What is Azure Container Instances?
Azure Container Instances (ACI) is a service for running Linux or Windows containers in Azure without managing virtual machines or an orchestrator. Containers start within seconds and are billed per second based on CPU and memory usage. ACI is suitable for isolated workloads, batch jobs, build agents, and scenarios that do not require full container orchestration like Kubernetes.
Core Features
- Container startup in seconds without VM provisioning, optionally accelerated with standby pools
- Container groups for multi-container scenarios with shared networking and storage
- NGroups for managing multiple container groups with rolling upgrades and multi-availability-zone distribution
- VNET integration for private networking (outbound traffic requires a NAT gateway)
- Confidential containers as a SKU for workloads requiring hardware-based protection of data in use
- Spot containers at reduced prices for interruption-tolerant workloads
- GPU support for compute-intensive Linux workloads (preview)
- Persistent storage via Azure Files mounts plus managed identity support
Typical Use Cases
CI/CD pipelines use ACI for build agents that automatically terminate after the build. Data teams run batch processing as one-time jobs. AKS clusters offload pods to ACI via virtual nodes to add capacity quickly without provisioning VM nodes.
Benefits
- No cluster management or VM infrastructure required
- Per-second billing without a minimum runtime
- Fast path from container image to running workload
- Complements AKS for serverless burst capacity via virtual nodes
Integration with innFactory
As a Microsoft Solutions Partner, innFactory supports you with Azure Container Instances: container migration, integration into CI/CD pipelines, and hybrid architectures with AKS.
Frequently Asked Questions
What is the difference between Container Instances and Container Apps?
Container Instances is optimized for simple, isolated container groups without built-in auto-scaling. Container Apps additionally offers HTTP/event-based scaling, traffic splitting, and Dapr integration, making it better suited for microservices. ACI is best for short-lived or isolated single workloads.
Can I use Azure Container Instances with Kubernetes?
Yes, via virtual nodes, AKS can run pods as container groups in ACI to add capacity quickly without waiting for VM nodes. This allows clusters to scale serverlessly for burst scenarios.
How long can containers run in ACI?
There is no fixed time limit for containers in ACI. Containers can run indefinitely and are billed per second based on CPU and memory usage. For continuous operation, other services are often more cost-effective depending on the workload.
Which container images can I use with ACI?
ACI supports Linux and Windows containers from Azure Container Registry, Docker Hub, or other registries, including private registries via credentials or managed identity. Container images must not exceed a certain size per the provider (see official FAQ).
What are Spot containers and NGroups in ACI?
Spot containers use unused Azure capacity at reduced prices but can be preempted during capacity shortages, making them suitable for interruption-tolerant workloads. NGroups manages multiple related container groups, including rolling upgrades, multi-availability-zone distribution, and load balancing.
Note: All product information on this page has been compiled with care, but is provided without guarantee and may be outdated or incomplete. Cloud services evolve rapidly — features, pricing, SLAs, and availability change frequently. Authoritative and up-to-date information can only be found on the official product page of Azure (official documentation). This page does not represent an offer by Azure.
