puck/lix
0
0
Fork 0
forked from lix-project/lix
Code Pull requests Activity

make separate section for builder execution

Browse source
This commit is contained in:
Valentin Gagarin 2023-07-18 13:49:59 +02:00
parent b19bd4f348
commit 541890463d
1 changed files with 59 additions and 57 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

116
doc/manual/src/language/derivations.md
View file

@ -93,69 +93,71 @@ wrapper around `derivation` that adds a default value for `system` and
always uses Bash as the builder, to which the supplied builder is passed always uses Bash as the builder, to which the supplied builder is passed
as a command-line argument. See the Nixpkgs manual for details. as a command-line argument. See the Nixpkgs manual for details.
The builder is executed as follows: ## Builder execution
- A temporary directory is created under the directory specified by The [`builder`](#attr-builder) is executed as follows:
`TMPDIR` (default `/tmp`) where the build will take place. The
current directory is changed to this directory.
- The environment is cleared and set to the derivation attributes, as - A temporary directory is created under the directory specified by
specified above. `TMPDIR` (default `/tmp`) where the build will take place. The
current directory is changed to this directory.
- In addition, the following variables are set: - The environment is cleared and set to the derivation attributes, as
specified above.
- `NIX_BUILD_TOP` contains the path of the temporary directory for
this build.
- Also, `TMPDIR`, `TEMPDIR`, `TMP`, `TEMP` are set to point to the
temporary directory. This is to prevent the builder from
accidentally writing temporary files anywhere else. Doing so
might cause interference by other processes.
- `PATH` is set to `/path-not-set` to prevent shells from
initialising it to their built-in default value.
- `HOME` is set to `/homeless-shelter` to prevent programs from
using `/etc/passwd` or the like to find the user's home
directory, which could cause impurity. Usually, when `HOME` is
set, it is used as the location of the home directory, even if
it points to a non-existent path.
- `NIX_STORE` is set to the path of the top-level Nix store
directory (typically, `/nix/store`).
- For each output declared in `outputs`, the corresponding
environment variable is set to point to the intended path in the
Nix store for that output. Each output path is a concatenation
of the cryptographic hash of all build inputs, the `name`
attribute and the output name. (The output name is omitted if
it’s `out`.)
- If an output path already exists, it is removed. Also, locks are - In addition, the following variables are set:
acquired to prevent multiple Nix instances from performing the same
build at the same time.
- A log of the combined standard output and error is written to - `NIX_BUILD_TOP` contains the path of the temporary directory for
`/nix/var/log/nix`. this build.
- The builder is executed with the arguments specified by the - Also, `TMPDIR`, `TEMPDIR`, `TMP`, `TEMP` are set to point to the
attribute `args`. If it exits with exit code 0, it is considered to temporary directory. This is to prevent the builder from
have succeeded. accidentally writing temporary files anywhere else. Doing so
might cause interference by other processes.
- The temporary directory is removed (unless the `-K` option was - `PATH` is set to `/path-not-set` to prevent shells from
specified). initialising it to their built-in default value.
- If the build was successful, Nix scans each output path for - `HOME` is set to `/homeless-shelter` to prevent programs from
references to input paths by looking for the hash parts of the input using `/etc/passwd` or the like to find the user's home
paths. Since these are potential runtime dependencies, Nix registers directory, which could cause impurity. Usually, when `HOME` is
them as dependencies of the output paths. set, it is used as the location of the home directory, even if
it points to a non-existent path.
- After the build, Nix sets the last-modified timestamp on all files - `NIX_STORE` is set to the path of the top-level Nix store
in the build result to 1 (00:00:01 1/1/1970 UTC), sets the group to directory (typically, `/nix/store`).
the default group, and sets the mode of the file to 0444 or 0555
(i.e., read-only, with execute permission enabled if the file was - For each output declared in `outputs`, the corresponding
originally executable). Note that possible `setuid` and `setgid` environment variable is set to point to the intended path in the
bits are cleared. Setuid and setgid programs are not currently Nix store for that output. Each output path is a concatenation
supported by Nix. This is because the Nix archives used in of the cryptographic hash of all build inputs, the `name`
deployment have no concept of ownership information, and because it attribute and the output name. (The output name is omitted if
makes the build result dependent on the user performing the build. it’s `out`.)
- If an output path already exists, it is removed. Also, locks are
acquired to prevent multiple Nix instances from performing the same
build at the same time.
- A log of the combined standard output and error is written to
`/nix/var/log/nix`.
- The builder is executed with the arguments specified by the
attribute `args`. If it exits with exit code 0, it is considered to
have succeeded.
- The temporary directory is removed (unless the `-K` option was
specified).
- If the build was successful, Nix scans each output path for
references to input paths by looking for the hash parts of the input
paths. Since these are potential runtime dependencies, Nix registers
them as dependencies of the output paths.
- After the build, Nix sets the last-modified timestamp on all files
in the build result to 1 (00:00:01 1/1/1970 UTC), sets the group to
the default group, and sets the mode of the file to 0444 or 0555
(i.e., read-only, with execute permission enabled if the file was
originally executable). Note that possible `setuid` and `setgid`
bits are cleared. Setuid and setgid programs are not currently
supported by Nix. This is because the Nix archives used in
deployment have no concept of ownership information, and because it
makes the build result dependent on the user performing the build.