Do a deep merge on bindings rather than a shallow

[n1koo]

What are you trying to accomplish with this PR?
Make it possible to have multiple overlapping configurations that will be deep merged to form one sane configuration.

Eg. lets say you have following configurations:

common.yaml:

common:
  registry: private-thingy
...
app:
  port: 4200
  name: cat-service
  lb_id: nonprod
....

and then you have environment specific one:

production.yaml:

app:
  lb_id: prod

Currently we only merge top level entries with merge so eg. if lb_id was on top this would be fine but for more complex configurations people tend to separate things in to nested entries. Another example could be eg. setting resources but overriding limits in certain env, think of:

  resources:
    limits:
      cpu: "3"
      memory: "1Gi"
    requests:
      cpu: "3"
      memory: "1Gi"

and then in nonprod you wanna override the requests for example.

How is this accomplished?

• Pull the bindings loop in to the parser
• do a deep_merge! instead of merge!
• profit

tl;dr s/merge/deep_merge but I thought its cleaner to pull the loop in to the parser too. Makes testing lot more easier and harder to screw up if doing changes in both deployer and renderer

What could go wrong?
Things dont get parsed, world blows up.

Seriously though, if someone is relying on the wrong behaviour (shallow merge) this might cause a surprise, but technically doing so is wrong .. so :)

[dturn]

Can you please rebase so we can get the tests ✅ before merge.

[n1koo]

Rebase done

[KnVerey]

I think this PR is 👍 functionality-wise, but I feel like this class's API is a bit weird now--it's not intuitive what the difference is between BindingsParser::parse and BindingsParser::parse_binding would be.

Here's a suggestion:

# If you need multiple, you do:
bindings = KubernetesDeploy::BindingsParser.new
# ...
  opts.on("--bindings=BINDINGS", "...") { |b| bindings.add(b) }
# ...
bindings.parse

# But you can still also use the exact same API as before:
KubernetesDeploy::BindingsParser.parse(bindings_string)

module KubernetesDeploy
  class BindingsParser
    def self.parse(string)
      new(string).parse
    end

    def initialize(initial_string=nil)
      @raw_bindings = Array(initial_string)
    end

    def add(string)
      @raw_bindings << string
    end

    def parse
      result = {}
      @raw_bindings.each do |string|
        # parse/merge
      end
      # etc
      result
    end

[n1koo]

Makes sense, refactored

[KnVerey]

Ready to ship after typo fix and tophat

[KnVerey]

This should be parser.parse, which reminds me that someone needs to tophat all affected executables before we merge this.

[n1koo]

Yeah, I did my tophat with render 🤦‍♂️

[KnVerey]

I was able to confirm successful 🎩 using the collection-with-erb fixtures with both kubernetes-render and kubernetes-deploy. We'll once CI passes.