TLDR; 2. Using the --foreground option in timeout command which calls docker exec or other commands might prevent the command hanging.
e.g. timeout --foreground 5 docker exec -i
$ timeout 1s sleep 10
$ echo $?
$ timeout 10s sleep 1
$ echo $?
$ timeout --help
Usage: timeout [OPTION] DURATION COMMAND [ARG]...
or: timeout [OPTION]
Start COMMAND, and kill it if still running after DURATION.
Mandatory arguments to long options are mandatory for short options too.
exit with the same status as COMMAND, even when the
command times out
when not running timeout directly from a shell prompt,
allow COMMAND to read from the TTY and get TTY signals;
in this mode, children of COMMAND will not be timed out
also send a KILL signal if COMMAND is still running
this long after the initial signal was sent
specify the signal to be sent on timeout;
SIGNAL may be a name like 'HUP' or a number;
see 'kill -l' for a list of signals
--help display this help and exit
--version output version information and exit
DURATION is a floating point number with an optional suffix:
's' for seconds (the default), 'm' for minutes, 'h' for hours or 'd' for days.
If the command times out, and --preserve-status is not set, then exit with
status 124. Otherwise, exit with the status of COMMAND. If no signal
is specified, send the TERM signal upon timeout. The TERM signal kills
any process that does not block or catch that signal. It may be necessary
to use the KILL (9) signal, since this signal cannot be caught, in which
case the exit status is 128+9 rather than 124.
GNU coreutils online help:
For complete documentation, run: info coreutils 'timeout invocation'