Add retry logic to get_changelog function

package_alerts/package_alerts

@@ -82,17 +82,35 @@ def do_execute(cmd, tdir="/tmp", return_output=False, return_error=False):
 
 def get_changelog(token, checksum):
     """get the changelog for a rpm, which requires downloading it"""
-    url = f"https://api.access.redhat.com/management/v1/packages/{checksum}/download"
-    result = call_api(token, url, stream=True)
+    # We don't usually retry stuff from api calls as the script runs
+    # frequently, however - in this case a failure results in a blank
+    # changelog which is not very useful
+    attempts = 0
+    max_attempts = 3
+    rpm_downloaded = False
     temp_file = generate_temp_file("checksum")
-    # TODO: try and do this with dnf 'add_remote_rpms', although we would need to auth
-    with open(temp_file, "wb") as f:
-        try:
-            for chunk in result.iter_content(chunk_size=1024):
-                if chunk:
-                    f.write(chunk)
-        except:
-            f.close()
+    url = f"https://api.access.redhat.com/management/v1/packages/{checksum}/download"
+    while attempts < max_attempts:
+        attempts += 1
+        result = call_api(token, url, stream=True)
+        if result.status_code == 200:
+            # TODO: try and do this with dnf 'add_remote_rpms', although we would need to auth
+            with open(temp_file, "wb") as f:
+                try:
+                    for chunk in result.iter_content(chunk_size=1024):
+                        if chunk:
+                             f.write(chunk)
+                    rpm_downloaded = True
+                except:
+                    print(f"Saving changelog appeared to have failed. Retrying {attempts}/{max_attempts}", flush=True)
+                    f.close()
+            if rpm_downloaded:
+                break
+        else:
+            print(f"API call failed, Retrying {attempts}/{max_attempts}", flush=True)
+    if not rpm_downloaded:
+        print(f"Changelog failed to download, exiting", flush=True)
+        sys.exit(1)
     # TODO: maybe have some better logic instead of the head command
     changelog = do_execute(f"rpm -qp {temp_file} --changelog | head -20", return_output=True)
     # Even though we are running through a container, let's clean up after ourselves