Homepage (TDD slice 2): the http probe method

Red test first: a raw TCP listener that never speaks HTTP must read down
under an http probe (up under tcp), while a real HTTP server reads up. This
test caught a real hang — the backgrounded listener inherited the test
runner's stdout pipe and held it open; fixed by redirecting its output and
killing both listeners in teardown.

scripts/homepage-status.py: probe() now dispatches on method. http does an
urlopen (any HTTP status = up; no connection = down); tcp connects.

The checker is now complete: tcp + http + wip + atomic write + generated_at.
Remaining slices: services.json schema, the pages + theme + toggle, the
Caddyfile (validate + two hashes), the git-driven deploy.

scripts/homepage-status.py

@@ -11,6 +11,8 @@ import os
 import socket
 import sys
 import tempfile
+import urllib.error
+import urllib.request
 from datetime import datetime, timezone
 
 TIMEOUT = 5  # seconds, per probe (Q11 / Q40)
@@ -18,6 +20,17 @@ TIMEOUT = 5  # seconds, per probe (Q11 / Q40)
 
 def probe(host, port, method="tcp"):
     """Return 'up' if the backend answers, else 'down'."""
+    if method == "http":
+        try:
+            urllib.request.urlopen(
+                urllib.request.Request("http://%s:%d/" % (host, port)),
+                timeout=TIMEOUT,
+            )
+            return "up"
+        except urllib.error.HTTPError:
+            return "up"  # an HTTP response of any status means the backend is up
+        except Exception:
+            return "down"
     try:
         with socket.create_connection((host, port), timeout=TIMEOUT):
             return "up"

tests/homepage_checker.bats

@@ -19,6 +19,8 @@ setup() {
 
 teardown() {
     [ -n "${LISTENER_PID:-}" ] && kill "$LISTENER_PID" 2>/dev/null
+    [ -n "${RAW_PID:-}" ] && kill "$RAW_PID" 2>/dev/null
+    [ -n "${HTTP_PID:-}" ] && kill "$HTTP_PID" 2>/dev/null
     rm -rf "$TMP"
 }
 
@@ -43,3 +45,46 @@ assert s["wip"] == "wip", s
 assert "generated_at" in d
 PY
 }
+
+@test "checker: http method — a non-HTTP listener is down, a real HTTP server is up" {
+    local svc="$TMP/services.json" out="$TMP/status.json"
+    local RAW_PORT=18903 HTTP_PORT=18904
+    # A raw TCP listener that accepts connections but never speaks HTTP.
+    # Redirect its output so it cannot hold the test runner's stdout pipe open.
+    python3 - "$RAW_PORT" >/dev/null 2>&1 <<'PY' &
+import socket, threading, time, sys
+s = socket.socket()
+s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+s.bind(("127.0.0.1", int(sys.argv[1])))
+s.listen(5)
+def hold():
+    while True:
+        try:
+            c, _ = s.accept()
+            c.close()
+        except Exception:
+            break
+threading.Thread(target=hold, daemon=True).start()
+time.sleep(300)
+PY
+    RAW_PID=$!
+    # A real HTTP server.
+    python3 -m http.server "$HTTP_PORT" --bind 127.0.0.1 >/dev/null 2>&1 &
+    HTTP_PID=$!
+    sleep 0.5
+    cat > "$svc" <<JSON
+[
+  {"name":"rawhttp","category":"user","probe":"127.0.0.1:$RAW_PORT","method":"http","wip":false},
+  {"name":"realhttp","category":"user","probe":"127.0.0.1:$HTTP_PORT","method":"http","wip":false}
+]
+JSON
+    python3 "$CHECKER" "$svc" "$out"
+    python3 - "$out" <<'PY'
+import json, sys
+d = json.load(open(sys.argv[1]))
+s = {x["name"]: x["state"] for x in d["services"]}
+assert s["rawhttp"] == "down", s
+assert s["realhttp"] == "up", s
+PY
+    kill "$RAW_PID" "$HTTP_PID" 2>/dev/null
+}