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).