DOCKER

How do you automate the deployment of Docker containers using CI/CD?

Configure your CI/CD pipeline to automatically build and push Docker images to a registry, then deploy those images to your target environment using orchestration tools like Kubernetes or Docker Swarm.

What are the benefits of using Docker in a CI/CD pipeline?

Consistent environment across stages. Isolation of dependencies. Faster deployment times. Improved reproducibility.

How can containers communicate with each other within the same network?

Containers within the same network can communicate using their container names as hostnames.

How do you remove a container?

docker rm <container_id>

How do you remove a Docker image?

docker rmi <image_id>

How do you stop a running container?

docker stop <container_id>

What is the purpose of Docker image layers?

Docker images are composed of layers, which are incremental changes on top of a base image. This allows for efficient image caching and sharing.

What is Docker networking?

Docker networking enables communication between containers and between containers and the outside world.

What is the default networking mode for a Docker container?

The default networking mode is the bridge network.

What is the purpose of the depends_on attribute in Docker Compose?

The depends_on attribute defines the order in which services start up. It doesn't ensure full service readiness; you might need additional checks for that.

What is Docker's docker events command used for?

The docker events command displays real-time events generated by Docker.

What is the difference between --link and user-defined bridge networks for container communication?

--link was a legacy method to connect containers, while user-defined bridge networks provide a more flexible and scalable solution.

What is the difference between a bind mount and a volume in Docker?

A bind mount maps a host directory into a container, while a volume is a managed filesystem that can be shared between containers.

What is a Canary deployment, and how can Docker be used to implement it?

A Canary deployment involves releasing a new version of your application to a subset of users. Docker can be used to create containers running the new version

What is Docker Stack in the context of Docker Swarm?

A Docker Stack is a group of interrelated services that share the same purpose or task, managed as a single unit in a Docker Swarm.

What is the difference between a Docker image and a container?

A Docker image is a read-only template that defines a set of instructions for creating a container. A container is a running instance of an image.

What is a Docker registry?

A Docker registry is a centralized repository for storing and distributing Docker images.

How can you troubleshoot issues with Docker containers?

Check container logs using docker logs. Access a shell in a running container using docker exec -it <container_id> /bin/bash. Monitor container resource usage using docker stats.

How do you run a Docker container?

Use the docker run command followed by the image name to run a Docker container.

How do you deploy a Docker Stack?

Use the docker stack deploy command followed by the stack name and the docker-compose.yml file.

How do you initialize a Docker Swarm?

Use the docker swarm init command on the manager node.

How do you create a Docker volume?

Use the docker volume create command followed by the volume name.

How do you remove a Docker volume?

Use the docker volume rm command followed by the volume name.

How do you scale a service defined in a Docker Compose file?

Use the docker-compose up --scale <service_name>=<desired_count> command.

How do you define services and networks in a Docker Compose file?

Use the services and networks sections in the Compose YAML file.

What is the difference between Docker and virtualization?

Virtualization uses (hypervisor)involves running multiple virtual machines on a single physical machine, each with its own operating system. Docker uses containerization, which shares the host OS and allows for more lightweight and efficient deployments.

How can you integrate Docker into a continuous integration/continuous deployment (CI/CD) pipeline?

You can use Docker to package applications and their dependencies into containers, ensuring consistency across various stages of development, testing, and deployment.

How do you create a private Docker registry?

You can use Docker's open-source registry software, Docker Distribution, to set up a private registry.

How do you view the layers of a Docker image?

You can use the docker history command followed by the image name.

How can you back up and restore Docker volumes?

You can use utilities like docker cp to copy data in and out of containers, or use tools like rsync to synchronize data.

What is the Docker Hub?

cloud-based registry service that allows you to store and share Docker images.

What is a Docker volume?

directory that exists outside of the container's filesystem and provides a way to persist and share data between containers.

How do you build a Docker image from a Dockerfile?

docker build -t <image_name>:<tag> <path_to_dockerfile_directory>

What command is used to list all Docker images on the system?

docker images

How do you view the logs of a running container?

docker logs <container_id>

What is the command to list all running containers?

docker ps

How can you inspect the configuration and settings of a Docker container?

Use the docker inspect command followed by the container ID or name.

How do you attach a container to a user-defined bridge network?

Use the docker network connect command.

What is the difference between the -d and -it flags when running a container?

-d runs the container in detached mode, while -it allocates a pseudo-TTY and attaches to the container's stdin, allowing interaction.

How do you create a user-defined bridge network in Docker?

Use the docker network create command followed by the network name.

What is a multi-stage Docker build?

A multi-stage Docker build involves using multiple FROM instructions in a single Dockerfile to create an efficient and lightweight final image.

What is Docker's tmpfs mount?

A tmpfs mount allows you to create a temporary filesystem in memory that's only accessible by a single container.

What is Docker's AppArmor?

AppArmor is a Linux security module that enforces security policies on containers, restricting their access to the host system.

What is Docker's BuildKit?

BuildKit is a modern build subsystem introduced by Docker that offers advanced features for building Docker images, such as improved caching and better performance.

What is the difference between data volumes and data volume containers?

Data volumes are created and managed directly using Docker commands, while data volume containers are a legacy pattern involving creating containers specifically for managing shared volumes.

How does Docker Compose handle scaling services?

Docker Compose doesn't directly handle scaling. You can run multiple instances of the same service using the docker-compose up --scale <service_name>=<desired_count> command.

What is Docker's Content Trust?

Docker Content Trust is a feature that allows you to verify the authenticity and integrity of Docker images.

What is Docker Hub?

Docker Hub is a cloud-based registry service provided by Docker to store and share Docker images.

What is the difference between Docker Swarm and Kubernetes?

Docker Swarm and Kubernetes are both orchestration platforms for managing containers, but Kubernetes is more feature-rich and complex, while Docker Swarm is simpler and easier to set up.

What is a Docker Swarm?

Docker Swarm is Docker's native clustering and orchestration solution for managing a cluster of Docker nodes.

What is the Docker image vulnerability scanning process?

Docker image vulnerability scanning tools analyze images for known security vulnerabilities in their libraries and dependencies.

How can you manage secrets in Docker?

Docker provides a feature called "Docker Secret" to manage sensitive data, like passwords or API keys, securely.

What is Docker's role in achieving container security?

Docker provides features like isolation, resource control, security profiles (AppArmor, seccomp), and the ability to restrict container capabilities to enhance security.

How does Docker achieve isolation?

Docker uses Linux namespaces and control groups (cgroups) to provide process isolation, filesystem isolation, network isolation, and resource allocation for containers.

What is Docker's official image naming convention?

Docker's official images are typically named with the format <namespace>/<image_name>:<tag>.

What is the purpose of Docker's health checks?

Health checks allow Docker to monitor the status of a container and take actions based on its health.

How can you perform blue-green deployments using Docker?

In a blue-green deployment, you have two identical environments, one with the current version (blue) and one with the new version (green). Docker can help manage this by creating, updating, and rolling back containers in the target environment.

What is Docker's host network mode?

In host network mode, a container shares the network namespace with the host, allowing it to use the host's network stack.

What are Docker Swarm managers and workers?

Managers control the swarm and make global decisions, while workers run tasks assigned to them by managers.

How do you configure a CI/CD tool to run Docker commands as part of a pipeline?

Most CI/CD tools provide native support for Docker integration. You can configure the pipeline steps to include Docker commands for building, testing, and deploying containers.

How can you enable Docker Content Trust?

Set the environment variable DOCKER_CONTENT_TRUST to 1 before using Docker commands, or use the export DOCKER_CONTENT_TRUST=1 command.

What tools can you use to monitor Docker containers and clusters?

Some monitoring tools include Prometheus, Grafana, Docker's native tools, and third-party solutions.

How do you pull a specific version of an image from Docker Hub?

Specify the desired tag when using the docker pull command. For example, docker pull nginx:1.19.

What is the purpose of Docker's --entrypoint flag?

The --entrypoint flag allows you to override the default entry point specified in the Docker image.

What is the purpose of Docker's --privileged mode?

The --privileged flag gives a container extended privileges, essentially giving it the same access to the host's resources as processes outside of containers.

What is a Dockerfile COPY instruction used for?

The COPY instruction is used to copy files from the host into the container.

What is the Docker event stream, and how can you access it?

The Docker event stream provides real-time notifications of events related to containers, images, and other Docker objects. You can access it using the docker events command.

What is Docker's data-only container pattern?

The data-only container pattern involves creating a container that holds shared volumes and is used solely for the purpose of sharing data between other containers.

What is Docker's docker top command used for?

The docker top command displays the running processes within a container.

How do you pull a Docker image from Docker Hub?

Use the docker pull command followed by the image name and tag.

How can you push a Docker image to Docker Hub?

Use the docker push command followed by the image name and tag.

What is Docker's macvlan network mode?

The macvlan network mode allows a container to have its own MAC address on the network, making it appear as a physical device on the network.

How can you use Docker to build and push images as part of a CI/CD process?

Use Docker build commands to create images from Dockerfiles, and then push those images to a Docker registry as part of your CI/CD pipeline.

How can you ensure data persistence when a container is stopped or removed?

Use Docker volumes to store data outside the container, ensuring that the data survives container restarts and removals.

How do you manage environment-specific configurations in Docker-based deployments?

Use environment variables or configuration files within your Docker containers to manage environment-specific configurations.

What are some best practices for securing Docker containers?

Use official base images. Limit the number of privileges given to containers. Use user namespaces to isolate container users from host users. Implement network segmentation and access controls.

How can you restrict a container's CPU and memory usage?

Use the --cpus and --memory flags when running a container.

How can you run a container in read-only mode?

Use the --read-only flag when running a container to prevent any changes to the container's filesystem.

How do you expose a port from a Docker container?

Use the -p flag with the docker run command. For example, -p 8080:80 maps port 8080 on the host to port 80 in the container.

How do you attach a volume to a Docker container?

Use the -v or --mount flag with the docker run command.

How do you add a health check to a Docker container?

Use the HEALTHCHECK instruction in the Dockerfile, or use the docker run command with the --health-cmd flag.

How do you check the IP address of a running container?

Use the docker inspect command along with the container ID or name and filter for the desired information.

What is a Docker container?

lightweight, standalone, and executable software package that includes everything needed to run a piece of software, including the code, runtime, libraries, and system tools.

What is an overlay network in Docker?

multi-host network that allows containers to communicate across different Docker hosts.

What is Docker?

platform that enables developers to automate the deployment and scaling of applications using containers.

What is a Dockerfile?

script that contains a set of instructions for building a Docker image.

What is Docker's seccomp security feature?

seccomp is a Linux security feature that allows you to restrict the system calls that a container can make.

What is Docker Compose used for?

tool for defining and running multi-container Docker applications using a YAML file.

What is Docker Compose used for?

tool for defining and running multi-container Docker applications using a single YAML file.

How do you create a Docker image?

using a Dockerfile, which is a text file containing a set of instructions for building an image.