goharbor/harbor

Azure ACR replication adapter does not support chunked/resumable blob uploads (413 error)

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#23015 opened on Mar 19, 2026

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Description

Description

Harbor's azure-acr replication adapter pushes blobs as single monolithic PUT requests. Azure ACR enforces a request body size limit and rejects uploads above ~20MB with HTTP 413. This makes push-based replication to Azure ACR unusable for any image with layers larger than ~20MB.

This is a continuation of #21640 which was closed without resolution.

Environment

  • Harbor version: v2.16.0 (Helm, Kubernetes)
  • Replication mode: Push-based, event-based trigger
  • Destination: Azure ACR Basic tier (*.azurecr.io)

Steps to reproduce

  1. Create a push-based replication rule targeting an Azure ACR registry
  2. Push an image with any blob layer > ~20MB
  3. Replication fails with 413

Error log [ERROR] failed to pushing the blob sha256:77dab3318d..., size 29154834: http status code: 413, body: 413 Request Entity Too Large - AzureContainerRegistry

What we tried

  • Set REPLICATION_CHUNK_SIZE=5242880 (5MB) as env var on jobservice pod — confirmed present but has no effect on the azure-acr adapter
  • Per the documentation: "Copy by chunk has not been verified officially between harbor and other type registries"
  • Docker CLI push to the same ACR endpoint works fine (uses OCI-compliant chunked uploads)

Expected behavior The azure-acr replication adapter should use chunked/resumable uploads (as per the OCI distribution spec) when pushing blobs, similar to how the Docker client handles it.

Contributor guide

Tech stack
go
Domain
backendcloud
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Go programmingOCI distribution spec basicsHarbor replication adapter architectureAzure ACR API
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Investigate the existing Azure ACR adapter implementation in the Harbor codebase, likely under src/pkg/reg/adapter/azure acr. Review the OCI distribution spec for chunked upload (POST /v2/<name>/blobs/uploads/, then PATCH with content ranges). Look at how other adapters (e.g., Docker Hub or GCR) implement chunked uploads. Consider modifying the PushBlob method in the Azure adapter to use chunked requests, respecting the REPLICATION CHUNK SIZE config. Test with a registry that enforces size limits.