Provide metadata to easily protect environments

CONSTRUCT.md

@@ -658,6 +658,22 @@ Allowed strings / keys: `hash`, `info.json`, `licenses`, `lockfile`, `pkgs_list`
 Use the standalone binary to perform the uninstallation on Windows.
 Requires conda-standalone 24.11.0 or newer.
 
+### `freeze_base`
+
+Protects the conda base environment against modifications by supported package managers.
+
+Supported package managers:
+    - `conda`: Protects against conda modifications
+
+For `conda`, the dictionary is written into the `frozen` marker file.
+See CEP-22 for the `frozen` marker file specification. For example:
+
+```
+freeze_base:
+    conda:
+        message: "This base environment is frozen and cannot be modified."
+```
+
 
 ## Available selectors
 - `aarch64`

constructor/_schema.py

@@ -98,6 +98,8 @@ class ExtraEnv(BaseModel):
     Same as the global option, but for this env.
     See global option for notes about overrides.
     """
+    freeze_env: dict[Literal["conda"], dict] | None = None
+    "Same as `freeze_base`, but for this conda environment."
 
 
 class BuildOutputs(StrEnum):
@@ -830,6 +832,22 @@ class ConstructorConfiguration(BaseModel):
     Use the standalone binary to perform the uninstallation on Windows.
     Requires conda-standalone 24.11.0 or newer.
     """
+    freeze_base: dict[Literal["conda"], dict] | None = None
+    """
+    Protects the conda base environment against modifications by supported package managers.
+
+    Supported package managers:
+        - `conda`: Protects against conda modifications
+
+    For `conda`, the dictionary is written into the `frozen` marker file.
+    See CEP-22 for the `frozen` marker file specification. For example:
+
+    ```
+    freeze_base:
+        conda:
+            message: "This base environment is frozen and cannot be modified."
+    ```
+    """
 
 
 def fix_descriptions(obj):

constructor/data/construct.schema.json

@@ -124,6 +124,26 @@
           "description": "Same as the global option, but for this env. See global option for notes about overrides.",
           "title": "Exclude"
         },
+        "freeze_env": {
+          "anyOf": [
+            {
+              "additionalProperties": {
+                "additionalProperties": true,
+                "type": "object"
+              },
+              "propertyNames": {
+                "const": "conda"
+              },
+              "type": "object"
+            },
+            {
+              "type": "null"
+            }
+          ],
+          "default": null,
+          "description": "Same as `freeze_base`, but for this conda environment.",
+          "title": "Freeze Env"
+        },
         "menu_packages": {
           "anyOf": [
             {
@@ -694,6 +714,26 @@
       "title": "Extra Files",
       "type": "array"
     },
+    "freeze_base": {
+      "anyOf": [
+        {
+          "additionalProperties": {
+            "additionalProperties": true,
+            "type": "object"
+          },
+          "propertyNames": {
+            "const": "conda"
+          },
+          "type": "object"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "default": null,
+      "description": "Protects the conda base environment against modifications by supported package managers.\nSupported package managers:   - `conda`: Protects against conda modifications\nFor `conda`, the dictionary is written into the `frozen` marker file. See CEP-22 for the `frozen` marker file specification. For example:\n```\nfreeze_base:\n    conda:\n        message: \"This base environment is frozen and cannot be modified.\"\n```",
+      "title": "Freeze Base"
+    },
     "header_image": {
       "anyOf": [
         {

constructor/main.py

@@ -105,6 +105,69 @@ def _win_install_needs_python_exe(conda_exe: str, conda_exe_type: StandaloneExe
     return results.returncode == 2
 
 
+# Validate frozen environments
+def validate_frozen_envs(info, exe_type, exe_version) -> bool:
+    """Validate frozen environments.
+
+    Checks:
+    - No conflicts between freeze_base/freeze_env and extra_files for same environment
+    - Conda-standalone version if frozen environments exist
+    """
+
+    def get_frozen_env(path) -> str | None:
+        """Extract environment name from frozen marker destination path.
+
+        Returns:
+            Environment name if frozen marker found in the path, otherwise None.
+        """
+        parts = Path(path).parts
+        if parts == ("conda-meta", "frozen"):
+            return "base"
+        if len(parts) == 4 and parts[0] == "envs" and parts[-2:] == ("conda-meta", "frozen"):
+            return parts[1]
+        return None
+
+    # Collect environments using freeze_base/freeze_env
+    frozen_envs = set()
+    if info.get("freeze_base", {}).get("conda") is not None:
+        frozen_envs.add("base")
+    for env_name, env_config in info.get("extra_envs", {}).items():
+        if env_config.get("freeze_env", {}).get("conda") is not None:
+            frozen_envs.add(env_name)
+
+    # Collect environments using extra_files frozen markers
+    frozen_envs_extra_files = set()
+    paths = []
+    for file in info.get("extra_files", ()):
+        if isinstance(file, dict):
+            paths.extend(file.values())
+        elif isinstance(file, str):
+            paths.append(file)
+
+    for path in paths:
+        if env := get_frozen_env(path):
+            frozen_envs_extra_files.add(env)
+
+    if not frozen_envs and not frozen_envs_extra_files:
+        return
+
+    # Check for conflicts with extra_files
+    if common_envs := frozen_envs.intersection(frozen_envs_extra_files):
+        raise RuntimeError(
+            f"Frozen marker files found from both "
+            f"'freeze_base / freeze_env' and 'extra_files' for the following environments: {', '.join(sorted(common_envs))}"
+        )
+
+    # Conda-standalone version validation
+    if exe_type == StandaloneExe.CONDA and check_version(
+        exe_version, min_version="25.5.0", max_version="25.7.0"
+    ):
+        sys.exit(
+            "Error: conda-standalone 25.5.x has known issues with frozen environments. "
+            "Please use conda-standalone 25.7.0 or newer."
+        )
+
+
 def main_build(
     dir_path,
     output_dir=".",
@@ -194,30 +257,7 @@ def main_build(
         if isinstance(info[key], str):
             info[key] = list(yield_lines(join(dir_path, info[key])))
 
-    def has_frozen_file(extra_files: list[str | dict[str, str]]) -> bool:
-        def is_conda_meta_frozen(path_str: str) -> bool:
-            path = Path(path_str)
-            return path.parts == ("conda-meta", "frozen") or (
-                len(path.parts) == 4
-                and path.parts[0] == "envs"
-                and path.parts[-2:] == ("conda-meta", "frozen")
-            )
-
-        for file in extra_files:
-            if isinstance(file, str) and is_conda_meta_frozen(file):
-                return True
-            elif isinstance(file, dict) and any(is_conda_meta_frozen(val) for val in file.values()):
-                return True
-        return False
-
-    if (
-        has_frozen_file(info.get("extra_files", []))
-        and exe_type == StandaloneExe.CONDA
-        and check_version(exe_version, min_version="25.5.0", max_version="25.7.0")
-    ):
-        sys.exit(
-            "Error: handling conda-meta/frozen marker files requires conda-standalone newer than 25.7.x"
-        )
+    validate_frozen_envs(info, exe_type, exe_version)
 
     # normalize paths to be copied; if they are relative, they must be to
     # construct.yaml's parent (dir_path)

constructor/nsis/main.nsi.tmpl

@@ -1637,6 +1637,12 @@ Section "Install"
     # channels and retain only the first transaction
     SetOutPath "{{ env.conda_meta }}"
     File "{{ env.history_abspath }}"
+
+{%- if env.frozen_abspath %}
+    # Add frozen marker file if configured
+    SetOutPath "{{ env.conda_meta }}"
+    File "{{ env.frozen_abspath }}"
+{%- endif %}
 {%- endfor %}
 
 {%- for condarc in WRITE_CONDARC %}

constructor/preconda.py

@@ -147,6 +147,7 @@ def write_files(info: dict, workspace: str):
 
     - `conda-meta/initial-state.explicit.txt`: Lockfile to provision the base environment.
     - `conda-meta/history`: Prepared history file with the right requested specs in input file.
+    - `conda-meta/frozen`: Frozen marker file used to protect conda environment state.
     - `pkgs/urls` and `pkgs/urls.txt`: Direct URLs of packages used, with and without MD5 hashes.
     - `pkgs/cache/*.json`: Trimmed repodata to mock offline channels in use.
     - `pkgs/channels.txt`: Channels in use.
@@ -199,6 +200,9 @@ def write_files(info: dict, workspace: str):
     # (list of specs/dists to install)
     write_initial_state_explicit_txt(info, join(workspace, "conda-meta"), final_urls_md5s)
 
+    # base environment frozen marker files
+    write_frozen(info.get("freeze_base"), join(workspace, "conda-meta"))
+
     for fn in files:
         os.chmod(join(workspace, fn), 0o664)
 
@@ -218,6 +222,8 @@ def write_files(info: dict, workspace: str):
         write_channels_txt(info, env_pkgs, env_config)
         # shortcuts
         write_shortcuts_txt(info, env_pkgs, env_config)
+        # frozen marker file
+        write_frozen(env_config.get("freeze_env"), env_conda_meta)
 
 
 def write_conda_meta(info, dst_dir, final_urls_md5s, user_requested_specs=None):
@@ -244,6 +250,14 @@ def write_conda_meta(info, dst_dir, final_urls_md5s, user_requested_specs=None):
         fh.write("\n".join(builder))
 
 
+def write_frozen(freeze_info, dst_dir):
+    if not freeze_info or "conda" not in freeze_info:
+        return
+    frozen_path = join(dst_dir, "frozen")
+    with open(frozen_path, "w") as ff:
+        json.dump(freeze_info["conda"], ff)
+
+
 def write_repodata_record(info, dst_dir):
     all_dists = info["_dists"].copy()
     for env_data in info.get("_extra_envs_info", {}).values():

constructor/shar.py

@@ -173,12 +173,20 @@ def create(info, verbose=False):
     pre_t.addfile(tarinfo=tarfile.TarInfo("conda-meta/history"))
     post_t.add(join(tmp_dir, "conda-meta", "history"), "conda-meta/history")
 
+    if os.path.exists(join(tmp_dir, "conda-meta", "frozen")):
+        post_t.add(join(tmp_dir, "conda-meta", "frozen"), "conda-meta/frozen")
+
     for env_name in info.get("_extra_envs_info", {}):
         pre_t.addfile(tarinfo=tarfile.TarInfo(f"envs/{env_name}/conda-meta/history"))
         post_t.add(
             join(tmp_dir, "envs", env_name, "conda-meta", "history"),
             f"envs/{env_name}/conda-meta/history",
         )
+        if os.path.exists(join(tmp_dir, "envs", env_name, "conda-meta", "frozen")):
+            post_t.add(
+                join(tmp_dir, "envs", env_name, "conda-meta", "frozen"),
+                f"envs/{env_name}/conda-meta/frozen",
+            )
 
     extra_files = copy_extra_files(info.get("extra_files", []), tmp_dir)
     for path in extra_files:

constructor/winexe.py

@@ -87,6 +87,9 @@ def setup_envs_commands(info, dir_path):
             "lockfile_txt_abspath": join(dir_path, "conda-meta", "initial-state.explicit.txt"),
             "conda_meta": r"$INSTDIR\conda-meta",
             "history_abspath": join(dir_path, "conda-meta", "history"),
+            "frozen_abspath": join(dir_path, "conda-meta", "frozen")
+            if info.get("freeze_base", {}).get("conda") is not None
+            else "",
             "final_channels": get_final_channels(info),
             "shortcuts": shortcuts_flags(info),
             "register_envs": str(info.get("register_envs", True)).lower(),
@@ -115,6 +118,9 @@ def setup_envs_commands(info, dir_path):
                 ),
                 "conda_meta": join("$INSTDIR", "envs", env_name, "conda-meta"),
                 "history_abspath": join(dir_path, "envs", env_name, "conda-meta", "history"),
+                "frozen_abspath": join(dir_path, "envs", env_name, "conda-meta", "frozen")
+                if env_info.get("freeze_env", {}).get("conda") is not None
+                else "",
                 "final_channels": get_final_channels(channel_info),
                 "shortcuts": shortcuts_flags(env_info),
                 "register_envs": str(info.get("register_envs", True)).lower(),

docs/source/construct-yaml.md

@@ -658,6 +658,22 @@ Allowed strings / keys: `hash`, `info.json`, `licenses`, `lockfile`, `pkgs_list`
 Use the standalone binary to perform the uninstallation on Windows.
 Requires conda-standalone 24.11.0 or newer.
 
+### `freeze_base`
+
+Protects the conda base environment against modifications by supported package managers.
+
+Supported package managers:
+    - `conda`: Protects against conda modifications
+
+For `conda`, the dictionary is written into the `frozen` marker file.
+See CEP-22 for the `frozen` marker file specification. For example:
+
+```
+freeze_base:
+    conda:
+        message: "This base environment is frozen and cannot be modified."
+```
+
 
 ## Available selectors
 - `aarch64`

examples/protected_base/construct.yaml

@@ -12,13 +12,18 @@ specs:
   - python
   - conda
 
+freeze_base:
+  conda: {}
+
 extra_envs:
-  default:
+  env1:
     specs:
       - python
       - pip
       - conda
+    freeze_env:
+      conda:
+        message: This environment is frozen.
 
 extra_files:
-  - frozen.json: conda-meta/frozen
-  - frozen.json: envs/default/conda-meta/frozen
+  - frozen.json: envs/env2/conda-meta/frozen

examples/protected_base/frozen.json

@@ -1 +1 @@
-{}
+{"message": "This env is frozen via extra_files."}

news/1149-add-support-for-frozen-envs

@@ -0,0 +1,19 @@
+### Enhancements
+
+* Add support for installing [protected conda environments](https://conda.org/learn/ceps/cep-0022#specification). (#1149)
+
+### Bug fixes
+
+* <news item>
+
+### Deprecations
+
+* <news item>
+
+### Docs
+
+* <news item>
+
+### Other
+
+* <news item>