Determining How Many Nodes to Deploy
To effectively implement high availability in your Composer environment, at least two nodes, each containing the following microservices, are required.
- Composer Web App microservice
- Query Engine microservice
- Data Writer microservice
- Appropriate connector microservices for your installation
- Configuration microservice
The Service Monitor, Screenshot, and Tracing microservices are not required on every node, but Composer recommends that you install these microservices on at least two nodes in your cluster to ensure that management of the nodes is retained should one node fail.
Finally, the Consul instance and the PostgreSQL data store used to store metadata, configuration data, and tracing data must be available to all the nodes in your Composer cluster. Composer recommends that you cluster the Consul instance and your PostgreSQL data store to ensure there is no single point of failure.