What kind of authorisation mechanisms do you leverage to achieve intra process/ intra server trust? Has there been any protocols which were written from scratc

What kind of authorisation mechanisms do you leverage to achieve intra process/ intra server trust? Has there been any protocols which were written from scratch because an out of the box solution simply didn't do what was needed? Do you leverage any kind of out of the box solutions to co-ordinate services? e.g apache zookeeper? Can you describe how nodes are added or removed to your swarm based on demand? I presume this is non linear? Edit: Ive been playing since pre alpha. glad its still going strong.