How to avoid downtime using PM2

[yuriescl]

I'm deploying my Next.js app in a Ubuntu Server machine using PM2 (pm2 start ...), but every time I run next build, I get Internal Server Error, I imagine that's because the app cannot be running at the same time it's building.
I'd like some suggestions on how to build and restart the app without downtime. PM2 has cluster mode but it also fails when I run next build with the app running.

• Should I use next export to a directory, and build the app in another directory before replacing it?
• What happens if I build the app as a PWA, any suggestions on how to avoid downtime?

I'm aware that Vercel has built-in support for 0-second-downtime, just wondering how I'd do that in Ubuntu directly.

[ghost]

You can use Capistrano-like deploy with PM2 https://pm2.keymetrics.io/docs/tutorials/capistrano-like-deployments

[Kamleshpaul]

i solve this by create a script

https://gist.github.com/Kamleshpaul/d22887c48e0c0d231734da24e8a80660

here to update my server i run this sh nextjs-pm2-deploy.sh it generate build on temp then replace with .next file and reload pm2

[GregoryWullimann]

Great script!

I've noticed that sometimes it fails when moving temp to .next, the error is rm: cannot remove '.next': Directory not empty

I guess it happens because some file are created in .next between rm -rf .next and the mv command.

I think one solution is to create the .next folder if it doesn't exists, and then move everything from temp to .next, it will be a little bit slower since it's moving the files and not renaming the folder (I think).

rm -rf .next

if [ ! -d ".next" ]; then
  mkdir .next
fi
mv temp/* .next

rm -rf temp

[Kamleshpaul]

@GregoryWullimann thank you.

can you tell me how can i create this error so i can test it.
i m using this in long time not getting any issue

[GregoryWullimann]

I wasn't able to reproduce it by running the commands individually, but this always happens in this way:

• Start script
• Go on website and keep refreshing a page (this will create files in .next) while the script is running
• Should get the error

[Kamleshpaul]

@GregoryWullimann i tried it all works

may be i have enable PWA in my website so if it broke it get from cache

[GregoryWullimann]

I tried it again on the live website, to be specific the error is

rm: cannot remove '.next/server/pages': Directory not empty
rm: cannot remove '.next/cache/images': Directory not empty

In this way the website will be down (error 502), and if I run again the script it works, since no file will be created in .next since the website is down.

Guess if anyone has a similar issue my fix would work. Otherwise yours should be a bit faster!

[marco910]

i solve this by create a script

https://gist.github.com/Kamleshpaul/d22887c48e0c0d231734da24e8a80660

here to update my server i run this sh nextjs-pm2-deploy.sh it generate build on temp then replace with .next file and reload pm2

@Kamleshpaul In which directory do you run the script. The root path of the Next.js project?

[Kamleshpaul]

yes i run this in root folder, i keep this nextjs-pm2-deploy.sh file in root

[DEGA-hoangmai]

Hi @Kamleshpaul,

BUILD_DIR=temp is not working on my side. It doesn't create the temp dir; the output is still in .next. Do you have any special setup in package.json or any config files? Thank you.

[smith1302]

For anyone reading, make sure you set this line in your in your next.config.js:

distDir: process.env.BUILD_DIR || '.next',

This is so NextJS can read from the BUILD_DIR=temp and build into that temp folder.

[isaacdarcilla]

Works for me.

[Nithur-M]

Hi,

It's 2025, is there a better solution for this?