Replace Traefik with kamal-proxy

README.md

@@ -1,6 +1,6 @@
 # Kamal: Deploy web apps anywhere
 
-From bare metal to cloud VMs, deploy web apps anywhere with zero downtime. Kamal has the dynamic reverse-proxy Traefik hold requests while a new app container is started and the old one is stopped. Works seamlessly across multiple hosts, using SSHKit to execute commands. Originally built for Rails apps, Kamal will work with any type of web app that can be containerized with Docker.
+From bare metal to cloud VMs, deploy web apps anywhere with zero downtime. Kamal uses [kamal-proxy](https://github.com/basecamp/kamal-proxy) to seamlessly switch requests between containers. Works seamlessly across multiple servers, using SSHKit to execute commands. Originally built for Rails apps, Kamal will work with any type of web app that can be containerized with Docker.
 
 ➡️ See [kamal-deploy.org](https://kamal-deploy.org) for documentation on [installation](https://kamal-deploy.org/docs/installation), [configuration](https://kamal-deploy.org/docs/configuration), and [commands](https://kamal-deploy.org/docs/commands).
 

bin/docs

@@ -22,14 +22,13 @@ DOCS = {
   "builder" => "Builders",
   "configuration" => "Configuration overview",
   "env" => "Environment variables",
-  "healthcheck" => "Healthchecks",
   "logging" => "Logging",
+  "proxy" => "Proxy",
   "registry" => "Docker Registry",
   "role" => "Roles",
   "servers" => "Servers",
   "ssh" => "SSH",
-  "sshkit" => "SSHKit",
-  "traefik" => "Traefik"
+  "sshkit" => "SSHKit"
 }
 
 class DocWriter

lib/kamal/cli.rb

@@ -1,4 +1,5 @@
 module Kamal::Cli
+  class BootError < StandardError; end
   class HookError < StandardError; end
   class LockError < StandardError; end
 end

lib/kamal/cli/accessory.rb

@@ -1,16 +1,17 @@
 class Kamal::Cli::Accessory < Kamal::Cli::Base
   desc "boot [NAME]", "Boot new accessory service on host (use NAME=all to boot all accessories)"
-  def boot(name, login: true)
+  def boot(name, prepare: true)
     with_lock do
       if name == "all"
         KAMAL.accessory_names.each { |accessory_name| boot(accessory_name) }
       else
+        prepare(name) if prepare
+
         with_accessory(name) do |accessory, hosts|
           directories(name)
           upload(name)
 
           on(hosts) do
-            execute *KAMAL.registry.login if login
             execute *KAMAL.auditor.record("Booted #{name} accessory"), verbosity: :debug
             execute *accessory.ensure_env_directory
             upload! accessory.secrets_io, accessory.secrets_path, mode: "0600"
@@ -57,15 +58,10 @@ def reboot(name)
       if name == "all"
         KAMAL.accessory_names.each { |accessory_name| reboot(accessory_name) }
       else
-        with_accessory(name) do |accessory, hosts|
-          on(hosts) do
-            execute *KAMAL.registry.login
-          end
-
-          stop(name)
-          remove_container(name)
-          boot(name, login: false)
-        end
+        prepare(name)
+        stop(name)
+        remove_container(name)
+        boot(name, prepare: false)
       end
     end
   end
@@ -97,10 +93,8 @@ def stop(name)
   desc "restart [NAME]", "Restart existing accessory container on host"
   def restart(name)
     with_lock do
-      with_accessory(name) do
-        stop(name)
-        start(name)
-      end
+      stop(name)
+      start(name)
     end
   end
 
@@ -251,11 +245,20 @@ def accessory_hosts(accessory)
     end
 
     def remove_accessory(name)
-      with_accessory(name) do
-        stop(name)
-        remove_container(name)
-        remove_image(name)
-        remove_service_directory(name)
+      stop(name)
+      remove_container(name)
+      remove_image(name)
+      remove_service_directory(name)
+    end
+
+    def prepare(name)
+      with_accessory(name) do |accessory, hosts|
+        on(hosts) do
+          execute *KAMAL.registry.login
+          execute *KAMAL.docker.create_network
+        rescue SSHKit::Command::Failed => e
+          raise unless e.message.include?("already exists")
+        end
       end
     end
 end

lib/kamal/cli/app.rb

@@ -4,7 +4,7 @@ def boot
     with_lock do
       say "Get most recent version available as an image...", :magenta unless options[:version]
       using_version(version_or_latest) do |version|
-        say "Start container with version #{version} using a #{KAMAL.config.readiness_delay}s readiness delay (or reboot if already running)...", :magenta
+        say "Start container with version #{version} (or reboot if already running)...", :magenta
 
         # Assets are prepared in a separate step to ensure they are on all hosts before booting
         on(KAMAL.hosts) do
@@ -38,8 +38,17 @@ def start
         roles = KAMAL.roles_on(host)
 
         roles.each do |role|
+          app = KAMAL.app(role: role, host: host)
           execute *KAMAL.auditor.record("Started app version #{KAMAL.config.version}"), verbosity: :debug
-          execute *KAMAL.app(role: role, host: host).start, raise_on_non_zero_exit: false
+          execute *app.start, raise_on_non_zero_exit: false
+
+          if role.running_proxy?
+            version = capture_with_info(*app.current_running_version, raise_on_non_zero_exit: false).strip
+            endpoint = capture_with_info(*app.container_id_for_version(version)).strip
+            raise Kamal::Cli::BootError, "Failed to get endpoint for #{role} on #{host}, did the container boot?" if endpoint.empty?
+
+            execute *KAMAL.proxy.deploy(role.container_prefix, target: endpoint)
+          end
         end
       end
     end
@@ -52,8 +61,18 @@ def stop
         roles = KAMAL.roles_on(host)
 
         roles.each do |role|
+          app = KAMAL.app(role: role, host: host)
           execute *KAMAL.auditor.record("Stopped app", role: role), verbosity: :debug
-          execute *KAMAL.app(role: role, host: host).stop, raise_on_non_zero_exit: false
+
+          if role.running_proxy?
+            version = capture_with_info(*app.current_running_version, raise_on_non_zero_exit: false).strip
+            endpoint = capture_with_info(*app.container_id_for_version(version)).strip
+            if endpoint.present?
+              execute *KAMAL.proxy.remove(role.container_prefix, target: endpoint), raise_on_non_zero_exit: false
+            end
+          end
+
+          execute *app.stop, raise_on_non_zero_exit: false
         end
       end
     end
@@ -212,6 +231,7 @@ def remove
       stop
       remove_containers
       remove_images
+      remove_app_directory
     end
   end
 
@@ -253,6 +273,20 @@ def remove_images
     end
   end
 
+  desc "remove_app_directory", "Remove the service directory from servers", hide: true
+  def remove_app_directory
+    with_lock do
+      on(KAMAL.hosts) do |host|
+        roles = KAMAL.roles_on(host)
+
+        roles.each do |role|
+          execute *KAMAL.auditor.record("Removed #{KAMAL.config.app_directory} on all servers", role: role), verbosity: :debug
+          execute *KAMAL.server.remove_app_directory, raise_on_non_zero_exit: false
+        end
+      end
+    end
+  end
+
   desc "version", "Show app version currently running on servers"
   def version
     on(KAMAL.hosts) do |host|

lib/kamal/cli/app/boot.rb

@@ -1,7 +1,7 @@
 class Kamal::Cli::App::Boot
   attr_reader :host, :role, :version, :barrier, :sshkit
   delegate :execute, :capture_with_info, :capture_with_pretty_json, :info, :error, :upload!, to: :sshkit
-  delegate :uses_cord?, :assets?, :running_traefik?, to: :role
+  delegate :assets?, :running_proxy?, to: :role
 
   def initialize(host, role, sshkit, version, barrier)
     @host = host
@@ -45,32 +45,30 @@ def old_version_renamed_if_clashing
 
     def start_new_version
       audit "Booted app version #{version}"
-
-      execute *app.tie_cord(role.cord_host_file) if uses_cord?
       hostname = "#{host.to_s[0...51].gsub(/\.+$/, '')}-#{SecureRandom.hex(6)}"
 
       execute *app.ensure_env_directory
       upload! role.secrets_io(host), role.secrets_path, mode: "0600"
-      execute *app.run(hostname: hostname)
 
-      Kamal::Cli::Healthcheck::Poller.wait_for_healthy(pause_after_ready: true) { capture_with_info(*app.status(version: version)) }
+      execute *app.run(hostname: hostname)
+      if running_proxy?
+        endpoint = capture_with_info(*app.container_id_for_version(version)).strip
+        raise Kamal::Cli::BootError, "Failed to get endpoint for #{role} on #{host}, did the container boot?" if endpoint.empty?
+        execute *KAMAL.proxy.deploy(role.container_prefix, target: endpoint)
+      else
+        Kamal::Cli::Healthcheck::Poller.wait_for_healthy(pause_after_ready: true) { capture_with_info(*app.status(version: version)) }
+      end
+    rescue => e
+      error "Failed to boot #{role} on #{host}"
+      raise e
     end
 
     def stop_new_version
       execute *app.stop(version: version), raise_on_non_zero_exit: false
     end
 
     def stop_old_version(version)
-      if uses_cord?
-        cord = capture_with_info(*app.cord(version: version), raise_on_non_zero_exit: false).strip
-        if cord.present?
-          execute *app.cut_cord(cord)
-          Kamal::Cli::Healthcheck::Poller.wait_for_unhealthy(pause_after_ready: true) { capture_with_info(*app.status(version: version)) }
-        end
-      end
-
       execute *app.stop(version: version), raise_on_non_zero_exit: false
-
       execute *app.clean_up_assets if assets?
     end
 

lib/kamal/cli/base.rb

@@ -101,7 +101,7 @@ def confirming(question)
       end
 
       def acquire_lock
-        ensure_run_and_locks_directory
+        ensure_run_directory
 
         raise_if_locked do
           say "Acquiring the deploy lock...", :magenta
@@ -174,14 +174,10 @@ def first_invocation
         instance_variable_get("@_invocations").first
       end
 
-      def ensure_run_and_locks_directory
+      def ensure_run_directory
         on(KAMAL.hosts) do
           execute(*KAMAL.server.ensure_run_directory)
         end
-
-        on(KAMAL.primary_host) do
-          execute(*KAMAL.lock.ensure_locks_directory)
-        end
       end
   end
 end

lib/kamal/cli/healthcheck/poller.rb

@@ -1,59 +1,38 @@
 module Kamal::Cli::Healthcheck::Poller
   extend self
 
-  TRAEFIK_UPDATE_DELAY = 5
-
-
-  def wait_for_healthy(pause_after_ready: false, &block)
+  def wait_for_healthy(role, &block)
     attempt = 1
-    max_attempts = KAMAL.config.healthcheck.max_attempts
+    timeout_at = Time.now + KAMAL.config.readiness_timeout
+    readiness_delay = KAMAL.config.readiness_delay
 
     begin
-      case status = block.call
-      when "healthy"
-        sleep TRAEFIK_UPDATE_DELAY if pause_after_ready
-      when "running" # No health check configured
-        sleep KAMAL.config.readiness_delay if pause_after_ready
-      else
-        raise Kamal::Cli::Healthcheck::Error, "container not ready (#{status})"
-      end
-    rescue Kamal::Cli::Healthcheck::Error => e
-      if attempt <= max_attempts
-        info "#{e.message}, retrying in #{attempt}s (attempt #{attempt}/#{max_attempts})..."
-        sleep attempt
-        attempt += 1
-        retry
-      else
-        raise
+      status = block.call
+
+      if status == "running"
+        # Wait for the readiness delay and confirm it is still running
+        if readiness_delay > 0
+          info "Container is running, waiting for readiness delay of #{readiness_delay} seconds"
+          sleep readiness_delay
+          status = block.call
+        end
       end
-    end
 
-    info "Container is healthy!"
-  end
-
-  def wait_for_unhealthy(pause_after_ready: false, &block)
-    attempt = 1
-    max_attempts = KAMAL.config.healthcheck.max_attempts
-
-    begin
-      case status = block.call
-      when "unhealthy"
-        sleep TRAEFIK_UPDATE_DELAY if pause_after_ready
-      else
-        raise Kamal::Cli::Healthcheck::Error, "container not unhealthy (#{status})"
+      unless %w[ running healthy ].include?(status)
+        raise Kamal::Cli::Healthcheck::Error, "container not ready after #{KAMAL.config.readiness_timeout} seconds (#{status})"
       end
     rescue Kamal::Cli::Healthcheck::Error => e
-      if attempt <= max_attempts
-        info "#{e.message}, retrying in #{attempt}s (attempt #{attempt}/#{max_attempts})..."
-        sleep attempt
+      time_left = timeout_at - Time.now
+      if time_left > 0
+        sleep [ attempt, time_left ].min
         attempt += 1
         retry
       else
         raise
       end
     end
 
-    info "Container is unhealthy!"
+    info "Container is healthy!"
   end
 
   private

lib/kamal/cli/lock.rb

@@ -12,7 +12,7 @@ def status
   option :message, aliases: "-m", type: :string, desc: "A lock message", required: true
   def acquire
     message = options[:message]
-    ensure_run_and_locks_directory
+    ensure_run_directory
 
     raise_if_locked do
       on(KAMAL.primary_host) do