How Tenkai runs your applications
See what Tenkai does from its control plane, what runs on your servers and how a deployment reaches them.
Tenkai has two parts. Tenkai itself is the control plane: the dashboard, your configuration and the jobs that run your deployments. Your clusters are your own servers, which run your applications. Tenkai gives instructions over SSH, and your servers do the work.
What Tenkai does
Tenkai keeps the configuration of your projects, resources and variables, and runs your deployments on your servers over SSH, with a key that only each server accepts.
Your traffic, your container images and the data of your managed services stay on your servers. Your backups go to the storage bucket you provide. Tenkai issues the HTTPS certificates of your hostnames and stores them, with their private keys encrypted.
What runs on your servers
When a server joins a cluster, server setup installs Docker Engine, a firewall, the encrypted cluster network between the nodes, and the Tenkai Agent, which sends server metrics and, on the edge node, request counts to Tenkai. It turns off password logins over SSH. The edge node also runs the edge router, which receives your traffic, and the cluster registry, which keeps your images.
Docker Swarm under the hood
Each cluster is a Docker Swarm. Swarm restarts a stopped container, and moves the replicas of a lost node to the other nodes as long as a majority of the managers still answer. A managed service stays on the node that holds its data.
You do not need to know Swarm. On a manager, docker service ls shows the services of your cluster. Do not change them by hand: Tenkai stops a deployment when it finds something it did not expect.
When Tenkai is unavailable
Your applications and managed services keep running without Tenkai. You cannot deploy, change a configuration or add a server until Tenkai is back. Deployments in progress then continue where they stopped.
Certificates are renewed weeks before they expire, so a short outage does not affect your visitors.
Read next
- Clusters and the roles of their nodesUnderstand the edge node, manager nodes, worker nodes and data nodes, how many failures a cluster survives, and how to keep replicas on separate nodes.
- How a deployment switches trafficUnderstand the blue-green deployment: Tenkai starts a candidate next to the active release, checks it, then moves the routes to it.