Improve integration test retry and backoff

Author: aarongable

test/chisel2.py

@@ -142,16 +142,16 @@ def auth_and_issue(domains, chall_type="dns-01", email=None, cert_output=None, c
     else:
         raise Exception("invalid challenge type %s" % chall_type)
 
-    # Retry up to twice upon badNonce errors
-    for n in range(2):
+    # Make up to three attempts, retrying on badNonce errors
+    for n in range(3):
+        time.sleep(0.2 * n)  # No sleep before the first attempt, then backoff
         try:
             order = client.poll_and_finalize(order)
             if cert_output is not None:
                 with open(cert_output, "w") as f:
                     f.write(order.fullchain_pem)
         except messages.Error as e:
             if e.typ == "urn:ietf:params:acme:error:badNonce":
-                time.sleep(0.01)
                 continue
         else:
             break
@@ -242,15 +242,8 @@ def expect_problem(problem_type, func):
     if len(domains) == 0:
         print(__doc__)
         sys.exit(0)
-    # Retry up to twice upon badNonce errors
-    for n in range(2):
-        try:
-            auth_and_issue(domains)
-        except messages.Error as e:
-            if e.typ == "urn:ietf:params:acme:error:badNonce":
-                time.sleep(0.01)
-                continue
-            print(e)
-            sys.exit(1)
-        else:
-            break
+    try:
+        auth_and_issue(domains)
+    except messages.Error as e:
+        print(e)
+        sys.exit(1)