log.Print(fmt.Errorf("error starting config server: %w", err).Error())
return
}
go func() {
httpErr := cs.server.Serve(listener)
defer cs.serverShutdown.Done()
if httpErr != http.ErrServerClosed {
log.Print(fmt.Errorf("config server error: %w", httpErr).Error())
}
}()
cs.serverShutdown.Add(1)
})
}
func (cs *ConfigServer) OnShutdown() {
if cs.serverCount.Add(-1) == 0 {
_ = cs.server.Close()
cs.serverShutdown.Wait()
}
}
func (cs *ConfigServer) muxHandleFunc(configType ConfigType) func(http.ResponseWriter, *http.Request) {
return func(writer http.ResponseWriter, request *http.Request) {
if request.Method != "GET" {
writer.WriteHeader(http.StatusMethodNotAllowed)
return
}
var configYAML []byte
if configType == initialConfig {
configYAML, _ = yaml.Marshal(cs.getInitial())
} else {
configYAML, _ = yaml.Marshal(simpleRedact(cs.getEffective()))
}
_, _ = writer.Write(configYAML)
}
}
func simpleRedact(config map[string]any) map[string]any {
redactedConfig := make(map[string]any)
for k, v := range config {
switch value := v.(type) {
case string:
if shouldRedactKey(k) {
v = "<redacted>"
}
case map[string]any:
v = simpleRedact(value)
case map[any]any:
v = simpleRedact(cast.ToStringMap(value))
}
redactedConfig[k] = v
}
return redactedConfig
}
// shouldRedactKey applies a simple check to see if the contents of the given key
// should be redacted or not.
func shouldRedactKey(k string) bool {
fragments := []string{
"access",
"api_key",
"apikey",
"auth",
"credential",
"creds",
"login",
"password",
"pwd",
"token",
"user",
"X-SF-Token",
}
for _, fragment := range fragments {
if strings.Contains(k, fragment) {
return true
}
}
return false
}