Canary deployments in Nginx - Step-by-Step Execution

Process Flow - Canary deployments

Start Deployment

↓

Deploy New Version to Small %

↓

Monitor Metrics & Logs

↓

Increase %

↓

Repeat

This flow shows deploying a new version to a small user portion, monitoring it, then either increasing traffic or rolling back.

Execution Sample

Nginx

upstream backend {
  server stable:80 weight=90;
  server canary:80 weight=10;
}

server {
  listen 80;
  location / {
    proxy_pass http://backend;
  }
}

This NGINX config snippet routes 10% of traffic to the canary backend.

Process Table

Step	Action	Traffic % to Canary	Traffic % to Stable	Result
1	Start deployment	0%	100%	All traffic to stable version
2	Deploy canary with 10% traffic	10%	90%	10% users see new version
3	Monitor metrics	10%	90%	No errors detected
4	Increase canary to 30%	30%	70%	More users see new version
5	Monitor metrics	30%	70%	No errors detected
6	Increase canary to 50%	50%	50%	Half users see new version
7	Monitor metrics	50%	50%	Errors detected
8	Rollback to stable	0%	100%	All traffic back to stable
9	End deployment	0%	100%	Deployment stopped due to errors

💡 Deployment stops after errors detected at 50% canary traffic and rollback occurs

Status Tracker

Variable	Start	After Step 2	After Step 4	After Step 6	After Step 8	Final
canary_traffic_percent	0%	10%	30%	50%	0%	0%
stable_traffic_percent	100%	90%	70%	50%	100%	100%
deployment_status	stable	canary started	canary increased	canary increased	rolled back	stable

Key Moments - 3 Insights

Why does traffic to canary start at a low percentage like 10%?

Starting with low traffic limits risk. As shown in execution_table step 2, only 10% users see the new version to catch issues early.

What happens if errors are detected during canary deployment?

As in step 7 and 8, if errors appear, traffic is rolled back to 0% canary and 100% stable to protect users.

Why do we increase canary traffic gradually?

Gradual increase (steps 4 and 6) helps verify stability before full rollout, reducing impact of bugs.

Visual Quiz - 3 Questions

Look at the execution_table, what is the canary traffic percentage at step 4?

A 50%

B 10%

C 30%

D 0%

💡 Hint

Check the 'Traffic % to Canary' column at step 4 in the execution_table.

At which step does the deployment rollback happen according to the execution_table?

A Step 8

B Step 7

C Step 6

D Step 9

💡 Hint

Look for the row where 'Rollback to stable' is the action.

If no errors were detected at step 7, what would likely happen next?

A Rollback to stable

B Increase canary traffic further

C Stop deployment

D Decrease canary traffic

💡 Hint

Refer to the pattern of increasing traffic after successful monitoring in the execution_table.

Concept Snapshot

Canary deployments gradually route a small % of traffic to a new version.
Monitor for errors before increasing traffic.
Rollback immediately if errors occur.
Use NGINX weighted routing to control traffic split.
This reduces risk of full rollout failures.

Full Transcript

Canary deployments start by sending a small portion of user traffic to a new version of an application. This is done to test the new version in real conditions with limited impact. Using NGINX, we can set weights to control how much traffic goes to the new version versus the stable one. We monitor metrics and logs carefully. If no problems appear, we increase the traffic gradually. If errors are detected, we rollback to the stable version immediately. This process helps keep users safe while deploying new features.