Capistrano recipe for Webpacker without Assets pipeline, put it into lib/capistrano/tasks/webpacker.rake and require it in Capfile

webpacker.rake

# frozen_string_literal: true

namespace :webpacker do
  desc "Compile webpacker assets"
  task :compile do
    on release_roles(fetch(:assets_roles)) do
      within release_path do
        with rails_env: fetch(:rails_env), rails_groups: fetch(:rails_assets_groups) do
          execute :rake, "yarn:install"
          execute :rake, "webpacker:compile"
        end
      end
    end
  end

  desc "Clobber webpacker assets"
  task :clobber do
    on release_roles(fetch(:assets_roles)) do
      within release_path do
        with rails_env: fetch(:rails_env), rails_groups: fetch(:rails_assets_groups) do
          execute :rake, "webpacker:clobber"
        end
      end
    end
  end

  desc "Check node installed"
  task :check do
    on release_roles(fetch(:assets_roles)) do
      required_node_version = "6.4"
      begin
        node_version = capture(:node, "-v")
      rescue SSHKit::Command::Failed
        error "Node.js not installed. Please download and install Node.js https://nodejs.org/en/download/"
        exit 1
      end
      if Gem::Version.new(node_version.strip.tr("v", "")) < Gem::Version.new(required_node_version)
        error <<-ERROR.strip_heredoc
            Webpacker requires Node.js >= v#{required_node_version} and you are using #{node_version}"
            Please upgrade Node.js https://nodejs.org/en/download/
        ERROR
        exit 1
      end

      info "Node.js installed."
    end
  end

  after "deploy:check", "webpacker:check"
  after "deploy:updated", "webpacker:compile"
end

namespace :load do
  task :defaults do
    set :assets_roles, fetch(:assets_roles, [:web])
  end
end