Fix minor ssh issues like stuck pipelines.

On hosts without ssh key, the _ssh command was stuck while asking for a password which it never received.

README.md

@@ -11,5 +11,7 @@ You need to adjust the paths in `prepare_exec`, `run_exec` and `cleanup_exec` wh
 
 Install dependencies: `brew install gitlab-runner daemonize cirruslabs/cli/tart`.
 
+Ensure your host system has an SSH private key. If not, create one using `ssh-keygen -t ed25519`.
+
 ## Configurations
 - The image can be selected using Gitlab-CI's `image:` tag. Choose a different tart image, e.g. from https://github.com/orgs/cirruslabs/packages?tab=packages&q=macos. The current default is `ghcr.io/cirruslabs/macos-monterey-xcode:14`.

base.sh

@@ -7,6 +7,9 @@ VM_IMAGE="${CUSTOM_ENV_CI_JOB_IMAGE:-$VM_IMAGE_FALLBACK}"
 VM_USER="admin"
 VM_PASSWORD="admin"
 
+# Load SSH keys from the host.
+ssh-add
+
 _get_vm_ip() {
     tart ip "$VM_ID" --wait 30 || true
 }
@@ -16,5 +19,5 @@ _get_vm_pid() {
 }
 
 _ssh() {
-    ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null "$VM_USER"@"$VM_IP" "/bin/zsh --login -c '$@'" >/dev/null 
+    ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/tmp/$VM_ID "$VM_USER"@"$VM_IP" "/bin/zsh --login -c '$@'" >/dev/null 
 }