improvement: register health checker only when one or more connection…

…s are using it

adonis-typings/database.ts

@@ -631,6 +631,8 @@ declare module '@ioc:Adonis/Lucid/Database' {
       ): SimplePaginatorContract<Row[]>
     },
 
+    hasHealthChecksEnabled: boolean
+
     /**
      * Pretty print query logs
      */

providers/DatabaseProvider.ts

@@ -77,7 +77,11 @@ export default class DatabaseServiceProvider {
   private registerHealthChecker () {
     this.$container.with(
       ['Adonis/Core/HealthCheck', 'Adonis/Lucid/Database'],
-      (HealthCheck) => HealthCheck.addChecker('lucid', 'Adonis/Lucid/Database'),
+      (HealthCheck, Db: Database) => {
+        if (Db.hasHealthChecksEnabled) {
+          HealthCheck.addChecker('lucid', 'Adonis/Lucid/Database')
+        }
+      },
     )
   }
 

src/Database/index.ts

@@ -16,6 +16,7 @@ import { ProfilerContract } from '@ioc:Adonis/Core/Profiler'
 
 import {
   DatabaseConfig,
+  ConnectionNode,
   DatabaseContract,
   DatabaseClientOptions,
   TransactionClientContract,
@@ -60,6 +61,8 @@ export class Database implements DatabaseContract {
    * A store of global transactions
    */
   public connectionGlobalTransactions: Map<string, TransactionClientContract> = new Map()
+  public hasHealthChecksEnabled = false
+  public prettyPrint = prettyPrint
 
   constructor (
     private config: DatabaseConfig,
@@ -69,9 +72,22 @@ export class Database implements DatabaseContract {
   ) {
     this.manager = new ConnectionManager(this.logger, this.emitter)
     this.registerConnections()
+    this.findIfHealthChecksAreEnabled()
   }
 
-  public prettyPrint = prettyPrint
+  /**
+   * Compute whether health check is enabled or not after registering the connections.
+   * There are chances that all pre-registered connections are not using health
+   * checks but a dynamic connection is using it. We don't support that use case
+   * for now, since it complicates things a lot and forces us to register the
+   * health checker on demand.
+   */
+  private findIfHealthChecksAreEnabled () {
+    this.hasHealthChecksEnabled = !!Object.keys(this.manager.connections).find((key) => {
+      const connection = this.manager.connections[key] as ConnectionNode
+      return !!connection.config.healthCheck
+    })
+  }
 
   /**
    * Registering all connections with the manager, so that we can fetch