Vercel Deployment

This page details the deployment strategy for the application on Vercel, covering automatic deployments, environment variable management, and configured cron jobs.

Automatic Deployment

The application is hosted on Vercel, leveraging its native integration with GitHub. Pushes to the main branch automatically trigger a production deployment. For pull requests, Vercel creates preview deployments, allowing for testing changes in an isolated environment before merging to main. This process is handled by Vercel's GitHub application, not by custom GitHub Actions workflows.

Environment Variables

Environment variables required for the application are managed directly within the Vercel dashboard. While a local .env.example file enumerates the necessary variables for local development, their production values are securely configured and injected by Vercel during the build and runtime phases.

Vercel Cron Jobs

Vercel Cron Jobs are used to schedule recurring tasks. These are declared in the vercel.json file:

{
  "crons": [
    {
      "path": "/api/cron/reminders",
      "schedule": "0 8 * * *"
    },
    {
      "path": "/api/cron/whatsapp-watchdog",
      "schedule": "0 9 * * *"
    }
  ]
}

The /api/cron/reminders endpoint is scheduled to run daily at 8 AM UTC, handling tasks such as sending WhatsApp reminders for appointments and trial expiration emails. The /api/cron/whatsapp-watchdog endpoint runs daily at 9 AM UTC.

Authentication for these cron job handlers relies on a shared secret, which is expected in either the x-cron-secret header or as a Bearer token in the Authorization header.

Sentry's integration, configured in next.config.ts, includes automaticVercelMonitors: true within its webpack options. This enables automatic instrumentation of Vercel Cron Monitors, providing visibility into the health and execution of these scheduled tasks.

Sentry Integration

The application integrates with Sentry for error monitoring and performance tracing, configured via next.config.ts. The withSentryConfig wrapper is used to set up Sentry for Next.js.

Key Sentry configurations include:

• org: "odys-hx" and project: "javascript-nextjs" identify the Sentry project.
• silent: !process.env.CI ensures Sentry logs for source map uploads are only printed in CI environments.
• widenClientFileUpload: true uploads a broader set of source maps for more detailed stack traces.
• tunnelRoute: "/monitoring" routes browser requests to Sentry through a Next.js rewrite, which can help circumvent ad-blockers.
• automaticVercelMonitors: true (as mentioned above) enables Sentry's Cron Monitors for Vercel cron jobs.

Known Gaps

The authentication mechanism for Vercel Cron Jobs, which checks for a shared secret in x-cron-secret or Authorization: Bearer <CRON_SECRET>, uses a plain === comparison. This is not a timing-safe comparison, which could potentially be vulnerable to timing attacks. A timing-safe comparison mechanism is needed to mitigate this risk.