Today, I encountered a problem when adding an SSH key to a new Gitlab account. I tried to add the key, but it showed an error: Fingerprint has already been taken. This means that I have used this key for another Gitlab account. Gitlab does not allow using the same SSH key for multiple different accounts.

So I need to generate a new key and add it to my new account. However, how do I know which account I am cloning the repo from so that I don’t get an authorization error?

Generate a new key

First, we need to create a new SSH key and save it with a different name to avoid overlapping with the previous key. For example, ~/.ssh/id_rsd_company.

ssh-keygen -t rsa -b 4096 -C "email@company.com"

Config

Now we need to add configuration in ~/.ssh/config

# Company account
Host gitlab.company
  HostName gitlab.com
  PreferredAuthentications publickey
  IdentityFile ~/.ssh/id_rsa_company

# Personal account
Host gitlab.personal
  HostName gitlab.com
  PreferredAuthentications publickey
  IdentityFile ~/.ssh/id_rsa_personal

As you can see, we define a Host with the name gitlab.company, with parameters such as HostName, IdentityFile being the path to the newly created SSH key.

Usage

Now when cloning repos from these two accounts, there will be a slight change in the URLs. Suppose we clone a repo named demo from the company account. The usual URL would be:

git@gitlab.com:username/demo.git

However, since we have reconfigured the host name for gitlab.com, the new URL will have to be:

git@gitlab.company:username/demo.git

In this way, gitlab.company will be resolved to gitlab.com and authenticated through the SSH key we just created.

Similarly, you also need to edit the URL for your personal account in the same way as in the ~/.ssh/config file.