Documentation

repository_ctx

The context of the repository rule containing helper functions and information about attributes. You get a repository_ctx object as an argument to the implementation function when you create a repository rule.

attr

struct repository_ctx.attr

A struct to access the values of the attributes. The values are provided by the user (if not, a default value is used).

download

None repository_ctx.download(url, output='', sha256='', executable=False)

Download a file to the output path for the provided url.

Parameters

Parameter Description
url

string; or sequence of strings

List of mirror URLs referencing the same file.

output

string; or Label; or path

path to the output file, relative to the repository directory.

sha256

string

the expected SHA-256 hash of the file downloaded. This must match the SHA-256 hash of the file downloaded. It is a security risk to omit the SHA-256 as remote files can change. At best omitting this field will make your build non-hermetic. It is optional to make development easier but should be set before shipping.

executable

bool

set the executable flag on the created file, false by default.

download_and_extract

None repository_ctx.download_and_extract(url, output='', sha256='', type='', stripPrefix='')

Download a file to the output path for the provided url, and extract it.

Parameters

Parameter Description
url

string; or sequence of strings

List of mirror URLs referencing the same file.

output

string; or Label; or path

path to the directory where the archive will be unpacked, relative to the repository directory.

sha256

string

the expected SHA-256 hash of the file downloaded. This must match the SHA-256 hash of the file downloaded. It is a security risk to omit the SHA-256 as remote files can change. At best omitting this field will make your build non-hermetic. It is optional to make development easier but should be set before shipping.

type

string

the archive type of the downloaded file. By default, the archive type is determined from the file extension of the URL. If the file has no extension, you can explicitly specify either "zip", "jar", "war", "tar.gz", "tgz", "tar.bz2", or "tar.xz" here.

stripPrefix

string

a directory prefix to strip from the extracted files. Many archives contain a top-level directory that contains all files in the archive. Instead of needing to specify this prefix over and over in the build_file, this field can be used to strip it from extracted files.

execute

exec_result repository_ctx.execute(arguments, timeout=600, environment={}, quiet=True)

Executes the command given by the list of arguments. The execution time of the command is limited by timeout (in seconds, default 600 seconds). This method returns an exec_result structure containing the output of the command. The environment map can be used to override some environment variables to be passed to the process.

Parameters

Parameter Description
arguments

sequence

List of arguments, the first element should be the path to the program to execute.

timeout

int

maximum duration of the command in seconds (default is 600 seconds).

environment

dict

force some environment variables to be set to be passed to the process.

quiet

bool

If stdout and stderr should be printed to the terminal.

file

None repository_ctx.file(path, content='', executable=True)

Generate a file in the repository directory with the provided content.

Parameters

Parameter Description
path

string; or Label; or path

path of the file to create, relative to the repository directory.

content

string

the content of the file to create, empty by default.

executable

bool

set the executable flag on the created file, true by default.

name

string repository_ctx.name

The name of the external repository created by this rule.

os

repository_os repository_ctx.os

A struct to access information from the system.

path

path repository_ctx.path()

Returns a path from a string or a label. If the path is relative, it will resolve relative to the repository directory. If the path is a label, it will resolve to the path of the corresponding file. Note that remote repositories are executed during the analysis phase and thus cannot depends on a target result (the label should point to a non-generated file).

None repository_ctx.symlink(from, to)

Create a symlink on the filesystem.

Parameters

Parameter Description
from

string; or Label; or path

path to which the created symlink should point to.

to

string; or Label; or path

path of the symlink to create, relative to the repository directory.

template

None repository_ctx.template(path, template, substitutions={}, executable=True)

Generate a new file using a template. Every occurrence in template of a key of substitutions will be replaced by the corresponding value. The result is written in path. An optionalexecutable argument (default to true) can be set to turn on or offthe executable bit.

Parameters

Parameter Description
path

string; or Label; or path

path of the file to create, relative to the repository directory.

template

string; or Label; or path

path to the template file.

substitutions

dict

substitutions to make when expanding the template.

executable

bool

set the executable flag on the created file, true by default.

which

unknown repository_ctx.which()

Returns the path of the corresponding program or None if there is no such program in the path