Execut binaries / tests on host that are built by non-host toolchain

Scenario:

• We would like to build our sources by an external / hermetic toolchain so all includes, libs and tools from the host are ignored
• To do so, a new toolchain is introduced to Bazel-Configuration. >>> working well
• Using -Wl,-rpath=$ORIGIN/%{runtime_library_search_directories}/... the relative path from the binary to the libs that should be loaded on runtime gets defined >>> works quite well
• When doing bazel run the Binary is executed but the host's LD is beeing used
• To get rid of this a wrapper (written in Bash) is injected using --run_under. >>> dirty workaround

Problem:

--run_under could only be used once. We also need this option to execute tests within a specific environment and so this option is not the way of choice for us. IMHO it's also a bit dirty workaround.

We also tried to use -Wl,--dynamic-linker=<<PATH_TO_LD>>. But we were not able to get neither a relative nor an absolute path to LD when linking the executable.

Questions:

Is there ...

• ... any way to get the absolute/relative path to LD when linking?
• ... any other way of running a binary on Host using a toolchain?
• ... a possibility to do sandboxing/chroot so the correct LD of the toolchain is being used automatically?

Sidenotes:

• Bazel 1.1.0 is used
• the toolchain is GCC8 build from sources
• the host is an Ubuntu 18.04.1 image running in docker