It's not clear how to set variables

[nedbat]

I love these templates. I was about to embark on creating my own templates, but these seem like just the thing I need.

But I need to override some of the defaults. The README says I can set variables, but it isn't clear how. Packer can support multiple var-files, but the bin/box scripts don't provide a way to supply one. Some of the other boxcutter repo README's suggest a Makefile.local file, but then the Makefile wants to build everything, I think?

Can you provide some specific instructions? I'll make a pull request adding them nicely to the README if you like.

[ferrarimarco]

This may help you, from Packer docs:

The -var-file flag can be specified multiple times and variables from multiple files will be read and applied. As you'd expect, variables read from files specified later override a variable set earlier if it has already been set.

And from boxcutter/ubuntu README:

We make use of JSON files containing user variables to build specific versions of Ubuntu. You tell packer to use a specific user variable file via the -var-file= command line option. This will override the default options on the core ubuntu.json packer template, which builds Ubuntu 16.04 by default.

So you can specify multiple var-files if building with Packer. I don't use bin/box scripts, so let's wait for someone who knows better.

[olberger]

You may use a combination of -var-file and -var if you want to override more. I find it a bit confusing however the mix of uppercase/lowercase variables description in the README. It makes it read as though one might use shell env vars to override stuff, but that wouldn't work in my experiments.

I managed to adjust bits with something like this, when I needed to override the iso_path (aka "ISO_PATH" in the README):

packer build -only=virtualbox-iso -var-file=ubuntu2004-desktop.json -var 'iso_path=/home/olivier/isos/' ubuntu.json

Hope this helps,