browser-harness-ats-automation

browser-harness-ats-automation

Automate job applications on ATS platforms (Ashby, Greenhouse, Workday) using browser-use/browser-harness with CDP.

Critical architecture: ATS forms live in iframes

Modern ATS platforms (Ashby, Greenhouse) render application forms inside cross-origin iframes. This is the root cause of most automation failures. You MUST attach to the iframe session before any DOM operations.

Standard setup

# Start Xvfb + Chrome with remote debugging
Xvfb :99 -screen 0 1280x800x24 &
export DISPLAY=:99
/usr/bin/chromium-browser --headless --no-sandbox --disable-gpu \
  --remote-debugging-port=9222 \
  --remote-debugging-address=127.0.0.1 &
sleep 3

# Install browser-harness
git clone https://github.com/browser-use/browser-harness.git
cd browser-harness && uv sync && uv tool install -e .

# Start daemon
cd browser-harness && nohup uv run bu-daemon &
sleep 2

CDP socket pattern

The socket is at /tmp/bu-default.sock. Use this helper inside uv run browser-harness <<'PY':

import socket, json

def cdp(method, session_id=None, **params):
    sk = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
    sk.connect("/tmp/bu-default.sock")
    r = {"method": method, "params": {"session_id": session_id, **params} if session_id else params}
    sk.sendall((json.dumps(r) + "\n").encode())
    data = b""
    while not data.endswith(b"\n"):
        chunk = sk.recv(1 << 20)
        if not chunk: break
        data += chunk
    sk.close()
    return json.loads(data).get("result", {})

FRAME_ID = "DFF978A387F9E4D8D8A8AF1EF7385A08"
sid = cdp("Target.attachToTarget", targetId=FRAME_ID, flatten=True).get("sessionId")

Finding the right iframe target

targets = cdp("Target.getTargets")
for t in targets.get("result", {}).get("targetInfos", []):
    if t["type"] in ("page", "iframe"):
        print(f"  {t['type']}: {t.get('url','')[:80]} id={t['targetId']}")

File upload in iframes