Gitlab public key authentication

I have used gitlab for quite a while as it provides me with quite some flexibility and have some additional advantages over it’s competitor github. I usually use public / private key authentication to push my codes onto the server. but after a fresh installation, I saw the following error when trying to work with gitlab.

$ git clone git@gitlab.com:nuclearpasta/vehiclebooking.git
Cloning into 'vehiclebooking'...
git@gitlab.com: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

As this was a fresh installation of my OS, my public key has changed so needed to update my keys to gitlab. So I navigated to my profile and checked out my public key.

So in my new Linux system, it does not have any previous keys so I had to generate

$ cd  ~/.ssh/
$ ll
total 12
drwx------  2 reza reza 4096 Aug 21 12:41 ./
drwxr-x--- 26 reza reza 4096 Aug 26 10:57 ../
-rw-r--r--  1 reza reza  142 Aug 21 12:41 known_hosts
reza@legion:~/.ssh$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/reza/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/reza/.ssh/id_rsa
Your public key has been saved in /home/reza/.ssh/id_rsa.pub
The key fingerprint is:
SHA256:SnWHOaiKzSCfq3XprK8tFyzmdH10/lzVBhFB1Nzithc reza@legion
The key's randomart image is:
+---[RSA 3072]----+
|  o          o**.|
|   *     . o  o +|
|        o = .. o.|
|   .++ o...o  oE+|
|. .. .o.So   . +.|
| o+*++... ... o .|
| +=o*...   o . . |
| .o*.       o    |
|..+*=            |
+----[SHA256]-----+
reza@legion:~/.ssh$ cat 
id_rsa       id_rsa.pub   known_hosts  
reza@legion:~/.ssh$ cat id_rsa.pub 
ssh-rsa AAAAB3NzaCp...[SNIP]...4E5tJmhvfzZVGoxoFQYz28= reza@legion

You now just have to copy the id_rsa.pub which contains your public key to the gitlab so that you can authenticate.

Now if you re-try, you will get the following:

$ git clone git@gitlab.com:nuclearpasta/vehiclebooking.git
Cloning into 'vehiclebooking'...
warning: You appear to have cloned an empty repository.