Project Atomic Developer Alexander Larsson Developer Colin Walters bwrap 1 User Commands bwrap container setup utility bwrap OPTION COMMAND 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 exists. 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 user namespace for the sandbox. Optionally it also sets up new ipc, pid, network and uts namespaces. 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. 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 --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 --dev-bind SRC DEST Bind mount the host path SRC on DEST, allowing device access --ro-bind SRC DEST Bind mount the host path SRC readonly on DEST --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. --info-fd FD Write information in JSON format about the sandbox to FD. HOME Used as the cwd in the sandbox if --cwd 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. The bwrap command returns the exit status of the initial application process (pid 2 in the sandbox).