Correctly handle component versions which are tags

Tags show up as heads in the remote, but without the remote name as
prefix. Previously the code would then try to checkout a branch with the
name of the tag.

This commit makes the assumption that any heads in a remote which don't
have the remote name as a prefix are tags, and handles checkout
accordingly.

To keep the things simple, tags are checked out in detached HEAD state.

Author: simu

CHANGELOG.md

@@ -22,6 +22,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Fixed
 
 * Values in `parameters.components` always have precedence over values in `parameters.component_versions` ([#289])
+* Correctly handle tags as component versions ([#290])
 
 ## [v0.4.2] - 2021-01-14
 
@@ -339,3 +340,4 @@ Initial implementation
 [#286]: https://github.com/projectsyn/commodore/pull/286
 [#287]: https://github.com/projectsyn/commodore/pull/287
 [#289]: https://github.com/projectsyn/commodore/pull/289
+[#290]: https://github.com/projectsyn/commodore/pull/290

commodore/component/__init__.py

@@ -114,7 +114,7 @@ def parameters_key(self):
         return component_parameters_key(self.name)
 
     def checkout(self):
-        remote_heads = self._repo.remote().fetch(prune=True)
+        remote_heads = self._repo.remote().fetch(prune=True, tags=True)
         remote_prefix = self._repo.remote().name + "/"
         version = self._version
         if self._version is None:
@@ -127,17 +127,23 @@ def checkout(self):
 
             version = version.replace(remote_prefix, "", 1)
         for head in remote_heads:
-            branch = head.name
-            if branch.startswith(remote_prefix):
-                branch = branch.replace(remote_prefix, "", 1)
-            if branch == version:
+            tag = None
+            branch = None
+            headname = head.name
+            if headname.startswith(remote_prefix):
+                branch = headname.replace(remote_prefix, "", 1)
+            else:
+                tag = headname
+
+            if headname == version:
                 commit = head.commit
                 break
         else:
-            # If we haven't found a branch matching the requested version,
+            # If we haven't found a branch or tag matching the requested version,
             # assume the version is a commit sha.
             commit = version
             branch = None
+            tag = None
 
         try:
             if branch:
@@ -152,6 +158,9 @@ def checkout(self):
 
                 head.set_tracking_branch(self.repo.remote().refs[branch])
                 self._repo.head.reference = head
+            elif tag:
+                # Simply create detached head pointing to tag
+                self._repo.head.reference = tag
             else:
                 # Create detached head by setting repo.head.reference as
                 # direct ref to commit object.

tests/test_component.py

@@ -37,11 +37,12 @@ def _setup_component(
     tmp_path: P,
     version="master",
     repo_url=REPO_URL,
+    name="argocd",
 ):
     return Component(
-        "argocd",
+        name,
         repo_url=repo_url,
-        directory=tmp_path / "argocd",
+        directory=tmp_path / name,
         version=version,
     )
 
@@ -128,6 +129,20 @@ def test_component_checkout_sha1version(tmp_path: P):
     assert c.repo.head.commit.hexsha == commit
 
 
+def test_component_checkout_tag(tmp_path: P):
+    c = _setup_component(
+        tmp_path,
+        version="v1.0.0",
+        repo_url="https://github.com/projectsyn/component-backup-k8up.git",
+        name="backup-k8up",
+    )
+
+    c.checkout()
+
+    assert c.repo.head.is_detached
+    assert c.repo.head.commit.hexsha == c.repo.tags["v1.0.0"].commit.hexsha
+
+
 def test_component_checkout_nonexisting_version(tmp_path: P):
     c = _setup_component(tmp_path, version="does-not-exist")