github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/g3doc/user_guide/FAQ.md (about)

     1  # FAQ
     2  
     3  [TOC]
     4  
     5  ### What operating systems are supported? {#supported-os}
     6  
     7  Today, gVisor requires Linux.
     8  
     9  ### What CPU architectures are supported? {#supported-cpus}
    10  
    11  gVisor currently supports [x86_64/AMD64](https://en.wikipedia.org/wiki/X86-64)
    12  compatible processors. Preliminary support is also available for
    13  [ARM64](https://en.wikipedia.org/wiki/ARM_architecture#AArch64).
    14  
    15  ### Do I need to modify my Linux application to use gVisor? {#modify-app}
    16  
    17  No. gVisor is capable of running unmodified Linux binaries.
    18  
    19  ### What binary formats does gVisor support? {#supported-binaries}
    20  
    21  gVisor supports Linux
    22  [ELF](https://en.wikipedia.org/wiki/Executable_and_Linkable_Format) binaries.
    23  
    24  Binaries run in gVisor should be built for the
    25  [AMD64](https://en.wikipedia.org/wiki/X86-64) or
    26  [AArch64](https://en.wikipedia.org/wiki/ARM_architecture#AArch64) CPU
    27  architectures.
    28  
    29  ### Can I run Docker images using gVisor? {#docker-images}
    30  
    31  Yes. Please see the [Docker Quick Start][docker].
    32  
    33  ### Can I run Kubernetes pods using gVisor? {#k8s-pods}
    34  
    35  Yes. Please see the [Kubernetes Quick Start][k8s].
    36  
    37  ### What's the security model? {#security-model}
    38  
    39  See the [Security Model][security-model].
    40  
    41  ## Troubleshooting
    42  
    43  ### My container runs fine with `runc` but fails with `runsc` {#app-compatibility}
    44  
    45  If you’re having problems running a container with `runsc` it’s most likely due
    46  to a compatibility issue or a missing feature in gVisor. See
    47  [Debugging][debugging].
    48  
    49  ### When I run my container, docker fails with: `open /run/containerd/.../<containerid>/log.json: no such file or directory` {#memfd-create}
    50  
    51  You are using an older version of Linux which doesn't support `memfd_create`.
    52  
    53  This is tracked in [bug #268](https://gvisor.dev/issue/268).
    54  
    55  ### When I run my container, docker fails with: `flag provided but not defined: -console` {#old-docker}
    56  
    57  You're using an old version of Docker. See [Docker Quick Start][docker].
    58  
    59  ### I can’t see a file copied with: `docker cp` {#fs-cache}
    60  
    61  For performance reasons, gVisor caches directory contents, and therefore it may
    62  not realize a new file was copied to a given directory. To invalidate the cache
    63  and force a refresh, create a file under the directory in question and list the
    64  contents again.
    65  
    66  As a workaround, shared root filesystem can be enabled. See
    67  [Filesystem][filesystem].
    68  
    69  This bug is tracked in [bug #4](https://gvisor.dev/issue/4).
    70  
    71  Note that `kubectl cp` works because it does the copy by exec'ing inside the
    72  sandbox, and thus gVisor's internal cache is made aware of the new files and
    73  directories.
    74  
    75  ### I'm getting an error like: `panic: unable to attach: operation not permitted` or `fork/exec /proc/self/exe: invalid argument: unknown` {#runsc-perms}
    76  
    77  Make sure that permissions is correct on the `runsc` binary.
    78  
    79  ```bash
    80  sudo chmod a+rx /usr/local/bin/runsc
    81  ```
    82  
    83  ### I'm getting an error like `mount submount "/etc/hostname": creating mount with source ".../hostname": input/output error: unknown.` {#memlock}
    84  
    85  There is a bug in Linux kernel versions 5.1 to 5.3.15, 5.4.2, and 5.5. Upgrade
    86  to a newer kernel or add the following to
    87  `/lib/systemd/system/containerd.service` as a workaround.
    88  
    89  ```
    90  LimitMEMLOCK=infinity
    91  ```
    92  
    93  And run `systemctl daemon-reload && systemctl restart containerd` to restart
    94  containerd.
    95  
    96  See [issue #1765](https://gvisor.dev/issue/1765) for more details.
    97  
    98  ### I'm getting an error like `RuntimeHandler "runsc" not supported` {#runtime-handler}
    99  
   100  This error indicates that the Kubernetes CRI runtime was not set up to handle
   101  `runsc` as a runtime handler. Please ensure that containerd configuration has
   102  been created properly and containerd has been restarted. See the
   103  [containerd quick start](containerd/quick_start.md) for more details.
   104  
   105  If you have ensured that containerd has been set up properly and you used
   106  kubeadm to create your cluster please check if Docker is also installed on that
   107  system. Kubeadm prefers using Docker if both Docker and containerd are
   108  installed.
   109  
   110  Please recreate your cluster and set the `--cri-socket` option on kubeadm
   111  commands. For example:
   112  
   113  ```bash
   114  kubeadm init --cri-socket=/var/run/containerd/containerd.sock ...
   115  ```
   116  
   117  To fix an existing cluster edit the `/var/lib/kubelet/kubeadm-flags.env` file
   118  and set the `--container-runtime` flag to `remote` and set the
   119  `--container-runtime-endpoint` flag to point to the containerd socket. e.g.
   120  `/var/run/containerd/containerd.sock`.
   121  
   122  ### My container cannot resolve another container's name when using Docker user defined bridge {#docker-bridge}
   123  
   124  This is normally indicated by errors like `bad address 'container-name'` when
   125  trying to communicate to another container in the same network.
   126  
   127  Docker user defined bridge uses an embedded DNS server bound to the loopback
   128  interface on address 127.0.0.10. This requires access to the host network in
   129  order to communicate to the DNS server. runsc network is isolated from the host
   130  and cannot access the DNS server on the host network without breaking the
   131  sandbox isolation. There are a few different workarounds you can try:
   132  
   133  *   Use default bridge network with `--link` to connect containers. Default
   134      bridge doesn't use embedded DNS.
   135  *   Use [`--network=host`][host-net] option in runsc, however beware that it
   136      will use the host network stack and is less secure.
   137  *   Use IPs instead of container names.
   138  *   Use [Kubernetes][k8s]. Container name lookup works fine in Kubernetes.
   139  
   140  ### I'm getting an error like `dial unix /run/containerd/s/09e4...8cff: connect: connection refused: unknown` {#shim-connect}
   141  
   142  This error may happen when using `gvisor-containerd-shim` with a `containerd`
   143  that does not contain the fix for [CVE-2020-15257]. The resolve the issue,
   144  update containerd to 1.3.9 or 1.4.3 (or newer versions respectively).
   145  
   146  [security-model]: /docs/architecture_guide/security/
   147  [host-net]: /docs/user_guide/networking/#network-passthrough
   148  [debugging]: /docs/user_guide/debugging/
   149  [filesystem]: /docs/user_guide/filesystem/
   150  [docker]: /docs/user_guide/quick_start/docker/
   151  [k8s]: /docs/user_guide/quick_start/kubernetes/
   152  [CVE-2020-15257]: https://github.com/containerd/containerd/security/advisories/GHSA-36xw-fx78-c5r4