[Docker] shim error: open /dev/ptmx



  • Since http://forums.docker.com looks a hive of activity, asking here just in case someone else has better google-fu than me, or actually knows what I'm looking at.

    I'm sure it's something I'm doing/not doing, rather than a problem with docker itself.

    Summary: This error, instead of starting the container. (Alpine is merely a tiny distro to reduce amount of space needed.)

    [root@host ~]# docker run -it alpine /bin/sh
    docker: Error response from daemon: shim error: open /dev/ptmx: no such file or directory.
    

    What I'd expect:

    pjh@hpdesktop:~$ docker run -it alpine /bin/sh
    / # ls
    bin    dev    etc    home   lib    media  mnt    proc   root   run    sbin   srv    sys    tmp    usr    var
    / # exit
    pjh@hpdesktop:~$ 
    

    Variations on googling that error message have provided me with no useful information whatsoever.

    However, what *does* work with any command is:
    [root@ccu ~]# docker run alpine ls | column -c180 
    bin     dev     etc     home    lib     media   mnt     proc    root    run     sbin    srv     sys     tmp     usr     var
    
    Even sh is happy to run. When tickled this way:
    [root@ccu ~]# docker run alpine sh --help
    BusyBox v1.26.2 (2017-06-11 06:38:33 GMT) multi-call binary.
    
    Usage: sh [-/+OPTIONS] [-/+o OPT]... [-c 'SCRIPT' [ARG0 [ARGS]] / FILE [ARGS]]
    
    Unix shell interpreter
    

    The system this is happening on has been built with buildroot, and while not truly embedded, is booting and running of a 2GB CF card. So it's basically running off rootfs with some other tempfs bits thrown in.

    This means it needs export DOCKER_RAMDISK=true before starting.

    Kernel:
    [root@host ~]# uname -a
    Linux host 4.11.8 #1 SMP Wed Nov 8 15:52:52 UTC 2017 i686 GNU/Linux
    
    Docker:
    [root@host ~]# docker info
    Containers: 9
     Running: 0
     Paused: 0
     Stopped: 9
    Images: 3
    Server Version: 17.04.0-ce
    Storage Driver: overlay2
     Backing Filesystem: ramfs
     Supports d_type: true
     Native Overlay Diff: false
    Logging Driver: json-file
    Cgroup Driver: cgroupfs
    Plugins: 
     Volume: local
     Network: bridge host macvlan null overlay
    Swarm: inactive
    Runtimes: runc
    Default Runtime: runc
    Init Binary: 
    containerd version: 422e31ce907fd9c3833a38d7b8fdd023e5a76e73
    runc version: N/A (expected: 9c2d8d184e5da67c95d601382adf14862e4f2228)
    init version: N/A (expected: 949e6facb77383876aeff8a6944dde66b3089574)
    Kernel Version: 4.11.8
    Operating System: Buildroot 2017.05.1
    OSType: linux
    Architecture: i686
    CPUs: 1
    Total Memory: 1.903GiB
    Name: ccu
    ID: K5AC:SVZP:BFNO:FC4Z:ZFFX:NBA4:S3SI:DNY3:NIZR:3IUQ:NITW:NYMW
    Docker Root Dir: /var/lib/docker
    Debug Mode (client): false
    Debug Mode (server): false
    Registry: https://index.docker.io/v1/
    Experimental: false
    Insecure Registries:
     127.0.0.0/8
    Live Restore Enabled: false
    
    Runc
    [root@host ~]# runc --version
    runc version commit: 9c2d8d184e5da67c95d601382adf14862e4f2228
    spec: 1.0.0-rc2-dev
    
    Startup log
    time="2017-11-13T14:34:37.086817175Z" level=info msg="libcontainerd: new containerd process, pid: 4735" 
    time="2017-11-13T14:34:37.123201967Z" level=warning msg="containerd: low RLIMIT_NOFILE changing to max" current=1024 max=4096 
    time="2017-11-13T14:34:38.114885547Z" level=info msg="[graphdriver] using prior storage driver: overlay2" 
    time="2017-11-13T14:34:38.140549144Z" level=info msg="Graph migration to content-addressability took 0.00 seconds" 
    time="2017-11-13T14:34:38.141016801Z" level=warning msg="Your kernel does not support cgroup blkio weight" 
    time="2017-11-13T14:34:38.141060662Z" level=warning msg="Your kernel does not support cgroup blkio weight_device" 
    time="2017-11-13T14:34:38.141788687Z" level=info msg="Loading containers: start." 
    time="2017-11-13T14:34:38.752964968Z" level=info msg="Loading containers: done." 
    time="2017-11-13T14:34:38.756510390Z" level=warning msg="Not using native diff for overlay2: failed to set opaque flag on middle layer: operation not supported" 
    time="2017-11-13T14:34:38.764741325Z" level=warning msg="failed to retrieve docker-runc version: unknown output format: runc version commit: 9c2d8d184e5da67c95d601382adf14862e4f2228\nspec: 1.0.0-rc2-dev\n" 
    time="2017-11-13T14:34:38.764852233Z" level=warning msg="failed to retrieve docker-init version" 
    time="2017-11-13T14:34:38.765126011Z" level=info msg="Daemon has completed initialization" 
    time="2017-11-13T14:34:38.765165122Z" level=info msg="Docker daemon" commit=4845c56 graphdriver=overlay2 version=17.04.0-ce 
    time="2017-11-13T14:34:38.877487498Z" level=info msg="API listen on /var/run/docker.sock" 
    
    Log from running the first example
    time="2017-11-13T16:25:57.295550866Z" level=info msg="No non-localhost DNS nameservers are left in resolv.conf. Using default external servers: [nameserver 8.8.8.8 nameserver 8.8.4.4]" 
    time="2017-11-13T16:25:57.295608975Z" level=info msg="IPv6 enabled; Adding default IPv6 external servers: [nameserver 2001:4860:4860::8888 nameserver 2001:4860:4860::8844]" 
    time="2017-11-13T16:25:57.368015082Z" level=error msg="containerd: start container" error="shim error: open /dev/ptmx: no such file or directory" id=11805d44d129b74b5e11057726d2e263db0674dfd635155ebd9d6ae74d343f06 
    time="2017-11-13T16:25:57.396213676Z" level=error msg="stream copy error: reading from a closed fifo\ngithub.com/docker/docker/vendor/github.com/tonistiigi/fifo.(*fifo).Read\n\t/data/src/embedded/host4/branches/pjh_main/buildroot/buildroot/output/build/docker-engine-v17.04.0-ce/gopath/src/github.com/docker/docker/vendor/github.com/tonistiigi/fifo/fifo.go:142\nbufio.(*Reader).fill\n\t/data/src/embedded/host4/branches/pjh_main/buildroot/buildroot/output/host/usr/lib/go/src/bufio/bufio.go:97\nbufio.(*Reader).WriteTo\n\t/data/src/embedded/host4/branches/pjh_main/buildroot/buildroot/output/host/usr/lib/go/src/bufio/bufio.go:472\nio.copyBuffer\n\t/data/src/embedded/host4/branches/pjh_main/buildroot/buildroot/output/host/usr/lib/go/src/io/io.go:380\nio.Copy\n\t/data/src/embedded/host4/branches/pjh_main/buildroot/buildroot/output/host/usr/lib/go/src/io/io.go:360\ngithub.com/docker/docker/pkg/pools.Copy\n\t/data/src/embedded/host4/branches/pjh_main/buildroot/buildroot/output/build/docker-engine-v17.04.0-ce/gopath/src/github.com/docker/docker/pkg/pools/pools.go:60\ngithub.com/docker/docker/container/stream.(*Config).CopyToPipe.func1.1\n\t/data/src/embedded/host4/branches/pjh_main/buildroot/buildroot/output/build/docker-engine-v17.04.0-ce/gopath/src/github.com/docker/docker/container/stream/streams.go:121\nruntime.goexit\n\t/data/src/embedded/host4/branches/pjh_main/buildroot/buildroot/output/host/usr/lib/go/src/runtime/asm_386.s:1612" 
    time="2017-11-13T16:25:57.398610377Z" level=error msg="Create container failed with error: shim error: open /dev/ptmx: no such file or directory" 
    time="2017-11-13T16:25:57.486411631Z" level=error msg="Handler for POST /v1.28/containers/11805d44d129b74b5e11057726d2e263db0674dfd635155ebd9d6ae74d343f06/start returned error: shim error: open /dev/ptmx: no such file or directory" 
    

    I've spent far too long on this already and am starting to pull what's left of my hair out.



  • Incidentally, it does this on other images as well - the other one (well the first one) I tried was Ubuntu..

    [root@host~]# docker run ubuntu ls -l /dev/ptmx /dev/pts
    lrwxrwxrwx 1 root root 8 Nov 13 16:32 /dev/ptmx -> pts/ptmx
    
    /dev/pts:
    total 0
    crw-rw-rw- 1 root root 5, 2 Nov 13 16:32 ptmx
    
    [root@host ~]# docker run -it ubuntu sh
    docker: Error response from daemon: shim error: open /dev/ptmx: no such file or directory.
    


  • And in case it's stuff on the host that's the problem I created the soft link here:

    [root@host ~]# ls /dev/ptmx -l
    crw-rw-rw- 1 root tty 5, 2 Nov 13 14:34 /dev/ptmx
    [root@host ~]# ls -l /dev/pts/ptmx 
    lrwxrwxrwx 1 root root 9 Nov 13 16:34 /dev/pts/ptmx -> /dev/ptmx
    


  • Shit. I've seen this before but definitely don't remember what the problem was. I'll search through old email archives. I don't think the soft link is all you need for ptmx, though, I think there's a special mount required as pseudo-terminals are created on the fly. All of this is normally handled by a distribution but it looks like you're doing Linux From Scratch to me.



  • Ok, two things that might help you in the future, since you already seem to have solved the problem with a symlink:

    • In docker run -it, i means "keep stdin open" and t means "tell the container that stdin is a tty". If you don't need a tty, just -i should work.
    • If you're using docker run interactively for a container that isn't going to run a service, add the --rm option so it doesn't leave the container on disk after it exits.


  • @heterodox said in [Docker] shim error: open /dev/ptmx:

    Linux From Scratch

    Yup.

    @ben_lubar said in [Docker] shim error: open /dev/ptmx:

    since you already seem to have solved the problem

    Er, no I haven't. Will try the other things though when I get access again.

    You both have given me ideas for further research though.



  • @heterodox said in Docker.:

    I think there's a special mount required as pseudo-terminals are created on the fly.

    @ben_lubar said in Docker.:

    • In docker run -it, i means "keep stdin open" and t means "tell the container that stdin is a tty". If you don't need a tty, just -i should work.

    Think I've found the problem. Cheers guys.

    Now - how to fix it....



  • Expected behaviour - Desktop:

    pjh@hpdesktop:~$ docker run -it ubuntu bash
    root@4ef46a7ff151:/# ls -l /dev/pts
    total 0
    crw--w---- 1 root tty  136, 0 Nov 14 12:24 0
    crw-rw-rw- 1 root root   5, 2 Nov 14 12:24 ptmx
    root@4ef46a7ff151:/# ls /proc/1/fd -l
    total 0
    lrwx------ 1 root root 64 Nov 14 12:24 0 -> /dev/pts/0
    lrwx------ 1 root root 64 Nov 14 12:24 1 -> /dev/pts/0
    lrwx------ 1 root root 64 Nov 14 12:24 2 -> /dev/pts/0
    lrwx------ 1 root root 64 Nov 14 12:24 255 -> /dev/pts/0
    root@4ef46a7ff151:/# exit
    
    pjh@hpdesktop:~$ docker run -i ubuntu bash
    ls -l /dev/pts
    total 0
    crw-rw-rw- 1 root root 5, 2 Nov 14 12:24 ptmx
    ls -l /proc/1/fd
    total 0
    lr-x------ 1 root root 64 Nov 14 12:24 0 -> pipe:[81256183]
    l-wx------ 1 root root 64 Nov 14 12:24 1 -> pipe:[81256184]
    l-wx------ 1 root root 64 Nov 14 12:24 2 -> pipe:[81256185]
    pjh@hpdesktop:~$ 
    

    LFS system:

    [root@lfs ~]# docker run -it ubuntu bash
    docker: Error response from daemon: shim error: open /dev/ptmx: no such device.
    
    [root@lfs ~]# docker run -i ubuntu bash
    ls -l /dev/pts
    total 0
    crw-rw-rw- 1 root root 5, 2 Nov 14 12:26 ptmx
    ls /proc/1/fd -l
    total 0
    lr-x------ 1 root root 64 Nov 14 12:26 0 -> pipe:[36409047]
    l-wx------ 1 root root 64 Nov 14 12:26 1 -> pipe:[36409048]
    l-wx------ 1 root root 64 Nov 14 12:26 2 -> pipe:[36409049]
    [root@lfs ~]# 
    

    Stumbled across a vague workaround for something totally different (this, via this) I need to do some more research on, but..

    LFS:

    [root@ccu ~]# docker run -i ubuntu script /dev/null
    Script started, file is /dev/null
    # ls -l /dev/pts
    ls -l /dev/pts
    total 0
    crw--w---- 1 root tty  136, 0 Nov 14 12:40 0
    crw-rw-rw- 1 root root   5, 2 Nov 14  2017 ptmx
    # ls /proc/$$/fd -l
    ls /proc/$$/fd -l
    total 0
    lrwx------ 1 root root 64 Nov 14 12:40 0 -> /dev/pts/0
    lrwx------ 1 root root 64 Nov 14 12:40 1 -> /dev/pts/0
    lrwx------ 1 root root 64 Nov 14 12:40 10 -> /dev/tty
    lrwx------ 1 root root 64 Nov 14 12:40 2 -> /dev/pts/0
    # 
    Script done, file is /dev/null
    [root@ccu ~]# 
    

    However still doesn't do what I'm totally after...

    [root@ccu ~]# docker run -di ubuntu script /dev/null
    af34c875980f32388da32c872e7f7a2253f1335139b933209802604eaa20f105
    [root@ccu ~]# docker exec -it af34c875980f32388da32c872e7f7a2253f1335139b933209802604eaa20f105  bash
    rpc error: code = 2 desc = shim error: open /dev/ptmx: no such device
    [root@ccu ~]# docker exec -i af34c875980f32388da32c872e7f7a2253f1335139b933209802604eaa20f105  bash
    ls -l /dev/pts
    total 0
    crw--w---- 1 root tty  136, 0 Nov 14 12:42 0
    crw-rw-rw- 1 root root   5, 2 Nov 14 12:42 ptmx
    ls /proc/$$/fd -l
    total 0
    lr-x------ 1 root root 64 Nov 14 12:43 0 -> pipe:[36894995]
    l-wx------ 1 root root 64 Nov 14 12:43 1 -> pipe:[36894996]
    l-wx------ 1 root root 64 Nov 14 12:43 2 -> pipe:[36894997]
    [root@ccu ~]# 
    [root@ccu ~]# docker exec -i af34c875980f32388da32c872e7f7a2253f1335139b933209802604eaa20f105  script /dev/null
    Script started, file is /dev/null
    # ls /proc/$$/fd -l
    ls /proc/$$/fd -l
    total 0
    lrwx------ 1 root root 64 Nov 14 12:45 0 -> /dev/pts/1
    lrwx------ 1 root root 64 Nov 14 12:45 1 -> /dev/pts/1
    lrwx------ 1 root root 64 Nov 14 12:45 10 -> /dev/tty
    lrwx------ 1 root root 64 Nov 14 12:45 2 -> /dev/pts/1
    # 
    


  • Ok - final workaround until I get more time to waste on this..

    [root@host ~]# docker run --name my_container -di ubuntu script -q -c /bin/bash /dev/null
    f859e4fa4ff78c0b7fe223ed8e49e2146e450b1b86ae8a544b19a947e994df17
    [root@host ~]# docker exec -i my_container env TERM=xterm script -q -c "/bin/bash" /dev/null
    root@f859e4fa4ff7:/# ls
    ls
    bin   dev  home  media  opt   root  sbin  sys  usr
    boot  etc  lib   mnt    proc  run   srv   tmp  var
    root@f859e4fa4ff7:/# ls /proc/self/fd -l
     ls /proc/self/fd -l
    total 0
    lrwx------ 1 root root 64 Nov 14 16:26 0 -> /dev/pts/1
    lrwx------ 1 root root 64 Nov 14 16:26 1 -> /dev/pts/1
    lrwx------ 1 root root 64 Nov 14 16:26 2 -> /dev/pts/1
    lr-x------ 1 root root 64 Nov 14 16:26 3 -> /proc/21/fd
    root@f859e4fa4ff7:/# 
    

    Don't like it, but I've wasted too much time on this already.

    Meanwhile, over on forums.docker where I asked a meta-question about where I should ask about this problem:

    0_1510677296735_90b3346b-eb15-4bf8-91f9-c374fe3f01b3-image.png


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