Linux Containers

A Dockerfile is a script that automatically creates containers on the Docker platform. A Dockerfile is basically a text document that contains all the commands a user could call on the command line to assemble an image. The Docker platform runs natively on Linux and allows developers to build and run containers, self-contained applications or systems with no dependencies on the underlying infrastructure. Built upon the resource-isolation features of the Linux kernel, Docker helps developers and system administrators port applications across different systems and machines by running them inside containers.

Docker containers, created by Dockerfiles, can run on any Linux server. Container environments for applications are created using Docker images, which can be built either by executing commands manually or automatically through Dockerfiles. Linux and Windows programs can run inside Docker containers. Using Dockerfiles, developers can create an automated container build that executes several command-line instructions in succession, step by step. Docker containerization is essentially operating-system-level virtualization. Multiple independent containers may run within a single Linux instance without the startup overhead of virtual machines.

Dockerfiles enable greater flexibility and portability of business applications. IT organizations use Dockerfiles to package applications and their dependencies in a virtual container that can run on premises, in public or private clouds, or on bare metal. Such containers allow multiple applications, worker tasks and other processes to run autonomously on a single physical machine or across multiple virtual machines. Kubernetes is an open source system for automatically managing and orchestrating containerized applications created by Dockerfiles.

Linux Dockerfile is a script that automatically creates Linux containers on the Docker platform. A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image. The Docker platform runs natively on Linux and allows developers to build and run containers, self-contained Linux applications or systems with no dependencies on the underlying infrastructure. Built upon the resource-isolation features of the Linux kernel, Docker helps developers and system administrators port applications across different systems and machines by running them inside containers.

Docker containers, created by Linux Dockerfiles, can run on any Linux server. Linux container environments for applications are created using Docker images, which can be built either by executing commands manually or automatically through Linux Dockerfiles. Using Dockerfiles, developers can create an automated container build that executes several command-line instructions in succession, step by step. Docker containerization is essentially operating-system-level virtualization. Multiple independent containers may run within a single Linux instance without the startup overhead of virtual machines.

Linux Dockerfiles enable greater flexibility and portability of business applications. IT organizations use Linux Dockerfiles to package applications and their dependencies in a virtual container that can run on premises, in public or private clouds, or on bare metal. Such containers allow multiple applications, worker tasks and other processes to run autonomously on a single physical machine or across multiple virtual machines. Kubernetes is an open source system for automatically managing and orchestrating containerized applications created by Linux Dockerfiles.

Containerization is an application or system distribution method that isolates the application or system and its dependencies from the underlying infrastructure. It is an OS-level virtualization that allows users to deploy and run distributed applications or systems in containers without launching an entire virtual machine for each app. Application containers include all of the runtime components – such as configuration files, binaries and libraries – needed to run the app. Multiple containers can run on a single host and access the same OS kernel via APIs. System containers, also called infrastructure containers, include the host operating system, application libraries and execution code. System containers can host application containers. Containers work on bare-metal systems, cloud instances and virtual machines, across Linux and some Windows and Mac OSes. A host machine could have multiple OSes supporting multiple containers – all sharing the same physical resources.

Application Containerization vs. Virtualization

Application containerization is like a lightweight alternative to full machine virtualization. It involves encapsulating an application in a container with its own operating environment so the application can run on any physical or virtual machine without dependency worries. Each container operates independently of others and uses minimal resources from the host OS. Containers create a safe space for app code to consume host resources without depending on (or conflicting with) other applications using the same OS. Application containers consume fewer resources than virtual machines because containers share resources without a full operating system under each app. Containers can scale up microservices to meet rising demand for an application component and distribute the load.

Docker is an open-source-distribution operating system level virtualized containerization platform with a light-weight application engine to run, build and distribute applications in Docker containers that run nearly anywhere. With Docker, users can manage your infrastructure in the same ways they manage their applications. Developers build container images from Dockerfiles and distribute container images from Docker registries. Docker containers, as part of Docker, are portable and light-weight alternative to virtual machines and eliminate the waste of resources and longer boot times common with the virtual-machine approach. Users take advantage of Docker’s methodologies for shipping, testing, and deploying code quickly, to significantly reduce the delay between writing code and pushing it to production.

Enterprises use containerization to save development time, speed application deployment, optimize existing resources and improve IT flexibility. Containerization allows applications to run reliably and predictably when moved from one computing environment to another, increasing portability. Compared to traditional virtualization and physical application hosting, containerization increases IT efficiency for memory, CPU and storage. Without the overhead required by VMs, many more application containers can be supported on the same infrastructure. Cloud providers offer Containers-as-a-Service (CaaS) for users to manage and deploy containers, Linux applications and clusters through container-based virtualization.