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What is BlueChi?

BlueChi (formerly known as hirte) is a deterministic multi-node service controller.

BlueChi can manage the states of different services across multiple nodes with a focus on highly regulated industries, such as those requiring functional safety. BlueChi integrates with systemd via its D-Bus API and relays D-Bus messages over TCP for multi-nodes support.

On the main node a service called bluechi-controller is running. On startup, the controller loads the configuration files which describe all the involved systems (called nodes) that are expected to be managed. Each node has a unique name that is used to reference it in the controller.

On each managed node that is under control of BlueChi a service called bluechi-agent is running. When the service starts, it connects (via D-Bus over TCP) to the controller and registers as available (optionally authenticating). It then receives requests from the controller and reports local state changes to it.


BlueChi is built around three components:

  • bluechi-controller service, running on the primary node, controls all connected nodes
  • bluechi-agent services, with one running on each managed node, is the agent talking locally to systemd to act on services
  • bluechictl command line program, is meant to be used by administrators to test, debug, or manually manage services across nodes.

BlueChi is meant to be used in conjunction with a state manager (a program or person) knowing the desired state of the system(s). This design choice has a few consequences:

BlueChi itself does not know the desired final state of the system(s), it only knows how to transition between states, i.e.: how to start, stop, restart a service on one or more nodes.

BlueChi monitors and reports changes in services running, so that another application like a state manager is notified when a service stops running or when the connection to a node is lost, but BlueChi itself does not act on these notifications.

BlueChi does not handle the “initial setup” of the system, it is assumed that the system boots in a desired state and BlueChi handles the transitions from this state.