Eclipse BlueChi™

Eclipse BlueChi™ is a deterministic multi-node service controller with a focus on highly regulated ecosystems. It is written in C and integrates seamless with systemd via its D-Bus API relaying D-Bus messages over TCP for multi-node support. BlueChi is built around three components:

• The bluechi-controller service, which is the primary controller that runs on the primary node
• The bluechi-agent services, which run on each managed node and are the agents that talk locally to systemd to instruct systemd to act on services
• The bluechictl command line, which is used by administrators to test, debug and manually manage services across nodes

Eclipse BlueChi™ is meant to be used in conjunction with a state manager (a program or person) that knows the desired state of the systems. This design choice has a few consequences: 

• Eclipse BlueChi does not know the desired final state of the systems; it only knows how to transition between states, such as how to start, stop or restart a service on one or more nodes 
• Eclipse BlueChi monitors and reports changes in the services that are running and alerts the state manager when a service stops or when the connection to a node is lost, but BlueChi itself does not act on these notifications
• Eclipse BlueChi does not handle the initial setup of the system; the system boots into a desired state and BlueChi handles the transitions from this state

The state manager program integrates with bluechi-controller over D-Bus. The state manager tells BlueChi to perform actions or to receive the outcome of actions. Eclipse BlueChi monitors services and nodes via D-Bus and reports state changes back to the state manager. Administrators can use the bluechictl interface to avoid interacting directly with bluechi-controller via D-Bus.