Our production/staging docker image build pulls the latest code from our repository and then it installs all required dependencies, this process takes a while.
This is why for development we are using a volume to map the application code to a local folder.
Is there a way to commit the local changes in the mapped volume to the actual image data storage? So that we don't have to rebuild it all the time?
Being able to put your code and label that docker image is what people use it for. You shouldn't be deploying code at run-time in production. Instead you should be building images and tagging them based on version.
You want to know what is running on your production and you also want the ability to rollback to previous version.
Now coming back to your rebuilding the code part. There are multiple ways to improve the build times
Create base images
You can create base images and just put code on top of that base image. This base image will have your necessary softwares (Node etc). And in your Dockerfile you will just copy the code.
Instead of Git Checkout Use Tag URL
You can download a specific branch/tag as a zip file instead of the whole repository and unzip it. I have seen sometimes Git repos are 100MB and the code is only 4-5 MB. This can save you time
Use multistage build
Multistage builds are not going to save you build time but they will save you image size. This is only needed if you deploy lots of containers
