Generate explicit lockfiles per environment

CONSTRUCT.md

@@ -860,6 +860,8 @@ Allowed keys are:
 - `info.json`: The internal `info` object, serialized to JSON. Takes no options.
 - `pkgs_list`: The list of packages contained in a given environment. Options:
     - `env` (optional, default=`base`): Name of an environment in `extra_envs` to export.
+- `lockfile`: An `@EXPLICIT` lockfile for a given environment. Options:
+    - `env` (optional, default=`base`): Name of an environment in `extra_envs` to export.
 - `licenses`: Generate a JSON file with the licensing details of all included packages. Options:
     - `include_text` (optional bool, default=`False`): Whether to dump the license text in the JSON.
       If false, only the path will be included.

constructor/build_outputs.py

@@ -10,6 +10,12 @@
 from collections import defaultdict
 from pathlib import Path
 
+from conda.base.constants import UNKNOWN_CHANNEL
+from conda.common.url import remove_auth, split_anaconda_token
+from conda.core.prefix_data import PrefixGraph
+
+from . import __version__
+
 logger = logging.getLogger(__name__)
 
 
@@ -86,6 +92,38 @@ def dump_packages_list(info, env="base"):
     return os.path.abspath(outpath)
 
 
+def dump_lockfile(info, env="base"):
+    if env == "base":
+        records = info["_records"]
+    elif env in info["_extra_envs_info"]:
+        records = info["_extra_envs_info"][env]["_records"]
+    else:
+        raise ValueError(f"env='{env}' is not a valid env name.")
+    lines = [
+        "# This file may be used to create an environment using:",
+        "# $ conda create --name <env> --file <this file>",
+        f"# installer-name: {info['name']}",
+        f"# installer-version: {info['version']}",
+        f"# env-name: {env}",
+        f"# platform: {info['_platform']}",
+        f"# created-by: constructor {__version__}",
+        "@EXPLICIT"
+    ]
+    for record in PrefixGraph(records).graph:
+        url = record.get("url")
+        if not url or url.startswith(UNKNOWN_CHANNEL):
+            print("# no URL for: {}".format(record["fn"]))
+            continue
+        url = remove_auth(split_anaconda_token(url)[0])
+        hash_value = record.get("md5")
+        lines.append(url + (f"#{hash_value}" if hash_value else ""))
+
+    outpath = os.path.join(info["_output_dir"], f'lockfile.{env}.txt')
+    with open(outpath, 'w') as f:
+        f.write("\n".join(lines))
+    return os.path.abspath(outpath)
+
+
 def dump_licenses(info, include_text=False, text_errors=None):
     """
     Create a JSON document with a mapping with schema:
@@ -140,5 +178,6 @@ def dump_licenses(info, include_text=False, text_errors=None):
     "hash": dump_hash,
     "info.json": dump_info,
     "pkgs_list": dump_packages_list,
+    "lockfile": dump_lockfile,
     "licenses": dump_licenses,
 }

constructor/construct.py

@@ -635,6 +635,8 @@
 - `info.json`: The internal `info` object, serialized to JSON. Takes no options.
 - `pkgs_list`: The list of packages contained in a given environment. Options:
     - `env` (optional, default=`base`): Name of an environment in `extra_envs` to export.
+- `lockfile`: An `@EXPLICIT` lockfile for a given environment. Options:
+    - `env` (optional, default=`base`): Name of an environment in `extra_envs` to export.
 - `licenses`: Generate a JSON file with the licensing details of all included packages. Options:
     - `include_text` (optional bool, default=`False`): Whether to dump the license text in the JSON.
       If false, only the path will be included.

constructor/fcp.py

@@ -403,7 +403,7 @@ def _main(name, version, download_dir, platform, channel_urls=(), channels_remap
         env_pc_recs, env_urls, env_dists, _ = _fetch_precs(
             env_precs, download_dir, transmute_file_type=transmute_file_type
         )
-        extra_envs_data[env_name] = {"_urls": env_urls, "_dists": env_dists}
+        extra_envs_data[env_name] = {"_urls": env_urls, "_dists": env_dists, "_records": env_precs}
         all_pc_recs += env_pc_recs
 
     duplicate_files = "warn" if ignore_duplicate_files else "error"
@@ -418,6 +418,7 @@ def _main(name, version, download_dir, platform, channel_urls=(), channels_remap
 
     return (
         all_pc_recs,
+        precs,
         _urls,
         dists,
         approx_tarballs_size,
@@ -466,8 +467,9 @@ def main(info, verbose=True, dry_run=False, conda_exe="conda.exe"):
 
         (
             pkg_records,
-            _urls,
-            dists,
+            _base_env_records,
+            _base_env_urls,
+            _base_env_dists,
             approx_tarballs_size,
             approx_pkgs_size,
             has_conda,
@@ -495,10 +497,11 @@ def main(info, verbose=True, dry_run=False, conda_exe="conda.exe"):
         )
 
     info["_all_pkg_records"] = pkg_records  # full PackageRecord objects
-    info["_urls"] = _urls  # needed to mock the repodata cache
-    info["_dists"] = dists  # needed to tell conda what to install
+    info["_urls"] = _base_env_urls  # needed to mock the repodata cache
+    info["_dists"] = _base_env_dists  # needed to tell conda what to install
+    info["_records"] = _base_env_records  # needed to generate optional lockfile
     info["_approx_tarballs_size"] = approx_tarballs_size
     info["_approx_pkgs_size"] = approx_pkgs_size
     info["_has_conda"] = has_conda
-    # contains {env_name: [_dists, _urls]} for each extra environment
+    # contains {env_name: [_dists, _urls, _records]} for each extra environment
     info["_extra_envs_info"] = extra_envs_info

docs/source/construct-yaml.md

@@ -860,6 +860,8 @@ Allowed keys are:
 - `info.json`: The internal `info` object, serialized to JSON. Takes no options.
 - `pkgs_list`: The list of packages contained in a given environment. Options:
     - `env` (optional, default=`base`): Name of an environment in `extra_envs` to export.
+- `lockfile`: An `@EXPLICIT` lockfile for a given environment. Options:
+    - `env` (optional, default=`base`): Name of an environment in `extra_envs` to export.
 - `licenses`: Generate a JSON file with the licensing details of all included packages. Options:
     - `include_text` (optional bool, default=`False`): Whether to dump the license text in the JSON.
       If false, only the path will be included.

examples/extra_envs/construct.yaml

@@ -31,6 +31,9 @@ build_outputs:
   - pkgs_list
   - pkgs_list:
       env: py310
+  - lockfile
+  - lockfile:
+      env: py310
   - licenses:
       include_text: True
       text_errors: replace

news/898-lockfile

@@ -0,0 +1,19 @@
+### Enhancements
+
+* Add new `lockfile` output in `build_outputs`. This generates a `@EXPLICIT` lockfile for the requested environment. (#898)
+
+### Bug fixes
+
+* <news item>
+
+### Deprecations
+
+* <news item>
+
+### Docs
+
+* <news item>
+
+### Other
+
+* <news item>