Spring Boot and how to configure connection details to MongoDB?

Question 1

Just to quote Boot Docs:

You can set spring.data.mongodb.uri property to change the url, or alternatively specify a host/port. For example, you might declare the following in your application.properties:

spring.data.mongodb.host=mongoserver
spring.data.mongodb.port=27017

All available options for spring.data.mongodb prefix are fields of MongoProperties:

private String host;

private int port = DBPort.PORT;

private String uri = "mongodb://localhost/test";

private String database;

private String gridFsDatabase;

private String username;

private char[] password;

Question 2

It's also important to note that MongoDB has the concept of "authentication database", which can be different than the database you are connecting to. For example, if you use the official Docker image for Mongo and specify the environment variables MONGO_INITDB_ROOT_USERNAME and MONGO_INITDB_ROOT_PASSWORD, a user will be created on 'admin' database, which is probably not the database you want to use. In this case, you should specify parameters accordingly on your application.properties file using:

spring.data.mongodb.host=127.0.0.1
spring.data.mongodb.port=27017
spring.data.mongodb.authentication-database=admin
spring.data.mongodb.username=<username specified on MONGO_INITDB_ROOT_USERNAME>
spring.data.mongodb.password=<password specified on MONGO_INITDB_ROOT_PASSWORD>
spring.data.mongodb.database=<the db you want to use>

Question 3

spring.data.mongodb.host and spring.data.mongodb.port are not supported if you’re using the Mongo 3.0 Java driver. In such cases, spring.data.mongodb.uri should be used to provide all of the configuration, like this:

spring.data.mongodb.uri=mongodb://user:secret@mongo1.example.com:12345

Question 4

In a maven project create a file src/main/resources/application.yml with the following content:

spring.profiles: integration
# use local or embedded mongodb at localhost:27017
---
spring.profiles: production
spring.data.mongodb.uri: mongodb://<user>:<passwd>@<host>:<port>/<dbname>

Spring Boot will automatically use this file to configure your application. Then you can start your spring boot application either with the integration profile (and use your local MongoDB)

java -jar -Dspring.profiles.active=integration your-app.jar

or with the production profile (and use your production MongoDB)

java -jar -Dspring.profiles.active=production your-app.jar

Question 5

You can define more details by extending AbstractMongoConfiguration.

@Configuration
@EnableMongoRepositories("demo.mongo.model")
public class SpringMongoConfig extends AbstractMongoConfiguration {
    @Value("${spring.profiles.active}")
    private String profileActive;

    @Value("${spring.application.name}")
    private String proAppName;

    @Value("${spring.data.mongodb.host}")
    private String mongoHost;

    @Value("${spring.data.mongodb.port}")
    private String mongoPort;

    @Value("${spring.data.mongodb.database}")
    private String mongoDB;

    @Override
    public MongoMappingContext mongoMappingContext()
        throws ClassNotFoundException {
        // TODO Auto-generated method stub
        return super.mongoMappingContext();
    }
    @Override
    @Bean
    public Mongo mongo() throws Exception {
        return new MongoClient(mongoHost + ":" + mongoPort);
    }
    @Override
    protected String getDatabaseName() {
        // TODO Auto-generated method stub
        return mongoDB;
    }
}

Question 6

In case that somebody is trying to connect to a Atlas MongoDB Cluster in application.properties has to have a config like:

spring.data.mongodb.uri=mongodb+srv://databaseUsername:usernamePassword@cluster0.j4koa.mongodb.net/databaseUsername?retryWrites=true&w=majority

Question 7

In my case I needed to set up MongoDB for integration tests using Testcontainers. Using properites file was not an option since Mongo port had to be specified during runtime. I wanted to preseve original MongoDB autoconfiguration provided by SpringBoot but override some of the properties. This can be achieved by defining a bean of type MongoClientSettingsBuilderCustomizer which can be used to customize mongo settings :

@Bean
public MongoClientSettingsBuilderCustomizer clientSettingsBuilderCustomizer(final GenericContainer<?> mongoDBContainer) {
     String database = environment.getProperty("spring.data.mongodb.database");
     ConnectionString connectionString = new ConnectionString(String.format("mongodb://localhost:%s/%s", mongoDBContainer.getFirstMappedPort(), database));
     return settings -> settings.applyConnectionString(connectionString);
}

Question 8

If you simply want to read a MongoDB connection string from an environment variable, one way is to set the following environment variable:

SPRING_DATA_MONGODB_URI=mongodb://localhost:27017/trying-mongo

This doesn't require any changes in the application.properties as the spring data mongo will read the value from the above environment variable by default.

Question 9

Here is How you can do in Spring Boot 2.0 by creating custom MongoClient adding Providing more control for Connection ,

Please follow github Link for Full Source Code

@Configuration
@EnableMongoRepositories(basePackages = { "com.frugalis.repository" })
@ComponentScan(basePackages = { "com.frugalis.*" })
@PropertySource("classpath:application.properties")
public class MongoJPAConfig extends AbstractMongoConfiguration {

    @Value("${com.frugalis.mongo.database}")
    private String database;
    @Value("${com.frugalis.mongo.server}")
    private String host;
    @Value("${com.frugalis.mongo.port}")
    private String port;
    @Value("${com.frugalis.mongo.username}")
    private String username;
    @Value("${com.frugalis.mongo.password}")
    private String password;


    @Override
    protected String getDatabaseName() {
        return database;
    }

    @Override
    protected String getMappingBasePackage() {
        return "com.frugalis.entity.mongo";
    }

    @Bean
    public MongoTemplate mongoTemplate() throws Exception {
        return new MongoTemplate(mongoClient(), getDatabaseName());
    }

    @Override
    @Bean
    public MongoClient mongoClient() {

        List<MongoCredential> allCred = new ArrayList<MongoCredential>();
        System.out.println("???????????????????"+username+" "+database+" "+password+" "+host+" "+port);
        allCred.add(MongoCredential.createCredential(username, database, password.toCharArray()));
        MongoClient client = new MongoClient((new ServerAddress(host, Integer.parseInt(port))), allCred);
        client.setWriteConcern(WriteConcern.ACKNOWLEDGED);

        return client;
    }}