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fiber.go
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fiber.go
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package epsagonfiber
import (
"encoding/json"
"fmt"
"runtime/debug"
"strconv"
"github.com/gofiber/fiber/v2"
"github.com/queueup-dev/epsagon-go/epsagon"
"github.com/queueup-dev/epsagon-go/protocol"
"github.com/queueup-dev/epsagon-go/tracer"
"github.com/valyala/fasthttp"
)
// FiberEpsagonMiddleware is an epsagon instumentation middleware for fiber apps
type FiberEpsagonMiddleware struct {
Config *epsagon.Config
}
func parseQueryArgs(args *fasthttp.Args) map[string]string {
result := make(map[string]string)
args.VisitAll(func(key, val []byte) {
result[string(key)] = string(val)
})
return result
}
// convert map values to string. On error, add exception to tracer with the
// given error message
func convertMapValuesToString(
values map[string]string,
wrapperTracer tracer.Tracer,
errorMessage string) string {
processed, err := json.Marshal(values)
if err != nil {
wrapperTracer.AddException(&protocol.Exception{
Type: "trigger-creation",
Message: errorMessage,
Traceback: string(debug.Stack()),
Time: tracer.GetTimestamp(),
})
return ""
}
return string(processed)
}
func processQueryFromURI(uriObj *fasthttp.URI, wrapperTracer tracer.Tracer) string {
if uriObj == nil {
return ""
}
args := parseQueryArgs(uriObj.QueryArgs())
return convertMapValuesToString(
args,
wrapperTracer,
fmt.Sprintf("Failed to serialize query params %s", uriObj.QueryString()))
}
func processRequestHeaders(requestHeaders *fasthttp.RequestHeader, wrapperTracer tracer.Tracer) string {
if requestHeaders == nil {
return ""
}
headers := make(map[string]string)
requestHeaders.VisitAll(func(key, val []byte) {
headers[string(key)] = string(val)
})
return convertMapValuesToString(
headers,
wrapperTracer,
fmt.Sprintf("Failed to serialize request headers"))
}
func processResponseHeaders(responseHeaders *fasthttp.ResponseHeader, wrapperTracer tracer.Tracer) string {
if responseHeaders == nil {
return ""
}
headers := make(map[string]string)
responseHeaders.VisitAll(func(key, val []byte) {
headers[string(key)] = string(val)
})
return convertMapValuesToString(
headers,
wrapperTracer,
fmt.Sprintf("Failed to serialize response headers"))
}
// Gets the request content type header, empty string if not found
func getRequestContentType(fiberCtx *fiber.Ctx) string {
return string(fiberCtx.Request().Header.ContentType())
}
// CreateHTTPTriggerEvent creates an HTTP trigger event
func CreateHTTPTriggerEvent(wrapperTracer tracer.Tracer, fiberCtx *fiber.Ctx, resourceName string) *protocol.Event {
request := fiberCtx.Request()
name := resourceName
if len(name) == 0 {
name = fiberCtx.Hostname()
}
event := &protocol.Event{
Id: "",
Origin: "trigger",
StartTime: tracer.GetTimestamp(),
Resource: &protocol.Resource{
Name: name,
Type: "http",
Operation: fiberCtx.Method(),
Metadata: map[string]string{
"path": fiberCtx.Path(),
},
},
}
if !wrapperTracer.GetConfig().MetadataOnly {
event.Resource.Metadata["query_string_params"] = processQueryFromURI(request.URI(), wrapperTracer)
event.Resource.Metadata["request_headers"] = processRequestHeaders(&request.Header, wrapperTracer)
event.Resource.Metadata["request_body"] = string(fiberCtx.Body())
}
return event
}
func fiberHandler(c *fiber.Ctx) (err error) {
err = c.Next()
return err
}
func (middleware *FiberEpsagonMiddleware) HandlerFunc() fiber.Handler {
config := middleware.Config
if config == nil {
config = &epsagon.Config{}
}
return func(c *fiber.Ctx) (err error) {
if epsagon.ShouldIgnoreRequest(getRequestContentType(c), c.Path()) {
return c.Next()
}
callingOriginalHandler := false
called := false
var triggerEvent *protocol.Event = nil
defer func() {
userError := recover()
if userError == nil {
return
}
if !callingOriginalHandler {
err = c.Next()
return
}
if !called { // panic only if error happened in original handler
triggerEvent.Resource.Metadata["status_code"] = "500"
panic(userError)
}
}()
wrapperTracer := tracer.CreateTracer(&config.Config)
wrapperTracer.Start()
defer wrapperTracer.SendStopSignal()
userContext := c.UserContext()
c.SetUserContext(epsagon.ContextWithTracer(wrapperTracer, userContext))
triggerEvent = CreateHTTPTriggerEvent(wrapperTracer, c, c.Hostname())
wrapperTracer.AddEvent(triggerEvent)
wrapper := epsagon.WrapGenericFunction(
func(c *fiber.Ctx) error {
err = c.Next()
return err
}, config, wrapperTracer, false, c.Path())
defer postExecutionUpdates(wrapperTracer, triggerEvent, c, wrapper)
callingOriginalHandler = true
wrapper.Call(c)
called = true
return err
}
}
func postExecutionUpdates(
wrapperTracer tracer.Tracer, triggerEvent *protocol.Event,
c *fiber.Ctx, handlerWrapper *epsagon.GenericWrapper) {
runner := handlerWrapper.GetRunnerEvent()
if runner != nil {
runner.Resource.Type = "fiber"
}
response := c.Response()
triggerEvent.Resource.Metadata["status_code"] = strconv.Itoa(response.StatusCode())
if !wrapperTracer.GetConfig().MetadataOnly {
triggerEvent.Resource.Metadata["response_headers"] = processResponseHeaders(&response.Header, wrapperTracer)
triggerEvent.Resource.Metadata["response_body"] = string(response.Body())
}
}