gdb does not hit any breakpoints when I run it from inside Docker container

update 2020.01.04: Use the answer given by Kevin W Matthews --- it's better because it grants the necessary individual capabilities without elevating the entire container.

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tldr; use

docker run --privileged

Longer: I was having some problems with gdb in docker---it was attempting (and failing) to disable address space layout randomization---but only on docker-machine, not on my native linux host.

When gdb failed to disable ASLR, all of my breakpoints would be ignored. Using the --privileged flag fixed my issue. Your mileage may vary.

Rather than elevating the entire container, I was able to use the option

--security-opt seccomp=unconfined

to fix address space randomization problems.

Some also recommend enabling the ptrace capability with

--cap-add=SYS_PTRACE

but this didn't seem to have any effect for me.

Here are the same settings for Docker compose:

security_opt:
  - seccomp:unconfined
cap_add:
  - SYS_PTRACE

Details are taken from this Stack Overflow post.