Change deletion signal of ssh keys

django_backend/backend/models.py

@@ -3,7 +3,7 @@ from django.db import models
 from django.conf import settings
 from django.dispatch import receiver, Signal
 from rest_framework.authtoken.models import Token
-from django.db.models.signals import post_save
+from django.db.models.signals import post_save, m2m_changed
 from datetime import datetime
 
 import requests
@@ -186,9 +186,15 @@ class SSHPublicKey(models.Model):
             editable=False,
             )
 
-    # does not directly delete the key, but merely starts the deletion process
-    # the receiver 'delete_old_ssh_key' does the actual deletion afterwards
+    # does not directly delete the key if the key is deployed or withdrawn
+    # somewhere
+    # the receiver 'delete_withdrawn_ssh_key' does the actual deletion
     def delete_key(self):
+        if (not self.deployments.exists()
+                and not self.withdrawn_deployments.exists()):
+            self.delete()
+            return
+
         self.deleted = True
         self.save()
 
@@ -201,11 +207,15 @@ class SSHPublicKey(models.Model):
         return self.name
 
 
-@receiver(post_save, sender=SSHPublicKey)
-def delete_old_ssh_key(
+# finally delete the key if all the deployments are withdrawn
+# and the withdrawal was seen by all clients
+@receiver(m2m_changed, sender=SSHPublicKey)
+def delete_withdrawn_ssh_key(
         sender, instance=None, created=False, **kwargs):
 
-    if instance.deleted and len(instance.deployments.all()) == 0:
+    if (instance.deleted
+            and not instance.deployments.exists()
+            and not instance.withdrawn_deployments.exists()):
         instance.delete()