Core Service Guide

The Morio Core Service (core) sits at the root of any Morio deployment and is responsible for orchestration, configuration resolution, and clustering.

Core is a Morio internal service, meaning that as a Morio user — or even administrator — you do not interact with it. As such, this guide covers the high-level responsibilities of the service, allowing you to get a grasp of what it is and what it does.

Core service responsibilities

The core service runs on every Morio node, and handles the following responsibilities:

Orchestration

The core service is responsible for creating and starting all other Morio services. If a service is not running that should be running, the core service will create a container for it, and start it. Or, if a service is running that should not be running, the core service will stop it.

Other tasks that fall under orchestration are things like creating the Docker network and attaching itself and other containers to it, as well as pulling down images that are not available on the local Docker host.

To be able to accomplish this task, the core service needs access to the Docker socket on the host OS, which is provided by mounting the socket in the container.

Given that access to the host OS’ Docker socket is a high-privilege access, the core service is internal, and not a user-facing service. Only its /status endpoint is accessible to users.

Configuration Resolution

The core service is also responsible for transforming the high-level Morio settings into a detailed configuration for the various Morio services.

For example, you do not need to worry about making certain the API is accessible through the proxy service, core will handle all of that and more for you.

To be able to accomplish this task, core need access to shared storage with the various services. For example, core will generate a configuration for the proxy service to disk, and the proxy service will then find its configuration ready to go when it starts up.

For this to be possible, core relies on access to mounted folders on the Host OS that are also mounted on the various services.

Clustering

Last but not least, core is also responsible for enabling clustering support in Morio, as well as keeping a cluster of Morio nodes running and healthy.

That includes initial cluster formation, where all you need is to install Morio on all the cluster nodes, and then setup 1 of the nodes with the clustered settings. Core will also run the cluster heartbeat, making sure that everything is ok, and ensure that the cluster has 1 leader node and the rest of the nodes will be follower nodes.

Clustering is not a goal as such, it provides high-availability, meaning that if a node goes down, Morio as a whole keeps on ticking.