Add remote configuration dispatcher

[lloeki]

What does this PR do?

Add a dispatcher.

The last commit is only adding some spec cleanup and has nothing to do with the actual logic of the PR e70ca73. Please review separately

Motivation

Remote configuration

Additional Notes

The dispatcher gets registered against using a receiver for a block to be called and a matcher to select relevant changes from the changeset.

Upon changes, the dispatcher matches changes against the matcher and calls the receiver, passing the subset of changes as well as the repository itself. This is because:

• A receiver might need not just the change but complement that change with the full state. therefore the repository state is needed.
• A receiver might need to understand a specific change in the changeset and act in a specific way according to the type (it might want to operate differently on an update vs a deletion) or content (it might want to look at the diff in state) so passing the current repository state is not sufficient. Therefore passing the list of changes is needed.

A generic matcher that takes a block is available, for other matchers to be implemented. A simple product matcher is implemented, based on the generic one.

How to test the change?

  require 'ddtrace'

  Datadog.configure do |c|
    c.agent.host = '192.168.135.133'
    c.diagnostics.debug = true
  end

  Datadog::Core::Remote.active_remote.sync
  repository = Datadog::Core::Remote.active_remote.client.instance_eval { @repository }

  require 'irb'

  sleep 1000

Wait a bit to receive first batch of RC. This should happen:

D, [2023-03-21T10:18:10.338264 #29926] DEBUG -- ddtrace: [ddtrace] (/Users/lloeki/Source/github.com/DataDog/dd-trace-rb-alt/lib/datadog/core/remote/client.rb:187:in `block (2 levels) in register_receivers') remote config change: #<Datadog::Core::Remote::Configuration::Path:0x00000001066225f8 @source="datadog", @org_id=603646, @product="ASM_DATA", @config_id="blocked_users", @name="config">
D, [2023-03-21T10:18:10.338312 #29926] DEBUG -- ddtrace: [ddtrace] (/Users/lloeki/Source/github.com/DataDog/dd-trace-rb-alt/lib/datadog/core/remote/client.rb:187:in `block (2 levels) in register_receivers') remote config change: #<Datadog::Core::Remote::Configuration::Path:0x00000001066223c8 @source="employee", @org_id=nil, @product="ASM_DD", @config_id="16.recommended.json", @name="config">
D, [2023-03-21T10:18:10.338326 #29926] DEBUG -- ddtrace: [ddtrace] (/Users/lloeki/Source/github.com/DataDog/dd-trace-rb-alt/lib/datadog/core/remote/client.rb:187:in `block (2 levels) in register_receivers') remote config change: #<Datadog::Core::Remote::Configuration::Path:0x0000000106622148 @source="datadog", @org_id=603646, @product="ASM", @config_id="blocking", @name="config">
D, [2023-03-21T10:18:10.338392 #29926] DEBUG -- ddtrace: [ddtrace] (/Users/lloeki/Source/github.com/DataDog/dd-trace-rb-alt/lib/datadog/core/remote/client.rb:187:in `block (2 levels) in register_receivers') remote config change: #<Datadog::Core::Remote::Configuration::Path:0x0000000106621950 @source="datadog", @org_id=603646, @product="ASM", @config_id="exclusion_filters", @name="config">
D, [2023-03-21T10:18:10.338406 #29926] DEBUG -- ddtrace: [ddtrace] (/Users/lloeki/Source/github.com/DataDog/dd-trace-rb-alt/lib/datadog/core/remote/client.rb:187:in `block (2 levels) in register_receivers') remote config change: #<Datadog::Core::Remote::Configuration::Path:0x00000001066202d0 @source="datadog", @org_id=603646, @product="ASM_DATA", @config_id="blocked_ips", @name="config">

Go in the DD Application Security UI and add a new IP to the list. Wait a bit. This should pop up:

D, [2023-03-21T10:20:50.616185 #29926] DEBUG -- ddtrace: [ddtrace] (/Users/lloeki/Source/github.com/DataDog/dd-trace-rb-alt/lib/datadog/core/remote/client.rb:187:in `block (2 levels) in register_receivers') remote config change: #<Datadog::Core::Remote::Configuration::Path:0x0000000106b17f68 @source="datadog", @org_id=603646, @product="ASM_DATA", @config_id="blocked_ips", @name="config">

[ivoanjo]

Minor note, just in case: Be careful not to add too noisy debug logs. They are indeed for us, but often we tell customers to enable DD_TRACE_DEBUG=true when investigating issues, so it's best if that mode doesn't add a torrent of extra logs ;)

[ivoanjo]

Minor note but... I::Think::We're::Getting::A::Bit::Too::Deep::With::All::The::Namespacing. Consider flattening things a bit maybe?

[GustavoCaso]

Super fair point.

I think we can have a cleanup PR once all the code has landed in master