Add option to set ReadOnly mode for badgerdb

[xshadowlegendx]

What would you like to be added

type Options struct {
	Database              string
	ValueDir              string
	BadgerFileLoadingMode string
    BadgerIsOpenInReadOnlyMode  bool // <- add this option, corresponding helper function for the option and set badger.Options.ReadOnly = true
}

Why this is needed

I am implementing a simple ocsp responder that read from step-ca badgerdb and needs to open it in readonly mode since step-ca server is opening badgerdb in rw mode, the db cannot be open by other process with rw mode since I am using github.com/smallstep/nosql library to interact with step-ca badgerdb

I can open a PR to add the option if it is ok

[hslatman]

Hey @xshadowlegendx,

Thank you for opening the issue. This sounds like a useful feature to have 😄

We would certainly be happy to review a PR!

There's some ongoing work in #53 that your PR maybe needs to be ported too, but I suppose it won't be a big issue.

[xshadowlegendx]

hello @hslatman, sorry for the late reply, I will look into this and just a quick thought is badgerdb able to open it in readonly mode while another process is opening it in rw mode like the main step-ca process thou?