2 minute read

Context

Package installation failures that look like “network issues” are often trust failures.

When GitLab rotates its repository signing keys, systems that rely on outdated keys will fail to:

  • update packages
  • install new versions
  • verify package integrity

Understanding how to fetch and manage repository signing keys is essential for maintaining secure, automated systems.

Why Repository Signing Keys Matter

APT repositories are secured using GPG keys.

These keys allow your system to:

  • verify the authenticity of packages
  • ensure packages haven’t been tampered with
  • establish trust between your host and the repository

If the key is missing, expired, or rotated, APT will refuse to proceed—and that’s a good thing.

The Modern APT Key Model

The traditional apt-key command is deprecated.

Modern best practice is to:

  • store keys as individual files
  • reference them explicitly per repository
  • avoid a global trust store

This reduces blast radius and improves auditability.

Fetching the Latest GitLab Signing Key

Download the key

curl -fsSL https://packages.gitlab.com/gitlab/gitlab-ce/gpgkey \
  | gpg --dearmor \
  | sudo tee /usr/share/keyrings/gitlab-archive-keyring.gpg > /dev/null

This:

  • fetches the current signing key
  • converts it to a binary keyring
  • stores it in a dedicated location

Registering the GitLab Repository

Reference the key explicitly in your APT source:

echo "deb [signed-by=/usr/share/keyrings/gitlab-archive-keyring.gpg] \
https://packages.gitlab.com/gitlab/gitlab-ce/ubuntu/ \
$(lsb_release -cs) main" \
| sudo tee /etc/apt/sources.list.d/gitlab.list

This binds trust for GitLab packages only to this repository.

Updating Package Metadata

After installing the key and repository:

sudo apt update

If the key is correct, APT should update cleanly without warnings.

Common Failure Modes

Expired or Rotated Keys

Symptoms:

  • NO_PUBKEY errors
  • signature verification failures

Solution:

  • re-fetch the latest key
  • replace the existing keyring file

Leftover Legacy Keys

Older systems may still trust keys added via apt-key.

Problems include:

  • unclear trust boundaries
  • difficulty auditing key usage
  • unexpected behavior after rotations

Clean up unused legacy keys when possible.

Automating Key Management

In automated environments:

  • fetch keys as part of bootstrap scripts
  • avoid copying keys between systems
  • prefer idempotent configuration management
  • monitor package install failures proactively

Key management should be boring and repeatable.

Security Considerations

  • Always fetch keys over HTTPS
  • Store keys with root-only permissions
  • Avoid global trust when possible
  • Treat key updates as security events

Repository keys are part of your supply chain security posture.

Takeaways

  • Package signing keys establish trust
  • Key rotation is normal and expected
  • Modern APT workflows favor per-repo keyrings
  • Explicit trust boundaries reduce risk
  • Broken package installs often signal trust issues

Fetching and managing signing keys correctly keeps automation working—and protects you from installing what you didn’t intend.

You May Also Enjoy