• What is Docker Machine?

    Docker Machine can be explain as a tool that allows you to install  Docker Engine on virtual hosts, Further it also manage the host with docker Machine commands. This Docker Machine can be use to create your Docker host on Windows box or on your local Mac, on your company network, on cloud providers like AWS, Digital ocean or AWS or in your Data center.

  • what is HTTP Strict Transport Security?

    It is a method used by websites to declare that they should only be accessed using a secure connection (HTTPS). If a website declares an HTTP Strict Transport Security policy, the browser must refuse all HTTP connections and prevent users from accepting insecure SSL certificates.

  • How to check for Docker Client and Docker Server version?

    To check your docker version information, please use below command. It will  show all information in an easy to read layout.

    >> $ docker version

  • How do you get the number of containers running, paused and stopped?

    The docker ps command only shows running containers by default. To see the specific output you can use the  “status” filter. This filter matches containers by status. You can filter using created, restarting, running, removing, paused, exited and dead.

    For example, to filter for running containers:

    $ docker ps –filter status=running

  • How to delete a stopped container?

    One can list all containers or the stopped container by using status command or following command:

    $ docker container ls -a

    To delete a stopped container use following command :

    $ docker container rm

    I.e. docker container rm cc3f2ff51cab

    To remove all stopped container one can use : docker container prune

    OUTPUT :

    WARNING! This will remove all stopped containers.

    Are you sure you want to continue? [y/N] y

    $ docker system prune -a

    WARNING! This will remove:

    – all stopped containers

    – all volumes not used by at least one container

    – all images without at least one container associated to them

    Are you sure you want to continue? [y/N] y

  • Can I use JSON instead of YAML for my compose file in Docker?

    Yes, you will only need to specify the file name to use.As yaml is a superset of json so any JSON file should be valid Yaml.

  • What Are the Benefits of Container Load Balancing?

    1. It ensures uninterrupted performance of the microservices-based applications running inside the container by switching the online servers as needed.

    2. Load balancers running in Docker containers make it possible for multiple containers to be accessed on the same host port.

    3. It reduces the load on your web servers and optimize traffic for a better user experience.

  • How does work load balancing across containers and hosts?

    Load balancing basically refers to distributing incoming traffic across a group of backend servers or pool/cluster. In a simple language it works as a traffic management services for containerized applications efficiently.

    Hundreds of thousands of incoming client requests are routed across all servers capable of fulfilling those requests in a manner that maximizes speed and capacity utilization and ensures that no one server is overworked, which could degrade performance. So if one server goes down, load balancer will redirect the traffic to other online server which ultimately reduces the downtime.

  • What platforms does docker run on?

    Docker is an open source containerization platform for developing, shipping, and running applications. They have build products that let you build and run containers on Linux, Windows and macOS.

  • Is there a way to identify the status of a Docker container?

    It list all containers , where a is short for -all. You can check the status and other useful information about the containers.

    $ docker container ls 

  • What is containerization?

    Containerization is encapsulating or packaging up software code and all its dependencies so that it can run uniformly and consistently on any infrastructure.

    It isolated user spaces called containers, all using the same shared operating system (OS) and allows developers to create/deploy applications faster and more securely.

    This will eliminate any problem occurring by bundling the application code with the configuration file, libraries, and dependencies required for it to run.

  • What is Virtual Machines?

    Virtualization involves using software to create a virtual machine (VM) copy of a server, complete with its own operating system, drivers, and libraries.
    Several virtual machines can be created using the processing power and storage capacity of a single server or multiple servers that are integrated to share resources between them.

  • What is Containers?

    Containers are much easier to manage than virtual machines because every container isn’t running its own operating system.
    This makes challenges like fixing bugs and installing patches much easier to address. On the downside, it also means that problems with any one system could take down multiple containers. The lightweight nature of containers, however, makes them easier to move, which is much more difficult with virtual machines.

  • Docker container security:

    Securing a Docker container is no different than securing other containers. It requires an all-inclusive approach, securing everywhere from the host to the network and everything in between. Because of their moving parts, ensuring the security of containers is difficult for many organizations, and it requires more than rudimentary level of vigilance.

    Things to consider:
    1)Utilise resource quotas
    2)Docker containers are not to be run as root
    3)Ensure the security of your docker container registries
    4)Use a trusted source
    5)Go to the source of the code
    6)Design APIs and networks with security in mind

  • What platforms does docker run on?

    The Docker platform runs natively on Linux and on Windows.

  • What is Hypervisor?

    A hypervisor, also known as a virtual machine monitor is software that creates and runs virtual machines.
    A hypervisor allows one host computer to support multiple guest VMs by virtually sharing its resources, such as memory and processing.

  • How many containers can run per host?

    Runs Eight (8) Containers per Host.

  • How will you monitor Docker in production?

    1. AppOptics Docker Monitoring with APM
    – AppOptics provides a robust monitoring solution for Docker containers.

    2. SolarWinds Server & Application Monitor
    -SolarWinds provides tracking for key performance metrics such as CPU, memory, and uptime of individual Docker containers through a simple dashboard.

    3. Prometheus
    -Prometheus is one of the best known open-source Docker monitoring tools and is one of the three solutions recommended by Docker.

    4. Docker API
    -Docker API is the official HTTP Web Service API for integrating with Docker.

    5. ManageEngine Applications Manager
    -The ManageEngine Applications Manager is a popular server monitoring solution with native support for monitoring Docker hosts

  • Data volume purpose in docker:

    A data volume is a specially-designated directory within one or more containers that bypasses the Union File System.
    Data volumes provide several useful features for persistent or shared data.Data volumes are designed to persist data, independent of the container’s lifecycle.

    Docker volume create a volume without having to define a Dockerfile and build an image and run a container.
    It is used to quickly allow other containers to mount said volume.

  • What is Data Volume and Its use in Docker?

    Data volume is the ability to efficiently store and process petabytes of data stored natively and in object storage. Its use in docker is to quickly allow other containers to mount said volume.

  • What are use of Container Images ?

    A container image is a static file with executable code that can create a container on a computing system. A container image is immutable—meaning it cannot be changed, and can be deployed consistently in any environment. It is a core component of a containerized architecture.

  • What are use of Docker Image ?

    A Docker image is a file used to execute code in a Docker container. Docker images act as a set of instructions to build a Docker container, like a template. Docker images also act as the starting point when using Docker. An image is comparable to a snapshot in virtual machine (VM) environments.

  • How to check container logs and their meaning ?

    It is used to check logs related to Docker Container. It is being used with some options they are as follows:

    Parent command:
    #docker container logs [OPTIONS] CONTAINER_ID


    –details               >> Show extra details provided to logs
    –follow , -f           >> Follow log output
    –since                  >> Show logs since timestamp (e.g. 2021-07-02T13:23:37Z) or relative (e.g. 42m for 42 minutes)
    –tail , -n , all        >> Number of lines to show from the end of the logs
    –timestamps , -t >> Show timestamps
    –until                    >> Show logs before a timestamp (e.g. 2021-07-02T13:23:37Z) or relative (e.g. 42m for 42 minutes)

  • What is Docker Registry and commands?
    Docker Registry is nothing but the repositories that contain images related to certain projects. concept call pull is nothing but downloads the images from the registry. push nothing but the uploading projects to the registry.
    For example, ubuntu and its versions projects like Tomcat, Magento, WordPress.
    Many registry services will offer additional features that help build and deploy processes and improve security.
    docker run -d -p 5000:5000 --name registry registry:2 >> to start your registry 
    docker pull project name >> to pull/download project
    docker push >> to push project registry
  • How to Signup On Apass Cloud ?
    1. Visit to official site of “https://apaascloud.io” and click on “sign up free” button. You will be redirect to the registration page.