From ce6d4c9a9ff0d65c92dbb4635249a4ee71bb6b27 Mon Sep 17 00:00:00 2001 From: Akihiro Suda Date: Tue, 6 Nov 2018 16:51:43 +0900 Subject: [PATCH] add docs/rootless.md Signed-off-by: Akihiro Suda --- docs/rootless.md | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 docs/rootless.md diff --git a/docs/rootless.md b/docs/rootless.md new file mode 100644 index 000000000..4440701a9 --- /dev/null +++ b/docs/rootless.md @@ -0,0 +1,41 @@ +# Running containerd as a non-root user + +A non-root user can execute containerd by using [`user_namespaces(7)`](http://man7.org/linux/man-pages/man7/user_namespaces.7.html). + +For example [RootlessKit](https://github.com/rootless-containers/rootlesskit) can be used for setting up a user namespace (along with mount namespace and optionally network namespace). Please refer to RootlessKit documentation for further information. + +## Daemon + +```console +$ rootlesskit --net=slirp4netns --copy-up=/etc \ + --state-dir=/run/user/1001/rootlesskit-containerd \ + containerd -c config.toml +``` + +* `--net=slirp4netns --copy-up=/etc` is only required when you want to unshare network namespaces +* Depending on the containerd plugin configuration, you may also need to add more `--copy-up` options, e.g. `--copy-up=/run`, which mounts a writable tmpfs on `/run`, with symbolic links to the files under the `/run` on the parent namespace. +* `--state-dir` is set to a random directory under `/tmp` if unset. RootlessKit writes the PID to a file named `child_pid` under this directory. +* You need to provide `config.toml` with your own path configuration. e.g. +```toml +root = "/home/penguin/.local/share/containerd" +state = "/run/user/1001/containerd" + +[grpc] + address = "/run/user/1001/containerd/containerd.sock" + +[plugins] + [plugins.linux] + runtime_root = "/run/user/1001/containerd/runc" +``` + +## Client + +A client program such as `ctr` also needs to be executed inside the daemon namespaces. +```console +$ nsenter -U --preserve-credentials -m -n -t $(cat /run/user/1001/rootlesskit-containerd/child_pid) +$ export CONTAINERD_SNAPSHOTTER=native +$ ctr -a /run/user/1001/containerd/containerd.sock pull docker.io/library/ubuntu:latest +$ ctr -a /run/user/1001/containerd/containerd.sock run -t --rm --fifo-dir /tmp/foo-fifo --cgroup "" docker.io/library/ubuntu:latest foo +``` + +* `overlayfs` snapshotter does not work inside user namespaces, except on Ubuntu kernel