Monotoring Your Symfony App using Datadog ? Nope Let’s use Sentry ^_^

5 min readMay 16, 2025

Introduction

Monitoring, observability, and error tracking are critical aspects of modern software development. Yet, many developers underestimate their value until the day an app breaks in production. In this article, I’ll walk you through how I integrated Sentry with my Symfony task management application — but more than that, I’ll share the structured reasoning and operational thinking that shaped this decision. You’ll understand why, when, and how to monitor your app intelligently, and how to make your choices serve long-term system health and evolution.

Why Monitoring and Observability Matter

Before jumping into tools like Sentry, it’s essential to grasp the underlying purpose:

Visibility: Know what’s happening in your app in real-time.
Alerting: Get notified when something goes wrong (not after a user complains).
Debugging: Save time by having stack traces, context, and breadcrumbs.
Quality: Improve your delivery speed with confidence.

After making all the tests and verifications, it’s still inevitable: issues will happen — maybe not now, but eventually. As we move forward in time, we are getting closer to the next bug, the next slowdown, the next unknown. That’s why it’s crucial to anticipate: how will we detect, analyze, and react to these issues? How will we measure whether a migration improved or degraded performance?

We need to track our system in a holistic way, not just to fix bugs, but to understand why things are better or worse over time. We need to understand how change propagates and how the application behaves under different operational conditions. This is where telemetry becomes essential.

What is telemetry?

Telemetry is data automatically sent by your application to help you monitor, observe, and analyze your system. It includes logs, metrics, traces, and events — all the signals that tell you what’s happening under the hood. Telemetry is not just about collecting noise — it’s about designing what your system emits and why.

When Should You Add It?

From the first production deployment
In staging environments for testing regressions
During development for critical paths

When It’s Overkill?

For small throwaway scripts
For MVPs without any external users
For static websites without dynamic logic

TL;DR: If your app has users and logic, start thinking observability.

Why I Chose Sentry

There are many tools for observability, but I picked Sentry for a few reasons:

Native integration with Symfony
Great developer experience (easy to set up, use, and navigate)
Automatic stack traces, breadcrumbs, release tracking
Hosted or self-hosted, depending on data constraints and compliance

Sentry is simple to put in place. Their documentation is clear and beginner-friendly, and makes integrating error tracking and monitoring into your project a frictionless experience.

From a broader system point of view, the decision to use Sentry wasn’t about adding a tool — it was about introducing a feedback loop into the application’s lifecycle. Something that could live with the system, evolve with it, and illuminate how it behaves in production.

That said, it’s worth knowing where Sentry fits — and where it doesn’t.

Step-by-Step Guide: Symfony + Sentry

1. Create Your Sentry Project

Go to sentry.io and create a new project. Choose PHP → Symfony.

2. Install the SDK in Symfony

composer require sentry/sentry-symfony

3. Configure DSN

Add your DSN (provided by Sentry) to your .env or .env.local:

SENTRY_DSN="https://xxxxxx.ingest.sentry.io/yyyyy"

4. Activate Sentry in your config

In config/packages/sentry.yaml:

sentry:
    dsn: '%env(SENTRY_DSN)%'
    options:
        send_default_pii: true # optional: capture user info

5. Allow Sentry in All Environments (optional tweak)

By default, Sentry is usually activated only in prod. For this article, I wanted to enable it in all environments to explore and test deeply. So I updated config/bundles.php:

return [
    Sentry\SentryBundle\SentryBundle::class => ['all' => true],
];

6. Add Context (User, Tags)

In a listener or controller:

use Sentry\SentrySdk;
use Sentry\State\Scope;

SentrySdk::getCurrentHub()->configureScope(function (Scope $scope): void {
    $scope->setUser([
        'id' => $user->getId(),
        'email' => $user->getEmail(),
    ]);
    $scope->setTag('project', $project->getName());
});

7. Test It!

Trigger an exception manually:

throw new \Exception("Manual test exception");

What It Gave Me (Real Feedback)

After integrating Sentry:

I caught two bugs I hadn’t noticed in staging
I could trace user issues with complete context
I gained confidence to refactor aggressively knowing I had a safety net

But more than debugging, Sentry gave me insight:

Since my app uses PostgreSQL, I could visualize SQL queries directly.
I saw the duration, frequency, and patterns of these queries.
I noticed repeated SELECT calls and started thinking: is this a caching opportunity?

This opened a new line of thought: integrating Redis as a read-through cache on repetitive access paths. That’s not just fixing an issue — that’s identifying an inefficiency before it hurts.

The stack was fully Dockerized, and the integration remained smooth across containers.

Pro Tips from the Field

Filter out noise: Use sampling and ignore rules to avoid irrelevant alerts
Set release identifiers: It helps track regressions between versions
Don’t track dev environment: Only activate Sentry in prod
Use breadcrumbs: Enable them to see the sequence of events before a crash
Use with GitHub: Link commits and issues directly
Observe external systems: I plan to connect additional services soon to evaluate how they affect performance and entry point behavior

Monitoring is not a patch. It’s a design practice.

Conclusion

Observability isn’t a luxury — it’s a superpower. With Sentry, Symfony developers can bring that power to their apps in just a few minutes. But more importantly, it’s a systemic discipline: you’re not just tracking exceptions — you’re shaping how your app communicates with its builders.

Go beyond logs. Design for understanding. Build with insight.

What’s Next?

If you want to go further:

Add performance monitoring (available in Sentry)