App engine flexible - how to implement distributed sessions

Question

In the flexible environment, App Engine doesn't provide built-in support for distributed sessions like it does in the standard environment with Memcache.

So after migrating to Flex, I am unable to autoscale the application anymore as the user session cannot be routed from an instance to another like it was in Standard.

We should specify a Session Storage (eg: Redis) to have the user sessions shared between all the instances.

I looked at this google documentation https://cloud.google.com/appengine/docs/flexible/nodejs/configuring-your-app-with-app-yaml but it didn't helped me.

Any ideas ?

Answer 1

Spring Session makes it very simple !

Include the spring-session-core & spring-session-data-redis libraries into your pom.xml file

<dependency>
    <groupId>org.springframework.session</groupId>
    <artifactId>spring-session-core</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.session</groupId>
    <artifactId>spring-session-data-redis</artifactId>
</dependency>

Configure your redis configuration. 2 ways exist here

• Option 1) Redis configuration via the properties file

Put the below into your application.properties

spring.data.redis.host=127.0.0.1
spring.data.redis.port=6379

• Option 2) Redis configuration from the java code

@Configuration
public class RedisConfiguration {

    private static final String redisHost = "127.0.0.1";
    private static final int redisPort = 6379;

    @Bean
    public RedisConnectionFactory redisConnectionFactory() {
        RedisStandaloneConfiguration redisStandaloneConfiguration = new RedisStandaloneConfiguration(redisHost, redisPort);

        return new JedisConnectionFactory(redisStandaloneConfiguration);
    }

}

Spring will automatically create the session in redis instead of the memory store as shown below

Answer 2

Sharing this as a community wiki for the benefit of others

As mentioned by @minou

Two suggestions: (1) Use cookies for sessions or (2) review the documentation for implementing redis in app engine and ask a more focused question if you have trouble.