Make networking/http test more resilient (bugfix)

providers/base/bin/networking_http.py

@@ -0,0 +1,84 @@
+#!/usr/bin/env python3
+#
+# This file is part of Checkbox.
+#
+# Copyright 2024 Canonical Ltd.
+# Written by:
+#   Pierre Equoy <[email protected]>
+#
+# Checkbox is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 3,
+# as published by the Free Software Foundation.
+#
+# Checkbox is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Checkbox.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import argparse
+import random
+import subprocess
+import sys
+import time
+
+
+def http_connect(
+    url, max_attempts: int = 5, initial_delay=1, backoff_factor=2, max_delay=60
+):
+    """
+    Use `wget` to try to connect to `url`. If attempt fails, the next one is
+    made after adding a random delay calculated using a backoff and a jitter
+    (with a maximum delay of 60 seconds).
+    """
+    for attempt in range(1, max_attempts + 1):
+        print(
+            "Trying to connect to {} (attempt {}/{})".format(
+                url, attempt, max_attempts
+            )
+        )
+        try:
+            subprocess.run(
+                [
+                    "wget",
+                    "-SO",
+                    "/dev/null",
+                    url,
+                ],
+                check=True,
+            )
+            return
+        except subprocess.CalledProcessError as exc:
+            print("Attempt {} failed: {}".format(attempt, exc))
+            print()
+            delay = min(initial_delay * (backoff_factor**attempt), max_delay)
+            jitter = random.uniform(
+                0, delay * 0.5
+            )  # Jitter: up to 50% of the delay
+            final_delay = delay + jitter
+            print(
+                "Waiting for {:.2f} seconds before retrying...".format(
+                    final_delay
+                )
+            )
+            time.sleep(final_delay)
+    raise SystemExit("Failed to connect to {}!".format(url))
+
+
+def main(args):
+    parser = argparse.ArgumentParser()
+    parser.add_argument("url", help="URL to try to connect to")
+    parser.add_argument(
+        "--attempts",
+        default="5",
+        help="Number of connection attempts (default %(default)s)",
+    )
+    args = parser.parse_args(args)
+    http_connect(args.url, int(args.attempts))
+
+
+if __name__ == "__main__":
+    sys.exit(main(sys.argv[1:]))

providers/base/tests/test_networking_http.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+#
+# This file is part of Checkbox.
+#
+# Copyright 2024 Canonical Ltd.
+# Written by:
+#   Pierre Equoy <[email protected]>
+#
+# Checkbox is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 3,
+# as published by the Free Software Foundation.
+#
+# Checkbox is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Checkbox.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import subprocess
+from unittest import TestCase
+from unittest.mock import patch
+
+import networking_http
+
+
+class NetworkingHTTPTests(TestCase):
+    @patch("networking_http.subprocess.run")
+    @patch("networking_http.time.sleep")
+    def test_http_connect_max_retries(self, mock_sleep, mock_run):
+        with self.assertRaises(SystemExit):
+            networking_http.http_connect("test", 0)
+
+    @patch("networking_http.subprocess.run")
+    @patch("networking_http.time.sleep")
+    def test_http_connect_success(self, mock_sleep, mock_run):
+        """
+        Test that `http_connect` returns safely if the wget command returns 0
+        """
+        self.assertEqual(networking_http.http_connect("test", 3), None)
+
+    @patch("networking_http.subprocess.run")
+    @patch("networking_http.time.sleep")
+    def test_http_connect_failure(self, mock_sleep, mock_run):
+        """
+        Test that if set to 3 retries, the connection command (wget, run
+        through subprocess.run) will be called 3 times
+        """
+        mock_run.side_effect = subprocess.CalledProcessError(1, "")
+        with self.assertRaises(SystemExit):
+            networking_http.http_connect("test", 3)
+        self.assertEqual(mock_run.call_count, 3)
+
+    @patch("networking_http.http_connect")
+    def test_main(self, mock_http_connect):
+        args = ["test", "--attempts", "6"]
+        networking_http.main(args)
+        mock_http_connect.assert_called_with("test", 6)

providers/base/units/networking/jobs.pxu

@@ -59,7 +59,8 @@ user: root
 plugin: shell
 category_id: com.canonical.plainbox::networking
 id: networking/http
-command: wget -SO /dev/null http://"$TRANSFER_SERVER"
+environ: TRANSFER_SERVER
+command: networking_http.py http://"$TRANSFER_SERVER"
 _description:
  Automated test case to make sure that it's possible to download files through HTTP
 
@@ -99,4 +100,4 @@ requires:
   model_assertion.gadget != "pi"
   {%- else %}
   lsb.release >= '18'
-  {% endif -%}
+  {% endif -%}