Docker Developer Hiring Guide

Almost every company across the world has started investing in container technology. There are so many good reasons for this. Containers encapsulate everything needed to run an application. Because of this, these containers can be deployed to any supporting platform.

For example, if you create an NGINX container (which includes a complete web-based application), you can deploy it to a Linux server or desktop, a Windows server or desktop, or a macOS server or desktop. You can deploy containers in your on-premises data center or at your cloud-based hosting provider.

Containers can make your life much simpler.

But containers are good for more than simplicity. One thing containers do better than any other technology is scale. Let's say, for example, you have a web-based application. You can deploy this application the traditional way (on a standard web server stack) and it will work fine. But what happens when demand grows exponentially? In this traditional stack, you may need to add more hardware to the mix to keep up with demand.

With a containerized application, you can simply deploy more nodes in the cluster and configure these containers to autoscale as needed. This level of automation cannot be achieved with traditional, monolithic applications.

Along with this automation, your business can also save money, especially when using a third-party cloud host which is a pay-as-you-go service. With autoscaling enabled, your containers will increase when demand increases and decrease when demand decreases. This can lead to significant cost savings for any company.

Hiring Guide for Docker Developers

But how do you deploy containers? One of the most important tools you need is a runtime engine like Docker. For years, Docker was the most popular container tool on the market. Although this popularity has waned with the rise of Kubernetes, Docker is still widely used. One of the reasons for this is because Docker is much easier to deploy and use than Kubernetes.

This doesn't mean Docker is easy. You won't throw a novice admin into this mix and get a lot of results. Docker requires a certain level of understanding of a few different technologies to get the most out of it.

Let's find out what Docker admins need to know.

Linux

Firstly, Docker administrators will need to know Linux. Yes, Docker containers can be deployed on macOS and Windows, but the vast majority of Docker containers are deployed on Linux. One of the biggest reasons for this is that most virtual machines deployed on cloud hosts are Linux. To this end, Docker administrators must have a solid understanding of how to use and administer Linux.

The most popular method of deploying Docker containers is through the command-line interface, so your administrators will need to be comfortable running commands in Linux.

Container technology

Of course, container administrators will need to have (at least) a fundamental understanding of container technology. There are a lot of moving parts in containers, so having a good grasp of what goes into developing and deploying containerized applications will be a big help for these administrators to get the job done right.

JSON

There are 2 ways to deploy a Docker container: Using the docker command and using docker-compose . The docker command uses all the options and restrictions of a single command. While this method is easier, it is also better suited for more simplistic containers. The second method is to use docker-compose . This command reads all necessary configurations from a Docker Compose file, which is written in JSON.

If you plan to make the most of Docker, you'll want these administrators to be well versed in JSON. One of the most important aspects is proper recoil. Being able to write a well-crafted Docker Compose file takes time. Getting the configuration right can be even more time consuming, especially as configurations become increasingly complex. You could deploy a single container that uses multiple applications, specific networks, and even localized volumes for persistent storage.

Interview Questions

What is a container?

A container is a pre-configured, platform-independent application that contains everything needed (from runtime to environment variables and application stacks) to run on a supported platform.

What is the difference between virtualization and containerization?

Containers provide an isolated environment to run an application, while virtualization provides an entire virtual machine to run a stack of applications.

What are Docker images?

Docker images are read-only templates that contain the necessary set of instructions for creating containers.

What is a Docker file?

A docker file is a manifest that contains all the configuration required to deploy a Docker container.

What is Docker Swarm?

Docker Swarm is the native clustering tool for Docker that turns a pool of Docker hosts into a single virtual host.

What is the lifecycle of a Docker Container?

• Create a container
• Run the container
• Pause the container (optional)
• Resume the container (optional)
• Start the container
• Stop the container
• Restart the container
• Kill the container
• Destroy the container

What is the command to log into a Docker repository?

docker login

What is the command to pull a Docker image from Docker Hub?

docker pull NAME

Where NAME is the name of the image to be extracted.

What is the command to create an NGINX Docker container, named nginx1, that points external port 8080 to internal port 80 of the official NGINX image in detached mode?

docker run –name nginx1 -p 8080:80 -d nginx

Job description

The ideal candidate will work on building, scaling, and monitoring multiple highly complex applications, as well as making our container orchestration cluster highly available. The candidate must be an expert in Docker and containerization technologies.

Responsibilities

• Develop and deploy scalable containers using the Docker engine.
• Cluster Docker nodes and manage multiple Docker Swarms.
• Manage third-party cloud hosting accounts that will host running containers.
• Optimize the performance of all containers.
• Automate container deployment and scaling.
• Review and interpret ongoing business reporting requirements.
• Provide timely scheduled management reports.
• Investigate exceptions relating to asset movements.
• Write reusable, testable, and efficient Docker files.
• Implement security and data protection.
• Integrate data storage solutions.

Skills and qualifications

• Minimum 3 years of experience in DevOps.
• At least 3 years of experience with Docker, containerization, DevOps best practices, distributed applications, deployment architecture, and AWS.
• Exposure to Kubernetes.
• Practical experience hosting and deploying in public cloud (AWS, Azure, Google).
• More than 3 years of practical infrastructure such as code architecture, development and automation.
• AWS certification(s) an advantage
• Experience with Provisioning, VM Provisioning – Virtual Machines
• Experience in managing VMware, VMs
• Experience/strong knowledge with Network Topologies, Network Research,
• Jenkins 2.0, BitBucket, Jira
• Ansible or other automation configuration management system tools
• Scripting and programming using languages ​​such as BASH, Perl, Python, AWK, SED, PHP, Shell
• Linux Systems Administration -: Redhat
• Excellent written and verbal communication and customer service skills
• Excellent analytical and problem-solving skills
• The ability to independently solve complex technical problems in a fast-paced environment.
• Good organizational skills.
• Ability to work as part of a team.
• Attention to the details.
• Understanding the nature of asynchronous programming and its peculiarities and workarounds
• A positive attitude.

Conclusion

If your company is serious about scaling and automating applications, containerization is the best option. And since they will be taking their first steps with containers, they should certainly start with Docker.