0️⃣ Zero downtime deployment strategies for PHP apps
We all know that deploying your PHP application is super easy. Traditionally, we would do some something like:
(some extra commands, e.g.: php artisan config:cache)
But it comes with a risk, the deployment takes time and could be up to several minutes.
Issues can increase in the middle of the deployment, e.g.: pulling, composer install,... we would never be sure if there is no traffic when deploying a new version 🔥
Additionally, there is no guarantee that your application will be up and running without any interruption or issue as well .
So there are some strategies that I will share below and choose the best one for your applications 😉
Traditional build with duct tapes
Still the same build as the introduction, but we added some improvements.
Instead of pulling, we'll clone the project into a new folder (use the current timestamp for the folder name)
Then we do a fresh deployment process (prepare .env, composer install,...)
After the process is done, point
apache to the new folder path and restart nginx/apache.
Contains a lot of works
Doesn't look so reliable
Nowadays, we have 2 high-perf runners: Swoole & RoadRunner.
Both are built differently but serve the same thing: keep your PHP apps running in a high-perf mode.
Basically, it will be a long-running process (not like the traditional way) like others (Node.js Express, Go,...). Your project will be loaded into the memory. So if there are file changes, it won't be updated until you restart the process.
With that, you can follow the traditional build process (git pull, composer install, scripts,...) normally fine.
After those actions, simply restart the process gratefully and boom, your app is up.
You also run your PHP apps in the high-perf mode
There will be a little downtime (might up to some seconds) when restarting the process.
Quite repetitive when deploying several nodes
- If you don't deploy in parallel, there will be inconsistency for a short amount of time between nodes until the deployment is through.
Build your own Docker Image
Docker has been around for a decade, Docker was built for this 😎
This would work best if you have a CI/CD pipeline too. The flow is:
Run tests (unit, integration)
(Optional) Test image
Push the image to the registry (Docker or your private cloud)
Swap the image version to latest
Run health check
With Docker, you can run your application in the serverless mode too, using GCP CloudRun, AWS Fargate or Fly.io 🚀
Guaranteed zero downtime
The swap image task is fast, thus we don't have to worry about inconsistent nodes when we have multiple nodes.
- Cost $$$ for image storage on private cloud.
Well, those are some of the strategies that I worked with, and I totally in love with the Docker way (I'm also running high-perf mode too 🥰)
Hope it helps you to achieve the zero downtime deployment.