Use .ssh/config to setup SSH proxy jump

Unfortunately, my previous attempt to route deployment through a
jumphost[^1] doesn't work. Turns out that specifying a proxyjump host
inline doesn't support specifying an SSH key to authenticate with. It
worked well on my machine because some _default_ key was used
transparently, but it fails on CD where no such key exist.

The new approach tries to address the problem by moving away from inline
SSH configuration towards the .ssh/config file, which has everything
needed specified.

[^1]: 7aec773

Author: ikalnytskyi

.github/workflows/cd.yaml

@@ -2,7 +2,7 @@ name: CD
 
 on:
   push:
-    branches: [master]
+    branches: [master, bug/cd-fixes]
   workflow_dispatch:
 
 jobs:
@@ -37,10 +37,20 @@ jobs:
           # Ensure that servers we're deploying to are known. Otherwise,
           # Ansible may fail with host key verification error.
           mkdir -p ~/.ssh && echo "${{ secrets.SSH_KNOWN_HOSTS }}" >> ~/.ssh/known_hosts
+          cat <<EOF > ~/.ssh/config
+          Host _jumphost
+            User bunny
+            HostName hoth.kalnytskyi.com
+            IdentityFile ${{ steps.ssh-key.outputs.uri }}
+
+          Host xsnippet.org
+            HostName 2a02:8084:4:e480:244a:d5a5:ac59:617d
+            ProxyJump _jumphost
+            IdentityFile ${{ steps.ssh-key.outputs.uri }}
+          EOF
 
           ansible-playbook \
             -vv \
-            -e ansible_ssh_private_key_file="${{ steps.ssh-key.outputs.uri }}" \
             -e goaccess_basicauth_password="${{ secrets.GOACCESS_PASSWORD }}" \
             --inventory inventories/production \
             site.yml

inventories/production/hosts

@@ -1,6 +1,5 @@
 [xsnippet]
-2a02:8084:4:e480:244a:d5a5:ac59:617d
+xsnippet.org
 
 [xsnippet:vars]
 ansible_user = provisioner
-ansible_ssh_common_args = -J bunny@hoth.kalnytskyi.com