Azure Container Instance (ACI) GatewayTimeout when pulling image from private Nexus repository

Hello @Žák Jiří ,

Creating an Azure Container Instance (ACI) directly from a Nexus repository; instead, the recommended approach is to clone the repository, build the container image locally using Docker, push it to Azure Container Registry (ACR), and then deploy it to ACI via the Azure CLI- https://learn.microsoft.com/en-us/azure/container-instances/container-instances-tutorial-prepare-app

This workflow avoids common operational challenges such as Nexus certificate management, custom ports, DNS dependencies, and private or self-signed CA trust issues, since ACI cannot validate private CA or self-signed TLS certificates and frequently fails image pulls from Nexus. By using ACR with Managed Identity or the admin account, ACI can pull images without additional configuration, while benefiting from zero network hops, no NAT or outbound firewall constraints, and eliminating the need to expose Nexus through public endpoints.

Please let us know if you require any further assistance. We’re happy to help.

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Azure Container Instance (ACI) GatewayTimeout when pulling image from private Nexus repository

Žák Jiří •

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Feb 5, 2026, 1:23 AM

I am trying to deploy an Azure Container Instance (ACI) into an existing Virtual Network (VNET) and subnet. The image is hosted on our private Nexus repository located at pi.test.cz.

While the domain pi.test.cz resolves correctly from an existing Ubuntu ACI within the same network, the creation command fails when I try to create a new instance using image from our nexus repository using the Azure CLI with this command:

az container create --resource-group test-dewc --name aci-test --cpu 1 --memory 1 --os-type Linux --image pi.test.cz/image/test-ci --registry-login-server pi.test.cz --registry-username $NEXUS_USER --registry-password $NEXUS_PASS --vnet vnet-test --subnet default

This fails on:

{

"status": "Failed",

"error": {

"code": "GatewayTimeout",

"message": "The gateway did not receive a response from 'Microsoft.ContainerInstance' within the specified time period."

}

}

I also created Virtual Machine in that VNET with Ubuntu and I am able to pull image from our nexus repository.

Any suggestions what to do ? We think it is internal problem in Azure.

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ACI supports image pulls from ACR and other non-Microsoft container registries such as DockerHub. ACI supports image pulls from ACR and other non-Microsoft OCI compatible container registries such as DockerHub with an endpoint that is publicly exposed to the internet.

https://learn.microsoft.com/en-us/azure/container-instances/container-instances-faq#what-types-of-container-registries-are-compatible-with-aci-