Clean up after apt-get (take 2)

[rvernica]

Install dependencies and shiny in one Docker command. This allows for cleaning after apt-get (rm -rf /var/lib/apt/lists/*) but not before gdebi which requires the apt cache. See #22 (comment)

This is an improvement over #22 which created problems. It should fix #19.

[rvernica]

@wch this patch seems pretty stable

[wch]

I'm not a fan of running this much stuff in one step, but if it reduces the problems people run into, I guess it's OK.

Can you explain why apt-get update results in the error in the first place? It's not clear to me.

[cboettig]

@wch see https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/#run
which shows an example much like this.

I think people are currently getting bitten by the way docker handles caching of layers. You have two run commands, only the first of which runs apt-get update. I think the problem comes if in building the image, docker loads that layer from cache instead of re-running it, which can cause the apt info to get out of date. Since the second run command call to gdebi needs apt-get sources, you run into trouble.

You'll see the example shown in that Dockerfile best practices link makes all the same suggestions as @rvernica : using a single layer, always using apt-get update before apt-get install, and removing the apt/list at the end (just to save space, though downstream users should always be running apt-get update anyway first so there's no point in keeping this). Hope that makes sense?

[wch]

@cboettig Thanks for the explanation. I'm still not sure why it was erroring on apt-get update though -- that's what it looks like, at least, from the comments on #19.