vendor=True feature

devops.rst

@@ -18,3 +18,4 @@ If you plan to use Conan in production in your project, team, or organization, t
    devops/metadata
    devops/versioning
    devops/save_restore
+   devops/vendoring

devops/vendoring.rst

@@ -0,0 +1,56 @@
+.. _devops_vendoring:
+
+Vendoring dependencies in Conan packages
+========================================
+
+.. include:: ../common/experimental_warning.inc
+
+From Conan 2.4 it is possible to create and use Conan packages that completely vendor their dependencies,
+that is, they completely hide and isolate their dependencies from their consumers. This can be useful
+in some different cases:
+
+- When sharing Conan packages with other organizations, that vendor (copy, embed or link) the dependencies,
+  so it is not necessary for hte consumers of those packages to have access to those dependencies and the
+  intention is that they always use the shared precompiled binaries.
+- To introduce a hard decoupling between parts of a project.
+
+To make a package vendor its dependencies, define in its recipe the following attribute:
+
+.. code-block:: bash
+
+
+   class MyPkg(ConanFile):
+      name = "mypkg"
+      version = "0.1"
+
+      vendor = True
+
+      requires = "somedep/1.2"
+
+
+When we have this recipe, we can create its binaries with a normal ``conan create .``.
+But when we use this package as a requirement for other packages, its dependencies will be fully invisible.
+The graph will not even expand the ``somedep/1.3`` requirement. This dependency doesn't even need to available
+in the remotes for the consumers, it will not be checked.
+
+Some important notes:
+
+- A package that vendors its dependencies is intended to be consumed always in binary form.
+- The dependencies of a vendoring package is always a fully private and isolated dependency graph, decoupled from
+  the rest of the dependency graph that uses this package.
+- It is the responsibility of the vendoring package and its users to guarantee that vendored dependencies do not
+  collide. If a vendoring package vendors for example ``libssl.a`` as a static library doing a regular copy of
+  it in its package, and there is another package in the graph that also provides ``libssl``, there will be a
+  conflict that Conan cannot detect as ``libssl.a`` is vendored as an internal implementation detail of the package,
+  but not explicitly modeled. Mechanisms like ``provides`` can be used for this purpose, but it is the responsibility
+  of the recipe authors to take it into account.
+- The ``package_id`` of a package that defines ``vendor=True`` is fully independent of its dependencies. The
+  dependencies versions will never affect the ``package_id`` of the vendoring package, so it is important
+  to note that the version of the vendoring package represents a full private dependency graph.
+- The regular ``default_options`` or options values definitions from consumer ``conanfile.py`` recipes do not
+  propagate over vendoring packages, as they don't even expand their dependencies.
+- If a vendoring package binary is missing and/or the user request to build such a package from sources, Conan
+  will fail, raising an error that it is not possible to build it.
+- To allow the expansion of the private dpenedency the ``tools.graph:vendor=build`` configuration can be activated.
+  If that is the case, the private dependency graph of the package will be computed and expanded and the package
+  will be allowed to build.