Running Wow

A Wow service is a Spring Boot application that runs as one or more nodes. Its nodes share the service's database, find each other through it, split its log's partitions among themselves, and talk on an internal port. Services of one system talk over Kafka. This section is for whoever deploys and runs them.

The pages

Page	Covers
Deployment Model	Services and nodes, the two ports, what a service needs, starting and stopping
Configure a Service	How configuration takes effect, what must match across nodes, development defaults
PostgreSQL	The tables, the schema, the connection pools, several databases
Kafka	When a service needs Kafka, its topics, durable command intake
Secure a Deployment	Callers, authorization, the internal port, personal data, tenants
The Ops Service and Console	The parked aggregates of every service in one place

Before production

Storage

• The service runs on a durable backend: the application gives a DataSource or a MongoClient, and no production node runs in a development profile.
• wow.log.partitions is chosen before the first deployment; it cannot change once the log holds entries.
• The database account matches wow.ddl: one that may create tables with auto, or the schema applied beforehand and validate.
• The log, checkpoints, leases, failure ledger, reservations and timers are backed up together.

The cluster

• Every node of a service has the same wow.service, partitions, stores and cluster tokens.
• Nodes reach each other's internal port, and nothing outside the cluster does.
• The platform's termination grace period covers the node's shutdown (Deployment Model).
• Readiness and liveness probes read the node's health groups.

Between services

• Each Kafka topic the service owns exists, with the partitions it needs: a command topic has exactly as many as the context's log (Kafka).
• Each service lists the services it trusts on its internal port, and the commands each may call.

Security

• Go through the checklist of Secure a Deployment.

Operations

• The ops service collects every service's failure ledger, and someone watches it (The Ops Service and Console).
• The configuration logs no warning about an unknown wow.* key at startup.