PostgreSQL is an object-RDBMS (ORDBMS) developed by the PostgreSQL Global Development Group.
RabbitMQ is an open source message broker. It acts as a middleware for sending and receiving messages between different components in an application.
Redis is an in-memory data structure store which can be used as database, cache or message broker.
Docker provides framework to isolate an application and its dependencies into self-contained unit called containers. These containers can be run anywhere. Containers can be considered as “light” version of virtual machines.