People addicted with technology.
Technology has indulged mankind.
Beware of technology dependency!
– Toba Beta
You need to force the ssh-rsa host key instead of the default one picked up by the tooling:
$ ssh-keygen -R gitlab.com
$ cat <<EOF >> ~/.ssh/config
Host gitlab.com
HostKeyAlgorithms ssh-rsa
EOF
$ ssh git@gitlab.com
You are using the brand new dependency resolution from the Clojure core team for the first time. You like the idea of fetching your dependency straight from git. You host all of your repos on GitLab, it just makes sense, right? Right.
You go ahead and start your new project, you just need to bring in the usual me/my-awesome-lib that you use everywhere. That’s just a new, empty folder in which you configure your deps.edn like the following:
{:deps {my-awesome-lib {:git/url "git@gitlab.com:me/my-awesome-lib.git" :sha "031aa264afc2cf6dee9e12de8b88c608faefea80"}}}
No more lein new, no more templates, no more nothing. You mentally pat yourself on the shoulder.
You’re now at the terminal, ready to sprinkle your clojure fairy powder all over. You fire clj -m my-awesome-lib.main and stand in awe as the tool fetches bits from GitLab and…
Cloning: git@gitlab.com:me/my-awesome-lib.git
Error building classpath. git@gitlab.com:me/my-awesome-lib.git: UnknownHostKey: gitlab.com. RSA key fingerprint is b6:03:0e:39:97:9e:d0:e7:24:ce:a3:77:3e:01:42:09
org.eclipse.jgit.api.errors.TransportException: git@gitlab.com:me/my-awesome-lib.git: UnknownHostKey: gitlab.com. RSA key fingerprint is b6:03:0e:39:97:9e:d0:e7:24:ce:a3:77:3e:01:42:09
Damn! Damn. Really? Mhhhhh…
$ ssh git@gitlab.com
PTY allocation request failed on channel 0
Welcome to GitLab, @carlo.sciolla!
Connection to gitlab.com closed.
Seems all good. One final check:
$ grep gitlab ~/.ssh/known_hosts
gitlab.com,35.231.145.151 ecdsa-sha2-nistp256 ****
Things are getting creepy. Worse of it all, you got stuck there. Fortunately, you have a little bird spilling some relevant beans: the specific host key crypto algorithm (ecdsa-sha2-nistp256 in the above) might be relevant! A lead is a lead, and this feels like a good one. Let’s explore.
First things first, you need to start from a clean slate. Let’s remove the currently installed host key:
$ ssh-keygen -R gitlab.com
Good. Now let’s have a look at what keys are provided by GitLab, just to have a feel for what could be a sensible one to pick:
$ ssh -Q key git@gitlab.com
ssh-ed25519
ssh-ed25519-cert-v01@openssh.com
ssh-rsa
ssh-dss
ecdsa-sha2-nistp256
ecdsa-sha2-nistp384
ecdsa-sha2-nistp521
ssh-rsa-cert-v01@openssh.com
ssh-dss-cert-v01@openssh.com
ecdsa-sha2-nistp256-cert-v01@openssh.com
ecdsa-sha2-nistp384-cert-v01@openssh.com
ecdsa-sha2-nistp521-cert-v01@openssh.com
Whoa! That’s quite a rich of a menu to choose from. But your spidey senses are tingling: that ssh-rsa feels good. Warm. Homey. Or maybe it’s just the closest to what the original error message said. Whatever, lets tell SSH to pick that one:
$ cat <<EOF >> ~/.ssh/config
Host gitlab.com
HostKeyAlgorithms ssh-rsa
EOF
Alright, time to shine. Let it fly, once again:
$ clj -m my-awesome-lib.main
Cloning: git@gitlab.com:me/my-awesome-lib.git
Error building classpath. git@gitlab.com:me/my-awesome-lib.git: UnknownHostKey: gitlab.com. RSA key fingerprint is b6:03:0e:39:97:9e:d0:e7:24:ce:a3:77:3e:01:42:09
org.eclipse.jgit.api.errors.TransportException: git@gitlab.com:me/my-awesome-lib.git: UnknownHostKey: gitlab.com. RSA key fingerprint is b6:03:0e:39:97:9e:d0:e7:24:ce:a3:77:3e:01:42:09
Damn! Really?! “Oh wait!” you think, as you realize that maybe now you need to first get the new host key:
$ ssh git@gitlab.com
The authenticity of host 'gitlab.com (35.231.145.151)' can't be established.
RSA key fingerprint is SHA256:ROQFvPThGrW4RuWLoL9tq9I9zJ42fK4XywyRtbOz/EQ.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'gitlab.com,35.231.145.151' (RSA) to the list of known hosts.
PTY allocation request failed on channel 0
Welcome to GitLab, @carlo.sciolla!
Connection to gitlab.com closed.
Good! Now, what if… you just did it? “Well, here goes nothing.” you think, mindlessly typing that dreaded command one last time:
$ clj -m my-awesome-lib.main
Cloning: git@gitlab.com:me/my-awesome-lib.git
Checking out: git@gitlab.com:me/my-awesome-lib.git at 031aa264afc2cf6dee9e12de8b88c608faefea80
Welcome to MyProject!
Good. That’s good, really. You feel like you deserve a coffee now. And you do.