From 1dec09b341f61836147d87656aea7f7be02aab6d Mon Sep 17 00:00:00 2001 From: Cory Fields Date: Wed, 23 Jul 2014 01:31:30 -0400 Subject: depends: add shared dependency builder See the README's in depends for documentation --- depends/README | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 depends/README (limited to 'depends/README') diff --git a/depends/README b/depends/README new file mode 100644 index 0000000000..fed2f9b5ab --- /dev/null +++ b/depends/README @@ -0,0 +1,55 @@ +This is a system of building and caching dependencies necessary for building +Bitcoin. + +There are several features that make it different from most similar systems: + +- It is designed to be builder and host agnostic + +In theory, binaries for any target OS/architecture can be created, from a +builder running any OS/architecture. In practice, build-side tools must be +specified when the defaults don't fit, and packages must be ammended to work +on new hosts. For now, a build architecture of x86_64 is assumed, either on +Linux or OSX. + +- No reliance on timestamps + +File presence is used to determine what needs to be built. This makes the +results distributable and easily digestable by automated builders. + +- Each build only has its specified dependencies available at build-time. + +For each build, the sysroot is wiped and the (recursive) dependencies are +installed. This makes each build deterministic, since there will never be any +unknown files available to cause side-effects. + +- Each package is cached and only rebuilt as needed. + +Before building, a unique build-id is generated for each package. This id +consists of a hash of all files used to build the package (Makefiles, packages, +etc), and as well as a hash of the same data for each recursive dependency. If +any portion of a package's build recipe changes, it will be rebuilt as well as +any other package that depends on it. If any of the main makefiles (Makefile, +funcs.mk, etc) are changed, all packages will be rebuilt. After building, the +results are cached into a tarball that can be re-used and distributed. + +- Package build results are (relatively) deterministic. + +Each package is configured and patched so that it will yield the same +build-results with each consequent build, within a reasonable set of +constraints. Some things like timestamp insertion are unavoidable, and are +beyond the scope of this system. Additionally, the toolchain itself must be +capable of deterministic results. When revisions are properly bumped, a cached +build should represent an exact single payload. + +- Sources are fetched and verified automatically + +Each package must define its source location and checksum. The build will fail +if the fetched source does not match. Sources may be pre-seeded and/or cached +as desired. + +- Self-cleaning + +Build and staging dirs are wiped after use, and any previous version of a +cached result is removed following a successful build. Automated builders +should be able to build each revision and store the results with no further +intervention. -- cgit v1.2.3