Containerization is still evolving, but the number of organizations adopting containerization techniques has gone up in recent times. While many organizations are aggressively adopting Docker and other container technologies, the downside of these techniques is still in the size of the containers and security concerns.

Currently, Docker images are generally heavy. In an elastic automated environment, where containers are created and destroyed quite frequently, size is still an issue. A larger size indicates more code, and more code means that it is more prone to security vulnerabilities.

The future is definitely in small footprint containers. Docker is working on unikernels, lightweight kernels that can run Docker even on low-powered IoT devices. Unikernels are not full-fledged operating systems, but they provide the basic necessary libraries to support the deployed applications.

The security issues of containers are much discussed and debated. The key security issues are around the user namespace segregation or user ID isolation. If the container is on root, then it can by default gain the root privilege of the host. Using container images from untrusted sources is another security concern. Docker is bridging these gaps as quickly as possible, but there are many organizations that use a combination of VMs and Docker to circumvent some of the security concerns.