Secure Your Docker Container…

Docker has come a long way is consistently striving to build a highly functional, yet a secure product, putting forth the best practices and being highly responsive to any vulnerability or issues.

Since its inception, Docker has seen a significant increase in its adoption year on year. On setting up diligently, without an element of ignorance, Docker becomes a powerful asset you would undoubtedly vouch for, for your IT practices.

The onus of securing your container environment does not only lie on hardening the containers or the servers they eventually run on but must be strategized to take care of every minuscule action right from the pulling of the container image from a registry to when the container is pushed to the production world.

As the containers are quite usually deployed at the DevOps speed as a part of CI/CD framework, it is imperative to get more tasks automated which enhance the efficiency, productivity, auditing/logging and hence the handling of security issues.

Following gives an overview of the security-related best practices you should take care while adopting Docker.

Authentic Docker Image

Many a time, developers put to use the base Docker images rather than re-building from scratch. But downloading these images from untrusted sources can add security vulnerabilities.

It is impervious to, therefore, check the authenticity before downloading the image by taking the following precautions:

  • Using the base image from trusted sources such as the Docker Hub which has images that are scanned and reviewed by the Docker’s Security Scanning Services.
  • Using the base image that is digitally signed by Docker Content Trust which protects against forgery.

Authorized Access

While working in large teams, it is essential to configure role-based access control (RBAC) for your Docker container stack. Large enterprise organization use directory solutions like Active Directory to manage the access and permission for applications across the organization.

It is essential to have a good access management solution for Docker in place that enables the containers to operate with minimal privileges and access required to get the task done which in turn reduces the risk factor.

This helps to take care of the scalability with the growing number of users.

Sensitive information management

According to the Docker Swarm services, secrets are the sensitive piece of data that should not be communicated or stored unencrypted in Dockerfile or application’s source code.

Secrets are sensitive information like the passwords, SSH keys, tokens, TLS certificates, etc. Secrets are encrypted during transit and at rest in a Docker swarm. A secret is only accessible to the services which have been explicitly granted access and only when those services are running.

It is essential to make sure that the secrets should be accessible only to the relevant containers and should not be exposed or stored at the host-level.

Code-level and Application Runtime Security

Docker security begins at the host–level, so it is essential to keep the host operating system updated. Also, the processes running inside the container should have the latest updates by incorporating the best security-related coding practice.

You must mainly ensure that the containers that are installed by the third-party vendors do not download anything and run anything at runtime. Everything a Docker container runs must be declared and included in the static container image.

Namespace and cgroups permissions should be optimally applied for access isolation and to control what each process can modify.

Containers connect with each other across cluster making their communication limiting the visibility to firewalls and networking tools. Leveraging nano-segmentation can be resourceful for limiting blast-radius in case of attacks.

Complete Lifecycle Management

Container security lies on how you handle the container lifecycle which involves the right from the creation, updating, and to the deletion of containers. The containers should be treated as immutable that is instead of changing or updating the running container with updates, creates a new image and tests these containers thoroughly for vulnerabilities and replace the existing containers.

Limiting Resources

Dockers are lightweight processes because you can run more containers than virtual machines. This is beneficial to make optimal use of the host resources. Though it can cause a threat of vulnerabilities like denial of attack which can be handled by limiting the system resources that individual containers can consume through the container framework such as Swarm.

Monitoring Container Activity

Like any other environment, it is essential to constantly actively monitor the user activity around your container ecosystem to identify and fix any malicious or suspicious activities.

Audit logs must be incorporated within the application to record events like when the account was created and activated, for what purpose, when the last password updated and similar actions at the organization level.

Having implemented such audit trails around every container that you create and deploy for your organization will be a good practice to identify a malicious intrusion.


Docker, by design, is built with the best security practice in mind, so security is not an issue in containers. But it is crucial that you never let your guard down and be vigilant.

With more updates and improvement coming up and putting these features into practice will help build secure apps. Leveraging the container security aspects like container images, access and permission rights, container segmentation, secrets and lifecycle management into IT practices can ensure optimized DevOps process with minimal security issues.

If you are completely new to Docker then you may be interested in this online course.