Updates handling of scale/replicas parameter in CLI and compose file

newsfragments/267.bugfix

@@ -0,0 +1 @@
+- Fixed the --scale flag as described in issue #267 [Podman not supporting --scale flag]

podman_compose.py

@@ -2107,7 +2107,23 @@ def _parse_compose_file(self):
         container_names_by_service = {}
         self.services = services
         for service_name, service_desc in services.items():
-            replicas = try_int(service_desc.get("deploy", {}).get("replicas"), fallback=1)
+            replicas = 1
+            if "scale" in args and args.scale is not None:
+                # Check `--scale` args from CLI command
+                scale_args = args.scale.split('=')
+                if service_name == scale_args[0]:
+                    replicas = try_int(scale_args[1], fallback=1)
+            elif "scale" in service_desc:
+                # Check `scale` value from compose yaml file
+                replicas = try_int(service_desc.get("scale"), fallback=1)
+            elif (
+                "deploy" in service_desc
+                and "replicas" in service_desc.get("deploy", {})
+                and "replicated" == service_desc.get("deploy", {}).get("mode", '')
+            ):
+                # Check `deploy: replicas:` value from compose yaml file
+                # Note: All conditions are necessary to handle case
+                replicas = try_int(service_desc.get("deploy", {}).get("replicas"), fallback=1)
 
             container_names_by_service[service_name] = []
             for num in range(1, replicas + 1):
@@ -3423,12 +3439,13 @@ def compose_up_parse(parser):
         action="store_true",
         help="Remove containers for services not defined in the Compose file.",
     )
+    # `--scale` argument needs to store as single value and not append,
+    # as multiple scale values could be confusing.
     parser.add_argument(
         "--scale",
         metavar="SERVICE=NUM",
-        action="append",
-        help="Scale SERVICE to NUM instances. Overrides the `scale` setting in the Compose file if "
-        "present.",
+        help="Scale SERVICE to NUM instances. "
+        "Overrides the `scale` setting in the Compose file if present.",
     )
     parser.add_argument(
         "--exit-code-from",

tests/integration/service_scale/scaleup_cli/docker-compose.yml

@@ -0,0 +1,6 @@
+name: podman-compose
+
+services:
+  service1:
+    image: docker.io/library/busybox:latest
+    tty: true

tests/integration/service_scale/scaleup_deploy_replicas_parameter/docker-compose.yml

@@ -0,0 +1,9 @@
+name: podman-compose
+
+services:
+  service1:
+    image: docker.io/library/busybox:latest
+    tty: true
+    deploy:
+      mode: replicated
+      replicas: 2

tests/integration/service_scale/scaleup_scale_parameter/docker-compose.yml

@@ -0,0 +1,7 @@
+name: podman-compose
+
+services:
+  service1:
+    image: docker.io/library/busybox:latest
+    tty: true
+    scale: 2

tests/integration/service_scale/test_podman_compose_scale.py

@@ -0,0 +1,111 @@
+# SPDX-License-Identifier: GPL-2.0
+
+import os
+import unittest
+
+from tests.integration.test_utils import RunSubprocessMixin
+from tests.integration.test_utils import podman_compose_path
+from tests.integration.test_utils import test_path
+
+
+def compose_yaml_path(test_ref_folder):
+    return os.path.join(test_path(), "service_scale", test_ref_folder, "docker-compose.yml")
+
+
+class TestComposeScale(unittest.TestCase, RunSubprocessMixin):
+    # scale-up using `scale` prarmeter in docker-compose.yml
+    def test_scaleup_scale_parameter(self):
+        try:
+            output, _, return_code = self.run_subprocess([
+                podman_compose_path(),
+                "-f",
+                compose_yaml_path("scaleup_scale_parameter"),
+                "up",
+                "-d",
+            ])
+            self.assertEqual(return_code, 0)
+            output, _, return_code = self.run_subprocess([
+                podman_compose_path(),
+                "-f",
+                compose_yaml_path("scaleup_scale_parameter"),
+                "ps",
+                "-q",
+            ])
+            self.assertEqual(len(output.splitlines()), 2)
+        finally:
+            self.run_subprocess_assert_returncode([
+                podman_compose_path(),
+                "-f",
+                compose_yaml_path("scaleup_scale_parameter"),
+                "down",
+                "-t",
+                "0",
+            ])
+
+    # scale-up using `deploy => replicas` prarmeter in docker-compose.yml
+    def test_scaleup_deploy_replicas_parameter(self):
+        try:
+            output, _, return_code = self.run_subprocess([
+                podman_compose_path(),
+                "-f",
+                compose_yaml_path('scaleup_deploy_replicas_parameter'),
+                "up",
+                "-d",
+            ])
+            self.assertEqual(return_code, 0)
+            output, _, return_code = self.run_subprocess([
+                podman_compose_path(),
+                "-f",
+                compose_yaml_path("scaleup_scale_parameter"),
+                "ps",
+                "-q",
+            ])
+            self.assertEqual(len(output.splitlines()), 2)
+        finally:
+            self.run_subprocess_assert_returncode([
+                podman_compose_path(),
+                "-f",
+                compose_yaml_path('scaleup_deploy_replicas_parameter'),
+                "down",
+                "-t",
+                "0",
+            ])
+
+    # scale-up using `--scale <SERVICE>=<number of replicas>` argument in CLI
+    def test_scaleup_cli(self):
+        try:
+            output, _, return_code = self.run_subprocess([
+                podman_compose_path(),
+                "-f",
+                compose_yaml_path('scaleup_cli'),
+                "up",
+                "-d",
+            ])
+            self.assertEqual(return_code, 0)
+            output, _, return_code = self.run_subprocess([
+                podman_compose_path(),
+                "-f",
+                compose_yaml_path('scaleup_cli'),
+                "up",
+                "-d",
+                "--scale",
+                "service1=2",
+            ])
+            self.assertEqual(return_code, 0)
+            output, _, return_code = self.run_subprocess([
+                podman_compose_path(),
+                "-f",
+                compose_yaml_path("scaleup_scale_parameter"),
+                "ps",
+                "-q",
+            ])
+            self.assertEqual(len(output.splitlines()), 2)
+        finally:
+            self.run_subprocess_assert_returncode([
+                podman_compose_path(),
+                "-f",
+                compose_yaml_path('scaleup_cli'),
+                "down",
+                "-t",
+                "0",
+            ])