Do not pass the password on the command line anymore to fix a warning

Since email notifications work now we do not want warnings. Write an
option file with the credentials for mysqldump
(https://dev.mysql.com/doc/refman/5.7/en/option-files.html)

site-cookbooks/backup/recipes/default.rb

@@ -63,18 +63,22 @@ mysql_client 'default' do
   not_if { node["backup"]["mysql"]["databases"].empty? }
 end
 
-  include_recipe 'logrotate'
-  unless node["backup"]["mysql"]["databases"].empty?
-    # Install MySQL client (includes mysqldump)
-    mysql_client 'default' do
-      action :create
-    end
-  end
-
-  logrotate_app 'backup' do
-    path '/var/log/backup.log'
-    frequency 'daily'
-    rotate 10
-    create '640 root root'
-  end
+# Write the credentials file to allow dumps without password for the root
+# user (https://dev.mysql.com/doc/refman/5.7/en/option-files.html)
+file "/root/.my.cnf" do
+  mode "600"
+  content lazy { <<-EOF
+[client]
+user=#{node["backup"]["mysql"]["username"]}
+password=#{node["backup"]["mysql"]["password"]}
+  EOF
+  }
+  not_if { node["backup"]["mysql"]["password"].nil? }
+end
+
+logrotate_app 'backup' do
+  path '/var/log/backup.log'
+  frequency 'daily'
+  rotate 10
+  create '640 root root'
 end

site-cookbooks/backup/templates/default/config.rb.erb

@@ -40,7 +40,6 @@ end
 Database::MySQL.defaults do |db|
   db.host               = "<%= node["backup"]["mysql"]["host"] %>"
   db.username           = "<%= node["backup"]["mysql"]["username"] %>"
-  db.password           = "<%= node["backup"]["mysql"]["password"] %>"
   db.additional_options = ['--quick', '--single-transaction']
 end
 <%- end -%>