Azure Container Instances (ACI) provides the fastest and simplest way to run containers in Azure without managing virtual machines or adopting higher-level orchestration services. ACI is ideal for scenarios requiring isolated containers, simple applications, task automation, and build jobs.
**Key …Azure Container Instances (ACI) provides the fastest and simplest way to run containers in Azure without managing virtual machines or adopting higher-level orchestration services. ACI is ideal for scenarios requiring isolated containers, simple applications, task automation, and build jobs.
**Key Features:**
1. **Fast Startup**: Containers can start in seconds, making ACI perfect for burst workloads and quick scaling scenarios.
2. **Per-Second Billing**: You pay only for the resources consumed while your container runs, calculated per second based on vCPU and memory allocation.
3. **Custom Sizing**: Specify exact CPU cores and memory requirements, ensuring you only pay for what you need.
4. **Persistent Storage**: Mount Azure Files shares to containers for persistent data storage across container restarts.
5. **Linux and Windows Support**: Run both Linux and Windows containers using the same API.
**Container Groups:**
Multiple containers can be deployed together in a container group, sharing the same host machine, local network, storage, and lifecycle. This is similar to a pod in Kubernetes.
**Deployment Methods:**
- Azure CLI using 'az container create'
- Azure Portal
- ARM templates or Bicep for multi-container deployments
- YAML files for container group definitions
**Common CLI Example:**
az container create --resource-group myRG --name mycontainer --image mcr.microsoft.com/azuredocs/aci-helloworld --ports 80 --dns-name-label myapp
**Restart Policies:**
- Always (default): Container always restarts
- Never: Container runs once only
- OnFailure: Restarts only on failure
**Environment Variables and Secure Values:**
Pass configuration through environment variables, with support for secure values that remain hidden in container properties.
**Networking:**
Containers receive public IP addresses and fully qualified domain names (FQDN), or can be deployed into virtual networks for private connectivity.
ACI excels for batch processing, CI/CD build agents, and microservices testing scenarios.
Run Containers by Using Azure Container Instances
Why It Is Important
Azure Container Instances (ACI) is a critical service for the AZ-204 exam because it represents the fastest and simplest way to run containers in Azure. Understanding ACI demonstrates your ability to deploy containerized applications efficiently, which is essential for modern cloud development. Microsoft emphasizes serverless container solutions, making this a frequently tested topic.
What Is Azure Container Instances?
Azure Container Instances is a serverless container service that allows you to run Docker containers on-demand in a managed Azure environment. Key characteristics include:
• No VM management required - You don't need to provision or manage virtual machines • Per-second billing - Pay only for the resources you consume • Fast startup times - Containers can start in seconds • Support for both Linux and Windows containers • Public IP connectivity and DNS name labels • Persistent storage via Azure Files
How It Works
Container Groups: ACI uses the concept of container groups, which are collections of containers scheduled on the same host machine. Containers in a group share lifecycle, resources, local network, and storage volumes.
Deployment Options: • Azure CLI using az container create • Azure Portal • ARM templates • YAML files • Docker CLI with ACI context
Key Configuration Parameters: • --image: Specifies the container image • --cpu: CPU cores allocation (default 1) • --memory: Memory in GB (default 1.5) • --ports: Ports to expose • --dns-name-label: DNS name for public access • --restart-policy: Always, OnFailure, or Never • --environment-variables: Set environment variables • --secure-environment-variables: For sensitive data
Restart Policies: • Always: Default, continuously running containers • OnFailure: Restarts only on failure, ideal for batch jobs • Never: Runs once and stops
Common Use Cases
• Simple web applications and APIs • Batch processing and task automation • CI/CD build agents • Event-driven processing • Dev/test environments
Exam Tips: Answering Questions on Azure Container Instances
1. Know when to choose ACI over AKS: ACI is best for simple, isolated containers with quick startup needs. Choose AKS for complex orchestration requirements.
2. Understand restart policies: Questions often test your knowledge of which restart policy to use. Remember OnFailure for batch jobs and Always for long-running services.
3. Remember the YAML deployment format: Be familiar with YAML structure for deploying container groups with multiple containers.
4. Secure environment variables: When questions mention sensitive data like connection strings or passwords, the answer involves --secure-environment-variables.
5. Container groups share resources: If a question describes multiple containers needing to communicate via localhost, container groups is the answer.
6. Mounting Azure Files: Know that ACI supports persistent storage through Azure Files shares mounted as volumes.
7. Virtual network deployment: ACI can be deployed into a virtual network for private connectivity scenarios.
8. GPU support: Remember that ACI supports GPU resources for compute-intensive workloads on Linux containers.
9. Managed identity: ACI supports both system-assigned and user-assigned managed identities for secure access to Azure resources.
10. Resource limits: Be aware that ACI has limits on CPU (4 cores) and memory (16 GB) per container group in most regions.