This was originally published on rollgate.io/blog/gradual-rollouts-guide.
What Is a Gradual Rollout?
A gradual rollout (also called progressive delivery or incremental rollout) is the practice of releasing a feature to a small subset of users first, then progressively expanding to the full user base. Instead of going from 0% to 100% in one step, you control the pace.
Day 1: 1% of users → Monitor
Day 2: 5% of users → Monitor
Day 3: 25% of users → Monitor
Day 5: 100% of users → Done
If something goes wrong at any stage, you roll back to 0% instantly. No code changes, no redeployment, no downtime.
Why Gradual Rollouts Matter
Reduce Blast Radius
A bug that affects 1% of users is very different from a bug that affects 100%. Gradual rollouts contain the impact of issues, giving you time to detect and fix problems before they reach everyone.
Build Confidence
Shipping a big feature to all users at once is stressful. Gradual rollouts let you validate in production with real traffic, real data, and real user behavior — at a safe scale.
Enable Data-Driven Decisions
By monitoring metrics at each stage (error rates, latency, conversion), you make rollout decisions based on data, not gut feeling.
Instant Rollback
Traditional rollbacks require reverting code, running CI, and redeploying. With feature flags, rollback is a single toggle that takes effect in seconds.
Rollout Strategies
1. Percentage-Based Rollout
The most common approach. You specify a percentage of users who should see the new feature. The feature flag service uses consistent hashing to ensure the same users always see the same variant (so a user at 5% who sees the feature will still see it at 25%).
// In your feature flag dashboard:
// new-search-algorithm: 10% rollout
const useNewSearch = rollgate.isEnabled('new-search-algorithm', {
userId: user.id
});
Best for: General feature releases, UI changes, algorithm updates.
2. Canary Release
Start with a tiny group (0.1–1%) of users. These are your "canaries in the coal mine." If metrics look good after a set period, expand to a larger group.
Typical canary schedule:
- 0.1% for 1 hour → Check error rates
- 1% for 4 hours → Check performance
- 10% for 24 hours → Check user feedback
- 50% for 24 hours → Final validation
- 100% → Full release
Best for: Backend changes, infrastructure updates, anything with high risk.
3. Ring Deployment
Expand through predefined rings of users, from least to most critical:
- Ring 0: Internal team (dogfooding)
- Ring 1: Beta users / early adopters
- Ring 2: 10% of general users
- Ring 3: 50% of general users
- Ring 4: All users
This approach is popular at Microsoft and gives you structured checkpoints.
Best for: Enterprise software, B2B platforms, features with compliance requirements.
4. User Segment Targeting
Instead of random percentages, target specific user segments first:
- Enable for users on the "Pro" plan first
- Enable for users in a specific region
- Enable for users who opted into the beta program
// Rollgate supports targeting rules:
// If user.plan == "pro" → enable
// Else → 10% rollout
const showAdvancedAnalytics = rollgate.isEnabled('advanced-analytics', {
userId: user.id,
attributes: {
plan: user.plan,
region: user.region
}
});
Best for: Tiered features, regional launches, B2B features.
Implementing Gradual Rollouts: Step by Step
Step 1: Create the Feature Flag
In your feature flag dashboard, create a flag with a clear name and description:
-
Key:
new-checkout-flow - Description: Redesigned checkout with one-page form
- Type: Boolean
-
Default:
false
Step 2: Add the Flag to Your Code
Wrap the new feature behind the flag check:
import { Rollgate } from '@rollgate/sdk-node';
const rollgate = new Rollgate({ apiKey: process.env.ROLLGATE_API_KEY });
app.get('/checkout', async (req, res) => {
const useNewCheckout = await rollgate.isEnabled('new-checkout-flow', {
userId: req.user.id,
attributes: { plan: req.user.plan }
});
if (useNewCheckout) {
return res.render('checkout-v2');
}
return res.render('checkout-v1');
});
Step 3: Deploy with Flag Off
Merge and deploy your code. The flag is off, so all users see the old checkout. Nothing changes.
Step 4: Enable for Internal Team
Set a targeting rule: enable for users with email ending in @yourcompany.com. Test the full flow with real production data.
Step 5: Expand Gradually
Once internal testing passes:
- Enable for 5% of users
- Monitor for 24 hours: error rates, latency, conversion rate
- If metrics are healthy, increase to 25%
- Monitor for another 24 hours
- Increase to 100%
Step 6: Clean Up
After successful full rollout:
- Remove the flag check from your code
- Delete the old code path
- Archive the flag in your dashboard
- Update documentation
What to Monitor During Rollout
Error Rates
Compare error rates between users with the flag on vs off. A spike in errors for the flag-on group means something is wrong.
Performance
Measure p50, p95, and p99 latency. New features sometimes introduce unexpected performance regressions.
Business Metrics
Track conversion rates, engagement, or whatever KPI the feature is meant to improve. If the new checkout reduces conversion, you want to know at 5%, not at 100%.
User Feedback
Watch support tickets and feedback channels. Sometimes metrics look fine but users are confused or frustrated.
Common Mistakes to Avoid
Rolling Out Too Fast
Going from 1% to 100% in one jump defeats the purpose. Give each stage enough time to surface issues. A 24-hour soak period at each stage is a good default.
Not Having a Rollback Plan
Before starting a rollout, define your rollback criteria. "If error rate increases by more than 2%, disable the flag." Don't wait to decide in the middle of an incident.
Ignoring Sticky Sessions
Users should consistently see the same variant. If a user sees the new checkout on Monday but the old one on Tuesday, the experience is confusing and your metrics are unreliable. Use consistent hashing on user ID.
Forgetting to Clean Up
A gradual rollout that reaches 100% is not done until the flag is removed from code. Schedule flag cleanup as part of your rollout plan, not as an afterthought.
No Monitoring
A gradual rollout without monitoring is just a slow release. The entire point is to observe metrics at each stage and make informed decisions.
Conclusion
Gradual rollouts are one of the highest-leverage practices in modern software delivery. They let you ship faster with less risk, validate changes with real production traffic, and roll back instantly when things go wrong.
The key ingredients are simple: a feature flag service, percentage-based rollout rules, and disciplined monitoring. Start with your next feature — create a flag, roll out to 5%, watch the metrics, and expand from there.
Try Rollgate free and implement your first gradual rollout in minutes.
Related reading: New to feature flags? Start with What Are Feature Flags?. Already using flags? Learn about A/B testing with feature flags, scheduled releases, and how feature flags compare to feature branches. For SDK-specific guides, see React, Go, or Python.