Substitution with service environment

newsfragments/substitution-with-service-environment.feature

@@ -0,0 +1 @@
+Add ability to substitute variables with the environment of the service.

podman_compose.py

@@ -264,6 +264,16 @@ def rec_subs(value, subs_dict):
     do bash-like substitution in value and if list of dictionary do that recursively
     """
     if is_dict(value):
+        if 'environment' in value and is_dict(value['environment']):
+            # Load service's environment variables
+            subs_dict = subs_dict.copy()
+            svc_envs = {k: v for k, v in value['environment'].items() if k not in subs_dict}
+            # we need to add `svc_envs` to the `subs_dict` so that it can evaluate the
+            # service environment that reference to another service environment.
+            subs_dict.update(svc_envs)
+            svc_envs = rec_subs(svc_envs, subs_dict)
+            subs_dict.update(svc_envs)
+
         value = {k: rec_subs(v, subs_dict) for k, v in value.items()}
     elif is_str(value):
 
@@ -1823,6 +1833,11 @@ def _parse_compose_file(self):
             "COMPOSE_FILE": pathsep.join(relative_files),
             "COMPOSE_PATH_SEPARATOR": pathsep,
         })
+
+        if args and 'env' in args and args.env:
+            env_vars = norm_as_dict(args.env)
+            self.environ.update(env_vars)
+
         compose = {}
         # Iterate over files primitively to allow appending to files in-loop
         files_iter = iter(files)

tests/integration/env-tests/container-compose.yml

@@ -1,9 +1,10 @@
-version: '3'
+version: "3"
 
 services:
   env-test:
     image: busybox
     command: sh -c "export | grep ZZ"
     environment:
-    - ZZVAR1=myval1
-
+      ZZVAR1: myval1
+      ZZVAR2: 2-$ZZVAR1
+      ZZVAR3: 3-$ZZVAR2

tests/unit/test_rec_subs.py

@@ -0,0 +1,62 @@
+# SPDX-License-Identifier: GPL-2.0
+# pylint: disable=protected-access
+
+import unittest
+
+from parameterized import parameterized
+
+from podman_compose import rec_subs
+
+
+class TestRecSubs(unittest.TestCase):
+    substitutions = [
+        # dict with environment variables
+        (
+            "service's environment is low priority",
+            {"environment": {"v1": "low priority", "actual-v1": "$v1"}},
+            {"environment": {"v1": "low priority", "actual-v1": "high priority"}},
+        ),
+        (
+            "service's environment can be used in other values",
+            {"environment": {"v100": "v1.0.0", "image": "abc:$v100"}},
+            {"environment": {"v100": "v1.0.0", "image": "abc:v1.0.0"}},
+        ),
+        (
+            "Non-variable should not be substituted",
+            {"environment": {"non_var": "$$v1", "vx": "$non_var"}, "image": "abc:$non_var"},
+            {"environment": {"non_var": "$v1", "vx": "$v1"}, "image": "abc:$v1"},
+        ),
+        # list
+        (
+            "Values in list are substituted",
+            ["$v1", "low priority"],
+            ["high priority", "low priority"],
+        ),
+        # str
+        (
+            "Value with ${VARIABLE} format",
+            "${v1}",
+            "high priority",
+        ),
+        (
+            "Value with ${VARIABLE:-default} format",
+            ["${v1:-default}", "${empty:-default}", "${not_exits:-default}"],
+            ["high priority", "default", "default"],
+        ),
+        (
+            "Value with ${VARIABLE-default} format",
+            ["${v1-default}", "${empty-default}", "${not_exits-default}"],
+            ["high priority", "", "default"],
+        ),
+        (
+            "Value $$ means $",
+            "$$v1",
+            "$v1",
+        ),
+    ]
+
+    @parameterized.expand(substitutions)
+    def test_rec_subs(self, desc, input, expected):
+        sub_dict = {"v1": "high priority", "empty": ""}
+        result = rec_subs(input, sub_dict)
+        self.assertEqual(result, expected, msg=desc)