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diff --git a/g3doc/user_guide/FAQ.md b/g3doc/user_guide/FAQ.md new file mode 100644 index 000000000..89df65e99 --- /dev/null +++ b/g3doc/user_guide/FAQ.md @@ -0,0 +1,122 @@ +# FAQ + +[TOC] + +### What operating systems are supported? {#supported-os} + +Today, gVisor requires Linux. + +### What CPU architectures are supported? {#supported-cpus} + +gVisor currently supports [x86_64/AMD64](https://en.wikipedia.org/wiki/X86-64) +compatible processors. Preliminary support is also available for +[ARM64](https://en.wikipedia.org/wiki/ARM_architecture#AArch64). + +### Do I need to modify my Linux application to use gVisor? {#modify-app} + +No. gVisor is capable of running unmodified Linux binaries. + +### What binary formats does gVisor support? {#supported-binaries} + +gVisor supports Linux +[ELF](https://en.wikipedia.org/wiki/Executable_and_Linkable_Format) binaries. + +Binaries run in gVisor should be built for the +[AMD64](https://en.wikipedia.org/wiki/X86-64) or +[AArch64](https://en.wikipedia.org/wiki/ARM_architecture#AArch64) CPU +architectures. + +### Can I run Docker images using gVisor? {#docker-images} + +Yes. Please see the [Docker Quick Start][docker]. + +### Can I run Kubernetes pods using gVisor? {#k8s-pods} + +Yes. Please see the [Kubernetes Quick Start][k8s]. + +### What's the security model? {#security-model} + +See the [Security Model][security-model]. + +## Troubleshooting + +### My container runs fine with `runc` but fails with `runsc` {#app-compatibility} + +If you’re having problems running a container with `runsc` it’s most likely due +to a compatibility issue or a missing feature in gVisor. See +[Debugging][debugging]. + +### When I run my container, docker fails with: `open /run/containerd/.../<containerid>/log.json: no such file or directory` {#memfd-create} + +You are using an older version of Linux which doesn't support `memfd_create`. + +This is tracked in [bug #268](https://gvisor.dev/issue/268). + +### When I run my container, docker fails with: `flag provided but not defined: -console` {#old-docker} + +You're using an old version of Docker. See [Docker Quick Start][docker]. + +### I can’t see a file copied with: `docker cp` {#fs-cache} + +For performance reasons, gVisor caches directory contents, and therefore it may +not realize a new file was copied to a given directory. To invalidate the cache +and force a refresh, create a file under the directory in question and list the +contents again. + +As a workaround, shared root filesystem can be enabled. See +[Filesystem][filesystem]. + +This bug is tracked in [bug #4](https://gvisor.dev/issue/4). + +Note that `kubectl cp` works because it does the copy by exec'ing inside the +sandbox, and thus gVisor's internal cache is made aware of the new files and +directories. + +### I'm getting an error like: `panic: unable to attach: operation not permitted` or `fork/exec /proc/self/exe: invalid argument: unknown` {#runsc-perms} + +Make sure that permissions and the owner is correct on the `runsc` binary. + +```bash +sudo chown root:root /usr/local/bin/runsc +sudo chmod 0755 /usr/local/bin/runsc +``` + +### I'm getting an error like `mount submount "/etc/hostname": creating mount with source ".../hostname": input/output error: unknown.` {#memlock} + +There is a bug in Linux kernel versions 5.1 to 5.3.15, 5.4.2, and 5.5. Upgrade +to a newer kernel or add the following to +`/lib/systemd/system/containerd.service` as a workaround. + +``` +LimitMEMLOCK=infinity +``` + +And run `systemctl daemon-reload && systemctl restart containerd` to restart +containerd. + +See [issue #1765](https://gvisor.dev/issue/1765) for more details. + +### My container cannot resolve another container's name when using Docker user defined bridge {#docker-bridge} + +This is normally indicated by errors like `bad address 'container-name'` when +trying to communicate to another container in the same network. + +Docker user defined bridge uses an embedded DNS server bound to the loopback +interface on address 127.0.0.10. This requires access to the host network in +order to communicate to the DNS server. runsc network is isolated from the host +and cannot access the DNS server on the host network without breaking the +sandbox isolation. There are a few different workarounds you can try: + +* Use default bridge network with `--link` to connect containers. Default + bridge doesn't use embedded DNS. +* Use [`--network=host`][host-net] option in runsc, however beware that it + will use the host network stack and is less secure. +* Use IPs instead of container names. +* Use [Kubernetes][k8s]. Container name lookup works fine in Kubernetes. + +[security-model]: /docs/architecture_guide/security/ +[host-net]: /docs/user_guide/networking/#network-passthrough +[debugging]: /docs/user_guide/debugging/ +[filesystem]: /docs/user_guide/filesystem/ +[docker]: /docs/user_guide/quick_start/docker/ +[k8s]: /docs/user_guide/quick_start/kubernetes/ |