Changed retry logic on buildah build

- Enable logging of retries as warnings
- Increase number of retries to 5 and switched delay from 1s
  to exponential, capping at 60s

Example:

WARNING...:Finished call to '__main__.foo' after 9.201(s), this was the 6th time calling it.

Change-Id: If13571b9e21251ced9a43fc1cc7f7d69fad06f0a
Tested-By: https://review.rdoproject.org/r/#/c/29917/
(cherry picked from commit a584a5bd4c)

tripleo_common/image/builder/buildah.py

@@ -126,13 +126,16 @@ class BuildahBuilder(base.BaseBuilder):
             if self.push_containers:
                 self.push(self._get_destination(container_name))
         except Exception as e:
-            self.log.exception(e)
+            LOG.exception(e)
             raise
 
-    @tenacity.retry(  # Retry up to 3 times with 1 second delay
+    @tenacity.retry(
+        # Retry up to 5 times: 0, 1, 5, 21, 85
+        # http://exponentialbackoffcalculator.com/
         reraise=True,
-        wait=tenacity.wait_fixed(1),
-        stop=tenacity.stop_after_attempt(3)
+        wait=tenacity.wait_random_exponential(multiplier=4, max=60),
+        stop=tenacity.stop_after_attempt(5),
+        before_sleep=tenacity.after_log(LOG, logging.WARNING)
     )
     def build(self, container_name, container_build_path):
         """Build an image from a given directory.
@@ -157,7 +160,8 @@ class BuildahBuilder(base.BaseBuilder):
                          self._get_destination(container_name),
                          container_build_path])
         args = self.buildah_cmd + bud_args
-        print("Building %s image with: %s" % (container_name, ' '.join(args)))
+        LOG.info("Building %s image with: %s" %
+                 (container_name, ' '.join(args)))
         process.execute(
             *args,
             check_exit_code=True,
@@ -168,7 +172,8 @@ class BuildahBuilder(base.BaseBuilder):
     @tenacity.retry(  # Retry up to 10 times with jittered exponential backoff
         reraise=True,
         wait=tenacity.wait_random_exponential(multiplier=1, max=15),
-        stop=tenacity.stop_after_attempt(10)
+        stop=tenacity.stop_after_attempt(10),
+        before_sleep=tenacity.after_log(LOG, logging.WARNING)
     )
     def push(self, destination):
         """Push an image to a container registry.
@@ -183,7 +188,8 @@ class BuildahBuilder(base.BaseBuilder):
         # else than a Docker registry.
         args = self.buildah_cmd + ['push', '--tls-verify=False', destination,
                                    'docker://' + destination]
-        print("Pushing %s image with: %s" % (destination, ' '.join(args)))
+        LOG.info("Pushing %s image with: %s" %
+                 (destination, ' '.join(args)))
         process.execute(*args, run_as_root=False, use_standard_locale=True)
 
     def build_all(self, deps=None):