docs/rootless.md: move to https://docs.docker.com/engine/security/rootless/

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

docs/rootless.md

@@ -1,191 +1,3 @@
-# Rootless mode (Experimental)
-
-The rootless mode allows running `dockerd` as an unprivileged user, using `user_namespaces(7)`, `mount_namespaces(7)`, `network_namespaces(7)`.
-
-No SETUID/SETCAP binary is required except `newuidmap` and `newgidmap`.
-
-## Requirements
-* `newuidmap` and `newgidmap` need to be installed on the host. These commands are provided by the `uidmap` package on most distros.
-
-* `/etc/subuid` and `/etc/subgid` should contain >= 65536 sub-IDs. e.g. `penguin:231072:65536`.
-
-```console
-$ id -u
-1001
-$ whoami
-penguin
-$ grep ^$(whoami): /etc/subuid
-penguin:231072:65536
-$ grep ^$(whoami): /etc/subgid
-penguin:231072:65536
-```
-
-### Distribution-specific hint
-
-Using Ubuntu kernel is recommended.
-
-#### Ubuntu
-* No preparation is needed.
-* `overlay2` is enabled by default ([Ubuntu-specific kernel patch](https://kernel.ubuntu.com/git/ubuntu/ubuntu-bionic.git/commit/fs/overlayfs?id=3b7da90f28fe1ed4b79ef2d994c81efbc58f1144)).
-* Known to work on Ubuntu 16.04 and 18.04.
-
-#### Debian GNU/Linux
-* Add `kernel.unprivileged_userns_clone=1` to `/etc/sysctl.conf` (or `/etc/sysctl.d`) and run `sudo sysctl -p`
-* To use `overlay2` storage driver (recommended), run `sudo modprobe overlay permit_mounts_in_userns=1` ([Debian-specific kernel patch, introduced in Debian 10](https://salsa.debian.org/kernel-team/linux/blob/283390e7feb21b47779b48e0c8eb0cc409d2c815/debian/patches/debian/overlayfs-permit-mounts-in-userns.patch)). Put the configuration to `/etc/modprobe.d` for persistence.
-* Known to work on Debian 9 and 10. `overlay2` is only supported since Debian 10 and needs `modprobe` configuration described above.
-
-#### Arch Linux
-* Add `kernel.unprivileged_userns_clone=1` to `/etc/sysctl.conf` (or `/etc/sysctl.d`) and run `sudo sysctl -p`
-
-#### openSUSE
-* `sudo modprobe ip_tables iptable_mangle iptable_nat iptable_filter` is required. (This is likely to be required on other distros as well)
-* Known to work on openSUSE 15.
-
-#### Fedora 31 and later
-* Run `sudo grubby --update-kernel=ALL --args="systemd.unified_cgroup_hierarchy=0"` and reboot.
-
-#### Fedora 30
-* No preparation is needed
-
-#### RHEL/CentOS 8
-* No preparation is needed
-
-#### RHEL/CentOS 7
-* Add `user.max_user_namespaces=28633` to `/etc/sysctl.conf` (or `/etc/sysctl.d`) and run `sudo sysctl -p`
-* `systemctl --user` does not work by default. Run the daemon directly without systemd: `dockerd-rootless.sh --experimental --storage-driver vfs`
-* Known to work on RHEL/CentOS 7.7. Older releases require extra configuration steps.
-* RHEL/CentOS 7.6 and older releases require [COPR package `vbatts/shadow-utils-newxidmap`](https://copr.fedorainfracloud.org/coprs/vbatts/shadow-utils-newxidmap/) to be installed.
-* RHEL/CentOS 7.5 and older releases require running `sudo grubby --update-kernel=ALL --args="user_namespace.enable=1"` and reboot.
-
-## Known limitations
-
-* Only `vfs` graphdriver is supported. However, on Ubuntu and Debian 10, `overlay2` and `overlay` are also supported.
-* Following features are not supported:
-  * Cgroups (including `docker top`, which depends on the cgroups device controller)
-  * Apparmor
-  * Checkpoint
-  * Overlay network
-  * Exposing SCTP ports
-* To use `ping` command, see [Routing ping packets](#routing-ping-packets)
-* To expose privileged TCP/UDP ports (< 1024), see [Exposing privileged ports](#exposing-privileged-ports)
-
-## Install
-
-The installation script is available at https://get.docker.com/rootless .
-
-```console
-$ curl -fsSL https://get.docker.com/rootless | sh
-```
-
-Make sure to run the script as a non-root user.
-
-The script will show the environment variables that are needed to be set:
-
-```console
-$ curl -fsSL https://get.docker.com/rootless | sh
-...
-# Docker binaries are installed in /home/penguin/bin
-# WARN: dockerd is not in your current PATH or pointing to /home/penguin/bin/dockerd
-# Make sure the following environment variables are set (or add them to ~/.bashrc):
-
-export PATH=/home/penguin/bin:$PATH
-export PATH=$PATH:/sbin
-export DOCKER_HOST=unix:///run/user/1001/docker.sock
-
-#
-# To control docker service run:
-# systemctl --user (start|stop|restart) docker
-#
-```
-
-To install the binaries manually without using the installer, extract `docker-rootless-extras-<version>.tar.gz` along with `docker-<version>.tar.gz`: https://download.docker.com/linux/static/stable/x86_64/
-
-## Usage
-
-### Daemon
-
-Use `systemctl --user` to manage the lifecycle of the daemon:
-```console
-$ systemctl --user start docker
-```
-
-To launch the daemon on system startup, enable systemd lingering:
-```console
-$ sudo loginctl enable-linger $(whoami)
-```
-
-To run the daemon directly without systemd, you need to run `dockerd-rootless.sh` instead of `dockerd`:
-```console
-$ dockerd-rootless.sh --experimental --storage-driver vfs
-```
-
-As Rootless mode is experimental, currently you always need to run `dockerd-rootless.sh` with `--experimental`.
-You also need `--storage-driver vfs` unless using Ubuntu or Debian 10 kernel.
-
-Remarks:
-* The socket path is set to `$XDG_RUNTIME_DIR/docker.sock` by default. `$XDG_RUNTIME_DIR` is typically set to `/run/user/$UID`.
-* The data dir is set to `~/.local/share/docker` by default.
-* The exec dir is set to `$XDG_RUNTIME_DIR/docker` by default.
-* The daemon config dir is set to `~/.config/docker` (not `~/.docker`, which is used by the client) by default.
-* The `dockerd-rootless.sh` script executes `dockerd` in its own user, mount, and network namespaces. You can enter the namespaces by running `nsenter -U --preserve-credentials -n -m -t $(cat $XDG_RUNTIME_DIR/docker.pid)`.
-* `docker info` shows `rootless` in `SecurityOptions`
-* `docker info` shows `none` as `Cgroup Driver`
-
-### Client
-
-You need to set the socket path explicitly.
-
-```console
-$ export DOCKER_HOST=unix://$XDG_RUNTIME_DIR/docker.sock
-$ docker run -d nginx
-```
-
-### Rootless Docker in Docker
-
-To run Rootless Docker inside "rootful" Docker, use `docker:<version>-dind-rootless` image instead of `docker:<version>-dind` image.
-
-```console
-$ docker run -d --name dind-rootless --privileged docker:19.03-dind-rootless --experimental
-```
-
-`docker:<version>-dind-rootless` image runs as a non-root user (UID 1000).
-However, `--privileged` is required for disabling seccomp, AppArmor, and mount masks.
-
-### Expose Docker API socket via TCP
-
-To expose the Docker API socket via TCP, you need to launch `dockerd-rootless.sh` with `DOCKERD_ROOTLESS_ROOTLESSKIT_FLAGS="-p 0.0.0.0:2376:2376/tcp"`.
-
-```console
-$ DOCKERD_ROOTLESS_ROOTLESSKIT_FLAGS="-p 0.0.0.0:2376:2376/tcp" \
- dockerd-rootless.sh --experimental \
- -H tcp://0.0.0.0:2376 \
- --tlsverify --tlscacert=ca.pem --tlscert=cert.pem --tlskey=key.pem
-```
-
-### Routing ping packets
-
-Add `net.ipv4.ping_group_range = 0   2147483647` to `/etc/sysctl.conf` (or `/etc/sysctl.d`) and run `sudo sysctl -p`.
-
-### Exposing privileged ports
-
-To expose privileged ports (< 1024), set `CAP_NET_BIND_SERVICE` on `rootlesskit` binary.
-
-```console
-$ sudo setcap cap_net_bind_service=ep $HOME/bin/rootlesskit
-```
-
-Or add `net.ipv4.ip_unprivileged_port_start=0` to `/etc/sysctl.conf` (or `/etc/sysctl.d`) and run `sudo sysctl -p`.
-
-### Limiting resources
-
-Currently rootless mode ignores cgroup-related `docker run` flags such as `--cpus` and `memory`.
-However, traditional `ulimit` and [`cpulimit`](https://github.com/opsengine/cpulimit) can be still used, though it works in process-granularity rather than container-granularity.
-
-### Changing network stack
-
-`dockerd-rootless.sh` uses [slirp4netns](https://github.com/rootless-containers/slirp4netns) (if installed) or [VPNKit](https://github.com/moby/vpnkit) as the network stack by default.
-These network stacks run in userspace and might have performance overhead. See [RootlessKit documentation](https://github.com/rootless-containers/rootlesskit/tree/v0.6.0#network-drivers) for further information.
-
-Optionally, you can use `lxc-user-nic` instead for the best performance.
-To use `lxc-user-nic`, you need to edit [`/etc/lxc/lxc-usernet`](https://github.com/rootless-containers/rootlesskit/tree/v0.6.0#--netlxc-user-nic-experimental) and set `$DOCKERD_ROOTLESS_ROOTLESSKIT_NET=lxc-user-nic`.
+Moved to https://docs.docker.com/engine/security/rootless/
 
+<!-- do not remove this file, as there is a lot of links to https://github.com/moby/moby/blob/master/docs/rootless.md -->