9d5749d2de
The Buildroot manual was already providing some details on how to integrate Cargo packages, and those details now need to be updated with a proper documentation for the cargo-package infrastructure, as well as updates related to vendoring support, which affects how dependencies are handled. In addition, now that we have vendoring support for Cargo packages, let's rewrite the dependency management section in a more accurate way. We drop the part about the local cache of the registry, because +CARGO_HOME+ in Buildroot points to $(HOST_DIR)/share/cargo, which is not shared between builds nor preserved accross builds, so its effect as a cache is limited. Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com> [Thomas: numerous updates and extensions.] Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
96 lines
3.4 KiB
Plaintext
96 lines
3.4 KiB
Plaintext
// -*- mode:doc; -*-
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// vim: set syntax=asciidoc:
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=== Infrastructure for Cargo-based packages
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Cargo is the package manager for the Rust programming language. It allows the
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user to build programs or libraries written in Rust, but it also downloads and
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manages their dependencies, to ensure repeatable builds. Cargo packages are
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called "crates".
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[[cargo-package-tutorial]]
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==== +cargo-package+ tutorial
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The +Config.in+ file of Cargo-based package 'foo' should contain:
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---------------------------
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01: config BR2_PACKAGE_FOO
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02: bool "foo"
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03: depends on BR2_PACKAGE_HOST_RUSTC_TARGET_ARCH_SUPPORTS
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04: select BR2_PACKAGE_HOST_RUSTC
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05: help
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06: This is a comment that explains what foo is.
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07:
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08: http://foosoftware.org/foo/
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---------------------------
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And the +.mk+ file for this package should contain:
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------------------------------
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01: ################################################################################
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02: #
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03: # foo
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04: #
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05: ################################################################################
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06:
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07: FOO_VERSION = 1.0
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08: FOO_SOURCE = foo-$(FOO_VERSION).tar.gz
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09: FOO_SITE = http://www.foosoftware.org/download
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10: FOO_LICENSE = GPL-3.0+
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11: FOO_LICENSE_FILES = COPYING
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12:
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13: $(eval $(cargo-package))
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--------------------------------
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The Makefile starts with the definition of the standard variables for
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package declaration (lines 7 to 11).
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As seen in line 13, it is based on the +cargo-package+
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infrastructure. Cargo will be invoked automatically by this
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infrastructure to build and install the package.
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It is still possible to define custom build commands or install
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commands (i.e. with FOO_BUILD_CMDS and FOO_INSTALL_TARGET_CMDS).
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Those will then replace the commands from the cargo infrastructure.
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==== +cargo-package+ reference
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The main macros for the Cargo package infrastructure are
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+cargo-package+ for target packages and +host-cargo-package+ for host
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packages.
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Just like the generic infrastructure, the Cargo infrastructure works
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by defining a number of variables before calling the +cargo-package+
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or +host-cargo-package+ macros.
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First, all the package metadata information variables that exist in
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the generic infrastructure also exist in the Cargo infrastructure:
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+FOO_VERSION+, +FOO_SOURCE+, +FOO_PATCH+, +FOO_SITE+,
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+FOO_DEPENDENCIES+, +FOO_LICENSE+, +FOO_LICENSE_FILES+, etc.
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A few additional variables, specific to the Cargo infrastructure, can
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also be defined. Many of them are only useful in very specific cases,
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typical packages will therefore only use a few of them.
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* +FOO_CARGO_ENV+ can be used to pass additional variables in the
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environment of +cargo+ invocations. It used at both build and
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installation time
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* +FOO_CARGO_BUILD_OPTS+ can be used to pass additional options to
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+cargo+ at build time.
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* +FOO_CARGO_INSTALL_OPTS+ can be used to pass additional options to
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+cargo+ at install time.
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A crate can depend on other libraries from crates.io or git
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repositories, listed in its +Cargo.toml+ file. Buildroot automatically
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takes care of downloading such dependencies as part of the download
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step of packages that use the +cargo-package+ infrastructure. Such
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dependencies are then kept together with the package source code in
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the tarball cached in Buildroot's +DL_DIR+, and therefore the hash of
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the package's tarball includes such dependencies.
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This mechanism ensures that any change in the dependencies will be
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detected, and allows the build to be performed completely offline.
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