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Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →To dockerize an app and deploy it to Azure Container Instances (ACI) using Docker Hub, package the app in a Docker image, test it locally, push a tagged image to Docker Hub, then tell ACI to pull and run that exact image. The Dockerfile and deployment settings depend on your app’s language, build process, listening port, and access needs, so treat the examples below as a workflow and replace each placeholder with your app’s actual values.
What you are building
A Dockerfile describes how to assemble your application and how it starts. Building it produces an image: the packaged artifact you publish. A container is a running instance of that image. Docker Hub hosts and shares images; ACI runs a selected image as a container in Azure. Microsoft’s Docker container training module walks through creating a Dockerfile, building an image, and running it.
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The flow is: source code → Dockerfile → local image → Docker Hub repository → ACI container. Keep the image name and version tag consistent between the push and deployment steps. ACI also needs to know which port the app listens on, and it needs credentials if the Docker Hub repository is private.
Before you start
- Your application source code and a working understanding of its build and startup process.
- Docker installed and available from a terminal, plus an account on Docker Hub.
- An Azure subscription and Azure CLI installed and signed in. Microsoft’s Azure CLI quickstart for ACI covers creating a resource group and deploying a container.
- The port the app actually listens on, the required runtime configuration, and whether the image repository should be public or private.
Do not assume that a web app listens on a conventional port or that it can run without environment variables, files, or persistent storage. Work out those requirements before building the image.
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Create an application-specific Dockerfile
Place a file named Dockerfile in the appropriate application directory. Select a base image that matches your language and runtime, copy the necessary files, install runtime dependencies, build the app if required, and specify the command that launches it. A generic structure looks like this:
FROM <language-or-runtime-base-image>
WORKDIR /app
COPY <required-files> ./
RUN <install-or-build-command>
EXPOSE <app-listening-port>
CMD ["<startup-executable>", "<startup-argument>"]This is a shape, not a ready-to-run Dockerfile: the base image, copy paths, build command, and startup command must be valid for your application. EXPOSE documents the intended container port; it does not make the app listen on that port. Configure the app itself to bind to the appropriate interface and port for container use, and use the same port in the ACI deployment.
Include only files and dependencies needed to build or run the app. Keep secrets out of the image and source repository; supply sensitive configuration through an appropriate deployment-time mechanism instead. If your app needs persistent data, determine where that data will live rather than assuming it will survive with the container.
Build and test the image locally
From the directory containing the Dockerfile, choose a Docker Hub account and repository name and a specific version tag. In the commands below, replace <dockerhub-user>, <repository>, and <version> with your values:
docker build -t <dockerhub-user>/<repository>:<version> .
docker run --rm -p <host-port>:<app-listening-port> <dockerhub-user>/<repository>:<version>Open the app at http://localhost:<host-port> or call it with an HTTP client. The left side of the -p mapping is the port on your computer; the right side must match the port the app listens on inside the container. If startup fails or the app is unreachable, check the build output, startup command, application logs, and port mapping before pushing.
Use a meaningful version tag rather than relying on latest to identify a deployment. A specific tag makes it clearer which build ACI is intended to run.
Push the tagged image to Docker Hub
Sign in to Docker Hub from the Docker CLI, then push the image using the same account, repository, and tag used in the build:
docker login
docker push <dockerhub-user>/<repository>:<version>Use Docker Hub’s current authentication guidance for your account, especially if it requires a token. Confirm that the repository and tag appear in Docker Hub before deploying. A public image can be pulled without private registry credentials; a private one requires ACI to authenticate to Docker Hub.
Deploy the image to Azure Container Instances
Sign in to Azure CLI if you have not already, then create a resource group in a supported region. Substitute a unique resource-group name and a region appropriate for your workload:
az login
az group create --name <resource-group> --location <azure-region>For a public Docker Hub image, the basic deployment pattern is:
az container create
--resource-group <resource-group>
--name <container-name>
--image <dockerhub-user>/<repository>:<version>
--cpu <cpu-count>
--memory <memory-in-gb>
--ports <app-listening-port>
--dns-name-label <unique-dns-label>This is an Azure CLI pattern, not a set of universal sizing values. Choose CPU and memory for the app, use its real listening port, and choose a DNS label that is available if you want a public endpoint. The DNS label and exposed port make the workload reachable from the internet; leave them out or use a more restricted design when public access is not intended. Microsoft’s ACI CLI quickstart demonstrates the command and its options; its sample values are illustrative, not a sizing recommendation.
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For a private Docker Hub repository
ACI must be able to authenticate when it pulls a private image. Microsoft lists Docker Hub as the registry and docker.io as its login server for private image pulls. Use the Docker Hub username and a suitable token or password with the Azure CLI’s registry credential options, and protect credentials from shell history and logs. See Microsoft’s guidance on managing registry access for container instances and its PowerShell deployment quickstart for registry-related deployment context. Do not include credentials in the image or commit them to source control.
Verify the running container
Wait for provisioning to complete, inspect the container’s state and logs, then make a real request to its endpoint. A successful create command alone does not establish that the application started correctly or that its route works.
az container show
--resource-group <resource-group>
--name <container-name>
--query instanceView.state
az container logs
--resource-group <resource-group>
--name <container-name>If you configured a DNS label, use the fully qualified domain name shown by Azure and the exposed application port as needed, then test the route in a browser or HTTP client. If the container is running but the request fails, check whether the app binds to the expected interface and port, whether the ACI port matches, and whether the app requires configuration that was not supplied. Microsoft’s CLI quickstart includes examples for retrieving logs and cleaning up the deployment.
Choose public access deliberately and clean up
A public Docker Hub repository is simpler for an unauthenticated pull, but its image is publicly available. A private repository limits who can access the image, while requiring working registry credentials at deployment. Separately, an ACI public DNS label and open port make a service reachable over the internet. These are two different access decisions: image visibility does not determine whether the running app is publicly reachable.
When the container is no longer needed, delete it:
az container delete
--resource-group <resource-group>
--name <container-name>Delete the resource group only if it contains no other resources you need. Docker Hub is the registry used in this workflow; Azure Container Registry is another option for Azure-hosted images, but it is not required to deploy an image from Docker Hub.
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