Add CaptureCommandOutputOnError

to include stdout & stderror in failed executions,
with docs.

Author: Greg Dubicki

docs/Hook-Definition.md

@@ -9,6 +9,7 @@ Hooks are defined as JSON objects. Please note that in order to be considered va
  * `response-message` - specifies the string that will be returned to the hook initiator
  * `response-headers` - specifies the list of headers in format `{"name": "X-Example-Header", "value": "it works"}` that will be returned in HTTP response for the hook
  * `include-command-output-in-response` - boolean whether webhook should wait for the command to finish and return the raw output as a response to the hook initiator. If the command fails to execute or encounters any errors while executing the response will result in 500 Internal Server Error HTTP status code, otherwise the 200 OK status code will be returned.
+ * `include-command-output-in-response-on-error` - boolean whether webhook should include command stdout & stderror as a response in failed executions. It only works if `include-command-output-in-response` is set to `true`.
  * `parse-parameters-as-json` - specifies the list of arguments that contain JSON strings. These parameters will be decoded by webhook and you can access them like regular objects in rules and `pass-arguments-to-command`.
  * `pass-arguments-to-command` - specifies the list of arguments that will be passed to the command. Check [Referencing request values page](Referencing-Request-Values) to see how to reference the values from the request. If you want to pass a static string value to your command you can specify it as
 `{ "source": "string", "name": "argumentvalue" }`

hook/hook.go

@@ -384,6 +384,7 @@ type Hook struct {
 	ResponseMessage                     string          `json:"response-message,omitempty"`
 	ResponseHeaders                     ResponseHeaders `json:"response-headers,omitempty"`
 	CaptureCommandOutput                bool            `json:"include-command-output-in-response,omitempty"`
+	CaptureCommandOutputOnError         bool            `json:"include-command-output-in-response-on-error,omitempty"`
 	PassEnvironmentToCommand            []Argument      `json:"pass-environment-to-command,omitempty"`
 	PassArgumentsToCommand              []Argument      `json:"pass-arguments-to-command,omitempty"`
 	PassFileToCommand                   []Argument      `json:"pass-file-to-command,omitempty"`

webhook.go

@@ -282,9 +282,13 @@ func hookHandler(w http.ResponseWriter, r *http.Request) {
 				response, err := handleHook(matchedHook, rid, &headers, &query, &payload, &body)
 
 				if err != nil {
-					w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 					w.WriteHeader(http.StatusInternalServerError)
-					fmt.Fprintf(w, "Error occurred while executing the hook's command. Please check your logs for more details.")
+					if matchedHook.CaptureCommandOutputOnError {
+						fmt.Fprintf(w, response)
+					} else {
+						w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+						fmt.Fprintf(w, "Error occurred while executing the hook's command. Please check your logs for more details.")
+					}
 				} else {
 					fmt.Fprintf(w, response)
 				}