What is a proxy?

A proxy is network equipment or software that filters all HTTP requests coming from clients inside a local network. Proxies can be used for several purposes:

• Restricting internet access
• Analyzing traffic to avoid viruses and attacks
• Caching content retrieved by a lot of people to speed up access

What is a reverse proxy?

A reverse proxy is network equipment or software present on the backend. Its role is to route incoming HTTP requests to the service that handles it. A reverse proxy allows us to hide the fact that multiple servers are used behind a single IP address.

What is a load balancer?

A load balancer allows us to easily scale a service. When several instances of a service are running, a load balancer distributes incoming request to these instances. Depending on the load-balancing strategy and the capacity of each instance, the distribution of the requests to the services may or may not be balanced.

What additional features are provided by Docker Compose compared to Docker?

Docker Compose provides the following facilities:

• Start and stop multiple containers in a single command
• Configure containers via a configuration file instead of many command-line arguments
• Scale the number of instances of a container

What is the purpose of a Dockerfile?

A Dockerfile is a configuration file that describes all the steps needed to build a Docker image. This configuration file is used by the docker build command to actually create a Docker image.

What are the prerequisites to scale a service horizontally?

A service can be scaled horizontally without any modifications if it is fully stateless. If a service is not stateless, then other components must be used to manage this state before the service can be scaled horizontally. This can be either by relying on another service or by implementing some communication between each service instance so that they form a cluster.

What service is provided by Let's Encrypt?

Let's Encrypt is a TLS certificate authority. They provide certificates that can be validated by HTTP clients such as web browsers without having to import the certificate on the server.