Connecting to Mongo fails with an UnknownHostException when spring.data.mongodb.additional-hosts is configured #36441
Description
I have some MongoDB config with Spring boot:
spring:
data:
mongodb:
database: admin
username: admin
password: pass
host: localhost
additional-hosts: [somehost]
When I start my application, I see the following error in logs:
com.mongodb.MongoSocketException: localhostsomehost
at com.mongodb.ServerAddress.getSocketAddresses(ServerAddress.java:217) ~[mongodb-driver-core-4.9.1.jar:na]
at com.mongodb.internal.connection.SocketStream.initializeSocket(SocketStream.java:78) ~[mongodb-driver-core-4.9.1.jar:na]
at com.mongodb.internal.connection.SocketStream.open(SocketStream.java:68) ~[mongodb-driver-core-4.9.1.jar:na]
at com.mongodb.internal.connection.InternalStreamConnection.open(InternalStreamConnection.java:204) ~[mongodb-driver-core-4.9.1.jar:na]
at com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.lookupServerDescription(DefaultServerMonitor.java:199) ~[mongodb-driver-core-4.9.1.jar:na]
at com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:159) ~[mongodb-driver-core-4.9.1.jar:na]
at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]
Caused by: java.net.UnknownHostException: localhostsomehost
at java.base/java.net.InetAddress$CachedAddresses.get(InetAddress.java:801) ~[na:na]
at java.base/java.net.InetAddress$NameServiceAddresses.get(InetAddress.java:887) ~[na:na]
at java.base/java.net.InetAddress.getAllByName0(InetAddress.java:1533) ~[na:na]
at java.base/java.net.InetAddress.getAllByName(InetAddress.java:1385) ~[na:na]
at java.base/java.net.InetAddress.getAllByName(InetAddress.java:1306) ~[na:na]
at com.mongodb.ServerAddress.getSocketAddresses(ServerAddress.java:209) ~[mongodb-driver-core-4.9.1.jar:na]
... 6 common frames omitted
I've found that in PropertiesMongoConnectionDetails class connection string (getConnectionString() function) is being built and comma is missing between host value and first additional host value:
builder.append((this.properties.getHost() != null) ? this.properties.getHost() : "localhost");
if (this.properties.getPort() != null) {
builder.append(":");
builder.append(this.properties.getPort());
}
if (this.properties.getAdditionalHosts() != null) {
builder.append(String.join(",", this.properties.getAdditionalHosts()));
}
String.join(",", this.properties.getAdditionalHosts()) will insert comma between additional-hosts values, but not at the start