Re: [GHC] #15230: unix tests fail under CircleCI's fedora environment

15 Jun 2018

      #15230: unix tests fail under CircleCI's fedora environment
-------------------------------------+-------------------------------------
        Reporter:  bgamari           |                Owner:  bgamari
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.6.1
       Component:  Continuous        |              Version:  8.4.3
  Integration                        |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by bgamari):

 I suspect that this is due to our use of Docker in the CircleCI
 infrastructure as I am unable to reproduce this under a Fedora VM.

 I have SSH'd into the CircleCI build machine and tried running
 `getGroupEntryForName` under `strace`. The relevant bit appears to be:
 {{{
 openat(AT_FDCWD, "/lib64/libpcre2-8.so.0", O_RDONLY|O_CLOEXEC) = 3
 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0 !\0\0\0\0\0\0"...,
 832) = 832
 fstat(3, {st_mode=S_IFREG|0755, st_size=533864, ...}) = 0
 mmap(NULL, 2626088, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0)
 = 0x7f00d3f75000
 mprotect(0x7f00d3ff6000, 2093056, PROT_NONE) = 0
 mmap(0x7f00d41f5000, 8192, PROT_READ|PROT_WRITE,
 MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x80000) = 0x7f00d41f5000
 close(3)                                = 0
 mprotect(0x7f00d41f5000, 4096, PROT_READ) = 0
 mprotect(0x7f00d440c000, 4096, PROT_READ) = 0
 --- SIGVTALRM {si_signo=SIGVTALRM, si_code=SI_TIMER, si_timerid=0,
 si_overrun=0, si_value={int=0, ptr=NULL}} ---
 rt_sigreturn({mask=[]})                 = 0
 mprotect(0x7f00d4633000, 4096, PROT_READ) = 0
 mprotect(0x7f00d4875000, 12288, PROT_READ) = 0
 statfs("/sys/fs/selinux", 0x7ffc3c3aec40) = -1 ENOENT (No such file or
 directory)
 statfs("/selinux", 0x7ffc3c3aec40)      = -1 ENOENT (No such file or
 directory)
 openat(AT_FDCWD, "/proc/filesystems", O_RDONLY|O_CLOEXEC) = 3
 fstat(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
 read(3, "nodev\tsysfs\nnodev\trootfs\nnodev\tr"..., 1024) = 351
 read(3, "", 1024)                       = 0
 close(3)                                = 0
 access("/etc/selinux/config", F_OK)     = -1 ENOENT (No such file or
 directory)
 munmap(0x7f00d6059000, 17156)           = 0
 rt_sigprocmask(SIG_BLOCK, [HUP USR1 USR2 PIPE ALRM CHLD TSTP URG VTALRM
 PROF WINCH IO], [], 8) = 0
 getpid()                                = 9044
 getpid()                                = 9044
 getpid()                                = 9044
 openat(AT_FDCWD, "/sys/fs/kdbus/0-system/bus", O_RDWR|O_NOCTTY|O_CLOEXEC)
 = -1 ENOENT (No such file or directory)
 socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 3
 getsockopt(3, SOL_SOCKET, SO_RCVBUF, [212992], [4]) = 0
 setsockopt(3, SOL_SOCKET, SO_RCVBUFFORCE, [8388608], 4) = -1 EPERM
 (Operation not permitted)
 setsockopt(3, SOL_SOCKET, SO_RCVBUF, [8388608], 4) = 0
 getsockopt(3, SOL_SOCKET, SO_SNDBUF, [212992], [4]) = 0
 setsockopt(3, SOL_SOCKET, SO_SNDBUFFORCE, [8388608], 4) = -1 EPERM
 (Operation not permitted)
 setsockopt(3, SOL_SOCKET, SO_SNDBUF, [8388608], 4) = 0
 connect(3, {sa_family=AF_UNIX,
 sun_path="/var/run/dbus/system_bus_socket"}, 33) = -1 ENOENT (No such file
 or directory)
 getpid()                                = 9044
 close(3)                                = 0
 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
 ioctl(1, TCGETS, {B38400 opost isig icanon echo ...}) = 0
 write(2, "getGroupEntryForName: ", 22getGroupEntryForName: )  = 22
 write(2, "getGroupEntryForName: does not e"..., 64getGroupEntryForName:
 does not exist (No such file or directory)) = 64
 write(2, "\n", 1
 )                       = 1
 }}}

 The most interesting line of the above is
 {{{
 connect(3, {sa_family=AF_UNIX,
 sun_path="/var/run/dbus/system_bus_socket"}, 33) = -1 ENOENT (No such file
 or directory)
 }}}
 which suggests that `dbus` isn't running (which `ps` confirms). Moreover
 `/var/run/dbus` doesn't exist. However, strangely, `dnf` suggests that the
 `dbus` package is indeed installed. Moreover, `systemctl status fails:
 {{{
 $ sudo systemctl status
 Failed to connect to bus: No such file or directory
 }}}
 This is somewhat expected given that this is a container and it explains
 why `dbus` wasn't started.

 The next question is why this testcase is calling for `dbus` at all. I do
 see a few mentions of `systemd` in the PAM configuration, although only as
 optional authentication steps. Perhaps more concerning is this in
 `/etc/nsswitch.conf`:
 {{{
 passwd:      sss files systemd
 shadow:     files sss
 group:       sss files systemd
 }}}
 Indeed removing the mentions of `systemd` from these lines allows the test
 to fail in the expected way:
 {{{
 $ getGroupEntryForName.run/getGroupEntryForName
 getGroupEntryForName: getGroupEntryForName: does not exist (no such group)
 }}}

 It looks like we will need to modify `nsswitch.conf` to eliminate mentions
 of systemd while building the Docker image.

-- 
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15230#comment:2
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler