Git clone failed while deploy (but ssh key works fine)

[maximeripaud]

• Deployer version : 6.8

When I try to deploy my app, I have an error on "git clone" :
The command "export SYMFONY_ENV='prod'; cd /PATH/app && (/usr/bin/git clone -b "master" --recursive [email protected]:USER/REPO.git /PATH/app/releases/1 2>&1)" failed.

I have created SSH key with "ssh-keygen", and add it on Github.

If I connect to the server via SSH, I can run the same "git clone" command without error, but I must run "ssh-add" first systematically :
ssh-add /PATH/.ssh/id_ed25519_github

I have added "AddKeysToAgent yes" in .ssh/config, but it makes no difference.

I try to add a task in Deployer to run it automatically before the task "deploy:update_code" :
run('ssh-add /PATH/.ssh/id_ed25519_github');

But it still doesn't work... Have you any idea please ?