Containers are considered to be a standard way of deploying these microservices to the cloud. Containers are better than virtual machines in almost all ways except security, which may be the main barrier to their widespread adoption.

This article will provide a better understanding of container security and available techniques to secure them.

A Linux container can be defined as a process or a set of processes running in the userspace that is/are isolated from the rest of the system by different kernel tools.

Containers are great alternatives to virtual machines (VMs). Even though containers and virtual machines provide the same isolation benefits, they differ in the way that containers provide operating system virtualization instead of hardware. This makes them lightweight, faster to start, and consumes less memory.

As multiple containers share the same kernel, the solution is less secure than the VMs, where they have their copies of OS, libraries, dedicated resources, and applications. That makes VM excellently secure but because of their high storage size and reduced performance, it creates a limitation on the total number of VMs which can be run simultaneously on a server. Further VMs take a lot of time to boot.

The introduction of microservice architecture has changed the way of developing software. Microservices allow the development of software in small self-contained independent services. This makes the application easier to scale and provides agility.

If a part of the software needs to be rewritten it can easily be done by changing only that part of the code without interrupting any other service, which wasn't possible with the monolithic kernel.

1) Linux Kernel Features

a. Namespaces

Namespaces ensure the isolation of resources for processes running in a container to that of others. They partition the kernel resources for different processes. One set of processes in a separate namespace will see one set of resources while another set of processes will see another. Processes in different see different process IDs, hostnames, user IDs, file names, names for network access, and some interprocess communication. Hence, each file system namespace has its private mount table and root directory.