Files
clan-core/pkgs/clan-cli/clan_lib/flake/flake.py
Jörg Thalheim d5b09f18ed RET504: fix
2025-08-26 15:55:23 +02:00

1129 lines
43 KiB
Python

import json
import logging
import os
import re
import shlex
from dataclasses import asdict, dataclass, field
from enum import Enum
from functools import cache
from hashlib import sha1
from pathlib import Path
from tempfile import NamedTemporaryFile
from typing import Any
from clan_lib.cmd import Log, RunOpts, run
from clan_lib.dirs import select_source, user_cache_dir
from clan_lib.errors import ClanCmdError, ClanError
from clan_lib.nix import (
nix_build,
nix_command,
nix_config,
nix_metadata,
nix_test_store,
)
log = logging.getLogger(__name__)
class FlakeDoesNotExistError(ClanError):
"""Raised when a flake does not exist"""
def __init__(self, flake_identifier: str, description: str | None = None) -> None:
msg = f"Flake '{flake_identifier}' does not exist or is not a valid flake."
super().__init__(msg, description=description, location=flake_identifier)
class FlakeInvalidError(ClanError):
"""Raised when a flake is invalid"""
def __init__(self, flake_identifier: str, description: str | None = None) -> None:
msg = f"Flake is invalid. Could not find a flake.nix file in '{flake_identifier}'."
super().__init__(msg, description=description, location=flake_identifier)
def get_nix_store_dir() -> str:
"""Get the Nix store directory path pattern for regex matching.
This always returns the pattern that Nix uses in its output,
which is typically /nix/store regardless of chroot.
"""
return os.environ.get("NIX_STORE_DIR", "/nix/store")
def get_physical_store_path(store_path: str) -> Path:
"""Convert a store path to its physical location, handling chroot environments.
When CLAN_TEST_STORE is set, paths like /nix/store/hash-name are
actually located at CLAN_TEST_STORE/nix/store/hash-name.
"""
test_store = os.environ.get("CLAN_TEST_STORE")
if test_store and store_path.startswith("/nix/store/"):
# Remove leading / to join properly
relative_path = store_path.lstrip("/")
return Path(test_store) / relative_path
return Path(store_path)
@cache
def get_store_path_regex(store_dir: str) -> re.Pattern[str]:
"""Get compiled regex for a specific store directory.
Matches store paths: store_dir/hash-name
The hash is base32 lowercase, name can contain [0-9a-zA-Z+-.?=_]
"""
# Pattern: store_dir/hash-name
pattern = (
re.escape(store_dir) + r"/[0-9a-z]+-[0-9a-zA-Z\+\-\._\?=]*" # hash-name
)
return re.compile(pattern)
def find_store_references(text: str) -> list[str]:
"""Find all store path references in a string."""
store_dir = get_nix_store_dir()
return get_store_path_regex(store_dir).findall(text)
def is_pure_store_path(path: str) -> bool:
"""Check if a path is a pure Nix store path without file references or metadata.
Pure store paths have the format: /nix/store/hash-name
They should NOT contain:
- Additional path components (/nix/store/hash-name/subdir/file.nix)
- Line numbers or metadata (/nix/store/hash-name:42)
"""
store_dir = get_nix_store_dir()
regex = get_store_path_regex(store_dir)
return bool(regex.fullmatch(path))
class SetSelectorType(str, Enum):
"""enum for the type of selector in a set.
For now this is either a string or a maybe selector.
"""
STR = "str"
MAYBE = "maybe"
@dataclass
class SetSelector:
"""Represents a selector used in a set.
type: SetSelectorType = SetSelectorType.STR
value: str = ""
a set looks like this:
{key1,key2}
"""
type: SetSelectorType = SetSelectorType.STR
value: str = ""
class SelectorType(str, Enum):
"""enum for the type of a selector
this can be all, string, set or maybe
"""
ALL = "all"
STR = "str"
SET = "set"
MAYBE = "maybe"
@dataclass
class Selector:
"""A class to represent a selector, which selects nix elements one level down.
consists of a SelectorType and a value.
if the type is all, no value is needed, since it selects all elements.
if the type is str, the value is a string, which is the key in a dict.
if the type is maybe the value is a string, which is the key in a dict.
if the type is set, the value is a list of SetSelector objects.
"""
type: SelectorType = SelectorType.STR
value: str | list[SetSelector] | None = None
def as_dict(self) -> dict[str, Any]:
if self.type == SelectorType.SET:
if not isinstance(self.value, list):
msg = f"Expected list for SET selector, got {type(self.value)}"
raise ClanError(msg)
return {
"type": self.type.value,
"value": [asdict(selector) for selector in self.value],
}
if self.type == SelectorType.ALL:
return {"type": self.type.value}
if self.type == SelectorType.STR:
if not isinstance(self.value, str):
msg = f"Expected str for STR selector, got {type(self.value)}"
raise ClanError(msg)
return {"type": self.type.value, "value": self.value}
if self.type == SelectorType.MAYBE:
if not isinstance(self.value, str):
msg = f"Expected str for MAYBE selector, got {type(self.value)}"
raise ClanError(msg)
return {"type": self.type.value, "value": self.value}
msg = f"Invalid selector type: {self.type}"
raise ValueError(msg)
class ClanSelectError(ClanError):
selectors: list[str]
failed_attr: str | None = None
flake_identifier: str
def __init__(
self,
flake_identifier: str,
selectors: list[str],
cmd_error: ClanCmdError | None = None,
description: str | None = None,
) -> None:
attribute = None
if cmd_error and description is None:
# Match for "error: <rest of error>"
error_match = re.search(r"error: (.+)", str(cmd_error))
if error_match:
description = error_match.group(1).strip()
if selectors == []:
msg = "failed to select []\n"
elif len(selectors) == 1:
msg = f"Error on: $ clan select '{selectors[0]}'\n"
else:
msg = "Error while executing:"
for selector in selectors:
msg += f"$ clan select '{selector}'\n"
self.selectors = selectors
self.failed_attr = attribute
self.flake_identifier = flake_identifier
super().__init__(msg, description=description, location=flake_identifier)
def __str__(self) -> str:
if self.description:
return f"{self.msg} Reason: {self.description}"
return self.msg
def __repr__(self) -> str:
return f"ClanSelectError({self})"
def selectors_as_dict(selectors: list[Selector]) -> list[dict[str, Any]]:
return [selector.as_dict() for selector in selectors]
def selectors_as_json(selectors: list[Selector]) -> str:
return json.dumps(selectors_as_dict(selectors))
def parse_selector(selector: str) -> list[Selector]:
"""Takes a string and returns a list of selectors.
a selector can be:
- a string, which is a key in a dict
- an integer, which is an index in a list
- a set of strings or integers, which are keys in a dict or indices in a list.
- the string "*", which selects all elements in a list or dict
"""
stack: list[str] = []
selectors: list[Selector] = []
acc_str: str = ""
# only used by set for now
submode = ""
acc_selectors: list[SetSelector] = []
for i in range(len(selector)):
c = selector[i]
mode = "start" if stack == [] else stack[-1]
if mode == "end":
if c == ".":
stack.pop()
if stack != []:
msg = "expected empty stack, but got {stack}"
raise ValueError(msg)
else:
msg = "expected ., but got {c}"
raise ValueError(msg)
elif mode == "start":
if c == "*":
stack.append("end")
selectors.append(Selector(type=SelectorType.ALL))
elif c == "?":
stack.append("maybe")
elif c == '"':
stack += ["str", "quote"]
elif c == "{":
stack.append("set")
elif c == ".":
selectors.append(Selector(type=SelectorType.STR, value=acc_str))
else:
stack.append("str")
acc_str += c
elif mode == "set":
if submode == "" and c == "?":
submode = "maybe"
elif c == "\\":
stack.append("escape")
if submode == "":
submode = "str"
elif c == '"':
stack.append("quote")
if submode == "":
submode = "str"
elif c == ",":
if submode == "maybe":
set_select_type = SetSelectorType.MAYBE
else:
set_select_type = SetSelectorType.STR
acc_selectors.append(SetSelector(type=set_select_type, value=acc_str))
submode = ""
acc_str = ""
elif c == "}":
# Only append selector if we have accumulated content
if acc_str != "" or submode != "":
if submode == "maybe":
set_select_type = SetSelectorType.MAYBE
else:
set_select_type = SetSelectorType.STR
acc_selectors.append(
SetSelector(type=set_select_type, value=acc_str),
)
# Check for invalid multiselect patterns with outPath
for subselector in acc_selectors:
if subselector.value == "outPath":
msg = (
"Cannot use 'outPath' in multiselect {...}. "
"When nix evaluates attrsets with outPath in a multiselect, "
"it collapses the entire attrset to just the outPath string, "
"breaking further selection. Use individual selectors instead."
)
raise ValueError(msg)
selectors.append(Selector(type=SelectorType.SET, value=acc_selectors))
submode = ""
acc_selectors = []
acc_str = ""
stack.pop()
stack.append("end")
else:
acc_str += c
if submode == "":
submode = "str"
elif mode == "quote":
if c == '"':
stack.pop()
elif c == "\\":
stack.append("escape")
else:
acc_str += c
elif mode == "escape":
stack.pop()
acc_str += c
elif mode in {"str", "maybe"}:
if c == ".":
stack.pop()
if mode == "maybe":
select_type = SelectorType.MAYBE
else:
select_type = SelectorType.STR
selectors.append(Selector(type=select_type, value=acc_str))
acc_str = ""
elif c == "\\":
stack.append("escape")
else:
acc_str += c
if stack != []:
if stack[-1] == "str" or stack[-1] == "maybe":
if stack[-1] == "maybe":
select_type = SelectorType.MAYBE
else:
select_type = SelectorType.STR
selectors.append(Selector(type=select_type, value=acc_str))
elif stack[-1] == "end":
pass
else:
msg = f"expected empty stack, but got {stack}"
raise ValueError(msg)
return selectors
@dataclass
class FlakeCacheEntry:
"""a recursive structure to store the cache.
consists of a dict with the keys being the selectors and the values being FlakeCacheEntry objects.
is_list is used to check if the value is a list.
exists is used to check if the value exists, which can be false if it was selected via maybe.
fetched_all is used to check if we have all keys on the current level.
"""
value: str | float | dict[str, Any] | None = field(default_factory=dict)
is_list: bool = False
exists: bool = True
fetched_all: bool = False
def insert(
self,
value: str | float | dict[str, Any] | list[Any] | None,
selectors: list[Selector],
) -> None:
selector: Selector
# if we have no more selectors, it means we select all keys from now one and futher down
selector = Selector(type=SelectorType.ALL) if selectors == [] else selectors[0]
# first we find out if we have all subkeys already
if self.fetched_all:
pass
elif selector.type == SelectorType.ALL:
self.fetched_all = True
# if we have a string selector, that means we are usually on a dict or a list, since we cannot walk down scalar values
# so we passthrough the value to the next level
if selector.type == SelectorType.STR:
if not isinstance(selector.value, str):
msg = f"Expected str for STR selector value, got {type(selector.value)}"
raise ClanError(msg)
if not isinstance(self.value, dict):
msg = f"Expected dict for cache value, got {type(self.value)}"
raise ClanError(msg)
if selector.value not in self.value:
self.value[selector.value] = FlakeCacheEntry()
self.value[selector.value].insert(value, selectors[1:])
# if we get a MAYBE, check if the selector is in the output, if not we create a entry with exists = False
# otherwise we just insert the value into the current dict
# we can skip creating the non existing entry if we already fetched all keys
elif selector.type == SelectorType.MAYBE:
if not isinstance(self.value, dict):
msg = f"Expected dict for cache value in MAYBE, got {type(self.value)}"
raise ClanError(msg)
if not isinstance(value, dict):
msg = f"Expected dict for value in MAYBE, got {type(value)}"
raise ClanError(msg)
if not isinstance(selector.value, str):
msg = (
f"Expected str for MAYBE selector value, got {type(selector.value)}"
)
raise ClanError(msg)
if selector.value in value:
if selector.value not in self.value:
self.value[selector.value] = FlakeCacheEntry()
self.value[selector.value].insert(value[selector.value], selectors[1:])
elif not self.fetched_all:
if selector.value not in self.value:
self.value[selector.value] = FlakeCacheEntry()
self.value[selector.value].exists = False
# insert a dict is pretty straight forward
elif isinstance(value, dict):
if not isinstance(self.value, dict):
msg = f"Expected dict for cache value in dict insert, got {type(self.value)}"
raise ClanError(msg)
for key, value_ in value.items():
if key not in self.value:
self.value[key] = FlakeCacheEntry()
self.value[key].insert(value_, selectors[1:])
# to store a list we also use a dict, so we know which indices we have
elif isinstance(value, list):
self.is_list = True
fetched_indices: list[str] = []
# if we are in a set, we take all the selectors
if selector.type == SelectorType.SET:
if not isinstance(selector.value, list):
msg = f"Expected list for SET selector value, got {type(selector.value)}"
raise ClanError(msg)
fetched_indices.extend(
subselector.value for subselector in selector.value
)
# if it's just a str, that is the index
elif selector.type == SelectorType.STR:
if not isinstance(selector.value, str):
msg = f"Expected str for STR selector value, got {type(selector.value)}"
raise ClanError(msg)
fetched_indices = [selector.value]
# otherwise we just take all the indices, which is the length of the list
elif selector.type == SelectorType.ALL:
fetched_indices = list(map(str, range(len(value))))
# insert is the same is insert a dict
if not isinstance(self.value, dict):
msg = f"Expected dict for cache value in list insert, got {type(self.value)}"
raise ClanError(msg)
for i, requested_index in enumerate(fetched_indices):
if not isinstance(requested_index, str):
msg = (
f"Expected str for requested index, got {type(requested_index)}"
)
raise ClanError(msg)
if requested_index not in self.value:
self.value[requested_index] = FlakeCacheEntry()
self.value[requested_index].insert(value[i], selectors[1:])
# strings need to be checked if they are pure store paths
# if they are, we store them as a dict with the outPath key
# this is to mirror nix behavior, where the outPath of an attrset is used if no further key is specified
elif isinstance(value, str) and is_pure_store_path(value):
if selectors != []:
msg = "Expected empty selectors for pure store path"
raise ClanError(msg)
self.value = {"outPath": FlakeCacheEntry(value)}
# if we have a normal scalar, we check if it conflicts with a maybe already store value
# since an empty attrset is the default value, we cannot check that, so we just set it to the value
elif isinstance(value, float | int | str) or value is None:
if selectors != []:
msg = "Expected empty selectors for scalar value"
raise ClanError(msg)
if self.value == {}:
self.value = value
# Only check for outPath wrapping conflicts for strings (store paths)
elif isinstance(value, str) and (
isinstance(self.value, dict)
and "outPath" in self.value
and isinstance(self.value["outPath"], FlakeCacheEntry)
):
# If the same value is already wrapped in outPath, it's not a conflict
if self.value["outPath"].value == value:
# Value already cached as outPath, no need to change
pass
else:
msg = f"Cannot insert {value} into cache, already have {self.value}"
raise TypeError(msg)
elif self.value != value:
msg = f"Cannot insert {value} into cache, already have {self.value}"
raise TypeError(msg)
def is_cached(self, selectors: list[Selector]) -> bool:
selector: Selector
# for store paths we have to check if they still exist, otherwise they have to be rebuild and are thus not cached
if isinstance(self.value, str):
store_refs = find_store_references(self.value)
if store_refs:
# Check if all store references exist at their physical location
return all(get_physical_store_path(ref).exists() for ref in store_refs)
# if self.value is not dict but we request more selectors, we assume we are cached and an error will be thrown in the select function
if isinstance(self.value, str | float | int | None):
return True
selector = Selector(type=SelectorType.ALL) if selectors == [] else selectors[0]
# we just fetch all subkeys, so we need to check of we inserted all keys at this level before
if selector.type == SelectorType.ALL:
if not isinstance(self.value, dict):
msg = f"Expected dict for ALL selector caching, got {type(self.value)}"
raise ClanError(msg)
if self.fetched_all:
return all(
self.value[sel].is_cached(selectors[1:]) for sel in self.value
)
return False
if (
selector.type == SelectorType.SET
and isinstance(selector.value, list)
and isinstance(self.value, dict)
):
for requested_selector in selector.value:
val = requested_selector.value
if val not in self.value:
# if we fetched all keys and we are not in the dict, we can assume we are cached
return self.fetched_all
# if a key does not exist from a previous fetch, we can assume it is cached
if self.value[val].exists is False:
return True
if not self.value[val].is_cached(selectors[1:]):
return False
return True
# string and maybe work the same for cache checking
if (selector.type in (SelectorType.STR, SelectorType.MAYBE)) and isinstance(
self.value,
dict,
):
if not isinstance(selector.value, str):
msg = f"Expected str for STR/MAYBE selector value in caching, got {type(selector.value)}"
raise ClanError(msg)
val = selector.value
if val not in self.value:
# if we fetched all keys and we are not in there, refetching won't help, so we can assume we are cached
return self.fetched_all
if self.value[val].exists is False:
return True
return self.value[val].is_cached(selectors[1:])
return False
def select(self, selectors: list[Selector]) -> Any:
selector: Selector
selector = Selector(type=SelectorType.ALL) if selectors == [] else selectors[0]
# mirror nix behavior where we return outPath if no further selector is specified
if selectors == [] and isinstance(self.value, dict) and "outPath" in self.value:
return self.value["outPath"].value
# if we are at the end of the selector chain, we return the value
if selectors == [] and isinstance(self.value, str | float | int | None):
return self.value
# if we fetch a specific key, we return the recurse into that value in the dict
if selector.type == SelectorType.STR and isinstance(self.value, dict):
if not isinstance(selector.value, str):
msg = f"Expected str for STR selector value in select, got {type(selector.value)}"
raise ClanError(msg)
return self.value[selector.value].select(selectors[1:])
# if we are a MAYBE selector, we check if the key exists in the dict
if selector.type == SelectorType.MAYBE:
if not isinstance(selector.value, str):
msg = f"Expected str for MAYBE selector value in select, got {type(selector.value)}"
raise ClanError(msg)
if isinstance(self.value, dict):
if selector.value in self.value:
if self.value[selector.value].exists:
return {
selector.value: self.value[selector.value].select(
selectors[1:],
),
}
return {}
# Key not found, return empty dict for MAYBE selector
return {}
# Non-dict value (including None), return empty dict for MAYBE selector
return {}
# Handle SET selector on non-dict values
if selector.type == SelectorType.SET and not isinstance(self.value, dict):
if not isinstance(selector.value, list):
msg = (
f"Expected list for SET selector value, got {type(selector.value)}"
)
raise ClanError(msg)
# Empty set or all sub-selectors are MAYBE
if len(selector.value) == 0:
# Empty set, return empty dict
return {}
all_maybe = all(
subselector.type == SetSelectorType.MAYBE
for subselector in selector.value
)
if all_maybe:
# All sub-selectors are MAYBE, return empty dict for non-dict values
return {}
# Not all sub-selectors are MAYBE, fall through to raise KeyError
# otherwise we return a list or a dict
if isinstance(self.value, dict):
keys_to_select: list[str] = []
# if we want to select all keys, we take all existing sub elements
if selector.type == SelectorType.ALL:
keys_to_select.extend(
key for key in self.value if self.value[key].exists
)
# if we want to select a set of keys, we take the keys from the selector
if selector.type == SelectorType.SET:
if not isinstance(selector.value, list):
msg = f"Expected list for SET selector value in select, got {type(selector.value)}"
raise ClanError(msg)
for subselector in selector.value:
# make sure the keys actually exist if we have a maybe selector
if subselector.type == SetSelectorType.MAYBE:
if (
subselector.value in self.value
and self.value[subselector.value].exists
):
keys_to_select.append(subselector.value)
else:
keys_to_select.append(subselector.value)
# if we are a list, return a list
if self.is_list:
result_list: list[Any] = [
self.value[index].select(selectors[1:]) for index in keys_to_select
]
return result_list
# otherwise return a dict
result_dict: dict[str, Any] = {}
for key in keys_to_select:
value = self.value[key].select(selectors[1:])
if self.value[key].exists and not (
isinstance(value, dict)
and len(value) == 0
and self.value[key].value is None
):
result_dict[key] = value
return result_dict
# return a KeyError if we cannot fetch the key
str_selector: str
if selector.type == SelectorType.ALL:
str_selector = "*"
elif selector.type == SelectorType.SET:
if not isinstance(selector.value, list):
msg = f"Expected list for SET selector value in error handling, got {type(selector.value)}"
raise ClanError(msg)
subselectors = [subselector.value for subselector in selector.value]
str_selector = "{" + ",".join(subselectors) + "}"
else:
if not isinstance(selector.value, str):
msg = f"Expected str for selector value in error handling, got {type(selector.value)}"
raise ClanError(msg)
str_selector = selector.value
raise KeyError(str_selector)
def __getitem__(self, name: str) -> "FlakeCacheEntry":
if isinstance(self.value, dict):
return self.value[name]
raise KeyError(name)
def as_json(self) -> dict[str, Any]:
json_data: Any = {}
if isinstance(self.value, dict):
value = json_data["value"] = {}
for k, v in self.value.items():
value[k] = v.as_json()
else: # == str | float | None
json_data["value"] = self.value
json_data["is_list"] = self.is_list
json_data["exists"] = self.exists
json_data["fetched_all"] = self.fetched_all
return json_data
@staticmethod
def from_json(json_data: dict[str, Any]) -> "FlakeCacheEntry":
raw_value = json_data.get("value")
if isinstance(raw_value, dict):
value: Any = {}
for k, v in raw_value.items():
value[k] = FlakeCacheEntry.from_json(v)
else: # == str | float | None
value = raw_value
is_list = json_data.get("is_list", False)
exists = json_data.get("exists", True)
fetched_all = json_data.get("fetched_all", False)
return FlakeCacheEntry(
value=value,
is_list=is_list,
exists=exists,
fetched_all=fetched_all,
)
def __repr__(self) -> str:
if isinstance(self.value, dict):
return f"FlakeCache {{{', '.join([str(k) for k in self.value])}}}"
return f"FlakeCache {self.value}"
@dataclass
class FlakeCache:
"""an in-memory cache for flake outputs, uses a recursive FLakeCacheEntry structure"""
def __init__(self) -> None:
self.cache: FlakeCacheEntry = FlakeCacheEntry()
def insert(self, data: dict[str, Any], selector_str: str) -> None:
selectors = parse_selector(selector_str) if selector_str else []
self.cache.insert(data, selectors)
def select(self, selector_str: str) -> Any:
selectors = parse_selector(selector_str)
return self.cache.select(selectors)
def is_cached(self, selector_str: str) -> bool:
selectors = parse_selector(selector_str)
return self.cache.is_cached(selectors)
def save_to_file(self, path: Path) -> None:
path.parent.mkdir(parents=True, exist_ok=True)
with NamedTemporaryFile(mode="w", dir=path.parent, delete=False) as temp_file:
data = {"cache": self.cache.as_json()}
json.dump(data, temp_file)
temp_file.close()
Path(temp_file.name).rename(path)
def load_from_file(self, path: Path) -> None:
with path.open("r") as f:
log.debug(f"Loading flake cache from file {path}")
data = json.load(f)
self.cache = FlakeCacheEntry.from_json(data["cache"])
@dataclass
class Flake:
"""Represents a flake, and is used to interact with it.
values can be accessed using the select method, which will fetch the value from the cache if it is present.
"""
identifier: str
hash: str | None = None
store_path: str | None = None
nix_options: list[str] | None = None
_flake_cache_path: Path | None = field(init=False, default=None)
_cache: FlakeCache | None = field(init=False, default=None)
_path: Path | None = field(init=False, default=None)
_is_local: bool | None = field(init=False, default=None)
@classmethod
def from_json(
cls: type["Flake"],
data: dict[str, Any],
*,
nix_options: list[str] | None = None,
) -> "Flake":
return cls(data["identifier"], nix_options=nix_options)
def __str__(self) -> str:
return self.identifier
def __hash__(self) -> int:
return hash(self.identifier)
def __eq__(self, other: object) -> bool:
if not isinstance(other, Flake):
return NotImplemented
return self.identifier == other.identifier
@property
def is_local(self) -> bool:
if self._is_local is None:
self.invalidate_cache()
if not isinstance(self._is_local, bool):
msg = f"Expected bool for is_local, got {type(self._is_local)}"
raise ClanError(msg)
return self._is_local
def get_input_names(self) -> list[str]:
log.debug("flake.get_input_names is deprecated and will be removed")
flakes = self.select("inputs.*._type")
return list(flakes.keys())
@property
def path(self) -> Path:
if self._path is None:
self.invalidate_cache()
if not isinstance(self._path, Path):
msg = f"Expected Path for path, got {type(self._path)}"
raise ClanError(msg)
return self._path
def load_cache(self) -> None:
path = self.flake_cache_path
if path is None or self._cache is None or not path.exists():
return
try:
self._cache.load_from_file(path)
except (OSError, json.JSONDecodeError, KeyError, ValueError) as e:
log.warning(f"Failed load eval cache: {e}. Continue without cache")
def prefetch(self) -> None:
"""Loads the flake into the store and populates self.store_path and self.hash such that the flake can evaluate locally and offline"""
if self.nix_options is None:
self.nix_options = []
cmd = [
"flake",
"prefetch",
"--json",
*self.nix_options,
"--option",
"flake-registry",
"",
self.identifier,
]
trace_prefetch = os.environ.get("CLAN_DEBUG_NIX_PREFETCH") == "1"
if not trace_prefetch:
log.debug(f"Prefetching flake {self.identifier}")
try:
flake_prefetch = run(nix_command(cmd), RunOpts(trace=trace_prefetch))
except ClanCmdError as e:
if (
f"error: getting status of '{self.identifier}': No such file or directory"
in str(e)
):
raise FlakeDoesNotExistError(self.identifier) from e
if "error: could not find a flake.nix file" in str(e):
raise FlakeInvalidError(self.identifier) from e
raise
flake_metadata = json.loads(flake_prefetch.stdout)
self.store_path = flake_metadata["storePath"]
self.hash = flake_metadata["hash"]
self.flake_metadata = flake_metadata
def invalidate_cache(self) -> None:
"""Invalidate the cache and reload it.
This method is used to refresh the cache by reloading it from the flake.
"""
self.prefetch()
self._cache = FlakeCache()
if self.hash is None:
msg = "Hash cannot be None"
raise ClanError(msg)
hashed_hash = sha1(self.hash.encode()).hexdigest() # noqa: S324 - SHA1 used only for cache directory naming, not security
self.flake_cache_path = (
Path(user_cache_dir()) / "clan" / "flakes-v2" / hashed_hash
)
self.load_cache()
if "original" not in self.flake_metadata:
self.flake_metadata = nix_metadata(self.identifier)
if self.flake_metadata["original"].get("url", "").startswith("file:"):
self._is_local = True
path = self.flake_metadata["original"]["url"].removeprefix("file://")
path = path.removeprefix("file:")
self._path = Path(path)
elif self.flake_metadata["original"].get("path"):
self._is_local = True
self._path = Path(self.flake_metadata["original"]["path"])
else:
self._is_local = False
if self.store_path is None:
msg = "Store path cannot be None"
raise ClanError(msg)
self._path = Path(self.store_path)
def get_from_nix(
self,
selectors: list[str],
) -> None:
"""Retrieves specific attributes from a Nix flake using the provided selectors.
This function interacts with the Nix build system to fetch and process
attributes from a flake. It uses the provided selectors to determine which
attributes to retrieve and optionally accepts additional Nix options for
customization. The results are cached for future use.
Used mostly as a lowlevel function for `precache` and `select` methods.
Args:
selectors (list[str]): A list of attribute selectors to fetch from the flake.
nix_options (list[str] | None): Optional additional options to pass to the Nix build command.
Raises:
ClanError: If the number of outputs does not match the number of selectors.
AssertionError: If the cache or flake cache path is not properly initialized.
"""
if self._cache is None:
self.invalidate_cache()
if self._cache is None:
msg = "Cache cannot be None after invalidation"
raise ClanError(msg)
nix_options = self.nix_options[:] if self.nix_options is not None else []
str_selectors = [
selectors_as_json(parse_selector(selector)) for selector in selectors
]
config = nix_config()
select_hash = "@select_hash@"
if not select_hash.startswith("sha256-"):
select_flake = Flake(str(select_source()), nix_options=nix_options)
select_flake.invalidate_cache()
if select_flake.hash is None:
msg = "this should be impossible as invalidate_cache() should always set `hash`"
raise ClanError(msg)
select_hash = select_flake.hash
# fmt: off
nix_code = f"""
let
flake = builtins.getFlake "path:{self.store_path}?narHash={self.hash}";
selectLib = (
builtins.getFlake
"path:{select_source()}?narHash={select_hash}"
).lib;
in
derivation {{
name = "clan-flake-select";
result = builtins.toJSON [
{" ".join(
[
f"(selectLib.applySelectors (builtins.fromJSON ''{attr}'') flake)"
for attr in str_selectors
]
)}
];
# We can always build this derivation locally, since /bin/sh is system independent,
# remote builders would introduce needless overhead.
preferLocalBuild = true;
# Save the roundtrip to check the binary caches for trival substitutions
allowSubstitutes = false;
passAsFile = [ "result" ];
system = "{config["system"]}";
builder = "/bin/sh";
args = [
"-c"
''
read -r x < "$resultPath"; printf %s "$x" > $out
''
];
}}
"""
trace = os.environ.get("CLAN_DEBUG_NIX_SELECTORS") == "1"
try:
build_output = Path(
run(
nix_build(["--expr", nix_code, *nix_options]),
RunOpts(log=Log.NONE, trace=trace),
).stdout.strip(),
)
except ClanCmdError as e:
if "error: attribute 'clan' missing" in str(e):
msg = ("This flake does not export the 'clan' attribute. \n"
"Please write 'clan = clan.config;' into the outputs of your flake.nix.")
raise ClanSelectError(
flake_identifier=self.identifier,
selectors=selectors,
cmd_error=e,
description=msg,
) from e
# If the error is about a missing attribute, we raise a ClanSelectError
# with the failed selectors and the flake identifier.
raise ClanSelectError(
flake_identifier=self.identifier,
selectors=selectors,
cmd_error=e,
) from e
if tmp_store := nix_test_store():
build_output = tmp_store.joinpath(*build_output.parts[1:])
outputs = json.loads(build_output.read_bytes())
if len(outputs) != len(selectors):
msg = f"flake_prepare_cache: Expected {len(outputs)} outputs, got {len(selectors)}"
raise ClanError(msg)
self.load_cache()
for i, selector in enumerate(selectors):
self._cache.insert(outputs[i], selector)
if self.flake_cache_path:
self._cache.save_to_file(self.flake_cache_path)
def precache(self, selectors: list[str]) -> None:
"""Ensures that the specified selectors are cached locally.
This function checks if the given selectors are already cached. If not, it
fetches them using the Nix build system and stores them in the local cache.
It ensures that the cache is initialized before performing these operations.
Args:
selectors (list[str]): A list of attribute selectors to check and cache.
"""
if self._cache is None:
self.invalidate_cache()
if self._cache is None:
msg = "Cache cannot be None after invalidation"
raise ClanError(msg)
if self.flake_cache_path is None:
msg = "Flake cache path cannot be None"
raise ClanError(msg)
not_fetched_selectors = [
selector for selector in selectors if not self._cache.is_cached(selector)
]
if not_fetched_selectors:
self.get_from_nix(not_fetched_selectors)
def select(
self,
selector: str,
) -> Any:
"""Selects a value from the cache based on the provided selector string.
Fetches it via nix_build if it is not already cached.
Args:
selector (str): The attribute selector string to fetch the value for.
"""
if self._cache is None:
self.invalidate_cache()
if self._cache is None:
msg = "Cache cannot be None after invalidation"
raise ClanError(msg)
if self.flake_cache_path is None:
msg = "Flake cache path cannot be None"
raise ClanError(msg)
if not self._cache.is_cached(selector):
log.debug(f"(cached) $ clan select {shlex.quote(selector)}")
log.debug(f"Cache miss for {selector}")
self.get_from_nix([selector])
else:
log.debug(f"$ clan select {shlex.quote(selector)}")
return self._cache.select(selector)
def select_machine(self, machine_name: str, selector: str) -> Any:
"""Select a nix attribute for a specific machine.
Args:
machine_name: The name of the machine
selector: The attribute selector string relative to the machine config
apply: Optional function to apply to the result
"""
config = nix_config()
system = config["system"]
full_selector = f'clanInternals.machines."{system}"."{machine_name}".{selector}'
return self.select(full_selector)
def require_flake(flake: Flake | None) -> Flake:
"""Require that a flake argument is provided, if not in a clan flake.
This should be called by commands that require a flake but don't have
a sensible default when no clan flake is found locally.
Args:
flake: The flake object to check, may be None
Returns:
The validated flake object
Raises:
ClanError: If the flake is None
"""
if flake is None:
msg = "No clan flake found in the current directory or its parents"
raise ClanError(
msg,
description="Use the --flake flag to specify a clan flake path or URL",
)
return flake