Persempre

The app name Persempre means Forever in Italian and was create to replace Nodemon in a docker environment.

Why you say?

I personally love Docker, and run everything through it, but the big issue is that Docker won't bobble the events related to a file change if your run a VM machine on your host, and inside the VM a Docker environment while mounting a folder with your code from the originally host environment inside the VM and then mount that folder inside a Docker container. As you can see there are lots of nesting.

This situation makes it so that a file change event won't reach Docker, and if you use Nodemon you'll need to use the legacy mode. Which is nothing more then a infinite while loop that constantly goes over each file in your project and thus uses a lot of CPU time - to the point that my VM is sign a constant 110% of the CPU and my MacBook Ari gets very hot.

The solution!

Because of this poorly designed legacy mode I decided to write my own solution that is more mindful of the CPU, and tries to minimize the CPU time used to check when a file was changed.

How it works?

My app uses one timer that runs every 4 sec and goes over each file in the project while checking the time a file was change. This approach is way more efficient because it uses the CPU only every 4 sec and in between the brakes the system has the time to perform other operation.

When should this project be used?

Only if you work with a Docker container or if you need to use the legacy mode of Nodemon. If that is the case fell free to use this project instead.

How to use this package?

Just install this package globally with the following command

$ npm install persempre -g

Then you can just type:

$ persempre FILE_TO_RUN

Is this an ideal solution?

Far from it. But this is the best solution for the problem. Ideally you would want to let the operating system tell you when a file was change, but since a Docker container is unable to provide this information as of now.

Please don't use this module if you run your NodeJS project directly on your machine.

The End

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