tbajer-retry-functionality-for-podman

tmt/steps/provision/podman.py

@@ -9,14 +9,16 @@
 import tmt.steps
 import tmt.steps.provision
 import tmt.utils
-from tmt.utils import Command, Path, ShellScript, field
+from tmt.utils import Command, Path, ShellScript, field, retry
 
 # Timeout in seconds of waiting for a connection
 CONNECTION_TIMEOUT = 60
 
 # Defaults
 DEFAULT_IMAGE = "fedora"
 DEFAULT_USER = "root"
+DEFAULT_PULL_ATTEMPTS = 5
+DEFAULT_PULL_INTERVAL = 5
 
 
 @dataclasses.dataclass
@@ -44,6 +46,26 @@ class PodmanGuestData(tmt.steps.provision.GuestData):
         metavar='NAME',
         help='Name or id of an existing container to be used.')
 
+    pull_attempts: Optional[int] = field(
+        default=DEFAULT_PULL_ATTEMPTS,
+        option='--pull-attempts',
+        metavar='ATTEMPT',
+        help=f"""
+             How many times to try pulling the image,
+             {DEFAULT_PULL_ATTEMPTS} attempts by default.
+             """,
+        normalize=tmt.utils.normalize_int)
+
+    pull_interval: Optional[int] = field(
+        default=DEFAULT_PULL_INTERVAL,
+        option='--pull-interval',
+        metavar='SECONDS',
+        help=f"""
+             How long to wait before a new pull attempt,
+             {DEFAULT_PULL_INTERVAL} seconds by default.
+             """,
+        normalize=tmt.utils.normalize_int)
+
 
 @dataclasses.dataclass
 class ProvisionPodmanData(PodmanGuestData, tmt.steps.provision.ProvisionStepData):
@@ -60,6 +82,9 @@ class GuestContainer(tmt.Guest):
     user: str
     force_pull: bool
     parent: tmt.steps.Step
+    pull_attempts: int
+    pull_interval: int
+    logger: tmt.log.Logger
 
     @property
     def is_ready(self) -> bool:
@@ -79,6 +104,15 @@ def wake(self) -> None:
         self.debug(
             f"Waking up container '{self.container}'.", level=2, shift=0)
 
+    def pull_image(self) -> None:
+        """ Pull image if not available or pull forced """
+        assert self.image is not None  # narrow type
+
+        self.podman(
+            Command('pull', '-q', self.image),
+            message=f"Pull image '{self.image}'."
+            )
+
     def start(self) -> None:
         """ Start provisioned guest """
         if self.is_dry_run:
@@ -95,11 +129,15 @@ def start(self) -> None:
         except tmt.utils.RunError:
             needs_pull = True
 
-        # Pull image if not available or pull forced
+        # Retry pulling the image in case of network issues
+        # Temporary solution until configurable in podman itself
         if needs_pull or self.force_pull:
-            self.podman(
-                Command('pull', '-q', self.image),
-                message=f"Pull image '{self.image}'."
+            retry(
+                self.pull_image,
+                self.pull_attempts,
+                self.pull_interval,
+                f"Pulling '{self.image}' image",
+                self._logger
                 )
 
         # Mount the whole plan directory in the container

tmt/utils.py

@@ -1695,6 +1695,13 @@ def __init__(
         self.check_success = check_success
 
 
+class RetryError(GeneralError):
+    """ Retries unsuccessful """
+
+    def __init__(self, label: str, exc: Optional[Exception]) -> None:
+        super().__init__(f"Retries of {label} unsuccessful. {exc}")
+
+
 # Step exceptions
 
 
@@ -6183,3 +6190,33 @@ def __exit__(self, *args: Any) -> None:
     @property
     def duration(self) -> datetime.timedelta:
         return self.end_time - self.start_time
+
+
+def retry(
+        func: Callable[..., T],
+        retries: int,
+        delay: int,
+        label: str,
+        logger: tmt.log.Logger,
+        *args: Optional[Any],
+        **kwargs: Optional[Any]
+        ) -> T:
+    """ Retry functionality to be used elsewhere in the code.
+
+    :param func: function to be called with any amount
+    of arguments of Any type, returning the value of type TypeVar
+    :param retries: number of tries to call the function
+    :param delay: amount of seconds to wait before a new try
+    :param label: action to retry
+    """
+    exc = None
+    for i in range(retries):
+        try:
+            return func(*args, **kwargs)
+        except Exception as e:
+            exc = e
+            logger.debug(
+                'retry',
+                f"{label} failed, {retries - i} retries left, trying again in {delay:.2f} seconds")
+            time.sleep(delay)
+    raise RetryError(label, exc)