> For the complete documentation index, see [llms.txt](https://justin-se.gitbook.io/justin-se-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://justin-se.gitbook.io/justin-se-docs/backend/deployment-strategy.md).

# Deployment  Strategy

### Blue Green deployment

**Pros**

* 0 down time on new version of release

**How It Work**

1. prepair two identical server, one serving live as blue server, another idle as green server. 
2. use load balancer direct live traffic into blue (live) server.
3. update new app version into green (idle) server, it can also act as a testnet/sandbox.
4. once green (idle) server ready to release, let load balancer direct traffic from blue server to green server, shiftting different app version without service downtime.
5. If any issues met in new version (green server), we can use same method rollback to previous version (blue server).