Apigee Hybrid 1.3 UDCA service name change

[theganyo]

Before 1.3, the UDCA service name was constructed as apigee-udca-{org}-{env}. However, with such an algorithm, some service names could be longer than Kubernetes DNS limit of 63 characters. To resolve this, Apigee is changing the service name to a truncation plus hash.

See also:
Org: https://edge-internal.git.corp.google.com/apigee-hybrid-setup/+/refs/heads/master/tmpl/tmpl_functions.go#520
Env: https://edge-internal.git.corp.google.com/apigee-hybrid-setup/+/refs/heads/master/tmpl/tmpl_functions.go#524

Unfortunately, there is no management API to determine the runtime version. However, per @srinandan there is a APIGEE_DPCOLOR env variable available in the runtime to the proxies that holds values such as:

APIGEE_DPCOLOR=v120
APIGEE_DPCOLOR=v130rc41

These would indicate Hybrid Runtime v1.2 and Hybrid Runtime v1.3, respectively. Presumably, this would indicate that the v12 or v13 is the major version.

Thus, we should be able to add an endpoint to our proxy to detect and return either an appropriate version information so we can create the appropriate service name for versions > 1.2 or have the proxy derive this and return the service name directly.