Validate Configuration on Startup

[ttschampel]

The platform should validate configuration state on startup, log configuration errors and then exit.

An example from bad configuration (ERS not enabled/defined in config) resulting in a runtime failure and the platform panics:

{"time":"2024-06-07T00:19:05.261969949Z","level":"DEBUG","msg":"verifying policy binding","namespace":"kas","requestBody.policy":"eyJ1dWlkIjoiNzRhNWZjODktZWFiZC00YWJkLTlkNmUtOGRkNjlhZTQwZjVhIiwiYm9keSI6eyJkYXRhQXR0cmlidXRlcyI6W3siYXR0cmlidXRlIjoiaHR0cHM6Ly9vcGVudGRmLmlvL2F0dHIvaW50ZWxsZWN0dWFscHJvcGVydHkvdmFsdWUvdHJhZGVzZWNyZXQiLCJpc0RlZmF1bHQiOmZhbHNlfV0sImRpc3NlbSI6W119fQ=="}
{"time":"2024-06-07T00:19:05.262143311Z","level":"DEBUG","msg":"extracting policy","namespace":"kas","requestBody.policy":"eyJ1dWlkIjoiNzRhNWZjODktZWFiZC00YWJkLTlkNmUtOGRkNjlhZTQwZjVhIiwiYm9keSI6eyJkYXRhQXR0cmlidXRlcyI6W3siYXR0cmlidXRlIjoiaHR0cHM6Ly9vcGVudGRmLmlvL2F0dHIvaW50ZWxsZWN0dWFscHJvcGVydHkvdmFsdWUvdHJhZGVzZWNyZXQiLCJpc0RlZmF1bHQiOmZhbHNlfV0sImRpc3NlbSI6W119fQ=="}
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x230 pc=0xe59f1a]

goroutine 227 [running]:
google.golang.org/grpc.(*ClientConn).Invoke(0x0, {0x1bc78b0?, 0xc0006e07b0?}, {0x18f9784?, 0xc0005fb600?}, {0x173c680?, 0xc0005fb600?}, {0x173c740?, 0xc0005fb640?}, {0x0, ...})
	/root/go/pkg/mod/google.golang.org/[email protected]/call.go:32 +0x5a
github.com/opentdf/platform/protocol/go/entityresolution.(*entityResolutionServiceClient).CreateEntityChainFromJwt(0xc0004bc420, {0x1bc78b0, 0xc0006e07b0}, 0xc0005fb600, {0x0, 0x0, 0x0})
	/app/protocol/go/entityresolution/entity_resolution_grpc.pb.go:53 +0xc8
github.com/opentdf/platform/service/authorization.(*AuthorizationService).GetDecisionsByToken(0xc00060a360, {0x1bc78b0, 0xc0006e07b0}, 0x4ab3c5?)
	/app/service/authorization/authorization.go:137 +0x1a3
github.com/opentdf/platform/protocol/go/authorization._AuthorizationService_GetDecisionsByToken_Handler({0x17067e0, 0xc00060a360}, {0x1bc78b0, 0xc0006e07b0}, 0xc000577b80, 0x0)
	/app/protocol/go/authorization/authorization_grpc.pb.go:131 +0x1a6
google.golang.org/grpc.(*Server).processUnaryRPC(0xc00070d400, {0x1bc78b0, 0xc000876090}, {0x1bd2ec0, 0xc00070e900}, 0xc0008645a0, 0xc000626030, 0x28ad6b8, 0x0)
	/root/go/pkg/mod/google.golang.org/[email protected]/server.go:1369 +0xdf8
google.golang.org/grpc.(*Server).handleStream(0xc00070d400, {0x1bd2ec0, 0xc00070e900}, 0xc0008645a0)
	/root/go/pkg/mod/google.golang.org/[email protected]/server.go:1780 +0xe8b
google.golang.org/grpc.(*Server).serveStreams.func2.1()
	/root/go/pkg/mod/google.golang.org/[email protected]/server.go:1019 +0x8b
created by google.golang.org/grpc.(*Server).serveStreams.func2 in goroutine 172
	/root/go/pkg/mod/google.golang.org/[email protected]/server.go:1030 +0x125