+ added MongoDb checker

[LouAdrien]

Hello, I created a checker to get configuration from a mongodb collection.
I added minimal documentation and test, if it proves useful to you i might work more onto adding a docker container with the test data and / or merging it to this fork to make it embedded directly.

Tell me if anything is not in order

[paked]

Just a couple things to fix here:

1. replace NewMongo("mongodb://127.0.0.1:27017/test_conf_db","confs") with NewMongo(dburl, dbname)
2. add a proper description to replace Retrieve values from an io.Reader containing HCL. Maybe something like retrieve values from a MongoDB database

[paked]

I just wanted to say: it's awesome that you're using configure, I hope it's serving you well.

I've left a comment above about the contents of this PR, once it's been addressed we'll be good to go.

Personally, I don't think it'd make sense to merge your MongoDB checker into the main library -- I'd really like to keep external dependencies to a minimum (we don't have any vendor lock files checked in at the moment and I'd like to keep it that way. Nice and simple.).

I realise in the past that I approved the HCL checker being merged into here, but I guess my stance has changed in retrospect (I won't be removing it, in case someone else is currently relying on it. If someone ever overhauls the library at all and it makes sense to draw a line in the sand for "version 2" it might be something to reconsider then).

[LouAdrien]

Hello, sorry I was in a rush an went to quickly on the readme update... Will update this properly soon.

As you wish for the merging into the main library. I agree the dependencies involved might be too much... However i think it's just a download issue, the compiler will probably not include the unused dependencies so the binary size won't be affected if they re not used.
On the other hand, considering the current relatively "small" size of this project, I think that effort for people to actually include another repo just for this use case might be a bit too much.

Just a thought :)

[paked]

Ping me when you're ready for another review.

RE minimising dependencies. it's not so much about output binary size, but instead:

1. preventing something like left-pad happening.
2. keeping the library being completely go getable, no need to worry about dependency locking
3. making sure the library is maintainable going into the future. the smaller and more concise the codebase is the better.

I don't think adding a dependency on your GitHub project is too much of a stretch for people who want to have MongoDB checkers.