feat: Deliver the deployed API version to an HTTP response header (#59)

* feat: Deliver the deployed API version to an HTTP response header

* Fix tests

* Improve typing

* Fix tests again ✨

* Fix HTTP header name

* Improve tests

* Apply the linter's take on my code

* Refactor reading the package version into the HTTP header

* Fix an unrelated test

* Revert "Fix an unrelated test"

This reverts commit 7dbd9a5.

* Improve function name

* Update src/common/core/utils.py

Co-authored-by: Kim Gustyr <[email protected]>

* Update src/common/core/utils.py

Co-authored-by: Kim Gustyr <[email protected]>

---------

Co-authored-by: Kim Gustyr <[email protected]>

Author: emyller

src/common/core/middleware.py

@@ -0,0 +1,22 @@
+from typing import Callable
+
+from django.http import HttpRequest, HttpResponse
+
+from common.core.utils import get_version
+
+
+class APIResponseVersionHeaderMiddleware:
+    """
+    Middleware to add the API version to the response headers
+    """
+
+    def __init__(
+        self,
+        get_response: Callable[[HttpRequest], HttpResponse],
+    ) -> None:
+        self.get_response = get_response
+
+    def __call__(self, request: HttpRequest) -> HttpResponse:
+        response = self.get_response(request)
+        response.headers["Flagsmith-Version"] = get_version()
+        return response

src/common/core/utils.py

@@ -17,14 +17,22 @@ class SelfHostedData(TypedDict):
     has_logins: bool
 
 
+VersionManifest = TypedDict(
+    "VersionManifest",
+    {
+        ".": str,  # This key is used to store the version of the package itself
+    },
+)
+
+
 class VersionInfo(TypedDict):
     ci_commit_sha: str
     image_tag: str
     has_email_provider: bool
     is_enterprise: bool
     is_saas: bool
     self_hosted_data: SelfHostedData | None
-    package_versions: NotRequired[dict[str, str]]
+    package_versions: NotRequired[VersionManifest]
 
 
 @lru_cache()
@@ -55,7 +63,7 @@ def has_email_provider() -> bool:
 
 
 def get_version_info() -> VersionInfo:
-    """Reads the version info baked into src folder of the docker container"""
+    """Returns the version information for the current deployment"""
     _is_saas = is_saas()
     version_json: VersionInfo = {
         "ci_commit_sha": get_file_contents("./CI_COMMIT_SHA") or UNKNOWN,
@@ -66,12 +74,9 @@ def get_version_info() -> VersionInfo:
         "self_hosted_data": None,
     }
 
-    manifest_versions_content = get_file_contents(VERSIONS_INFO_FILE_LOCATION)
-
-    if manifest_versions_content:
-        manifest_versions = json.loads(manifest_versions_content)
-        version_json["package_versions"] = manifest_versions
-        version_json["image_tag"] = manifest_versions["."]
+    manifest_versions = get_versions_from_manifest()
+    version_json["package_versions"] = manifest_versions
+    version_json["image_tag"] = manifest_versions["."]
 
     if not _is_saas:
         user_objects: Manager[AbstractBaseUser] = getattr(get_user_model(), "objects")
@@ -84,6 +89,23 @@ def get_version_info() -> VersionInfo:
     return version_json
 
 
+def get_version() -> str:
+    """Return the version number of the current deployment"""
+    manifest_versions = get_versions_from_manifest()
+    return manifest_versions.get(".", UNKNOWN)
+
+
+@lru_cache()
+def get_versions_from_manifest() -> VersionManifest:
+    """Read the version info from the manifest file"""
+    raw_content = get_file_contents(VERSIONS_INFO_FILE_LOCATION)
+    if not raw_content:
+        return {".": UNKNOWN}
+
+    manifest: VersionManifest = json.loads(raw_content)
+    return manifest
+
+
 @lru_cache()
 def get_file_contents(file_path: str) -> str | None:
     """Attempts to read a file from the filesystem and return the contents"""

tests/unit/common/core/test_middleware.py

@@ -0,0 +1,27 @@
+from pytest_mock import MockerFixture
+
+from common.core import middleware as middleware_module
+
+
+def test_APIResponseVersionHeaderMiddleware__adds_version_header(
+    mocker: MockerFixture,
+) -> None:
+    # Given
+    request = mocker.Mock()
+    response = mocker.Mock(headers={})
+    get_response = mocker.Mock(return_value=response)
+    middleware = middleware_module.APIResponseVersionHeaderMiddleware(get_response)
+    get_version = mocker.patch.object(
+        middleware_module,
+        "get_version",
+        return_value="v1.2.3",
+    )
+
+    # When
+    result = middleware(request)
+
+    # Then
+    assert result == response
+    assert response.headers["Flagsmith-Version"] == "v1.2.3"
+    get_response.assert_called_once_with(request)
+    get_version.assert_called_once_with()

tests/unit/common/core/test_utils.py

@@ -7,7 +7,9 @@
 
 from common.core.utils import (
     get_file_contents,
+    get_version,
     get_version_info,
+    get_versions_from_manifest,
     has_email_provider,
     is_enterprise,
     is_oss,
@@ -21,6 +23,7 @@
 def clear_lru_caches() -> Generator[None, None, None]:
     yield
     get_file_contents.cache_clear()
+    get_versions_from_manifest.cache_clear()
     has_email_provider.cache_clear()
     is_enterprise.cache_clear()
     is_saas.cache_clear()
@@ -89,6 +92,7 @@ def test_get_version_info_with_missing_files(fs: FakeFilesystem) -> None:
         "has_email_provider": False,
         "is_enterprise": True,
         "is_saas": False,
+        "package_versions": {".": "unknown"},
         "self_hosted_data": {
             "has_logins": False,
             "has_users": False,
@@ -145,3 +149,37 @@ def test_get_version_info__email_config_disabled__return_expected(
 
     # Then
     assert result["has_email_provider"] is False
+
+
+def test_get_version__valid_file_contents__returns_version_number(
+    fs: FakeFilesystem,
+) -> None:
+    # Given
+    fs.create_file("./.versions.json", contents='{".": "v1.2.3"}')
+
+    # When
+    result = get_version()
+
+    # Then
+    assert result == "v1.2.3"
+
+
+@pytest.mark.parametrize(
+    "manifest_contents",
+    [
+        '{"foo": "bar"}',
+        "",
+    ],
+)
+def test_get_version__invalid_file_contents__returns_unknown(
+    fs: FakeFilesystem,
+    manifest_contents: str,
+) -> None:
+    # Given
+    fs.create_file("./.versions.json", contents=manifest_contents)
+
+    # When
+    result = get_version()
+
+    # Then
+    assert result == "unknown"