Update modes on ssh keys

Author: taylorific

cookbooks/boxcutter_builder/recipes/default.rb

@@ -60,6 +60,7 @@
       file_location '/home/github-runner/.ssh/known_hosts'
       owner 'github-runner'
       group 'github-runner'
+      mode '0600'
     end
 
     craft_rsa_ssh_key_private = \
@@ -121,13 +122,15 @@
       file_location '/home/github-runner/.ssh/known_hosts'
       owner 'github-runner'
       group 'github-runner'
+      mode '0600'
     end
 
     # arm64 builder
     ssh_known_hosts_entry '10.0.1.175' do
       file_location '/home/github-runner/.ssh/known_hosts'
       owner 'github-runner'
       group 'github-runner'
+      mode '0600'
     end
 
     node.default['boxcutter_docker']['buildx']['github-runner'] = {