fix(tests): prevent race conditions in firecracker_release fixture

There are some new errors[1]:

    FileExistsError: [Errno 17] File exists:
    (from /firecracker/tests/integration_tests/functional/conftest.py)

We removed some locks when simplifying the build. This function was
depending on get_binary to serialize accesses, but it was always
vulnerable to race conditions to begin with.

[1]: https://buildkite.com/firecracker/firecracker-pr/builds/9536#018e65dd-d001-4c41-afc0-6a4ef97d2790/58-586

Fixes: df112e3

Signed-off-by: Pablo Barbáchano <[email protected]>

Author: pb8o

tests/framework/artifacts.py

@@ -14,6 +14,7 @@
 from framework.defs import ARTIFACT_DIR
 from framework.properties import global_props
 from framework.utils import get_firecracker_version_from_toml, run_cmd
+from framework.with_filelock import with_filelock
 from host_tools.cargo_build import get_binary
 
 
@@ -131,6 +132,7 @@ def snapshot_version(self):
         return ".".join(str(x) for x in self.snapshot_version_tuple)
 
 
+@with_filelock
 def current_release(version):
     """Massage this working copy Firecracker binary to look like a normal
     release, so it can run the same tests.
@@ -139,8 +141,9 @@ def current_release(version):
     for binary in ["firecracker", "jailer"]:
         bin_path1 = get_binary(binary)
         bin_path2 = bin_path1.with_name(f"{binary}-v{version}")
-        bin_path2.unlink(missing_ok=True)
-        bin_path2.hardlink_to(bin_path1)
+        if not bin_path2.exists():
+            bin_path2.unlink(missing_ok=True)
+            bin_path2.hardlink_to(bin_path1)
         binaries.append(bin_path2)
     return binaries