Install Node.js on deploy

We use FNM instead of NVM. Reason: the setup seems easier with just
`eval "$(fnm env)"`.

config/deploy.rb

@@ -37,6 +37,16 @@ def main_deploy_server
 
 set :local_user, ENV["USER"]
 
+set :fnm_path, "$HOME/.fnm"
+set :fnm_install_command, "curl -fsSL https://fnm.vercel.app/install | " \
+ "bash -s -- --install-dir \"#{fetch(:fnm_path)}\""
+set :fnm_update_command, "#{fetch(:fnm_install_command)} --skip-shell"
+set :fnm_setup_command, -> do
+ "export PATH=\"#{fetch(:fnm_path)}:$PATH\" && " \
+ "cd #{release_path} && eval \"$(fnm env)\""
+ end
+set :fnm_install_node_command, -> { "#{fetch(:fnm_setup_command)} && fnm use --install-if-missing" }
+
 set :puma_conf, "#{release_path}/config/puma/#{fetch(:rails_env)}.rb"
 
 set :delayed_job_workers, 2
@@ -50,6 +60,7 @@ def main_deploy_server
  Rake::Task["puma:smart_restart"].clear_actions
 
  after :updating, "install_ruby"
+ after "bundler:install", "install_node"
 
  after "deploy:migrate", "add_new_settings"
 
@@ -89,6 +100,26 @@ def main_deploy_server
  end
 end
 
+task :install_node do
+ on roles(:app) do
+ with rails_env: fetch(:rails_env) do
+ begin
+ execute fetch(:fnm_install_node_command)
+ rescue SSHKit::Command::Failed
+ begin
+ execute fetch(:fnm_setup_command)
+ rescue SSHKit::Command::Failed
+ execute fetch(:fnm_install_command)
+ else
+ execute fetch(:fnm_update_command)
+ end
+
+ execute fetch(:fnm_install_node_command)
+ end
+ end
+ end
+end
+
 task :refresh_sitemap do
  on roles(:app) do
  within release_path do