How can I add an SSH key to Gitlab through a bash executable?

Question

I am creating a bash executable, which creates an SSH key, and uploads it to a user's Gitlab account. I am aware of how to create the SSH key via the bash executable:

ssh-keygen -o -f ~/.ssh/id_rsa

and I also know how to retrieve from it, however I don't know how to upload it to a user's Gitlab account.

I have found multiple documentations for uploading a user's SSH to Github however not Gitlab (I assume mostly similar...?). So I would use this for Github

curl -u "USERNAME:PASSWORD" --data "{\"title\": \"TITLE\", \"key\": \"$(cat ~/.ssh/id_rsa.pub)\"}" https://api.github.com/user/keys

and I would make USERNAME, PASSWORD, and TITLE input fields for the user to customize.

I want to say that it would be as simple for Gitlab (I found POST /users/:id/keys on their API site, but don't know how to implement it as a curl command), but I don't know how closely related Gitlab and Github are.

Answer 1

The first problem you need to solve when using the Gitlab REST API is the authentification, nicely explained in the docs here. I use a personal access token in this post which creation is explained here, but for you with a script authenticating as a specific user an Impersonation token (see here for the creation) may be better suited.

To add an ssh key I need:

POST /user/keys

To send data (and subsequently use the POST method) curl provides the -d option, required fields are title and key. As the default header is Content-Type: application/x-www-form-urlencoded but the API expects json I have to specify that using the -H option:

$ curl -d '{"title":"test key","key":"'"$(cat ~/.ssh/id_rsa.pub)"'"}' -H 'Content-Type: application/json' https://gitlab.com/api/v4/user/keys?private_token=<my_access_token>
{"id":3889765,"title":"test key","key":"ssh-rsa <my_ssh_key>","created_at":"2019-08-01T21:26:40.952Z"}

Now to test the change I just list my ssh keys. The docs say I have to use GET /user/keys, as GET is curl’s default method I just do:

$ curl https://gitlab.com/api/v4/user/keys?private_token=<my_access_token>
[{"id":3889765,"title":"test key","key":"ssh-rsa <my_ssh_key>","created_at":"2019-08-01T21:26:40.952Z"}]

I did this just for testing, so I’m going to delete the key with DELETE /user/keys/:key_id – note that :key_id needs to be substituted by the id of the key to delete:

$ curl -X DELETE https://gitlab.com/api/v4/user/keys/3889765?private_token=<my_access_token>

Here’s a nice article about curl and the common REST methods.