[flux/v2.8.x] auth/azure: use ACR-scoped token for registry authentication#1139
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matheuscscp merged 1 commit intoflux/v2.8.xfrom Feb 26, 2026
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[flux/v2.8.x] auth/azure: use ACR-scoped token for registry authentication#1139matheuscscp merged 1 commit intoflux/v2.8.xfrom
matheuscscp merged 1 commit intoflux/v2.8.xfrom
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The access token scope for Azure Container Registry was derived from cloud.ResourceManager, which resolves to the ARM endpoint (e.g. https://management.azure.com/.default\). This is an ARM-scoped token, not an ACR-scoped one. Microsoft recommends disabling ARM audience authentication on ACR registries for enhanced security and least-privilege compliance. When organizations follow this recommendation and disable authentication-as-arm, Flux's ARM-scoped tokens are rejected, causing unauthorized errors for workload identity users. Use azcontainerregistry.ServiceName audience instead, which resolves to https://containerregistry.azure.net/.default -- the correct ACR scope as documented by Microsoft: https://learn.microsoft.com/en-us/azure/container-registry/container-registry-disable-authentication-as-arm Signed-off-by: Lukáš Kubín <lukas.kubin@gmail.com> (cherry picked from commit 68b8866)
matheuscscp
approved these changes
Feb 26, 2026
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Automated backport to
flux/v2.8.x, triggered by a label in #1130.