Docs
Start Building for Free
CircleCI.comAcademyBlogCommunitySupport

Add additional SSH keys to CircleCI

2 months ago2 min read
Cloud
Server v4.x
Server v3.x
On This Page

If deploying to your servers requires SSH access, you will need to add SSH keys to CircleCI.

Overview

If you are looking to set up an SSH key in order to check out code from GitHub or Bitbucket, refer to the GitHub or Bitbucket integration pages.

If you are using GitLab as your VCS, or if you need additional SSH keys to access other services, follow the steps below for the version of CircleCI you are using to add an SSH key to your project.

You may need to add the public key to ~/.ssh/authorized_keys in order to add SSH keys.

Steps to add additional SSH keys

Since CircleCI cannot decrypt SSH keys, every new key must have an empty passphrase. The below examples are for macOS. See GitHub or Bitbucket documentation for additional details on creating SSH keys.

  1. In a terminal, generate the key with ssh-keygen -t ed25519 -C "your_email@example.com". See Secure Shell documentation for additional details.

  2. In the CircleCI application, go to your project’s settings by clicking the Project Settings button (top-right on the Pipelines page of the project).

  3. On the Project Settings page, click on SSH Keys.

  4. Scroll down to the Additional SSH Keys section.

  5. Click the Add SSH Key button.

  6. In the Hostname field, enter the key’s associated host (for example, git.heroku.com). If you do not specify a hostname, the key will be used for all hosts.

  7. In the Private Key field, paste the SSH key you are adding.

  8. Click the Add SSH Key button.

Add SSH Keys to a Job

Even though all CircleCI jobs use ssh-agent to automatically sign all added SSH keys, you must use the add_ssh_keys key to actually add keys to a container.

To add a set of SSH keys to a container, use the add_ssh_keys special step within the appropriate job in your configuration file.

For a self-hosted runner, ensure that you have an ssh-agent on your system to successfully use the add_ssh_keys step. The SSH key is written to $HOME/.ssh/id_rsa_<fingerprint>, where $HOME is the home directory of the user configured to execute jobs, and <fingerprint> is the fingerprint of the key. A host entry is also appended to $HOME/.ssh/config, along with a relevant IdentityFile option to use the key.

version: 2.1
jobs:
  deploy-job:
    steps:
      - add_ssh_keys:
          fingerprints:
            - "SO:ME:FIN:G:ER:PR:IN:T"

All fingerprints in the fingerprints list must correspond to keys that have been added through the CircleCI application. Fingerprints in CircleCI environment variables will fail.

Adding multiple keys with blank hostnames

If you need to add multiple SSH keys with blank hostnames to your project, you will need to make some changes to the default SSH configuration provided by CircleCI. In the scenario where you have multiple SSH keys that have access to the same hosts, but are for different purposes the default IdentitiesOnly no is set causing connections to use ssh-agent. This will always cause the first key to be used, even if that is the incorrect key. If you have added the SSH key to a container, you will need to either set IdentitiesOnly no in the appropriate block, or you can remove all keys from the ssh-agent for this job using ssh-add -D, and reading the key added with ssh-add /path/to/key.

See Also

Help make this document better

This guide, as well as the rest of our docs, are open source and available on GitHub. We welcome your contributions.

Need support?

Our support engineers are available to help with service issues, billing, or account related questions, and can help troubleshoot build configurations. Contact our support engineers by opening a ticket.

You can also visit our support site to find support articles, community forums, and training resources.

Creative Commons License

CircleCI Documentation by CircleCI is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.