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Disable config switch #191

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merged 11 commits into from
Sep 22, 2023
Merged

Disable config switch #191

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3fce15c
Config related to disabling the metrics extension and also setting th…
johnbley Sep 22, 2023
900236a
Bit of debug code
johnbley Sep 22, 2023
d4568f3
More debugging code
johnbley Sep 22, 2023
0e779b8
More debug code... why did it not fail the last compile?
johnbley Sep 22, 2023
5f5f0ec
Forced compilation failure - am I building what I think I am building?
johnbley Sep 22, 2023
c5025f4
Was not in fact building the right code... remove compilation failure
johnbley Sep 22, 2023
7120661
Remove some debugging and allow http 202 to proceed
johnbley Sep 22, 2023
443e6c1
nil check
johnbley Sep 22, 2023
31cd529
Add comment and remove debugging code
johnbley Sep 22, 2023
dd4c725
Update cmd/splunk-extension-wrapper/splunk-extension-wrapper.go
johnbley Sep 22, 2023
c5bffd2
Document better way to implement disabled mode with a comment
johnbley Sep 22, 2023
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42 changes: 34 additions & 8 deletions cmd/splunk-extension-wrapper/splunk-extension-wrapper.go
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Original file line number Diff line number Diff line change
Expand Up @@ -33,16 +33,32 @@ import (
// the correct value is set by the go linker (it's done during build using "ldflags")
var gitVersion string

const enabledKey = "SPLUNK_EXTENSION_WRAPPER_ENABLED"
const extensionNameKey = "SPLUNK_EXTENSION_WRAPPER_NAME"

func enabled() bool {
s := strings.ToLower(os.Getenv(enabledKey))
return s != "0" && s != "false"
}

func main() {
enabled := enabled()

configuration := config.New()

initLogging(&configuration)

ossignal.Watch()

m := metrics.New()
// When we are running "disabled", don't actually try to emit metrics.
// A cleaner design for this would use an interface with a stub implementation,
// but 3 or 4 nil checks will do for now, since they're all in one file
var m *metrics.MetricEmitter = nil
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Kind of a nit, especially if this library is going away, but might be nice to instead extract an interface and use a no-op implementation so we don't have to check for nil before calling methods on the variable.

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Yeah, I like that. I'll add a comment to this effect for now.

if enabled {
m = metrics.New()
}

shutdownCondition := registerApiAndStartMainLoop(m, &configuration)
shutdownCondition := registerApiAndStartMainLoop(enabled, m, &configuration)
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Also a nit and just a personal style preference (it's also in Clean Code!): instead of passing in a boolean flag then modifying the behavior of the function based on its value, consider creating two separate functions.


if shutdownCondition.IsError() {
log.SetOutput(os.Stderr)
Expand All @@ -51,10 +67,12 @@ func main() {
log.Println("shutdown reason:", shutdownCondition.Reason())
log.Println("shutdown message:", shutdownCondition.Message())

m.Shutdown(shutdownCondition)
if m != nil {
m.Shutdown(shutdownCondition)
}
}

func registerApiAndStartMainLoop(m *metrics.MetricEmitter, configuration *config.Configuration) (sc shutdown.Condition) {
func registerApiAndStartMainLoop(enabled bool, m *metrics.MetricEmitter, configuration *config.Configuration) (sc shutdown.Condition) {
var api *extensionapi.RegisteredApi

defer func() {
Expand All @@ -67,7 +85,7 @@ func registerApiAndStartMainLoop(m *metrics.MetricEmitter, configuration *config
}
}()

api, sc = extensionapi.Register(extensionName(), configuration)
api, sc = extensionapi.Register(enabled, extensionName(), configuration)

if sc == nil {
sc = mainLoop(api, m, configuration)
Expand All @@ -81,13 +99,17 @@ func registerApiAndStartMainLoop(m *metrics.MetricEmitter, configuration *config
}

func mainLoop(api *extensionapi.RegisteredApi, m *metrics.MetricEmitter, configuration *config.Configuration) (sc shutdown.Condition) {
m.SetFunction(api.FunctionName, api.FunctionVersion)
if m != nil {
m.SetFunction(api.FunctionName, api.FunctionVersion)
}

var event *extensionapi.Event
event, sc = api.NextEvent()

for sc == nil {
sc = m.Invoked(event.InvokedFunctionArn, configuration.SplunkFailFast)
if m != nil {
sc = m.Invoked(event.InvokedFunctionArn, configuration.SplunkFailFast)
}
if sc == nil {
event, sc = api.NextEvent()
}
Expand Down Expand Up @@ -121,5 +143,9 @@ func initLogging(configuration *config.Configuration) {
}

func extensionName() string {
return path.Base(os.Args[0])
name := os.Getenv(extensionNameKey)
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Nit: another way to write this function using Go idioms:

	if name := os.Getenv(extensionNameKey); name != "" {
		return name
	}
	return path.Base(os.Args[0])

if name == "" {
name = path.Base(os.Args[0])
}
return name
}
12 changes: 9 additions & 3 deletions internal/extensionapi/extensionapi.go
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Original file line number Diff line number Diff line change
Expand Up @@ -53,11 +53,17 @@ type RegisteredApi struct {
registerResponse
}

func Register(name string, configuration *config.Configuration) (*RegisteredApi, shutdown.Condition) {
log.Println("Registering...")
func Register(enabled bool, name string, configuration *config.Configuration) (*RegisteredApi, shutdown.Condition) {
log.Println("Registering... " + name)
// extensions have to at least call Register and Next; they can't actually be "disabled"
// so if we are not enabled, at least subscribe to SHUTDOWN
events := []string{ shutdownType }
if enabled {
events = []string{ invokeType, shutdownType }
}

rb, err := json.Marshal(map[string][]string{
"events": {invokeType, shutdownType}})
"events": events})

if err != nil {
return nil, shutdown.Api(fmt.Sprintf("can't marshall body: %v", err))
Expand Down