add feature to validate the platform in the lockfile against the syst…

…em platform

conda_lock/conda_lock.py

@@ -51,6 +51,9 @@
 # Captures the domain in the second group.
 DOMAIN_PATTERN = re.compile(r"^(https?:\/\/)?([^\/]+)(.*)")
 
+# Captures the platform in the first group.
+PLATFORM_PATTERN = re.compile(r"^# platform: (.*)$")
+
 if not (sys.version_info.major >= 3 and sys.version_info.minor >= 6):
     print("conda_lock needs to run under python >=3.6")
     sys.exit(1)
@@ -59,6 +62,38 @@
 CONDA_PKGS_DIRS = None
 DEFAULT_PLATFORMS = ["osx-64", "linux-64", "win-64"]
 
+_PLATFORM_MAP = {"osx-64": "darwin", "linux-64": "linux", "win-64": "win"}
+
+
+def _extract_platform(line):
+    search = PLATFORM_PATTERN.search(line)
+    if search:
+        return search.group(1)
+
+
+def extract_platform(lockfile: str) -> str:
+    for line in lockfile.strip().split("\n"):
+        platform = _extract_platform(line)
+        if platform:
+            return platform
+    raise RuntimeError("Cannot find platform in lockfile.")
+
+
+def _do_validate_platform(platform: str) -> Tuple[bool, str]:
+    return sys.platform.startswith(_PLATFORM_MAP[platform]), sys.platform
+
+
+def do_validate_platform(lockfile: str):
+    platform_lockfile = extract_platform(lockfile)
+    try:
+        success, platform_sys = _do_validate_platform(platform_lockfile)
+    except KeyError:
+        raise RuntimeError(f"Unknown platform type in lockfile '{platform_lockfile}'.")
+    if not success:
+        raise RuntimeError(
+            f"Platform in lockfile '{platform_lockfile}' is not compatible with system platform '{platform_sys}'."
+        )
+
 
 def conda_pkgs_dir():
     global CONDA_PKGS_DIRS
@@ -734,12 +769,36 @@ def lock(
     default="",
 )
 @click.option("--auth-file", help="Path to the authentication file.", default="")
+@click.option(
+    "--validate-platform",
+    is_flag=True,
+    default=True,
+    help="Whether the platform compatibility between your lockfile and the host system should be validated.",
+)
 @click.argument("lock-file")
-def install(conda, mamba, micromamba, prefix, name, lock_file, auth, auth_file):
+def install(
+    conda,
+    mamba,
+    micromamba,
+    prefix,
+    name,
+    lock_file,
+    auth,
+    auth_file,
+    validate_platform,
+):
     """Perform a conda install"""
     auth = json.loads(auth) if auth else read_json(auth_file) if auth_file else None
     _conda_exe = determine_conda_executable(conda, mamba=mamba, micromamba=micromamba)
     install_func = partial(do_conda_install, conda=_conda_exe, prefix=prefix, name=name)
+    if validate_platform:
+        lockfile = read_file(lock_file)
+        try:
+            do_validate_platform(lockfile)
+        except RuntimeError as error:
+            raise RuntimeError(
+                error.args[0] + " Disable validation with `--validate-platform=False`."
+            )
     if auth:
         lockfile = read_file(lock_file)
         with _add_auth(lockfile, auth) as lockfile_with_auth: