Remote LLDB debugging - Docker container - linux

Question

I'm trying to set up a remote debugging with LLDB 4.0.1.
There's a docker (17.06.0-ce) container with Arch linux.
Docker container is set in privileged mode, so now LLDB can be started in container.
Container contains core_service which is Rust executable.
Commands run inside container
(lldb) target create target/debug/core_service
Current executable set to 'target/debug/core_service' (x86_64).
(lldb) process launch
Process 182 launched: '/srv/core_service/target/debug/core_service' (x86_64)
Problem exists with remote debugging, lldb-server is started inside container with lldb-server platform --server --listen 0.0.0.0:1234.
I can connect from host lldb to container lldb-server, but I can't attach/create processes.
Commands run on host (lldb-server in container = localhost:1234)
(lldb) platform select remote-linux
Platform: remote-linux
Connected: no
(lldb) platform connect connect://localhost:1234
Platform: remote-linux
Triple: x86_64-*-linux-gnu
OS Version: 4.12.4 (4.12.4-1-ARCH)
Kernel: #1 SMP PREEMPT Fri Jul 28 18:54:18 UTC 2017
Hostname: 099bd76c07c9
Connected: yes
WorkingDir: /srv/core_service
(lldb) target create target/debug/core_service
Current executable set to 'target/debug/core_service' (x86_64).
(lldb) process launch
error: connect remote failed (Connection refused)
error: process launch failed: Connection refused
How can I fix it? Are there any docker, arch linux settings that would cause this error?
It seems, like there's some problem with lldb-server permissions in docker container.
Commands run on host (lldb-server in container)
(lldb) platform shell ps -A
PID TTY TIME CMD
1 ? 00:00:00 bash
9 ? 00:00:00 nginx
10 ? 00:00:00 nginx
11 ? 00:00:00 lldb-server
25 ? 00:00:00 core_service
59 ? 00:00:00 lldb-server
68 ? 00:00:00 ps
(lldb) platform shell kill -9 25
(lldb) platform process launch target/debug/core_service
error: connect remote failed (Connection refused)
error: Connection refused
(lldb) platform process launch anything
error: connect remote failed (Connection refused)
error: Connection refused
But I can't figure out what can it be. lldb-server is run as root in container, I can execute shell commands using lldb.

Answer 1

There is needed both platform port (1234 in your case) and gdbserver port (randomly generated by default). You can enforce the gdbserver port by lldb-server option --gdbserver-port.
Tested on Fedora 29 x86_64:
docker run --privileged -p 5000:5000 -p 5001:5001 fedora bash -c 'dnf -y install lldb;lldb-server platform --server --listen 0.0.0.0:5000 --gdbserver-port 5001'
and
echo 'int main(){}' >main.c;gcc -g -o main main.c;lldb -o 'platform select remote-linux' -o 'platform connect connect://localhost:5000' -o "target create ./main" -o 'b main' -o 'process launch'
(lldb) process launch
Process 45 stopped
* thread #1, name = 'main', stop reason = breakpoint 1.1
frame #0: 0x000000000040110f main`main at main.c:1
-> 1 int main(){}
Process 45 launched: '/root/main' (x86_64)
(lldb) _

Answer 2

This may be because the server cannot see any process on the host. It is still wrapped in its own PID namespace. When you launch the LLDB server, use a host pid name space
docker run --pid=host --privileged <yourimage>
Hopefully this will allow your container see all the host processes