即使数据库失败，如何运行 Spring Boot 应用程序

Question

I have a spring boot app which has multiple databases. I want to run the app regardless of the state of the database. Here is how my application yaml looks like

logging:
  level:
    org:
      hibernate:
        SQL: DEBUG
        type:
          descriptor:
            sql:
              BasicBinder: TRACE

spring:
  sql:
    init:
      continue-on-error: true # <-- didn't work
  jpa:
    properties:
      hibernate:
        format_sql: 'true'
    show-sql: 'true'
  datasource:
    azure-read-only:
      url: <azure_db1_url>
      username: '<username>'
      password: '<password>'
      driver-class-name: com.microsoft.sqlserver.jdbc.SQLServerDriver
      continue-on-error: true
      hikari: # <--- add this to bypass boot failure but it didn't work either
        minimum-idle: 0
        maximum-pool-size: 15
        connection-timeout: 10000 #10s
        idle-timeout: 300000 #5m
        max-lifetime: 600000 #10m
        initialization-fail-timeout: -1
        validation-timeout: 1000 #1s
    azure-read-write:
      url: <azure_db2_url>
      username: '<username>'
      password: '<password>'
      driver-class-name: com.microsoft.sqlserver.jdbc.SQLServerDriver
      continue-on-error: true
      hikari:
        minimum-idle: 0
        maximum-pool-size: 15
        connection-timeout: 10000 #10s
        idle-timeout: 300000 #5m
        max-lifetime: 600000 #10m
        initialization-fail-timeout: -1
        validation-timeout: 1000 #1s
    db2-testdb1:
      url: <another_db_not_hosted_on_azure>
      username: '<username>'
      password: '<passwor'
      driver-class-name: com.ibm.db2.jcc.DB2Driver
      continue-on-error: true
      hikari:
        minimum-idle: 0
        maximum-pool-size: 15
        connection-timeout: 10000 #10s
        idle-timeout: 300000 #5m
        max-lifetime: 600000 #10m
        initialization-fail-timeout: -1
        validation-timeout: 1000 #1s

For datasources, I have one datasource which is Primary bean and others are non-primary. How can i run spring boot app even if it fails to connect to ALL dbs.

Answer 1

You can instantiate a datasource "manually" then feed it to Spring. For example:

@Configuration
public class MyConfigBean {

  @Lazy
  @Autowired
  private DataSource dataSource;
  
  @Bean
  public DataSource getDataSource() {
    log.debug(">>> Building the DATA-SOURCE");
    DataSourceBuilder<?> dataSourceBuilder = DataSourceBuilder.create();
    dataSourceBuilder.driverClassName(JDBC_DRIVER_CLASS_NAME);
    dataSourceBuilder.url(props.getJDBCUrl());
    dataSourceBuilder.username(props.getJDBCUsername());
    dataSourceBuilder.password(props.getJDBCPassword());
    return dataSourceBuilder.build();
  }
  
}

The @Lazy annotation leaves the call to getDataSource() method to the last. This way you can retrieve/populate the URL and credentials earlier, so they are ready for the moment they are needed.