* If istio-agent does not find either the socket, or the certificate files in their respective paths it will start its own SDS Server using a `caClient` to connect to istiod or an external CA, to fetch cryptographic materials (See Default CA Flow).

![SDS decision flow](docs/sds-flow.svg)

### Default CA Flow through istio-agent

![CA Flow](docs/ca.svg)

digraph { grpc -> ca [label="Send CSR gRPC Request"] subgraph cluster_istioagent { label = "Istio Agent" color="orange" sds SecretManager -> caClient [label="Sign CSR"] caClient -> grpc grpc -> TokenProvider [dir=none,label="Fetch JWT",color=purple] grpc -> cfiles [dir=none,label="Fetch Cert",color=purple] sds -> SecretManager [label="Generate certificate"] SecretManager -> cfiles [label="Write certs to file"] cfiles [label="Certificate Files"] grpc [shape=diamond] } subgraph cluster_istiod { label = "Istiod"...