Clone the private Mastodon repo with an SSH deploy key

The repository is private, so use git@gitea.kosmos.org with a read-only deploy key stored in credentials/mastodon (repo_deploy_key). The pinned gitea host key is an attribute.

site-cookbooks/kosmos-mastodon/attributes/default.rb

@@ -1,4 +1,4 @@
-node.default["kosmos-mastodon"]["repo"]              = "https://gitea.kosmos.org/kosmos/mastodon.git"
+node.default["kosmos-mastodon"]["repo"]              = "git@gitea.kosmos.org:kosmos/mastodon.git"
 node.default["kosmos-mastodon"]["revision"]          = "production-4.7"
 node.default["kosmos-mastodon"]["directory"]         = "/opt/mastodon"
 node.default["kosmos-mastodon"]["bind_ip"]           = "127.0.0.1"
@@ -22,6 +22,12 @@ node.default["kosmos-mastodon"]["nodejs_version"]      = "24.21.0"
 node.default["kosmos-mastodon"]["ruby_version"]        = "4.0.7"
 node.default["kosmos-mastodon"]["ruby_build_version"]  = "v20260924"
 
+# SSH deploy key access to the (private) repository. The private key is stored
+# in the credentials/mastodon data bag as `repo_deploy_key`; this is the pinned
+# host key of gitea.kosmos.org.
+node.default["kosmos-mastodon"]["gitea_ssh_host_key"] =
+  "gitea.kosmos.org ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJycWc3U9P/6BzE0HcPiTdmaDN8zKRx+0/jGXYuKiwx7"
+
 # External Redis cluster (see the kosmos_redis cookbook)
 node.default["kosmos-mastodon"]["redis_server_role"] = "redis_server"
 node.default["kosmos-mastodon"]["redis_port"]        = 6379

site-cookbooks/kosmos-mastodon/recipes/build.rb

@@ -42,16 +42,54 @@ deploy_env = {
 build_uptodate = "test -f #{mastodon_path}/tmp/built-revision && " \
                  "test \"$(cat #{mastodon_path}/tmp/built-revision)\" = \"$(git -C #{mastodon_path} rev-parse HEAD)\""
 
+credentials = data_bag_item('credentials', 'mastodon')
+
+# The repository is private; clone it with a read-only SSH deploy key.
+directory "#{mastodon_path}/.ssh" do
+  owner mastodon_user
+  group mastodon_user
+  mode  "0700"
+end
+
+file "#{mastodon_path}/.ssh/id_ed25519" do
+  content credentials["repo_deploy_key"]
+  owner mastodon_user
+  group mastodon_user
+  mode  "0600"
+  sensitive true
+end
+
+file "#{mastodon_path}/.ssh/known_hosts" do
+  content "#{node['kosmos-mastodon']['gitea_ssh_host_key']}\n"
+  owner mastodon_user
+  group mastodon_user
+  mode  "0644"
+end
+
+file "#{mastodon_path}/.ssh/config" do
+  content <<-EOF
+Host gitea.kosmos.org
+  IdentityFile #{mastodon_path}/.ssh/id_ed25519
+  IdentitiesOnly yes
+  StrictHostKeyChecking yes
+  UserKnownHostsFile #{mastodon_path}/.ssh/known_hosts
+  EOF
+  owner mastodon_user
+  group mastodon_user
+  mode  "0600"
+end
+
 git mastodon_path do
   user mastodon_user
   group mastodon_user
 
   repository node["kosmos-mastodon"]["repo"]
   revision   node["kosmos-mastodon"]["revision"]
+  environment "GIT_SSH_COMMAND" =>
+    "ssh -i #{mastodon_path}/.ssh/id_ed25519 -o IdentitiesOnly=yes " \
+    "-o StrictHostKeyChecking=yes -o UserKnownHostsFile=#{mastodon_path}/.ssh/known_hosts"
 end
 
-credentials = data_bag_item('credentials', 'mastodon')
-
 ldap_config = {
   host: "ldap.kosmos.local",
   port: 389,