Support for image extraction of environment constants (#2)

* feat: Add get_environment_constants()

* test: Add test for constants

* ci: Update action versions

---------

Co-authored-by: a.b.christie <alan.christie@matildapeak.com>

Author: achristie-im

.github/workflows/build.yaml

@@ -37,9 +37,9 @@ jobs:
         - '3.13'
     steps:
     - name: Checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@v6
       with:
         python-version: ${{ matrix.python-version }}
     - name: Install requirements

.github/workflows/publish.yaml

@@ -31,11 +31,11 @@ jobs:
       id-token: write  # IMPORTANT: this permission is mandatory for trusted publishing
     steps:
     - name: Checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
     - name: Inject slug/short variables
-      uses: rlespinasse/github-slug-action@v4
+      uses: rlespinasse/github-slug-action@v5
     - name: Set up Python
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@v6
       with:
         python-version: '3.12'
     - name: Install dependencies

decoder/decoder.py

@@ -323,6 +323,27 @@ def get_environment_assets(job_definition: Dict[str, Any]) -> List[Dict[str, str
     return env_assets
 
 
+def get_environment_constants(job_definition: Dict[str, Any]) -> List[Dict[str, str]]:
+    """Given a Job definition this function returns the list of all the
+    environment-based image constants declared. What's returned is a list
+    of the environment variable's name and its value.
+    """
+    env_constants: List[Dict[str, str]] = []
+    # Iterate through the environment block...
+    environment: List[Dict[str, Any]] = job_definition.get("image", {}).get(
+        "environment", []
+    )
+    env_constants.extend(
+        {
+            item["name"]: item["value-from"]["constant"]["value"],
+        }
+        for item in environment
+        if "constant" in item["value-from"]
+    )
+
+    return env_constants
+
+
 def get_jobs_replaced(job_definition: Dict[str, Any]) -> Optional[List[str]]:
     """Given a Job Definition this function returns the Jobs it replaces.
     The returned list is a list of jobs identified by collection and

tests/test_get_environment_constants.py

@@ -0,0 +1,29 @@
+# Tests for the decoder's get_environment_assets() function.
+from typing import Dict
+
+import pytest
+
+pytestmark = pytest.mark.unit
+
+from decoder import decoder
+
+
+def test_get_environment_constants():
+    # Arrange
+    job_definition: Dict = {
+        "image": {
+            "environment": [
+                {
+                    "name": "BLOB",
+                    "value-from": {"constant": {"value": "42"}},
+                }
+            ],
+        },
+    }
+
+    # Act
+    env_assets = decoder.get_environment_constants(job_definition)
+
+    # Assert
+    assert len(env_assets) == 1
+    assert env_assets[0]["BLOB"] == "42"