# Thoughts on docker and making it better

Docker works, and I fully recommend using it for basically everything you deploy.

This said, I think there is massive room for improvement.  Layers are a pretty terrible way to handle defining an environment.


Take this example

```
FROM ubuntu:latest

RUN  apt-get -y update && \
     apt-get install -y apache2 \
                    git \
                    golang \
                    python
```

When you add a new dependency, you then rerun everything on the run line, including re-downloading all the previously downloaded dependencies.  Not to mention if the packages upstream changed, your docker image won't be the same between runs.


A much better approach would be for your container tech to more directly handle dependencies.  For example

```
{
  // Describes a specific point in time
  "version": "F58C0AEFBFEBFBBB4112", 
  "devDependencies": ["git","golang","python"],
}
```

Where rather than re-downloading each, the container tech grabs only the ones that haven't previously been downloaded.


Several notes
- You can of course setup a cache for these dependencies so it doesn't actually fetch from a remote location.  I don't think most devs have that setup for their machines though.
- Nix can pretty much do this, however it seems to have a huge learning curve when I've tried it.