Docker is one of the fastest-growing technologies in 2020, and with good reason. Dockeris a piece of software for performing virtualization. Essentially, Docker mimics the environment that an operating system provides. However, it uses containers to make sure these resources stand alone and are isolated from the settings, dependencies, and environment of the host machine. Containerization allows a developer to package up an application with all of the parts it needs, such as libraries and dependencies, and deploy it as one package. This package is then stored as a docker image. You can create Docker images using the following steps:
- Create a Dockerfile in the root directory of the app.
- Much like in GitHub, if you want to prevent unnecessary files from being pushed on your image, you can make a ‘.dockerignore’ file and fill it with ignored files. It is helpful if you are working with node.js and don't want to include the node modules.
- Create docker-compose.yml for defining and running multi-container Docker applications.
- Next, you can build your docker image and execute the ‘docker run’ command to define the container’s resources at runtime.
You might be tempted to think that since Docker uses virtualization, it is a virtual machine. However, virtual machines involve installing an operating system while Docker containers aren’t full installations of operating systems. They just require access to your native OS’s kernel, memory, and other functionality. The Docker container engine works in conjunction with your native OS without needing a full install of the container’s OS. To learn more about Docker and virtual machines, check our blog post - Docker Vs Virtual Machines Explained.
To make the most of these Docker Containers, you can use various tools to achieve unique results. Here are some of the tools and resources for containerized applications that we love!
Vendors have developed container-optimized builds that attempt to balance the capabilities that your teams might need in a Linux distribution with the minimalism that containers demand. Here are a few of the most popular ones to alter the Docker daemon.
Alpine Linuxis a simple distribution that will try to stay out of your way. It uses its package manager called ‘apk’, the OpenRC init system, script-driven setups, and that’s it! That offers a simple, crystal-clear Linux environment without all the noise. Whether it’s building a home PVR, an iSCSI storage controller, a wafer-thin mail server container, or a rock-solid embedded switch, you can optimize the packages you need for your project without altering your workflow.
Canonical, the parent company of Ubuntu Linux, claims that Ubuntu is the most prevalent OS for containers. Within the Ubuntu, distribution is Ubuntu Core, the small, secure release designed for IoT (Internet of Things) devices and containers. The core is designed to allow high performance, a small footprint, and transactional updates, ensuring that updates that fail roll back successfully. Moreover, using Ubuntu Core means you can purchase support from Canonical.
Microsoft Nano Server
Nano Serveris a remotely administered command-line operating system optimized for private clouds and data centers. It is similar to Windows Server in Server Core mode but significantly smaller, has no local logon capability, and only supports 64-bit applications, tools, and agents. It takes up far less disk space, sets up significantly faster, and requires far fewer updates and restarts than Windows Server.
Cluster Management and Deployment
After your team creates container images and passes them around in development comes the hard part: running containers and supporting them in the production environment. That means defining container registries, deploying them to production as a system, and managing collections of servers. The latter includes a collection of servers in the cloud, known as a "cluster."
Cluster management tools manage workloads, including moving instances from one virtual host to another based on load and allocate resources such as CPU and memory. Here are some orchestration tools which can help with that:
While there is no standard for cluster management, the Kubernetes open-source cluster manager, originally developed by Google, is by far the most popular. Supported by Amazon's AWS, Google Cloud Engine (GCE), and Microsoft's Azure Container Service, Kubernetes is relatively portable, which helps prevent vendor lock-in.
Docker Swarm "Classic" allows native clustering for Docker. It turns a pool of Docker hosts into a single, virtual host. You can use the Docker Engine CLI to create a swarm of Docker Engines where you can deploy application services, and you won’t need any additional container orchestration software to create or manage it.
A tool for abstracting computing resources, Apache Mesos, can run both Docker and rkt images side by side in the same cluster. DC/OS is a platform built on Mesos that functions as a data center operating system.
Containers are designed to be interchangeable, like currency. That works exceptionally well for web services and microservices that can scale on demand. Storage and databases, on the other hand, need dedicated locations to house data, or at least a standard interface layer. Organizations that want to move to an all-container infrastructure need storage, and many companies now meet that demand.
The Blockbridge Volume Pluginprovides high-performance storage for container applications with advanced security, mobility, backup, and restore capabilities. With the ‘Managed Docker Plugin’ for Docker 1.13+, installation and lifecycle management is taken care of by Docker natively.
The Portworx Enterprise Storage Platform is your end-to-end storage and data management solution for all your Kubernetes projects, including container-based CaaS, DBaaS, SaaS, and Disaster Recovery initiatives. With Portworx, your apps will benefit from container-granular storage, disaster recovery, data security, multi-cloud migrations, and more.
It is a Docker volume plugin created by Rancherfor managing persistent container volumes. Convoy, an open-source Docker volume driver, can snapshot, backup, and restore Docker volumes anywhere. Create Docker volumes on AWS, supported by all the features and performance of Elastic Block Store. Also, you can take an existing EBS volume and use it to generate a volume attached to a Docker container.
With the Container Runtime Interface (CRI) creation, you have many ways to store virtual machines and communicate through that interface in real-time.
The first and still most popular container technology, Docker's open-source containerization engine, works with most of the products that follow and many other open-source tools.
The first implementation of the Container Runtime Interface, CRI-O, is an incredibly lightweight, open-source reference implementation.
Containerdis available as a daemon for Linux and Windows. It manages the complete container lifecycle of its host system, from image transfer and storage to container execution and supervision, to low-level storage to network attachments and beyond.
Single sign-on, LDAP integration, auditing, intrusion detection and prevention, and vulnerability scanning—all are pain points of organizations moving to containers. Even traditional devices and software can be challenging, if not impossible, to configure on container clusters. Fortunately, a handful of vendors are working to address this need.
Twistlock Security Suite aims to solve the security issues in the container-based application process. It is an end-to-end security solution that detects vulnerabilities by increasing the monitoring layers for the way Docker containers work. Twistlock hardens container images and enforces security policies across an application’s lifecycle.
Clair is an open-source project designed to identify and analyze vulnerabilities in Docker and App Container (appc) application containers. Clair regularly ingests container vulnerability metadata from a customized and configured group of sources to identify threats in container images, including those upstream.
Aqua Security works on any platform to secure container-based applications by providing full-stack security. A purpose-built platform, Aqua Security, allows tight control of your docker environments and processes from the development environment. It is a comprehensive tool that provides full visibility and management.
Flannel is a virtual network that gives each host a subnet to use with container runtimes. Platforms like Google's Kubernetes assume that each container (pod) has a unique, routable IP inside the cluster. The advantage of this model is that it reduces the complexity of mapping ports.
Weaveworks delivers a productive way for developers to connect, observe, and control Docker containers. It creates a flexible virtual network infrastructure that connects containers deployed across multiple hosts. Weaveworks extends container orchestrators’ efficiency like Kubernetes and Docker Swarm and simplifies containers’ management in production.
A highly scalable open-source project, Calico provides a Layer 3 approach to virtual networking, which can support a vast number of virtual machine clusters across countless computing hosts. This tool’s simplified network model design supports the configuration of fine-grained connectivity policies for each of your workloads and allows SDNs to be centrally managed.
Once you've committed to containers, the hardest part will be implementing and supporting them. From conferences to support forums to commercial support, here are the resources you need.
Docker Community Forums
If you want official sites for support on Docker, you can try out the community forums at https://forums.docker.com/.
The largest, most popular online Q&A site for programmers, StackOverflow, offers plenty of information on deploying your applications in containers. It also does so without intrusive ads or insisting you to register to get the information.
Worried about how to migrate your application to containers? Engine Yard makes it simple with predefined templates, detailed documentation, and their rockstar services team, so you can easily containerize your applications without changing the source code.
You can run Docker containers on utility instances through custom chef recipes.
The utility instances use EBS volumes that are backed up by the Engine Yard platform. That makes our Docker support useful for both stateless and stateful containers. For example, Memcache and Redis can save data to the EBS volume. Applications written in any language can be deployed on Engine Yard V5 through the supported use of Docker containers.