1 files changed, 111 insertions, 0 deletions
diff --git a/tests/topotests/munet/mucmd.py b/tests/topotests/munet/mucmd.py
new file mode 100644
index 0000000..5518c6d
--- /dev/null
+++ b/tests/topotests/munet/mucmd.py
@@ -0,0 +1,111 @@
+# -*- coding: utf-8 eval: (blacken-mode 1) -*-
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# December 5 2021, Christian Hopps <chopps@labn.net>
+#
+# Copyright 2021, LabN Consulting, L.L.C.
+#
+"""A command that allows external command execution inside nodes."""
+import argparse
+import json
+import os
+import subprocess
+import sys
+
+from pathlib import Path
+
+
+def newest_file_in(filename, paths, has_sibling=None):
+    new = None
+    newst = None
+    items = (x for y in paths for x in Path(y).rglob(filename))
+    for e in items:
+        st = os.stat(e)
+        if has_sibling and not e.parent.joinpath(has_sibling).exists():
+            continue
+        if not new or st.st_mtime_ns > newst.st_mtime_ns:
+            new = e
+            newst = st
+            continue
+    return new, newst
+
+
+def main(*args):
+    ap = argparse.ArgumentParser(args)
+    ap.add_argument("-d", "--rundir", help="runtime directory for tempfiles, logs, etc")
+    ap.add_argument("node", nargs="?", help="node to enter or run command inside")
+    ap.add_argument(
+        "shellcmd",
+        nargs=argparse.REMAINDER,
+        help="optional shell-command to execute on NODE",
+    )
+    args = ap.parse_args()
+    if args.rundir:
+        configpath = Path(args.rundir).joinpath("config.json")
+    else:
+        configpath, _ = newest_file_in(
+            "config.json",
+            ["/tmp/munet", "/tmp/mutest", "/tmp/unet-test"],
+            has_sibling=args.node,
+        )
+        print(f'Using "{configpath}"')
+
+    if not configpath.exists():
+        print(f'"{configpath}" not found')
+        return 1
+    rundir = configpath.parent
+
+    nodes = []
+    config = json.load(open(configpath, encoding="utf-8"))
+    nodes = list(config.get("topology", {}).get("nodes", []))
+    envcfg = config.get("mucmd", {}).get("env", {})
+
+    # If args.node is not a node it's part of shellcmd
+    if args.node and args.node not in nodes:
+        if args.node != ".":
+            args.shellcmd[0:0] = [args.node]
+        args.node = None
+
+    if args.node:
+        name = args.node
+        nodedir = rundir.joinpath(name)
+        if not nodedir.exists():
+            print('"{name}" node doesn\'t exist in "{rundir}"')
+            return 1
+        rundir = nodedir
+    else:
+        name = "munet"
+    pidpath = rundir.joinpath("nspid")
+    pid = open(pidpath, encoding="ascii").read().strip()
+
+    env = {**os.environ}
+    env["MUNET_NODENAME"] = name
+    env["MUNET_RUNDIR"] = str(rundir)
+
+    for k in envcfg:
+        envcfg[k] = envcfg[k].replace("%NAME%", str(name))
+        envcfg[k] = envcfg[k].replace("%RUNDIR%", str(rundir))
+
+    # Can't use -F if it's a new pid namespace
+    ecmd = "/usr/bin/nsenter"
+    eargs = [ecmd]
+
+    output = subprocess.check_output(["/usr/bin/nsenter", "--help"], encoding="utf-8")
+    if " -a," in output:
+        eargs.append("-a")
+    else:
+        # -U doesn't work
+        for flag in ["-u", "-i", "-m", "-n", "-C", "-T"]:
+            if f" {flag}," in output:
+                eargs.append(flag)
+    eargs.append(f"--pid=/proc/{pid}/ns/pid_for_children")
+    eargs.append(f"--wd={rundir}")
+    eargs.extend(["-t", pid])
+    eargs += args.shellcmd
+    # print("Using ", eargs)
+    return os.execvpe(ecmd, eargs, {**env, **envcfg})
+
+
+if __name__ == "__main__":
+    exit_status = main()
+    sys.exit(exit_status)