Test Your Docker Knowledge

Hypervisor and Containerization

• The main task of a hypervisor is to manage and allocate resources to virtual machines (VMs) or containers.
• There are two categories of hypervisors: Type 1 (bare-metal) and Type 2 (hosted).
• A Docker container is a lightweight and standalone executable package of software that includes everything an application needs to run.

Docker Advantages and Scalability

• Advantages of using Docker over other containerization methods include:
  • Lightweight and portable
  • Fast deployment and scaling
  • Isolated and secure environments
  • Easy management and orchestration
• Docker containers are highly scalable, and scaling requirements include:
  • Adequate system resources (CPU, memory, and storage)
  • Proper network configuration and connectivity
  • Efficient use of Docker Swarm and other orchestration tools
• Docker currently supports six types of namespaces: pid, net, ipc, mnt, utc, and user.

Docker Architecture and Components

• The main component of Docker architecture is the Docker Engine, which consists of:
  • Docker daemon (dockerd)
  • Docker client (docker)
  • Container runtime (runc)
• The default value of the restart flag for a Docker container is "no".
• Docker supports multiple platforms, including Windows, Linux, and macOS.

Docker Commands and Usage

• The docker login command is used to log into a Docker registry.
• The docker build command is used to build a Docker image from a Dockerfile.
• The docker run command is used to create a Docker container from an image.
• The docker ps command is used to see all the running containers.
• Docker volumes are stored on a Docker host in the /var/lib/docker/volumes directory.

Docker Containers and Data

• The purpose of Docker containers is to provide a lightweight and portable way to package and deploy applications.
• A DockerFile is a text file that contains instructions for building a Docker image.
• Docker images are templates for creating containers.
• Docker Compose is a tool for defining and running multi-container Docker applications.
• When a Docker container exits, the data inside the container is discarded.
• Stateful applications can be run over Docker, but it is not recommended.

Container Orchestration and Management

• Docker Swarm is a container orchestration tool for deploying and managing containers at scale.
• Docker Machine is a tool for creating and managing Docker hosts.
• The purpose of container orchestration is to automate the deployment, scaling, and management of containers.
• CNM stands for Container Network Model, which is a Docker networking system.
• Docker Trusted Registry (DTR) is a secure registry for storing and managing Docker images.
• Kubernetes is a popular container orchestration system that can be used with Docker.

Docker Interview and Best Practices

• When preparing for a Docker interview, be prepared to discuss:
  • Docker architecture and components
  • Docker commands and usage
  • Container orchestration and management
  • Docker networking and security
• The recommended use of Docker-compose in production is for development and testing environments.
• Tools for monitoring Docker in production include:
  • Docker logs and metrics
  • Prometheus and Grafana
  • New Relic and Datadog
• There is no limit to the number of containers that can run per host, but it depends on system resources.
• The recommended way to remove a container is to use the docker rm command.

Docker Labels and Networking

• The purpose of Docker object labels is to add metadata to Docker objects, such as containers and images.
• The memory-swap flag is used to set the amount of swap space available to a container.
• Docker supports IPv6, and the docker network command is used to manage Docker networks.
• The difference between a registry and a repository is:
  • A registry is a collection of repositories
  • A repository is a collection of Docker images
• The CMD instruction in a Dockerfile is used to set the default command to run when a container is started.
• The ENTRYPOINT instruction in a Dockerfile is used to set the default entry point for a container.