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diff --git a/README.md b/README.md new file mode 100644 index 0000000..04bc382 --- /dev/null +++ b/README.md @@ -0,0 +1,50 @@ +# config_binding_service + +# Interface Diagram +This repo is the thing in red: + + + +# Overview + +DCAE has a "templating language" built into components' configurations, as explained further below. +The orchestrator populates one/two keys (depending on the blueprint) into Consul that are used to *bind* component configurations config, a "rels key" and a "dmaap key". +If component A wants to connect to a component of type B, then A's rels key holds what specific service component name of B that A should connect to over direct HTTP. +Service component name here means the full name that the component of type B is registered under in Consul (there can be multiple components of type B registered in Consul). +The CBS (config binding service) then pulls down that rels key, fetches the connection information about that B (IP:Port), and replaces it into A's config. +There is also a "dmaap key", which is the same concept, except what gets injected is a JSON of DMaaP connection information instead of an IP:Port. + +# Usage +hit `url_of_this/service_component/service_component_name` and you are returned your bound config. + +(Note: there is also a backdoor in the `client` module that allows you to pass in a direct JSON and a direct rels, but this isn't exposed via the HTTP API as of now) + +# Assumptions +1. `CONSUL_HOST` is set as an environmental variable where this binding service is run. If it is not, it defaults to the Rework Consul which is probably not what you want. +2. `service_component_name` is in consul as a key and holds the config +3. `service_component_name:rel` is in consul as a key *if* you are expecting a direct HTTP resolution, and holds the service component names of connections. +4. `service_component_name:dmaap` is in consul *if* you are expecting a DMaaP resolution, and holds the components DMaaP information. + +# Templating Language +The CBS tries to resolve a component's configuration with a templating language. We have two templating languages embedded in our component's configuration (`{{...}}` and `<<...>>`). There are two because the CBS has to be able to distinguish between a rels-key-resolve and a dmaap-key-resolve. That is, if component X is trying to bind their component, and they want to talk to Y, someone has to tell the CBS whether they are trying to talk via IP:port or a feed. + +Specifically, if the CBS sees: + +``` +X's configuration: +{ + ... + config_key : << F >> // will try to resolve via X:dmaap and look for F + config_key : {{ F }} // will try to resolve via X:rels and look for F +} +``` + +# Tests +Run: +``` +set -x CONSUL_HOST "your_consul_dns_name.somedomain.com"; set -x HOSTNAME "config_binding_service" +cd tests/ +pytest +``` + + |