pkgs.uvms: init

...with some basic optional persistence and without having to rebuild
images for every app

nix run -f . pkgs.uvms -- --persist-home librewolf alacritty --run librewolf --run alacritty

pkgs/uvms-guest/guest.py

@@ -0,0 +1,76 @@
+import json
+import os
+import select
+import socket
+import subprocess
+
+
+def handle_run(run: dict) -> dict:
+    res = {}
+    text = run.get("text", False)
+    env = {
+        **os.environ,
+        "PATH": ":".join(
+            os.environ.get("PATH", "").split(":") + run.get("EXTRA_PATH", [])
+        ),
+    }
+    proc = None
+    try:
+        proc = subprocess.Popen(
+            req["run"]["argv"],
+            text=text,
+            env=env,
+            cwd="/home/user",
+            stdin=subprocess.PIPE,
+            stdout=subprocess.PIPE,
+        )
+        res["status"] = "exec succeeded"
+    except Exception as e:
+        res["status"] = "exec failed"
+        res["exception"] = repr(e)
+    res["pid"] = getattr(proc, "pid", None)
+    try:
+        if proc is not None:
+            proc.wait(0.125)
+        res["long_running"] = False
+        res["returncode"] = getattr(proc, "returncode", None)
+    except subprocess.TimeoutExpired:
+        res["long_running"] = True
+    return res, proc
+
+
+if __name__ == "__main__":
+    serv = socket.fromfd(3, socket.AF_VSOCK, socket.SOCK_STREAM)
+
+    procs = []
+    conns = [serv]
+
+    while True:
+        rr, rw, xs = select.select(conns, [], [])
+
+        for con in rr:
+            if con is serv:
+                con, (cid, port) = serv.accept()
+                assert cid == 2, cid
+                conns.append(con)
+                continue
+            req = con.recv(8192)
+            # IDK why but I keep getting empty messages
+            if req == b"":
+                continue
+            try:
+                req = json.loads(req)
+                print(f"Received {req=}")
+            except json.JSONDecodeError as e:
+                print(f"Couldn't interpret {req=}: {e}")
+                continue
+            if "run" in req:
+                res, proc = handle_run(req["run"])
+                procs.append(proc)
+            else:
+                res = {"status": "unknown command"}
+            _, rw, _ = select.select([], [con], [])
+            assert rw, rw
+            res = json.dumps(res).encode("utf8")
+            print(f"Responding with {res=}")
+            con.send(res)