compile: add WithRoots compiler option

[kubaj]

What is the underlying problem you're trying to solve?

I'd like to build an OPA bundle from Go using the compile API (github.com/open-policy-agent/opa/compile) but it's missing the support for providing bundle roots. I've tried to find some workaround for this, but I wasn't successful.

Describe the ideal solution

Ideal situation would be that Go compile API has the same options when building OPA bundles as the OPA CLI's build command.

Describe a "Good Enough" solution

Adding WithRoots compiler option used for specifying bundle's roots.

[ashutosh-narkar]

I'd like to build an OPA bundle from Go using the compile API (github.com/open-policy-agent/opa/compile) but it's missing the support for providing bundle roots.

Have you tried using WithPaths with WithAsBundle enabled? I think this should allow you specify the bundle manifest.

[kubaj]

I've tried this combination but based on error I've got:

load error: bundle policy.rego: bundle read failed: archive read failed: gzip: invalid header"

it looked that this option is used when you want to use the content of the already existing bundle to build the bundle. (e.g. combine multiple bundles together).

[ashutosh-narkar]

Let's say you have a folder with your policy, data and manifest file. Are you saying if you set WithPaths to point to that with bundle mode enabled, you get an error?

Adding a WithRoots option seems fine btw. If you'd like to contribute that would be great!