provide documentation how to use `--runtime-flag` of run command

[TomasTomecek]

I literally have no idea what the flags are and how I should specify them. I went on and read source code which didn't help me really:

$ buildah --debug run --runtime-flag=WithoutTerminal -- buildah-container /bin/sh -c '/usr/bin/python && sleep 0'
DEBU[0000] [graphdriver] trying provided driver "overlay"
DEBU[0000] using "/tmp/buildah566769552" to hold bundle data
DEBU[0000] config = {"ociVersion":"1.0.0-rc5","platform":{"os":"linux","arch":"amd64"},"process":{"terminal":true,"consoleSize":{"height":0,"width":0},"user":{"uid":0,"gid":0},"args":["/bin/sh","-c","/usr/bin/python \u0026\u0026 sleep 0"],"env":["PATH=/usr/local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin","TERM=xterm","LANG=C.UTF-8","GPG_KEY=C01E1CAD5EA2C4F0B8E3571504C367C218ADD4FF","PYTHON_VERSION=2.7.13","PYTHON_PIP_VERSION=9.0.1"],"cwd":"/","capabilities":{"bounding":["CAP_CHOWN","CAP_DAC_OVERRIDE","CAP_FSETID","CAP_FOWNER","CAP_MKNOD","CAP_NET_RAW","CAP_SETGID","CAP_SETUID","CAP_SETFCAP","CAP_SETPCAP","CAP_NET_BIND_SERVICE","CAP_SYS_CHROOT","CAP_KILL","CAP_AUDIT_WRITE"],"effective":["CAP_CHOWN","CAP_DAC_OVERRIDE","CAP_FSETID","CAP_FOWNER","CAP_MKNOD","CAP_NET_RAW","CAP_SETGID","CAP_SETUID","CAP_SETFCAP","CAP_SETPCAP","CAP_NET_BIND_SERVICE","CAP_SYS_CHROOT","CAP_KILL","CAP_AUDIT_WRITE"],"inheritable":["CAP_CHOWN","CAP_DAC_OVERRIDE","CAP_FSETID","CAP_FOWNER","CAP_MKNOD","CAP_NET_RAW","CAP_SETGID","CAP_SETUID","CAP_SETFCAP","CAP_SETPCAP","CAP_NET_BIND_SERVICE","CAP_SYS_CHROOT","CAP_KILL","CAP_AUDIT_WRITE"],"permitted":["CAP_CHOWN","CAP_DAC_OVERRIDE","CAP_FSETID","CAP_FOWNER","CAP_MKNOD","CAP_NET_RAW","CAP_SETGID","CAP_SETUID","CAP_SETFCAP","CAP_SETPCAP","CAP_NET_BIND_SERVICE","CAP_SYS_CHROOT","CAP_KILL","CAP_AUDIT_WRITE"],"ambient":["CAP_CHOWN","CAP_DAC_OVERRIDE","CAP_FSETID","CAP_FOWNER","CAP_MKNOD","CAP_NET_RAW","CAP_SETGID","CAP_SETUID","CAP_SETFCAP","CAP_SETPCAP","CAP_NET_BIND_SERVICE","CAP_SYS_CHROOT","CAP_KILL","CAP_AUDIT_WRITE"]},"rlimits":[{"type":"RLIMIT_NOFILE","hard":1024,"soft":1024}]},"root":{"path":"/var/lib/containers/storage/overlay/9b20ff75c09d5a38c2fa4690790b4f972e57655621cade4dddd15d03433a7e40/merged"},"hostname":"e11aa17d2971","mounts":[{"destination":"/proc","type":"proc","source":"proc"},{"destination":"/dev","type":"tmpfs","source":"tmpfs","options":["nosuid","strictatime","mode=755","size=65536k"]},{"destination":"/dev/pts","type":"devpts","source":"devpts","options":["nosuid","noexec","newinstance","ptmxmode=0666","mode=0620","gid=5"]},{"destination":"/dev/shm","type":"tmpfs","source":"shm","options":["nosuid","noexec","nodev","mode=1777","size=65536k"]},{"destination":"/dev/mqueue","type":"mqueue","source":"mqueue","options":["nosuid","noexec","nodev"]},{"destination":"/sys","type":"sysfs","source":"sysfs","options":["nosuid","noexec","nodev","ro"]},{"destination":"/etc/hosts","type":"bind","source":"/etc/hosts","options":["rbind","ro"]},{"destination":"/etc/resolv.conf","type":"bind","source":"/etc/resolv.conf","options":["rbind","ro"]}],"linux":{"resources":{"devices":[{"allow":false,"access":"rwm"}]},"namespaces":[{"type":"pid"},{"type":"ipc"},{"type":"uts"},{"type":"mount"}],"seccomp":{"defaultAction":"SCMP_ACT_ERRNO","architectures":["SCMP_ARCH_X86_64","SCMP_ARCH_X86","SCMP_ARCH_X32"],"syscalls":[{"names":["accept","accept4","access","alarm","bind","brk","capget","capset","chdir","chmod","chown","chown32","clock_getres","clock_gettime","clock_nanosleep","close","connect","copy_file_range","creat","dup","dup2","dup3","epoll_create","epoll_create1","epoll_ctl","epoll_ctl_old","epoll_pwait","epoll_wait","epoll_wait_old","eventfd","eventfd2","execve","execveat","exit","exit_group","faccessat","fadvise64","fadvise64_64","fallocate","fanotify_mark","fchdir","fchmod","fchmodat","fchown","fchown32","fchownat","fcntl","fcntl64","fdatasync","fgetxattr","flistxattr","flock","fork","fremovexattr","fsetxattr","fstat","fstat64","fstatat64","fstatfs","fstatfs64","fsync","ftruncate","ftruncate64","futex","futimesat","getcpu","getcwd","getdents","getdents64","getegid","getegid32","geteuid","geteuid32","getgid","getgid32","getgroups","getgroups32","getitimer","getpeername","getpgid","getpgrp","getpid","getppid","getpriority","getrandom","getresgid","getresgid32","getresuid","getresuid32","getrlimit","get_robust_list","getrusage","getsid","getsockname","getsockopt","get_thread_area","gettid","gettimeofday","getuid","getuid32","getxattr","inotify_add_watch","inotify_init","inotify_init1","inotify_rm_watch","io_cancel","ioctl","io_destroy","io_getevents","ioprio_get","ioprio_set","io_setup","io_submit","ipc","kill","lchown","lchown32","lgetxattr","link","linkat","listen","listxattr","llistxattr","_llseek","lremovexattr","lseek","lsetxattr","lstat","lstat64","madvise","memfd_create","mincore","mkdir","mkdirat","mknod","mknodat","mlock","mlock2","mlockall","mmap","mmap2","mprotect","mq_getsetattr","mq_notify","mq_open","mq_timedreceive","mq_timedsend","mq_unlink","mremap","msgctl","msgget","msgrcv","msgsnd","msync","munlock","munlockall","munmap","nanosleep","newfstatat","_newselect","open","openat","pause","pipe","pipe2","poll","ppoll","prctl","pread64","preadv","prlimit64","pselect6","pwrite64","pwritev","read","readahead","readlink","readlinkat","readv","recv","recvfrom","recvmmsg","recvmsg","remap_file_pages","removexattr","rename","renameat","renameat2","restart_syscall","rmdir","rt_sigaction","rt_sigpending","rt_sigprocmask","rt_sigqueueinfo","rt_sigreturn","rt_sigsuspend","rt_sigtimedwait","rt_tgsigqueueinfo","sched_getaffinity","sched_getattr","sched_getparam","sched_get_priority_max","sched_get_priority_min","sched_getscheduler","sched_rr_get_interval","sched_setaffinity","sched_setattr","sched_setparam","sched_setscheduler","sched_yield","seccomp","select","semctl","semget","semop","semtimedop","send","sendfile","sendfile64","sendmmsg","sendmsg","sendto","setfsgid","setfsgid32","setfsuid","setfsuid32","setgid","setgid32","setgroups","setgroups32","setitimer","setpgid","setpriority","setregid","setregid32","setresgid","setresgid32","setresuid","setresuid32","setreuid","setreuid32","setrlimit","set_robust_list","setsid","setsockopt","set_thread_area","set_tid_address","setuid","setuid32","setxattr","shmat","shmctl","shmdt","shmget","shutdown","sigaltstack","signalfd","signalfd4","sigreturn","socket","socketcall","socketpair","splice","stat","stat64","statfs","statfs64","symlink","symlinkat","sync","sync_file_range","syncfs","sysinfo","syslog","tee","tgkill","time","timer_create","timer_delete","timerfd_create","timerfd_gettime","timerfd_settime","timer_getoverrun","timer_gettime","timer_settime","times","tkill","truncate","truncate64","ugetrlimit","umask","uname","unlink","unlinkat","utime","utimensat","utimes","vfork","vmsplice","wait4","waitid","waitpid","write","writev"],"action":"SCMP_ACT_ALLOW","args":[],"comment":""},{"names":["personality"],"action":"SCMP_ACT_ALLOW","args":[{"index":0,"value":0,"valueTwo":0,"op":"SCMP_CMP_EQ"},{"index":0,"value":8,"valueTwo":0,"op":"SCMP_CMP_EQ"},{"index":0,"value":4294967295,"valueTwo":0,"op":"SCMP_CMP_EQ"}],"comment":""},{"names":["chroot"],"action":"SCMP_ACT_ALLOW","args":[],"comment":""},{"names":["chroot"],"action":"SCMP_ACT_ALLOW","args":[],"comment":""},{"names":["chroot"],"action":"SCMP_ACT_ALLOW","args":[],"comment":""},{"names":["chroot"],"action":"SCMP_ACT_ALLOW","args":[],"comment":""},{"names":["chroot"],"action":"SCMP_ACT_ALLOW","args":[],"comment":""},{"names":["clone"],"action":"SCMP_ACT_ALLOW","args":[{"index":0,"value":2080505856,"valueTwo":0,"op":"SCMP_CMP_MASKED_EQ"}],"comment":""},{"names":["arch_prctl"],"action":"SCMP_ACT_ALLOW","args":[],"comment":""},{"names":["modify_ldt"],"action":"SCMP_ACT_ALLOW","args":[],"comment":""}]}}}
No help topic for 'WithoutTerminal'
DEBU[0000] error running runc [/bin/sh -c /usr/bin/python && sleep 0]: exit status 3
DEBU[0000] error running [/bin/sh -c /usr/bin/python && sleep 0] in container "buildah-container": exit status 3

[nalind]

Runtime flags are global flags that we pass to the runtime command (specified with the --runtime flag, runc by default) when we use it to run a command in a container. In other words, they're options we place in the arguments list for the runtime before the run command. Flags my installed copy of runc recognizes include --debug, --log, and --root, among others.

[rhatdan]

Perhaps we need to update the man page to clarify this.