Here we have compiled the most probable DevOps interview questions asked in the industry. You will learn about software version control, Git repository, reverting a commit in Git, Vagrant, continuous testing elements, and the importance of continuous integration, testing, and deployment. These questions are curated after discussing with many interviewers and DevOps Training experts.
Almost all MNCs run container technology. Containers can be scaled to hundreds of thousands folds and can run parallely. For scaling docker needs the memory at all times and a way to use this memory efficiently when scaled up.
Docker can run on almost all environments a linux based physical machine or cloud environment and in windows using Docker Toolbox.
various Linux versions are:
Ubuntu 16.04, 18.04+
various Cloud platforms are:
Google Compute Engine
Microsoft Azure and etc..
Use the following command that displays the list running containers
$ docker ps
To display all containers, use the following command:
$ docker ps -a
It shows the status of the docker container.
No, You cannot remove a paused container. The container should be stopped before removing it. But to remove a paused container you need to apply force, by using this command
$ docker rm -f
By default No, it’s not possible for a container to restart by itself as the flag "--restart" is set to false by default.
It is always better to stop the container and then remove it using the remove command.
$ docker stop
$ docker rm
Stopping the container and then removing it will allow sending SIG_HUP signal to recipients. This will ensure that all the containers have enough time to clean up their tasks. This method is considered a good practice, avoiding unwanted errors.
My or may not be, it is a business, whoever provides a good service they may gain popularity. Of Course no service is permanent one comes after another. Docker containers are gaining popularity but at the same time, Cloud services are a good competitor.
Some notable drawbacks of Docker as follows:
* Doesn't provide a proper storage option
* Offer a poor monitoring option (docker stat or docker event)
* Complicated automatic horizontal scaling set up
* No automatic rescheduling of inactive Nodes
You can run as many containers as you wish per host until your machine memory is full. Docker does not put any restrictions on it. But each container needs storage space, CPU and memory which the hardware needs to support. Containers are considered to be lightweight but very dependent on the host OS.
Suppose if you have your application running on multiple containers, it is good to maintain a Load Balancer because it diverts the user request equally to all containers. So that no container goes down due to heavy traffic. If any container goes down the traffic of that container will be shared equally to remaining containers. The same is in case of hosts.