Recipe and Sources in the Same Repo

Sometimes it is more convenient to have the recipe and source code together in the same repository. This is true especially if you are developing and packaging your own library, and not one from a third-party.

There are two different approaches:

Using the exports sources attribute of the conanfile to
export the source code together with the recipe. This way the recipe is self-contained and will not need to fetch the code from external origins when building from sources. It can be considered a “snapshot” of the source code.
Using the scm attribute of the conanfile to capture the remote and commit of your repository automatically.

Exporting the Sources with the Recipe: `exports_sources`

This could be an appropriate approach if we want the package recipe to live in the same repository as the source code it is packaging.

First, let’s get the initial source code and create the basic package recipe:

$ conan new hello/0.1 -t -s

A src folder will be created with the same “hello” source code as in the previous example. You can have a look at it and see that the code is straightforward.

Now let’s have a look at conanfile.py:

from conans import ConanFile, CMake

class HelloConan(ConanFile):
    name = "hello"
    version = "0.1"
    license = "<Put the package license here>"
    url = "<Package recipe repository url here, for issues about the package>"
    description = "<Description of hello here>"
    settings = "os", "compiler", "build_type", "arch"
    options = {"shared": [True, False]}
    default_options = {"shared": False}
    generators = "cmake"
    exports_sources = "src/*"

    def build(self):
        cmake = CMake(self)
        cmake.configure(source_folder="src")
        cmake.build()

        # Explicit way:
        # self.run('cmake "%s/src" %s' % (self.source_folder, cmake.command_line))
        # self.run("cmake --build . %s" % cmake.build_config)

    def package(self):
        self.copy("*.h", dst="include", src="src")
        self.copy("*.lib", dst="lib", keep_path=False)
        self.copy("*.dll", dst="bin", keep_path=False)
        self.copy("*.dylib*", dst="lib", keep_path=False)
        self.copy("*.so", dst="lib", keep_path=False)
        self.copy("*.a", dst="lib", keep_path=False)

    def package_info(self):
        self.cpp_info.libs = ["hello"]

There are two important changes:

Added the exports_sources field, indicating to Conan to copy all the files from the local src folder into the package recipe.
Removed the source() method, since it is no longer necessary to retrieve external sources.

Also, you can notice the two CMake lines:

include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)
conan_basic_setup()

They are not added in the package recipe, as they can be directly added to the src/CMakeLists.txt file.

And simply create the package for user and channel demo/testing as described previously:

$ conan create . demo/testing
...
hello/0.1@demo/testing test package: Running test()
Hello world Release!

Capturing the Remote and Commit: `scm`

Warning

This is an experimental feature subject to breaking changes in future releases. Although this is an experimental feature, the use of the feature using scm_to_conandata is considered stable.

You can use the scm attribute with the url and revision field set to auto. When you export the recipe (or when conan create is called) the exported recipe will capture the remote and commit of the local repository:

 import os
 from conans import ConanFile, CMake, tools

 class HelloConan(ConanFile):
     scm = {
         "type": "git",  # Use "type": "svn", if local repo is managed using SVN
         "subfolder": "hello",
         "url": "auto",
         "revision": "auto",
         "password": os.environ.get("SECRET", None)
     }
     ...

You can commit and push the conanfile.py to your origin repository, which will always preserve the auto values. When the file is exported to the Conan local cache (except you have uncommitted changes, read below), these data will be stored in the conanfile.py itself (Conan will modify the file) or in a special file conandata.yml that will be stored together with the recipe, depending on the value of the configuration parameter scm_to_conandata.

If the scm_to_conandata is not activated (default behavior in Conan v1.x) Conan will store a modified version of the conanfile.py with the values of the fields in plain text:
    import os
    from conans import ConanFile, CMake, tools

    class HelloConan(ConanFile):
        scm = {
            "type": "git",
            "subfolder": "hello",
            "url": "https://github.com/conan-io/hello.git",
            "revision": "437676e15da7090a1368255097f51b1a470905a0",
            "password": "MY_SECRET"
        }
        ...
So when you upload the recipe to a Conan remote, the recipe will contain the “resolved” URL and commit.
If scm_to_conandata is activated, the value of these fields (except username and password) will be stored in the conandata.yml file that will be automatically exported with the recipe.

Whichever option you choose, the data resolved will be asigned by Conan to the corresponding field when the recipe file is loaded, and they will be available for all the methods defined in the recipe. Also, if building the package from sources, Conan will fetch the code in the captured url/commit before running the method source() in the recipe (if defined).

As SCM attributes are evaluated in the local directory context (see scm attribute), you can write more complex functions to retrieve the proper values, this source conanfile.py will be valid too:

 import os
 from conans import ConanFile, CMake, tools

 def get_remote_url():
      """ Get remote url regardless of the cloned directory """
      here = os.path.dirname(__file__)
      svn = tools.SVN(here)
      return svn.get_remote_url()

 class HelloConan(ConanFile):
      scm = {
         "type": "svn",
         "subfolder": "hello",
         "url": get_remote_url(),
         "revision": "auto"
      }
     ...

Tip

When doing a conan create or conan export, Conan will capture the sources of the local scm project folder in the local cache.

This allows building packages making changes to the source code without the need of committing them and pushing them to the remote repository. This convenient to speed up the development of your packages when cloning from a local repository.

So, if you are using the scm feature, with some auto field for url and/or revision and you have uncommitted changes in your repository a warning message will be printed:

$ conan export . hello/0.1@demo/testing

 hello/0.1@demo/testing: WARN: There are uncommitted changes, skipping the replacement of 'scm.url'
 and 'scm.revision' auto fields. Use --ignore-dirty to force it.
 The 'conan upload' command will prevent uploading recipes with 'auto' values in these fields.

As the warning message explains, the auto fields won’t be replaced unless you specify --ignore-dirty, and by default, the conan upload will block the upload of the recipe. This prevents recipes to be uploaded with incorrect scm values exported. You can use conan upload --force to force uploading the recipe with the auto values un-replaced.

Recipe and Sources in the Same Repo

Exporting the Sources with the Recipe: exports_sources

Capturing the Remote and Commit: scm

Exporting the Sources with the Recipe: `exports_sources`

Capturing the Remote and Commit: `scm`