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FAQ – Docker Repository

Frequently asked questions about TUKE Harbor Docker Repository.

Access and Login

Do I need special permission to use the repository?

No. Every TUKE student and staff member with a valid TUKE ID has automatic access.

Can I log in from outside the university?

Yes. The service is available without VPN, but we recommend VPN for better security and speed.

How do I know if I'm logged in? 
cat ~/.docker/config.json | grep repository.cloud.tuke.sk

If you see an entry, you are logged in.

Projects and Organization

How do I create a new project in Harbor?
  1. Log in to Harbor web UI
  2. Click New Project
  3. Enter project name (lowercase, no spaces)
  4. Select visibility (Private/Public)
  5. Click OK
Can I have multiple projects?

Yes, you can create an unlimited number of projects.

What is the difference between Private and Public project?
Type Visibility Pull without login
Private Authorized users only No
Public Anyone Yes
Can I share a project with other users?

Yes. In project settings under Members section, add users:

Role Permissions
Guest Read only
Developer Push/Pull
Master Full management

Images and Storage

What is the maximum image size?

There is no hard limit set. We recommend optimizing images and keeping them under 5 GB.

How much storage do I have available?

Currently, no quota limit is set. Please use the space responsibly.

How long are images kept?

Images are kept indefinitely, unless you delete them yourself.

Can I upload an old version of a Docker image?

Yes, Harbor supports all versions of Docker image format.

Push and Pull

Why did my push command fail?

Most common reasons:

Problem Solution
Not logged in docker login repository.cloud.tuke.sk
Project doesn't exist Create it in Harbor web UI
No permissions Check access permissions
Incorrect name format repository.cloud.tuke.sk/<project>/<image>:<tag>
How many times can I download an image?

Unlimited. Unlike Docker Hub, there are no rate limits.

Why is pull/push slow?

If you are outside the TUKE network, connect via VPN. Within the university network, transfer is fast.

Can I download images without login?

Only from Public projects. For Private projects, login is required.

Security

Is my Docker image secure?

Harbor automatically scans images for known vulnerabilities. You can see scan results in Harbor web UI.

How can I secure my project?
  1. Set project as Private
  2. Use Robot accounts for automation
  3. Regularly update base images
  4. Check vulnerability scans
Can I use the repository for commercial projects?

The repository is intended for academic and research purposes. For commercial projects, contact IT support.

CI/CD and Automation

How do I use the repository in GitLab CI?

Create CI/CD variables:

  • HARBOR_USER – TUKE ID
  • HARBOR_PASSWORD – password (protected + masked)
before_script:
  - docker login -u $HARBOR_USER -p $HARBOR_PASSWORD repository.cloud.tuke.sk
What is a Robot Account and when should I use it?

Robot Account is a special account for automated systems (CI/CD, scripts).

Best practice

Use Robot Account instead of personal login credentials in pipelines.

Can I integrate the repository with GitHub Actions?

Yes. Add credentials to GitHub Secrets and use docker/login-action:

- uses: docker/login-action@v2
  with:
    registry: repository.cloud.tuke.sk
    username: ${{ secrets.HARBOR_USERNAME }}
    password: ${{ secrets.HARBOR_PASSWORD }}

Technical Problems

unauthorized: authentication required

Log in again:

docker logout repository.cloud.tuke.sk
docker login repository.cloud.tuke.sk
denied: requested access to the resource is denied

Check:

  • Does the project exist in Harbor?
  • Do you have permissions to write to the project?
  • Is the image name correct?
x509: certificate signed by unknown authority

Add TUKE CA certificate to Docker:

sudo mkdir -p /etc/docker/certs.d/repository.cloud.tuke.sk
# Contact support to obtain CA certificate
Docker daemon is not running 
# Linux
sudo systemctl start docker

# macOS/Windows
# Launch Docker Desktop application
How do I delete all local images from repository? 
docker images | grep repository.cloud.tuke.sk | awk '{print $1":"$2}' | xargs docker rmi

Helm Charts

Does Harbor support Helm charts?

Yes, Harbor supports storing Helm charts. Use Harbor as a Helm repository.

How do I upload a Helm chart? 
helm registry login repository.cloud.tuke.sk
helm push my-chart.tgz oci://repository.cloud.tuke.sk/my-project

Support

Where can I report an issue?

vcloud@helpdesk.tuke.sk

When reporting, include:

  • Time of problem
  • Command that failed
  • Error message
  • Screenshot (if relevant)
Is there documentation for Harbor?

Yes, official Harbor documentation:

goharbor.io/docs

Can I get training on using Docker Repository?

Contact the Cloud team for information about workshops and training.

  • Login

    Logging in to repository.

    Guide

  • Working with images

    Push and pull Docker images.

    Guide