100 Days of Cloud – Day 85: Security for Azure Containers

Its Day 85 of my 100 Days of Cloud journey, and in todays post I’m looking at the options for Container Security in Azure.

Image Credit: Docker Saigon Github

We looked at an overview of Containers on Day 81, how they work like a virtual machines in that they utilize the underlying resources offered by the Container Host, but instead of packaging your code with an Operating System, each container only contains the code and dependencies needed to run the application and runs as a process inside the OS Kernel. This means that containers are smaller and more portable, and much faster to deploy and run.

We need to secure Containers in the same way as we would any other services running on the Public Cloud. Lets take a look at the different options that are available to us for securing Containers.

Use a Private registry

Containers are built from images that are stored in either public repositories such as Docker Hub, a private registry such as Docker Trusted Registry, which can be installed on-premises or in a virtual private cloud, or a cloud-based private registry such as Azure Container Registry.

Like all software that is publicly available on the internet, a publicly available container image does not guarantee security. Container images consist of multiple software layers, and each software layer might have vulnerabilities.

To help reduce the threat of attacks, you should store and retrieve images from a private registry, such as Azure Container Registry or Docker Trusted Registry. In addition to providing a managed private registry, Azure Container Registry supports service principal-based authentication through Azure Active Directory for basic authentication flows. This authentication includes role-based access for read-only (pull), write (push), and other permissions.

Ensure that only approved images are used in your environment

Allow only approved container images. Have tools and processes in place to monitor for and prevent the use of unapproved container images. One option is to control the flow of container images into your development environment. For example, you only allow a single approved Linux distribution as a base image in order to minimize the surface for potential attacks.

Another option is to utilize Azure Container Registry support for Docker’s content trust model, which allows image publishers to sign images that are pushed to a registry, and image consumers to pull only signed images.

Monitoring and Scanning Images

Use solutions that have the ability to scan container images in a private registry and identify potential vulnerabilities. Azure Container Registry optionally integrates with Microsoft Defender for Cloud to automatically scan all Linux images pushed to a registry to detect image vulnerabilities, classify them, and provide remediation guidance.


Credential management is one of the most basic tyes of security. Because containers can spread across several clusters and Azure regions, you need to ensure that you have secure credentials required for logins or API access, such as passwords or tokens.

Using tools such as TLS encryption for secrets data in transit, least-privilege Azure role-based access control (Azure RBAC), and Azure Key Vault to securely store encryption keys and secrets (such as certificates, connection strings, and passwords) for containerized applications.

Removing unneeded privileges from Containers

You can also minimize the potential attack surface by removing any unused or unnecessary processes or privileges from the container runtime. Privileged containers run as root. If a malicious user or workload escapes in a privileged container, the container will then run as root on that system.

Enable Auditing Logging for all Container administrative user access

Use native Azure Solutions to maintain an accurate audit trail of administrative access to your container ecosystem. These logs might be necessary for auditing purposes and will be useful as forensic evidence after any security incident. Azure solutions include:

  • Integration of Azure Kubernetes Service with Microsoft Defender for Cloud to monitor the security configuration of the cluster environment and generate security recommendations
  • Azure Container Monitoring solution
  • Resource logs for Azure Container Instances and Azure Container Registry


So thats a brief overview of how we can secure containers running in Azure and ensure that we are only using approved images that have been scanned for vulnerabilities.

Hope you enjoyed this post, until next time!

100 Days of Cloud – Day 82: Options for Managing Containers in Azure

Its Day 82 of my 100 Days of Cloud journey, and in todays post I’m going to look at options for managing Containers in Azure.

In the last post, we looked at the comparison between Bare Metal or Physical Servers, Virtual Servers and Containers and the pros and cons of each.

We also introducted Docker, which is the best known method of managing containers using the Docker Engine and built-in Docker CLI for command management.

The one thing we didn’t show was how to install Docker or use any of the commands to manage our containers. This is because I’ve previously blogged about this and you can find all of the details as part of my series about Monitoring with Grafana and InfluxDB using Docker Containers. Part 1 shows how you can create your Docker Host running on an Ubuntu Server VM (this could also run on a Bare Metal Physical Server), and Part 2 shows the setup and configuration of Docker Containers that have been pulled from Docker Hub. So head over there and check that out, but don’t forget to come back here!

Docker Context

By default when running any Docker commands from the CLI, Docker automatically assumes that you wish to use the local Docker Host for storing and running your containers. However, you can manage multiple Docker or Kubernetes hosts or nodes by specifying contexts. A single Docker CLI can have multiple contexts. Each context contains all of the endpoint and security information required to manage a different cluster or node. The docker context command makes it easy to configure these contexts and switch between them.

In short, this means that you can manage container instances that are installed on multiple hosts and/or multiple cloud providers from a single Docker CLI.

Let take a look at the different options for managing containers in Azure.

The Docker CLI Method

In order to use containers in Azure using Docker, we first need to log on to Azure using the docker login azure command, which will prompt us for Azure credentials. Once entered, this will return “login succeeded”:

We then need to create a context by running the docker context create aci command. This will associate Docker with an Azure subscription and resource group that you can use to create and manage container instances. So we would run docker context create aci myacicontext to create a context called myacicontext.

This will select your Azure subscription ID, then prompt to select an existing resource group or create a new resource group. If you choose a new resource group, it’s created with a system-generated name. Like all Azure resources, Azure container instances must be deployed into a resource group

Once thats completed, we then run docker context use myacicontext – this ensures that any subsequent commands will run in this context. We can now use docker run to deploy containers into our Azure resource group and manage these using the Azure CLI. So lets run the following command to deploy a quickstart container runing Node.js that will give us a static website:

docker run -p 80:80 mcr.microsoft.com/azuredocs/aci-helloworld

We can now run docker ps to see the running container and get the Public IP that we can use to browse to it:

And if we log onto the Portal, we can see our running container:

So as we’ve always done, lets remember to remove the container by running docker stop sweet-chatterjee, and then docker rm sweet-chatterjee. These commands stops and deletes the Azure Container Instance:

Finally, run docker ps to ensure the container has stopped and is no longer running.

The Azure Portal Method

There are multiple ways to create and manage containers natively in Azure. We’ll look at the portal method in this post, and reference the remaining options at the end of the page.

To create the container, log on to the Portal and select Container Instances from the Marketplace:

Once we select create, we are brought into the now familiar screen for creating resources in Azure:

One important thing to note on this screen is the “Image Source” option – we can select container images from either:

  • The quickstarts that are available in Azure.
  • Images stored in your Azure Container Registry.
  • Other registry – this can be Docker or other public or private container registry.

On the “Networking” screen, we need to specify a public DNS name for our container, and also the ports we wish to expose across the Public Internet

And once thats done, we click “Review and Create” to deploy our container:

Once thats done, we can see the FQDN or Public IP that we can use to browse to the container:

As always, make sure to stop and delete the container instance once finished if you are running these in a test environment.

There are a total of four other options in Azuire for creating and managing containers:


So thats a look at how we can create and manage Azure Container Instances using both Docker CLI and the wide range of options available in Azure.

Azure Container Instances is a great solution for any scenario that can operate in isolated containers, including simple applications, task automation, and build jobs. You can find all of the documentation on Azure Container Instances here.

Hope you enjoyed this post, until next time!