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Azure Container Instances.md

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Azure Container Instances

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Contents

Overview

Azure Container Instances (ACI) is a great solution for any scenario that can operate in isolated containers, including simple applications, task automation, and build jobs. Here are some of the benefits:

  • Fast startup: ACI can start containers in Azure in seconds, without the need to provision and manage VMs
  • Container access: ACI enables exposing your container groups directly to the internet with an IP address and a fully qualified domain name (FQDN)
  • Hypervisor-level security: Isolate your application as completely as it would be in a VM
  • Customer data: The ACI service stores the minimum customer data required to ensure your container groups are running as expected
  • Custom sizes: ACI provides optimum utilization by allowing exact specifications of CPU cores and memory
  • Persistent storage: Mount Azure Files shares directly to a container to retrieve and persist state
  • Linux and Windows: Schedule both Windows and Linux containers using the same API.

For scenarios where you need full container orchestration, including service discovery across multiple containers, automatic scaling, and coordinated application upgrades, we recommend Azure Kubernetes Service (AKS).

Container groups

The top-level resource in Azure Container Instances is the container group. A container group is a collection of containers that get scheduled on the same host machine. The containers in a container group share a lifecycle, resources, local network, and storage volumes. It's similar in concept to a pod in Kubernetes.

The following diagram shows an example of a container group that includes multiple containers:

Example container group with two containers, one listening on port 80 and the other listening on port 5000.

This example container group:

  • Is scheduled on a single host machine.
  • Is assigned a DNS name label.
  • Exposes a single public IP address, with one exposed port.
  • Consists of two containers. One container listens on port 80, while the other listens on port 5000.
  • Includes two Azure file shares as volume mounts, and each container mounts one of the shares locally.

Multi-container groups currently support only Linux containers. For Windows containers, Azure Container Instances only supports deployment of a single instance.

Deployment

There are two common ways to deploy a multi-container group: use a Resource Manager template or a YAML file. A Resource Manager template is recommended when you need to deploy additional Azure service resources (for example, an Azure Files share) when you deploy the container instances. Due to the YAML format's more concise nature, a YAML file is recommended when your deployment includes only container instances.

Resource Allocation

Azure Container Instances allocates resources such as CPUs, memory, and optionally GPUs (preview) to a container group by adding the resource requests of the instances in the group. Taking CPU resources as an example, if you create a container group with two instances, each requesting 1 CPU, then the container group is allocated 2 CPUs.

Networking

Container groups share an IP address and a port namespace on that IP address. To enable external clients to reach a container within the group, you must expose the port on the IP address and from the container. Because containers within the group share a port namespace, port mapping isn't supported. Containers within a group can reach each other via localhost on the ports that they have exposed, even if those ports aren't exposed externally on the group's IP address.

Storage

You can specify external volumes to mount within a container group. You can map those volumes into specific paths within the individual containers in a group. Supported volumes include:

  • Azure file share
  • Secret
  • Empty directory
  • Cloned git repo

Common scenarios

Multi-container groups are useful in cases where you want to divide a single functional task into a small number of container images. These images can then be delivered by different teams and have separate resource requirements.

Example usage could include:

  • A container serving a web application and a container pulling the latest content from source control.
  • An application container and a logging container. The logging container collects the logs and metrics output by the main application and writes them to long-term storage.
  • An application container and a monitoring container. The monitoring container periodically makes a request to the application to ensure that it's running and responding correctly, and raises an alert if it's not.
  • A front-end container and a back-end container. The front end might serve a web application, with the back end running a service to retrieve data.

Code - Azure CLI

See Also: Azure CLI

Create a Container

You create a container by providing a name, a Docker image, and an Azure resource group to the az container create command. You will expose the container to the Internet by specifying a DNS name label.

  1. Create resource group:
az group create --name my-resource-group --location eastus
  1. Create Container
  • Create DNS name to expose your container to the internet. The DNS must be unique.
DNS_NAME_LABEL=aci-example-$RANDOM

Run the following az container create command to start a container instance. Be sure to replace the <myLocation> with the region you specified earlier. It will take a few minutes for the operation to complete.

az container create --resource-group my-resource-group \
    --name mycontainer \
    --image mcr.microsoft.com/azuredocs/aci-helloworld \
    --ports 80 \
    --dns-name-label $DNS_NAME_LABEL --location eastus \

In the commands above, $DNS_NAME_LABEL specifies your DNS name. The image name, mcr.microsoft.com/azuredocs/aci-helloworld, refers to a Docker image hosted on Docker Hub that runs a basic Node.js web application.

Verify the container is running

  1. When the az container create command completes, run az container show to check its status.
az container show --resource-group az204-aci-rg \
    --name mycontainer \
    --query "{FQDN:ipAddress.fqdn,ProvisioningState:provisioningState}" \
	--out table \

You see your container's fully qualified domain name (FQDN) and its provisioning state. Here's an example.

FQDN                                    ProvisioningState
--------------------------------------  -------------------
aci-wt.eastus.azurecontainer.io         Succeeded
 Note

If your container is in the **Creating** state, wait a few moments and run the command again until you see the **Succeeded** state.
  1. From a browser, navigate to your container's FQDN to see it running. You may get a warning that the site isn't safe.

Clean up resources

When no longer needed, you can use the az group delete command to remove the resource group, the container registry, and the container images stored there.

az group delete --name az204-aci-rg --no-wait

Appendix: Links

Backlinks:

list from [[Azure Container Instances]] AND -"Changelog"