NAME

       bwrap - container setup utility

SYNOPSIS

       bwrap [OPTION...] [COMMAND]

DESCRIPTION

       bwrap is a privileged helper for container setup. You are unlikely to use it directly from the
       commandline, although that is possible.

       It works by creating a new, completely empty, filesystem namespace where the root is on a tmpfs that is
       invisible from the host, and which will be automatically cleaned up when the last process exits. You can
       then use commandline options to construct the root filesystem and process environment for the command to
       run in the namespace.

       By default, bwrap creates a new mount namespace for the sandbox. Optionally it also sets up new user,
       ipc, pid, network and uts namespaces (but note the user namespace is required if bwrap is not installed
       setuid root). The application in the sandbox can be made to run with a different UID and GID.

       If needed (e.g. when using a PID namespace) bwrap is running a minimal pid 1 process in the sandbox that
       is responsible for reaping zombies. It also detects when the initial application process (pid 2) dies and
       reports its exit status back to the original spawner. The pid 1 process exits to clean up the sandbox
       when there are no other processes in the sandbox left.

OPTIONS

       When options are used multiple times, the last option wins, unless otherwise specified.

       General options:

       --help
           Print help and exit

       --version
           Print version

       --args FD
           Parse nul-separated arguments from the given file descriptor. This option can be used multiple times
           to parse options from multiple sources.

       Options related to kernel namespaces:

       --unshare-user
           Create a new user namespace

       --unshare-user-try
           Create a new user namespace if possible else skip it

       --unshare-ipc
           Create a new ipc namespace

       --unshare-pid
           Create a new pid namespace

       --unshare-net
           Create a new network namespace

       --unshare-uts
           Create a new uts namespace

       --unshare-cgroup
           Create a new cgroup namespace

       --unshare-cgroup-try
           Create a new cgroup namespace if possible else skip it

       --unshare-all
           Unshare all possible namespaces. Currently equivalent with: --unshare-user-try --unshare-ipc
           --unshare-pid --unshare-net --unshare-uts --unshare-cgroup-try

       --userns FD
           Use an existing user namespace instead of creating a new one. The namespace must fulfil the
           permission requirements for setns(), which generally means that it must be a decendant of the
           currently active user namespace, owned by the same user.

           This is incompatible with --unshare-user, and doesn't work in the setuid version of bubblewrap.

       --userns2 FD
           After setting up the new namespace, switch into the specified namespace. For this to work the
           specified namespace must be a decendant of the user namespace used for the setup, so this is only
           useful in combination with --userns.

           This is useful because sometimes bubblewrap itself creates nested user namespaces (to work around
           some kernel issues) and --userns2 can be used to enter these.

       --pidns FD
           Use an existing pid namespace instead of creating one. This is often used with --userns, because the
           pid namespace must be owned by the same user namespace that bwrap uses.

           Note that this can be combined with --unshare-pid, and in that case it means that the sandbox will be
           in its own pid namespace, which is a child of the passed in one.

       --uid UID
           Use a custom user id in the sandbox (requires --unshare-user)

       --gid GID
           Use a custom group id in the sandbox (requires --unshare-user)

       --hostname HOSTNAME
           Use a custom hostname in the sandbox (requires --unshare-uts)

       Options about environment setup:

       --chdir DIR
           Change directory to DIR

       --setenv VAR VALUE
           Set an environment variable

       --unsetenv VAR
           Unset an environment variable

       Options for monitoring the sandbox from the outside:

       --lock-file DEST
           Take a lock on DEST while the sandbox is running. This option can be used multiple times to take
           locks on multiple files.

       --sync-fd FD
           Keep this file descriptor open while the sandbox is running

       Filesystem related options. These are all operations that modify the filesystem directly, or mounts stuff
       in the filesystem. These are applied in the order they are given as arguments. Any missing parent
       directories that are required to create a specified destination are automatically created as needed.

       --bind SRC DEST
           Bind mount the host path SRC on DEST

       --bind-try SRC DEST
           Equal to --bind but ignores non-existent SRC

       --dev-bind SRC DEST
           Bind mount the host path SRC on DEST, allowing device access

       --dev-bind-try SRC DEST
           Equal to --dev-bind but ignores non-existent SRC

       --ro-bind SRC DEST
           Bind mount the host path SRC readonly on DEST

       --ro-bind-try SRC DEST
           Equal to --ro-bind but ignores non-existent SRC

       --remount-ro DEST
           Remount the path DEST as readonly. It works only on the specified mount point, without changing any
           other mount point under the specified path

       --proc DEST
           Mount procfs on DEST

       --dev DEST
           Mount new devtmpfs on DEST

       --tmpfs DEST
           Mount new tmpfs on DEST

       --mqueue DEST
           Mount new mqueue on DEST

       --dir DEST
           Create a directory at DEST

       --file FD DEST
           Copy from the file descriptor FD to DEST

       --bind-data FD DEST
           Copy from the file descriptor FD to a file which is bind-mounted on DEST

       --ro-bind-data FD DEST
           Copy from the file descriptor FD to a file which is bind-mounted readonly on DEST

       --symlink SRC DEST
           Create a symlink at DEST with target SRC

       Lockdown options:

       --seccomp FD
           Load and use seccomp rules from FD. The rules need to be in the form of a compiled eBPF program, as
           generated by seccomp_export_bpf.

       --exec-label LABEL
           Exec Label from the sandbox. On an SELinux system you can specify the SELinux context for the sandbox
           process(s).

       --file-label LABEL
           File label for temporary sandbox content. On an SELinux system you can specify the SELinux context
           for the sandbox content.

       --block-fd FD
           Block the sandbox on reading from FD until some data is available.

       --userns-block-fd FD
           Do not initialize the user namespace but wait on FD until it is ready. This allow external processes
           (like newuidmap/newgidmap) to setup the user namespace before it is used by the sandbox process.

       --info-fd FD
           Write information in JSON format about the sandbox to FD.

       --new-session
           Create a new terminal session for the sandbox (calls setsid()). This disconnects the sandbox from the
           controlling terminal which means the sandbox can't for instance inject input into the terminal.

           Note: In a general sandbox, if you don't use --new-session, it is recommended to use seccomp to
           disallow the TIOCSTI ioctl, otherwise the application can feed keyboard input to the terminal.

       --die-with-parent
           Ensures child process (COMMAND) dies when bwrap's parent dies. Kills (SIGKILL) all bwrap sandbox
           processes in sequence from parent to child including COMMAND process when bwrap or bwrap's parent
           dies. See prctl, PR_SET_PDEATHSIG.

       --as-pid-1
           Do not create a process with PID=1 in the sandbox to reap child processes.

       --cap-add CAP
           Add the specified capability when running as privileged user. It accepts the special value ALL to add
           all the permitted caps.

       --cap-drop CAP
           Drop the specified capability when running as privileged user. It accepts the special value ALL to
           drop all the caps. By default no caps are left in the sandboxed process. The --cap-add and --cap-drop
           options are processed in the order they are specified on the command line. Please be careful to the
           order they are specified.

ENVIRONMENT

       HOME
           Used as the cwd in the sandbox if --chdir has not been explicitly specified and the current cwd is
           not present inside the sandbox. The --setenv option can be used to override the value that is used
           here.

EXIT STATUS

       The bwrap command returns the exit status of the initial application process (pid 2 in the sandbox).