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OrlinVasilev merged 1 commit into from
Feb 26, 2026
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docs: clarify proxy cache trust boundary for upstream token-service discovery #706

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7 changes: 6 additions & 1 deletion docs/administration/configure-proxy-cache/_index.md
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Expand Up @@ -38,6 +38,12 @@ The next time a user requests that image, Harbor checks the image's latest manif

As of Harbor v2.1.1, Harbor proxy cache fires a HEAD request to determine whether any layer of a cached image has been updated in the Docker Hub registry. Using this method to check the target registry will not trigger the [Docker Hub rate limiter](https://www.docker.com/blog/scaling-docker-to-serve-millions-more-developers-network-egress/). If any image layer was updated, the proxy cache will pull the new image, which will count towards the Docker Hub rate limiter.

{{< note >}}
Proxy cache follows upstream registry authentication challenges (for example, `WWW-Authenticate: Bearer realm="..."`) to obtain tokens.
The token service endpoint can be different from the registry host (for example, Docker Hub).
Only configure proxy cache endpoints that are within your trust boundary, and use least-privilege credentials for the upstream access account.
{{< /note >}}

## Create Proxy Cache Project

To set up a proxy cache, a Harbor system administrators can create a proxy cache project that connects to a target registry using a registry endpoint.
Expand Down Expand Up @@ -66,4 +72,3 @@ To start using the proxy cache, configure your docker pull commands or pod manif
```bash
> docker pull <harbor_server_name>/<proxy_project_name>/goharbor/harbor-core:dev
```

6 changes: 6 additions & 0 deletions docs/administration/configuring-replication/create-replication-endpoints.md
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Expand Up @@ -47,6 +47,12 @@ You can also use an endpoint in a proxy cache project. Read more about how to [C
If you plan to use this endpoint with a proxy cache project, the access accounts you provide here enables the proxy cache project to pull every image from the target registry that the access account has permission to pull.
{{< /note >}}

{{< note >}}
When an endpoint is used for proxy cache, Harbor may obtain tokens by following the upstream `WWW-Authenticate: Bearer realm="..."` challenge.
The token service can be hosted on a different domain from the registry.
Configure only trusted upstream registries/endpoints and use least-privilege access credentials.
{{< /note >}}

1. Optionally, select the **Verify Remote Cert** check box.

Deselect the check box if the remote registry uses a self-signed or untrusted certificate.
Expand Down