cj-cloud-init.yml

# This config was written for Ubuntu 22.04
# If you are using a more recent version, see the comments of this gist for fixes
#cloud-config
users:
  - name: cj
    ssh_authorized_keys:
      - "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAINBlfqermlV44zAU+iTCa5im5O0QWXid6sHqh2Z4L1Cm cj@null.computer"
    sudo: ALL=(ALL:ALL) ALL
    groups: sudo
    shell: /bin/bash
chpasswd:
  expire: true
  users:
    - name: cj
      password: changeme
      type: text
runcmd:
  - sed -i '/PermitRootLogin/d' /etc/ssh/sshd_config
  - echo "PermitRootLogin without-password" >> /etc/ssh/sshd_config
  - sed -i '/PubkeyAuthentication/d' /etc/ssh/sshd_config
  - echo "PubkeyAuthentication yes" >> /etc/ssh/sshd_config
  - sed -i '/PasswordAuthentication/d' /etc/ssh/sshd_config
  - echo "PasswordAuthentication no" >> /etc/ssh/sshd_config
  - systemctl restart sshd
  - echo "\$nrconf{kernelhints} = -1;" > /etc/needrestart/conf.d/99disable-prompt.conf
  - apt update
  - apt upgrade -y --allow-downgrades --allow-remove-essential --allow-change-held-packages
  - reboot

Facing an issue where I tried to use the cloud config. I have triple checked to see if my public keys are correct but after the server spins up, i get
ssh root@[xxx.xxx.xxx.xxx]
ssh: connect to host [xxx.xxx.xxx.xxx]: port 22: Connection refused.

If I restart the server, I get
root@[xxx.xxxx.xxx.xxx]: Permission denied (publickey).

FYI: I have attached my ssh keys during server creation

Facing an issue where I tried to use the cloud config. I have triple checked to see if my public keys are correct but after the server spins up, i get ssh root@[xxx.xxx.xxx.xxx] ssh: connect to host [xxx.xxx.xxx.xxx]: port 22: Connection refused.

I have also experienced this error. In my testing, it appears as if the issue lies with the command systemctl restart sshd as the SSH service name varies from system to system between ssh and sshd. This can be checked using the command sudo systemctl list-units --type=service | grep ssh.

My solution is to edit line 22 in the clout-init.yml file to systemctl restart ssh || systemctl restart sshd in an attempt to target both SSH service names.

If I restart the server, I get root@[xxx.xxxx.xxx.xxx]: Permission denied (publickey).

Had the same issue as @ahamedzoha .What I did was edit line 22 as @irvdude said to " - systemctl restart ssh" because it looked like in an earlier run the service on my system wasn't called sshd. Ultimately I don't know if that has changed anything.
Because after some troubleshooting the issue was I had to start the ssh login with:
ssh -o "IdentitiesOnly=yes" -i privatekeyfilename root@serveripaddress
privatekeyfilename being the name you gave when creating the ssh key, assuming you're following the coolify guide as well.
Edit: This is also assuming you're running the ssh command in the folder where the privatekey file is located. Otherwise you might need to specificy the path to it as well.

My solution is to edit line 22 in the clout-init.yml file to systemctl restart ssh || systemctl restart sshd in an attempt to target both SSH service names.

Ubuntu 24.04 has removed the d alias for various systemd services (https://www.reddit.com/r/Ubuntu/comments/1cl5qiq/systemctl_restart_sshd_does_not_work_any_more_in/). Since CJ's example used 22.04, its most likely that this is one the reasons that, potentially, we're having some issues when spinning up new 24.04 VM's with this cloud init that was intended for 22.04 :)

My solution is to edit line 22 in the clout-init.yml file to systemctl restart ssh || systemctl restart sshd in an attempt to target both SSH service names.

I also left out one small (huge) detail. On line 21 of cloud-init.yml, I also happened to have changed "PasswordAuthentication no" to "PasswordAuthentication yes".

Thus, conveniently disabling PasswordAuthentication, enabling access to the server (my mistake).

One could simply pipe echo "PasswordAuthentication no" >> /etc/ssh/sshd_config back into the session once connected, then wait for the system to reboot and then ssh back in. (unless you are plan adding a new server through Coolify I'd highly recommend doing that well after your new server is configured.)

I'm also testing @adrnd method to ssh into the session using ssh -o "IdentitiesOnly=yes" -i ~/.ssh/id_ed25519 root@serveripaddress, will follow up here.

The server kept asking me for my password. @adrnd's solution worked for me.

If I restart the server, I get root@[xxx.xxxx.xxx.xxx]: Permission denied (publickey).

Did you set the permissions right?

chmod -R 644 ~/.ssh/your_key.pub
chmod -R 600 ~/.ssh/authorized_keys

An alternative to @adrnd solution would be to create an ssh config entry like the following:

Host my_awesome_server
 HostName xxx.xxx.xxx.xxx
 User <YOUR_USER_NAME_SPECIFIED_IN_CLOUD_CONFIG>
 Port 22
 IdentityFile ~/.ssh/<PRIVATE_KEY_FILE>

And then run ssh my_awesome_server. This should enforce a user login on the given IP to use your public/private key for authentication. Make sure to also follow @swrrvr suggestion to add systemctl restart ssh || systemctl restart sshd to the cloud config. in line 22

Here's an updated version for ubuntu 24.04: https://gist.github.com/dziamid/0de2761e0ecc4b3e68e2461c60f82930

I am struggling with getting a new public key stored in known_hosts locally when trying to run ssh root@{ip-adress} rather than the public key I set in cloud.init script. Using @dziamid new file for Ubuntu 24.04, also added the systemctl restart ssh || systemctl restart sshd, does anyone know why this happens?