Can we declare spring bean conditionally?

You can use @Conditional from Spring4 or @ConditionalOnProperty from Spring Boot.

1. Using Spring4 (only)

if you are NOT using Spring Boot, this can be overkill.

First, create a Condition class, in which the ConditionContext has access to the Environment:

public class MyCondition implements Condition {
    @Override
    public boolean matches(ConditionContext context,
                           AnnotatedTypeMetadata metadata) {
        Environment env = context.getEnvironment();
        return null != env
                && "true".equals(env.getProperty("server.host"));
    }
}

Then annotate your bean:

@Bean
@Conditional(MyCondition.class)
public ObservationWebSocketClient observationWebSocketClient() {
    //return bean
}

2.Using Spring Boot:

@ConditionalOnProperty(name="server.host", havingValue="localhost")

And in your abcd.properties file ,

server.host=localhost