Address cphc service_checker issue in sidecar container

Author: FengPan-Frank

dockers/docker-telemetry-sidecar/Dockerfile.j2

@@ -18,6 +18,7 @@ ENV IS_V1_ENABLED=false
 COPY ["systemd_stub.py", "/usr/bin/"]
 COPY ["systemd_scripts/", "/usr/share/sonic/systemd_scripts/"]
 COPY ["files/container_checker", "/usr/share/sonic/systemd_scripts/container_checker"]
+COPY ["files/service_checker.py", "/usr/share/sonic/systemd_scripts/service_checker.py"]
 COPY ["files/telemetry.sh", "/usr/share/sonic/systemd_scripts/telemetry_v1.sh"]
 COPY ["files/k8s_pod_control.sh", "/usr/share/sonic/scripts/k8s_pod_control.sh"]
 COPY ["supervisord.conf", "/etc/supervisor/conf.d/"]

dockers/docker-telemetry-sidecar/cli-plugin-tests/test_systemd_stub.py

@@ -197,6 +197,11 @@ def fake_read_file_bytes_local(path: str):
     container_fs["/usr/share/sonic/systemd_scripts/container_checker"] = b"default-checker"
     host_fs["/bin/container_checker"] = b"default-checker"
 
+    # Provide a default service_checker.py in both filesystems so the auto-appended
+    # SyncItem from ensure_sync() is always satisfied and is a no-op.
+    container_fs["/usr/share/sonic/systemd_scripts/service_checker.py"] = b"default-service-checker"
+    host_fs["/usr/local/lib/python3.11/dist-packages/health_checker/service_checker.py"] = b"default-service-checker"
+
     return ss, container_fs, host_fs, commands, config_db
 
 
@@ -466,6 +471,10 @@ def test_ensure_sync_uses_202411_checker(ss):
     container_fs["/usr/share/sonic/systemd_scripts/container_checker_202411"] = b"checker-202411"
     host_fs["/bin/container_checker"] = b"old-checker"
 
+    # Also provide 202411 service_checker so it doesn't fail
+    container_fs["/usr/share/sonic/systemd_scripts/service_checker.py_202411"] = b"service-checker-202411"
+    host_fs[ss_mod.HOST_SERVICE_CHECKER] = b"service-checker-202411"
+
     # Clear SYNC_ITEMS to focus only on the container_checker logic
     ss_mod.SYNC_ITEMS[:] = []
 
@@ -507,3 +516,63 @@ def test_ensure_sync_202411_missing_checker_fails(ss):
 
     ok = ss_mod.ensure_sync()
     assert ok is False
+
+
+# ─────────── Tests for branch-conditional service_checker.py in ensure_sync ───────────
+
+def test_ensure_sync_uses_202411_service_checker(ss):
+    """When branch is 202411, ensure_sync uses the branch-specific service_checker.py."""
+    ss_mod, container_fs, host_fs, commands, config_db = ss
+
+    ss_mod._get_branch_name = lambda: "202411"
+
+    # Provide the 202411-specific service_checker in the container and a different one on host
+    container_fs["/usr/share/sonic/systemd_scripts/service_checker.py_202411"] = b"service-checker-202411"
+    host_fs[ss_mod.HOST_SERVICE_CHECKER] = b"old-service-checker"
+
+    # Also provide container_checker so it doesn't fail
+    container_fs["/usr/share/sonic/systemd_scripts/container_checker_202411"] = b"checker-202411"
+    host_fs["/bin/container_checker"] = b"checker-202411"
+
+    ss_mod.SYNC_ITEMS[:] = []
+
+    ok = ss_mod.ensure_sync()
+    assert ok is True
+    assert host_fs[ss_mod.HOST_SERVICE_CHECKER] == b"service-checker-202411"
+
+
+def test_ensure_sync_uses_default_service_checker(ss):
+    """When branch is not 202411, ensure_sync uses the default service_checker.py."""
+    ss_mod, container_fs, host_fs, commands, config_db = ss
+
+    # _get_branch_name already returns "202412" from fixture default
+
+    # Provide the default service_checker in the container and a different one on host
+    container_fs["/usr/share/sonic/systemd_scripts/service_checker.py"] = b"service-checker-default"
+    host_fs[ss_mod.HOST_SERVICE_CHECKER] = b"old-service-checker"
+
+    ss_mod.SYNC_ITEMS[:] = []
+
+    ok = ss_mod.ensure_sync()
+    assert ok is True
+    assert host_fs[ss_mod.HOST_SERVICE_CHECKER] == b"service-checker-default"
+
+
+def test_ensure_sync_202411_missing_service_checker_fails(ss):
+    """When branch is 202411 but the branch-specific service_checker is missing, sync fails."""
+    ss_mod, container_fs, host_fs, commands, config_db = ss
+
+    ss_mod._get_branch_name = lambda: "202411"
+
+    # Provide container_checker so only service_checker causes the failure
+    container_fs["/usr/share/sonic/systemd_scripts/container_checker_202411"] = b"checker-202411"
+    host_fs["/bin/container_checker"] = b"checker-202411"
+
+    # Remove service_checker sources
+    container_fs.pop("/usr/share/sonic/systemd_scripts/service_checker.py_202411", None)
+    container_fs.pop("/usr/share/sonic/systemd_scripts/service_checker.py", None)
+
+    ss_mod.SYNC_ITEMS[:] = []
+
+    ok = ss_mod.ensure_sync()
+    assert ok is False