Enable strace for docker container

[huan]

上帝说，要有光。于是就有了光。

KCN: 方便动态调试，docker启动需要允许strace

docker run --cap-add=SYS_PTRACE  ...

Links

• 如何在Docker容器内部使用gdb进行debug
• Why strace doesn't work in Docker
• ptrace(ltrace/strace) does not work on non-privileged mode even apparmor is disabled and SYS_PTRACE is enabled. moby/moby#21051 (comment)

[huan]

Online system updated, it seems to work now:

bbs@bbs:~$ gdb /kbs/bin/bbsd 
GNU gdb (Debian 7.7.1+dfsg-5) 7.7.1
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
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<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from /kbs/bin/bbsd...done.
(gdb) r
Starting program: /kbs/bin/bbsd 
warning: Error disabling address space randomization: Operation not permitted
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Inferior 1 (process 310) exited normally]
(gdb) b main
Breakpoint 1 at 0x412850: file bbsd_single.c, line 673.
(gdb) r
Starting program: /kbs/bin/bbsd 
warning: Error disabling address space randomization: Operation not permitted
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Breakpoint 1, main (argc=1, argv=0x7ffd18f648e8) at bbsd_single.c:673
673	bbsd_single.c: No such file or directory.
(gdb) l
668	in bbsd_single.c
(gdb) n
676	in bbsd_single.c
(gdb) n
673	in bbsd_single.c
(gdb) n
676	in bbsd_single.c
(gdb) n
673	in bbsd_single.c
(gdb)