tests/topotests/munet/mucmd.py

   1 # -*- coding: utf-8 eval: (blacken-mode 1) -*-
   2 # SPDX-License-Identifier: GPL-2.0-or-later
   3 #
   4 # December 5 2021, Christian Hopps <chopps@labn.net>
   5 #
   6 # Copyright 2021, LabN Consulting, L.L.C.
   7 #
   8 """A command that allows external command execution inside nodes."""
   9 import argparse
  10 import json
  11 import os
  12 import subprocess
  13 import sys
  14
  15 from pathlib import Path
  16
  17
  18 def newest_file_in(filename, paths, has_sibling=None):
  19     new = None
  20     newst = None
  21     items = (x for y in paths for x in Path(y).rglob(filename))
  22     for e in items:
  23         st = os.stat(e)
  24         if has_sibling and not e.parent.joinpath(has_sibling).exists():
  25             continue
  26         if not new or st.st_mtime_ns > newst.st_mtime_ns:
  27             new = e
  28             newst = st
  29             continue
  30     return new, newst
  31
  32
  33 def main(*args):
  34     ap = argparse.ArgumentParser(args)
  35     ap.add_argument("-d", "--rundir", help="runtime directory for tempfiles, logs, etc")
  36     ap.add_argument("node", nargs="?", help="node to enter or run command inside")
  37     ap.add_argument(
  38         "shellcmd",
  39         nargs=argparse.REMAINDER,
  40         help="optional shell-command to execute on NODE",
  41     )
  42     args = ap.parse_args()
  43     if args.rundir:
  44         configpath = Path(args.rundir).joinpath("config.json")
  45     else:
  46         configpath, _ = newest_file_in(
  47             "config.json",
  48             ["/tmp/munet", "/tmp/mutest", "/tmp/unet-test"],
  49             has_sibling=args.node,
  50         )
  51         print(f'Using "{configpath}"')
  52
  53     if not configpath.exists():
  54         print(f'"{configpath}" not found')
  55         return 1
  56     rundir = configpath.parent
  57
  58     nodes = []
  59     config = json.load(open(configpath, encoding="utf-8"))
  60     nodes = list(config.get("topology", {}).get("nodes", []))
  61     envcfg = config.get("mucmd", {}).get("env", {})
  62
  63     # If args.node is not a node it's part of shellcmd
  64     if args.node and args.node not in nodes:
  65         if args.node != ".":
  66             args.shellcmd[0:0] = [args.node]
  67         args.node = None
  68
  69     if args.node:
  70         name = args.node
  71         nodedir = rundir.joinpath(name)
  72         if not nodedir.exists():
  73             print('"{name}" node doesn\'t exist in "{rundir}"')
  74             return 1
  75         rundir = nodedir
  76     else:
  77         name = "munet"
  78     pidpath = rundir.joinpath("nspid")
  79     pid = open(pidpath, encoding="ascii").read().strip()
  80
  81     env = {**os.environ}
  82     env["MUNET_NODENAME"] = name
  83     env["MUNET_RUNDIR"] = str(rundir)
  84
  85     for k in envcfg:
  86         envcfg[k] = envcfg[k].replace("%NAME%", str(name))
  87         envcfg[k] = envcfg[k].replace("%RUNDIR%", str(rundir))
  88
  89     # Can't use -F if it's a new pid namespace
  90     ecmd = "/usr/bin/nsenter"
  91     eargs = [ecmd]
  92
  93     output = subprocess.check_output(["/usr/bin/nsenter", "--help"], encoding="utf-8")
  94     if " -a," in output:
  95         eargs.append("-a")
  96     else:
  97         # -U doesn't work
  98         for flag in ["-u", "-i", "-m", "-n", "-C", "-T"]:
  99             if f" {flag}," in output:
 100                 eargs.append(flag)
 101     eargs.append(f"--pid=/proc/{pid}/ns/pid_for_children")
 102     eargs.append(f"--wd={rundir}")
 103     eargs.extend(["-t", pid])
 104     eargs += args.shellcmd
 105     # print("Using ", eargs)
 106     return os.execvpe(ecmd, eargs, {**env, **envcfg})
 107
 108
 109 if __name__ == "__main__":
 110     exit_status = main()
 111     sys.exit(exit_status)