---
title: Canary release
description: >-
  Send a share of the users to a new version, the team first, and copy traffic
  to it before that.
---
> ## Documentation Index
> Fetch the complete documentation index at: https://docs.page/luizfonseca/super/llms.txt
> Use this file to discover all available pages before exploring further.

A new version goes out in three steps, each a small change to the configuration.

## 1. Copy traffic to it

Before it takes any request, the new version gets copies of the real ones with a [mirror](/routing/mirror). Its answers are dropped, so users never see them, and you can watch its errors and latency.

```hcl
host "app.example.com" {
  location "/" {
    upstream "app-v1:8080" {}

    mirror {
      percent = 20
      upstream "app-v2:8080" {}
    }
  }
}
```

## 2. The team, then a share of the users

A [traffic split](/routing/traffic-split) sends the team to the new version with a rule, and a share of everyone else. Each user keeps their side, through a cookie.

```hcl
host "app.example.com" {
  location "/" {
    upstream "app-v1:8080" {}

    traffic_split "v2" {
      percent = 5
      upstream "app-v2:8080" {}
    }

    rule "the team" {
      and {
        client {
          in = ["203.0.113.0/24"]
        }
      }
      then {
        traffic_split = "v2"
      }
    }
  }
}
```

Raise `percent` as it holds up: users already on `v2` stay there.

## 3. Everyone

When `v2` takes 100% of the users, make it the location's upstream and remove the split.

```hcl
host "app.example.com" {
  location "/" {
    upstream "app-v2:8080" {}
  }
}
```

To roll back at any step, lower `percent` to `0` or remove the block: the configuration is reloaded without dropping connections.