healthcheck.java

@Readiness
@ApplicationScoped
public class Neo4jHealthCheck implements HealthCheck {
   private static final String CYPHER = "RETURN 1 AS result";
   private static final SessionConfig DEFAULT_SESSION_CONFIG = SessionConfig.builder()
           .withDefaultAccessMode(AccessMode.WRITE)
           .build();
   private final Driver driver;
   @Inject
   //will be ignored outside of CDI
   Neo4jHealthCheck(Driver driver) {
       this.driver = driver;
   }
   public static Neo4jHealthCheck create(Driver driver) {
       return new Neo4jHealthCheck(driver);
   }
   private static HealthCheckResponse buildStatusUp(ResultSummary resultSummary, HealthCheckResponseBuilder builder) {
       ServerInfo serverInfo = resultSummary.server();
       builder.withData("server", serverInfo.version() + "@" + serverInfo.address());
       String databaseName = resultSummary.database().name();
       if (!(databaseName == null || databaseName.trim().isEmpty())) {
           builder.withData("database", databaseName.trim());
       }
       return builder.build();
   }
   @Override
   public HealthCheckResponse call() {
       HealthCheckResponseBuilder builder = HealthCheckResponse.named("Neo4j connection health check").up();
       try {
           ResultSummary resultSummary;
           // Retry one time when the session has been expired
           try {
               resultSummary = runHealthCheckQuery();
           } catch (SessionExpiredException sessionExpiredException) {
               resultSummary = runHealthCheckQuery();
           }
           return buildStatusUp(resultSummary, builder);
       } catch (Exception e) {
           return builder.down().withData("reason", e.getMessage()).build();
       }
   }
   private ResultSummary runHealthCheckQuery() {
       // We use WRITE here to make sure UP is returned for a server that supports
       // all possible workloads
       if (driver != null) {
           Session session = this.driver.session(DEFAULT_SESSION_CONFIG);
           Result run = session.run(CYPHER);
           return run.consume();
       }
       return null;
   }
}