Monitoring Appsmith with Vigilmon: Health Endpoint, Web Editor Availability, RTS TCP Port & SSL Alerts

Appsmith is a self-hosted low-code platform for building internal tools — admin panels, dashboards, approval workflows, and CRUD interfaces — backed by your own databases and APIs. Engineering teams use Appsmith to give non-engineers access to operational data without building bespoke UIs. When Appsmith's server goes down, internal tools go dark: customer support can't access admin panels, operations teams lose their dashboards, and any automated workflows hitting the Appsmith API stop. The real-time service (RTS) enables live collaboration and widget updates — when it crashes, editors see stale data and multi-user editing breaks silently. Vigilmon gives you external visibility into Appsmith's health endpoint, web editor, RTS TCP port, and SSL certificate so failures are caught within 60 seconds.

What You'll Build

• A monitor on Appsmith's /api/v1/health health endpoint
• An HTTP monitor for the Appsmith web editor
• A TCP monitor for the Appsmith real-time service (RTS) port
• A monitor for MongoDB connectivity via the Appsmith health API
• SSL certificate monitoring for your Appsmith domain
• An alerting setup that separates application-level failures from real-time service degradation

Prerequisites

• A running Appsmith instance with a public or network-reachable domain
• HTTPS configured (e.g., https://appsmith.example.com)
• A free account at vigilmon.online

Step 1: Verify Appsmith's Health Endpoint

Appsmith exposes a health check endpoint at /api/v1/health that returns the status of the application server and its connected services, including MongoDB:

curl https://appsmith.example.com/api/v1/health

A healthy Appsmith instance returns HTTP 200 with a JSON body that includes the overall status and service states:

{
  "status": "UP",
  "components": {
    "db": {
      "status": "UP"
    },
    "redis": {
      "status": "UP"
    }
  }
}

This endpoint requires no authentication and is designed for health probes. A status: UP response confirms the Spring Boot application server is running, MongoDB is reachable, Redis is connected, and the application is ready to serve requests. A status: DOWN or a non-200 response indicates a critical service dependency has failed.

Step 2: Create a Vigilmon HTTP Monitor for the Health Endpoint

1. Log in to Vigilmon → Add Monitor → HTTP.
2. URL: https://appsmith.example.com/api/v1/health.
3. Check interval: 60 seconds.
4. Response timeout: 15 seconds.
5. Expected status: 200.
6. Keyword: UP.
7. Label: Appsmith API Health.
8. Click Save.

This monitor catches:

• Appsmith Spring Boot server process crashes
• MongoDB connectivity failures — Appsmith stores all app definitions, pages, and data source configurations in MongoDB, so a database outage means the entire platform is unavailable
• Redis session failures that prevent user authentication
• Container restarts or OOM kills from large workspace memory usage

The UP keyword check ensures the response reflects a healthy application state — not just a 200 from a reverse proxy serving a cached or partial health response.

MongoDB connectivity: Appsmith stores all application definitions, widget configurations, action queries, and workspace data in MongoDB. If MongoDB becomes unavailable, Appsmith cannot load any apps, which means your entire internal tooling suite goes dark. The /api/v1/health endpoint's db.status: UP field makes this the most critical monitor in your Appsmith setup.

Step 3: Monitor the Appsmith Web Editor

The Appsmith web editor is a React single-page application that your developers use to build and modify internal tools. Monitor it independently from the API to catch reverse proxy failures and static asset serving issues:

1. Add Monitor → HTTP.
2. URL: https://appsmith.example.com.
3. Check interval: 60 seconds.
4. Expected status: 200.
5. Keyword: Appsmith.
6. Label: Appsmith Web Editor.
7. Click Save.

This monitor catches nginx or reverse proxy failures, CDN issues, and static file serving errors that would prevent developers from opening the editor — even if the Java backend API is healthy. A broken editor means no app modifications, no widget changes, and no debugging of data source connections.

Step 4: Create a TCP Monitor for the Real-Time Service (RTS)

Appsmith's real-time service (RTS) runs as a Node.js microservice and handles WebSocket connections for:

• Live collaboration between multiple editors working on the same app simultaneously
• Real-time widget state updates across users
• Cursor positions and selection highlights during collaborative editing

The RTS listens on port 8091 by default in Appsmith's Docker deployment. When it crashes, collaborative editing breaks without a visible error — editors see stale widget states, changes from other users don't appear, and the collaboration cursor indicators disappear.

1. Add Monitor → TCP.
2. Host: appsmith.example.com (or the internal container name if the RTS port is not publicly exposed).
3. Port: 8091.
4. Check interval: 60 seconds.
5. Response timeout: 10 seconds.
6. Label: Appsmith RTS TCP.
7. Click Save.

Note: In Appsmith's default Docker Compose deployment, the RTS runs inside the main appsmith container and is proxied through nginx. The port may not be directly externally accessible. If that's the case, skip the TCP monitor and rely on the API health endpoint to catch RTS failures that bubble up as application errors. Alternatively, use the internal Docker network address of the container.

Step 5: Monitor SSL Certificates

Appsmith hosts internal tools that your team uses daily. An expired SSL certificate:

• Locks engineers and operations teams out of the editor entirely
• Prevents end users of deployed apps from accessing internal tools
• Breaks any external webhooks or API integrations that call Appsmith's API
• May silently block data source connections if Appsmith calls HTTPS endpoints that validate client-side certificates

1. Add Monitor → SSL Certificate.
2. Domain: appsmith.example.com.
3. Alert when expiry is within: 30 days.
4. Alert again: 14 days, 7 days, 3 days, 1 day.
5. Click Save.

Step 6: Configure Alerting

In Vigilmon under Settings → Notifications, configure your alert channels:

| Monitor | Trigger | Action | |---|---|---| | /api/v1/health | Non-200 or UP missing | Check Appsmith container; inspect MongoDB and Redis connectivity; review Spring Boot logs | | Web Editor | Non-200 or keyword missing | Check nginx/reverse proxy; verify static files are served; inspect container logs | | RTS TCP Port | Connection refused or timeout | Restart the Appsmith container; check Node.js RTS process; inspect WebSocket proxy config | | SSL certificate | < 30 days to expiry | Renew certificate; verify ACME/Let's Encrypt auto-renewal is running |

Alert after: 2 consecutive failures for HTTP monitors. 1 failure for the TCP monitor — a crashed RTS process won't recover on its own without a container restart.

Common Appsmith Failure Modes and What Vigilmon Catches

| Scenario | Vigilmon monitor | |---|---| | Spring Boot server OOM-killed | Health endpoint unreachable; alert within 60 s | | MongoDB down or unreachable | Health check returns db: DOWN; no apps load | | Redis failure | Session authentication fails; users logged out; health returns degraded | | RTS (real-time service) crash | RTS TCP monitor fires; collaborative editing breaks silently | | MongoDB disk full | Write operations fail; app saves and configuration changes fail | | Reverse proxy misconfiguration | Web editor monitor fires; API may still be healthy | | Static assets not served after upgrade | Web editor keyword check fails; blank screen for editors | | SSL certificate expires | SSL monitor alerts at 30 days; all team access blocked | | MongoDB replica set failover | Brief health check degradation; apps may be read-only during failover | | Container memory pressure | Java heap exhaustion; server becomes unresponsive; health check times out | | DNS misconfiguration | All monitors fire simultaneously |

Internal tools are the nervous system of your operations team — when Appsmith goes down, customer support, ops, and data teams lose the visibility they need to do their jobs. Vigilmon watches Appsmith's API health, web editor, real-time service, and SSL certificate so you're alerted within 60 seconds of any failure, before your team files a help ticket wondering why their admin panel is blank.

Start monitoring Appsmith in under 5 minutes — register free at vigilmon.online.