At this point in our Docker Tutorial Series, we have learned how to get Docker installed, run some Nginx containers, tested out MongoDB in a container, spun up more than one container, learned about Docker networking, DNS, images, volumes, and much more. You may have noticed that when using the Docker command-line interface, the commands can be somewhat verbose and require a lot of memorization of what commands to run to accomplish all of the prior mentioned tasks.…
Let’s take a look at Bind Mounting in Docker and how persistent data works with those mounts. Bind Mounts are a little different than Docker Volumes, however the syntax to use them is quite similar. Bind Mounts are really cool since they allow local development with files on your host to update in real-time in a container. Technically, a Bind Mount is a mapping of the host files or directories into the container’s files or directories.…
Docker has a feature known as Volumes, that allow developers to persist data in use with containers. They are entirely managed by the Docker Engine making them seamless to the end-user. Docker volumes are a very important and useful concept and in this tutorial, we’ll learn all about Docker volumes, how to create volumes, how to list volumes, and how to delete volumes. We’ll also see how to share a volume among containers by spinning up several containers which all make use of the same volume for data sharing.…
In the earlier Docker articles, we were able to build images and get them running as containers manually. In this tutorial, we will explore how to take this a step further by building images with code. This is where the Dockerfile comes into play. Dockerfiles are small programs that describe how to assemble a Docker image. You can run these small programs using the docker build command.…
DNS Round Robin is the concept that you can have two different hosts with DNS Aliases that respond to the same DNS Name. Where might you find something like this? Consider a service like Instagram. They need more than one server to provide their service, yet users always go to the same Instagram.com domain to use the service. One name, many servers providing the service. In addition to load balancing and server scaling, DNS Round Robin is another technique big companies can use to ensure 24/7/365 uptime.…
This tutorial will explore learning about and testing DNS in Docker. DNS works a little differently depending on if you are using custom or default networks in your environment. Good working DNS is important with containers since you can’t rely on IP addresses in containers because containers are very dynamic. Containers tend to be ephemeral and changing. That is to say, they get launched, torn down, and moved frequently across environments.…
Docker makes it fairly easy to set up virtual networking in a local environment. In fact, in using Docker to this point, we haven’t had the need to tinker with any network settings as typically the network portion of Docker “Just Works”. In other words, the defaults provided are common to work with but you can change any of the default options with regard to networks under the hood.…
At this point, we are pretty familiar with getting containers running in Docker and how to monitor them from the cli or Docker desktop. Now we want to look at how to connect to a docker container while it is running. Connecting to a docker container is similar to how you would SSH into a remote machine to perform administrative tasks. With Docker, you don’t actually need SSH, as there are commands built into Docker that allow you to connect to a shell of running containers easily.…