How do I consume a dependent C library from a Conan package registry using Conan and Cmake in a CI/CD pipeline?

Question

I have two C libaries, where Lib_a.a has a dependency on lib_b.a I am developing a GitLab CI/CD pipeline that will download from the package registry and link to lib_b.a when building lib_a.a

So far, the when building lib_a in the CI/CD pipeline. lib_b.a is downloaded and installed by conan. However I am unsure how or where to reference the header file for lib_b.a

cmake version: 3.26.5 conan version: 1.66.0

I have shared the related settings from the conan and GitLab pipeline configuration files as well as the pipeline terminal output below.

conanfile.py:

class helloRecipe(ConanFile):
    
    name = "lib_a"
    version = "1.0"
    package_type = "library"

    # Optional metadata
    license = "foo"
    author = "bar"
    url = "https://foo.bar"
    description = """text"""
    topics = ("lib_a")

    # Binary configuration
    settings = "os", "compiler", "build_type", "arch"
    requires = "lib_b/1.0beta"
    generators = "CMakeDeps"
    options = {"shared": [True, False], "fPIC": [True, False]}
    default_options = {"shared": False, "fPIC": True}

    def generate(self):
        '''
        The generate() method prepares the build of the package from source. In this 
        case, it could be simplified to an attribute generators = "CMakeToolchain", but 
        it is left to show this important method. In this case, the execution of 
        CMakeToolchain generate() method will create a conan_toolchain.cmake file that 
        translates the Conan settings and options to CMake syntax. The CMakeDeps 
        generator is added for completitude, but it is not strictly necessary until 
        requires are added to the recipe.
        '''
        deps = CMakeDeps(self)
        deps.generate()
        tc = CMakeToolchain(self)
        tc.generate()

    def requirements(self):
        self.requires("lib_b/1.0")

.gitlab-ci.yml:

    - conan profile new ./profile --detect
    - conan remote add lib_b_registry ${CI_API_V4_URL}/projects/11112/packages/conan False -f
    - conan user ci_user -r lib_b_registry -p ${CI_JOB_TOKEN}
    - conan create . -c "tools.build:verbosity='verbose'" --remote=toollib_registry
    - conan remote add gitlab ${CI_API_V4_URL}/projects/11111/packages/conan False -f
    - CONAN_LOGIN_USERNAME=ci_user CONAN_PASSWORD=${CI_JOB_TOKEN} conan upload "*" --confirm --force --all --remote=gitlab

pipeline terminal output:

lib_b/1.0: Retrieving from server 'lib_b_registry' 
lib_b/1.0: Trying with 'lib_b_registry'...
Downloading conanmanifest.txt
Downloading conanfile.py
Downloading conan_export.tgz
lib_b/1.0: Downloaded recipe revision 0
lib_a/1.0: Forced build from source
Installing package: lib_a/1.0
Requirements
    lib_a/1.0 from local cache - Cache
    lib_b/1.0 from 'lib_b_registry' - Downloaded
Packages
    lib_a/1.0:aid9fd64001b74d0ce5hg51de03d17e0b785558fs- Build
    lib_b/1.0:gdw8aba822ahgf46849d2f1bafe4a2a62a9f83b74 - Download
Installing (downloading, building) binaries...
lib_b/1.0: Retrieving package gdw8aba822ahgf46849d2f1bafe4a2a62a9f83b74 from remote 'lib_b_registry' 
Downloading conanmanifest.txt
Downloading conaninfo.txt
Downloading conan_package.tgz
lib_b/1.0: Package installed gdw8aba822ahgf46849d2f1bafe4a2a62a9f83b74 
lib_b/1.0: Downloaded package revision 0

...


/root/.conan/data/lib_a/1.0/_/_/build/aid9fd64001b74d0ce5hg51de03d17e0b785558fs/src/lib_a.h:18:10: fatal error: lib_b.h: No such file or directory
   18 | #include "lib_b.h"
      |          ^~~~~~~~
compilation terminated.

Answer 1

I needed the import() method in my conanfile.py, to import files from lib_b to lib_a, as shown below. Knowing the underlying conan install led me to the answer.

   def imports(self):
      self.copy("*.h", dst="src", src="include")