Manage non topic specific topicctl errors (#32)

* Process errors between topicctl and parser

* Add more details to the error msg

Author: fpacifici

cmd/topicctl/subcmd/apply.go

@@ -7,8 +7,10 @@ import (
 	"os"
 	"os/signal"
 	"path/filepath"
+	"strings"
 	"syscall"
 	"time"
+	"unicode"
 
 	"github.com/segmentio/topicctl/pkg/admin"
 	"github.com/segmentio/topicctl/pkg/apply"
@@ -215,6 +217,16 @@ func applyRun(cmd *cobra.Command, args []string) error {
 }
 
 // prints changes as JSON to stdout
+// sanitizeErrorString replaces all non-printable characters with spaces
+func sanitizeErrorString(s string) string {
+	return strings.Map(func(r rune) rune {
+		if unicode.IsPrint(r) {
+			return r
+		}
+		return ' '
+	}, s)
+}
+
 func printJson(changes apply.NewOrUpdatedChanges) (map[string]interface{}, error) {
 	jsonChanges, err := json.Marshal(changes)
 	if err != nil {
@@ -320,11 +332,16 @@ func applyTopic(
 			// Some topic creation errors also still create the topic
 			log.Error("Error detected while creating or updating a topic")
 			log.Error("The following changes were still made:")
-			partialChanges, printErr := printJson(topicChanges)
-			if printErr != nil {
-				log.Error("Error printing JSON changes data")
+
+			if topicChanges == nil {
+				fmt.Printf("{\"error\": \"%s\"}\n", sanitizeErrorString(err.Error()))
 			} else {
-				log.Errorf("%#v", partialChanges)
+				partialChanges, printErr := printJson(topicChanges)
+				if printErr != nil {
+					log.Error("Error printing JSON changes data")
+				} else {
+					log.Errorf("%#v", partialChanges)
+				}
 			}
 			return err
 		}

py/parse_and_notify.py

@@ -251,7 +251,21 @@ def main():
     )
 
     for line in sys.stdin:
-        topic = json.loads(line)
+        try:
+            topic = json.loads(line)
+        except json.JSONDecodeError as e:
+            title = f"Topicctl failed to apply in region {SENTRY_REGION}"
+            slack_notifier.send(
+                title=title, body=f"Topicctl produced invalid JSON: {e}"
+            )
+            raise
+
+        if "error" in topic:
+            title = f"Topicctl failed to apply in region {SENTRY_REGION}"
+            slack_notifier.send(title=title, body=topic["error"])
+            print(f"Error: {topic['error']}", file=sys.stderr)
+            exit(-1)
+
         action = topic["action"]
         topic_content = (
             NewTopic.build(topic)