Include <headers.h> installed in non standard location

I'm currently working with a third party library, which has headers declared using angular brackets, like a standard library :

#include <header.h>

However, these headers are installed in a non standard place, something like /opt/company/software/version/part_software/include

With a more traditional builder like MAKE, I can just use CXXFLAGS to indicate to g++ to look in this folder too for libraries, which finally comes down to pass a -I/opt/company/software/version/part_software/include option to g++.

When trying to do the same thing in bazel, using copts = [ "-I/opt/company/software/version/part_software/include" ], I get a "path outside of the execution root" error.

It's my understanding that bazel don't like the place where the lib is installed because the build needs to be reproducible, and including a library located outside the execution root violate this constraint.

A ugly hack I've come with is to create symbolic link of the headers in /usr/local/include, and use copts = [ "-I/usr/local/include" ] in the bazel build. However, I find this approach very hacky, and I'd like to find a more bazely approach to the problem.

Note : I can't install the program during the bazel build, as it uses a closed installer on which I have no control over. This installer can't be run in the bazel's sandboxed environment, as it needs to write on certain paths not accessible within the environment.

Solution

So, it turns out that the bazelesque way of including a third part library is simply to create package encapsulating the library.

Thanks to this useful discussion, I've managed to create a package with my third party library.

First we need a BUILD file, here named package_name.BUILD

package(
    default_visibility = ["//visibility:public"]
)

cc_library(
    name = "third_party_lib_name", #name to reference the third party library in other BUILD files
    srcs = [
        "external/soft/lib/some_lib.so", #.so files to include in the lib
        "software/lib/os/arch/lib_some_plugin.so",
    ],
    hdrs = glob([ # the glob takes all the headers needed
        "software/include/**/*.h",
        "software/include/**/*.hpp",
    ]), 
    includes = ["software/include/"], # Specify which files are included when we use the library
)

Now we need to reference the lib a a submodule in the WORKSPACE file :

  new_local_repository(
      name = "package_name",
      path = "opt/company/software/version",
      # build_file: path to the BUILD file, here in the same directory that the main WORKSPACE one
      build_file = __workspace_dir__ + "/package_name.BUILD", 
      )

Now, instead of using copt to references the needed headers, I'm just adding a line to the deps of the cc_rule when needed, e.g :

cc_library(
    name="some_internal_lib",
    srcs = ["some_internal_lib.cc"],
    deps = [
         "@package_name//:third_party_lib_name", #referencing the third party lib
           ],
)