Agent Local Cloud Sync

Agent local ↔ cloud sync

A ~100-line Python listener + a user-systemd unit. When you git push to your tracked branch, the host fast-forwards within seconds. No extra dependencies, no ngrok, no CI runner.

Good fit for:

• A single VPS or droplet that tracks a repo.
• Agent/bot runtimes where the workspace repo is the source of truth (e.g. a Hermes or Claude Code agent runtime, a Discord bot, a content scheduler).
• Anything where "ssh in and git pull" is getting tedious.

Not a fit for:

• Multi-host deploys (use a CI runner with a deploy step).
• Anything that needs a build step beyond git pull (add a post-pull hook, or just use CI).

How it works

1. GitHub POSTs push events to http://:/webhook with an X-Hub-Signature-256 header.
2. Listener verifies HMAC-SHA256 against a secret file. 401 on mismatch.
3. On valid push to your tracked branch: git -C pull --ff-only origin .
4. Everything logs to journalctl --user -u github-webhook.

ping events and pushes to other branches return 200 with "ignored" and are logged.

Prerequisites

• A Linux host you can SSH to as a user that can run systemctl --user. Root is fine. Non-root works with loginctl enable-linger .
• Python 3.8+ (stdlib only — no pip install).
• The repo already cloned on the host with SSH or HTTPS auth that git pull can use non-interactively (deploy key, SSH agent, or stored credential).
• The host must be reachable from the public internet on the port you pick (default 9000). If you're behind a firewall/NAT, this recipe won't work without a tunnel.

Install

# 1. Pick values
HOST=your-ssh-alias              # e.g. from ~/.ssh/config
REPO_PATH=/root/DEV/my-repo      # absolute path on the host
BRANCH=main
PORT=9000

# 2. Generate the HMAC secret on the host (only place it should exist in plaintext)
ssh "$HOST" "
  mkdir -p /root/.config/github-webhook /root/bin /root/.config/systemd/user
  python3 -c 'import secrets; print(secrets.token_hex(32))' > /root/.config/github-webhook/secret
  chmod 600 /root/.config/github-webhook/secret
"

# 3. Copy the script + unit
scp github_webhook.py "$HOST":/root/bin/github_webhook.py
scp github-webhook.service "$HOST":/root/.config/systemd/user/github-webhook.service

# 4. Edit the unit's Environment= lines to match your REPO_PATH / BRANCH / PORT, then:
ssh "$HOST" "
  chmod +x /root/bin/github_webhook.py
  systemctl --user daemon-reload
  systemctl --user enable --now github-webhook.service
"

# 5. Register the webhook with GitHub
SECRET=$(ssh "$HOST" 'cat /root/.config/github-webhook/secret')
IP=$(ssh "$HOST" 'curl -s -4 ifconfig.me')
gh api -X POST /repos/OWNER/REPO/hooks \
  -f name=web -F active=true -f 'events[]=push' \
  -f "config[url]=http://$IP:$PORT/webhook" \
  -f 'config[content_type]=json' \
  -f "config[secret]=$SECRET" \
  -f 'config[insecure_ssl]=0'

If you're not a gh user, configure the webhook manually: repo → Settings → Webhooks → Add webhook. Content type application/json, set the secret, events = "Just the push event".

Verify

# Listener up?
ssh "$HOST" "curl -s http://127.0.0.1:$PORT/health"       # → ok

# External reach?
curl -s -m 5 "http://$IP:$PORT/health"                    # → ok

# GitHub ping delivered on hook creation?
ssh "$HOST" 'journalctl --user -u github-webhook -n 20 --no-pager'
# → "ping received"

End-to-end:

git commit --allow-empty -m "test webhook" && git push
sleep 4
ssh "$HOST" "cd $REPO_PATH && git rev-parse HEAD"         # matches your laptop HEAD

Day-2 ops

# Tail logs
ssh "$HOST" 'journalctl --user -u github-webhook -f'

# Restart
ssh "$HOST" 'systemctl --user restart github-webhook'

# Rotate secret
NEW=$(python3 -c 'import secrets; print(secrets.token_hex(32))')
ssh "$HOST" "echo '$NEW' > /root/.config/github-webhook/secret && chmod 600 /root/.config/github-webhook/secret && systemctl --user restart github-webhook"
HOOK_ID=$(gh api /repos/OWNER/REPO/hooks --jq '.[] | select(.config.url | contains("/webhook")) | .id')
gh api -X PATCH "/repos/OWNER/REPO/hooks/$HOOK_ID" -f "config[secret]=$NEW"

# Redeliver a past payload (repo → Settings → Webhooks → pick hook → Recent Deliveries)

Security model

• Secret is the only gate. The webhook URL is public. An attacker without the secret can only trigger 401s.
• With the secret (if it leaks), an attacker can forge push payloads and force git pull --ff-only. That can't inject code — --ff-only refuses anything except fast-forwards of what GitHub actually has — but it can be noisy. Rotate the secret if the host is compromised.
• No TLS in this recipe. Payloads travel over plain HTTP. The HMAC protects integrity but not confidentiality. GitHub signs the body; there's nothing sensitive in a push event beyond ref + commit SHAs that are already public on a public repo. For private repos or extra paranoia, put the listener behind a reverse proxy (Caddy / nginx) with a Let's Encrypt cert and switch to HTTPS.
• Runs as the SSH user. The listener runs git pull with the same credentials the user has. If that's root, git pull runs as root. Fine for a single-tenant droplet — use a dedicated user if you want to narrow blast radius.

If the host's public IP changes

IP=$(ssh "$HOST" 'curl -s -4 ifconfig.me')
HOOK_ID=$(gh api /repos/OWNER/REPO/hooks --jq '.[] | select(.config.url | contains("/webhook")) | .id')
gh api -X PATCH "/repos/OWNER/REPO/hooks/$HOOK_ID" \
  -f "config[url]=http://$IP:$PORT/webhook" \
  -f 'config[content_type]=json'

For a long-lived setup, use a reserved IP or a domain.

Uninstall

# On the host
ssh "$HOST" '
  systemctl --user disable --now github-webhook.service
  rm /root/.config/systemd/user/github-webhook.service
  rm /root/bin/github_webhook.py
  rm -rf /root/.config/github-webhook
  systemctl --user daemon-reload
'

# On GitHub
HOOK_ID=$(gh api /repos/OWNER/REPO/hooks --jq '.[] | select(.config.url | contains("/webhook")) | .id')
gh api -X DELETE "/repos/OWNER/REPO/hooks/$HOOK_ID"

Gotchas

• Zsh glob error on gh api: config[url]=... needs single quotes — bare brackets trigger glob expansion. Error looks like "no matches found".
• Repeated fields: events[]=push uses the repeated-field form — not a JSON array.
• ping vs push: GitHub fires ping immediately on hook creation. The listener returns 200 for it. Use this to confirm delivery without a real push.
• "Everything up-to-date": git push only triggers the webhook if there's a new commit. Use git commit --allow-empty to force a test push.
• UFW: If UFW is active, ufw allow /tcp. And don't forget ufw allow 22/tcp before enabling UFW or you lose SSH.
• Hostname/IP in unit file: The unit doesn't care about the public IP — only GitHub does. If the host's IP changes, update the GitHub hook, not the unit.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: cobibean
• Source: cobibean/agent-local-cloud-sync
• License: MIT

Install and usage instructions live in the source repository linked above.