Add kamal proxy update

For easy updates from Traefik to kamal-proxy, add `kamal proxy update`.

This stops and removes Traefik and kamal-proxy containers (just in case
it is run after an update). Then it starts kamal-proxy and calls
`kamal-proxy deploy` to route to any app containers that are already
running.

It can be run with a rolling option and calls the `pre-proxy-reboot` and
`post-proxy-reboot` hooks for each host.

lib/kamal/cli/proxy.rb

@@ -60,6 +60,50 @@ class Kamal::Cli::Proxy < Kamal::Cli::Base
     end
   end
 
+  desc "update", "Update from Traefik to kamal-proxy, for when moving from Kamal v1 to Kamal v2"
+  option :rolling, type: :boolean, default: false, desc: "Reboot proxy on hosts in sequence, rather than in parallel"
+  option :confirmed, aliases: "-y", type: :boolean, default: false, desc: "Proceed without confirmation question"
+  def update
+    confirming "This will cause a brief outage on each host. Are you sure?" do
+      with_lock do
+        host_groups = options[:rolling] ? KAMAL.proxy_hosts : [ KAMAL.proxy_hosts ]
+        host_groups.each do |hosts|
+          host_list = Array(hosts).join(",")
+          run_hook "pre-proxy-reboot", hosts: host_list
+          on(hosts) do
+            info "Updating proxy from Traefik to kamal-proxy on #{host}..."
+            execute *KAMAL.auditor.record("Updated proxy from Traefik to kamal-proxy"), verbosity: :debug
+            execute *KAMAL.registry.login
+
+            info "Stopping and removing Traefik on #{host}..."
+            execute *KAMAL.proxy.stop(name: "traefik"), raise_on_non_zero_exit: false
+            execute *KAMAL.proxy.remove_container(filter: "label=org.opencontainers.image.title=traefik")
+            execute *KAMAL.proxy.remove_image(filter: "label=org.opencontainers.image.title=traefik")
+
+            info "Stopping and removing kamal-proxy on #{host}, if running..."
+            execute *KAMAL.proxy.stop, raise_on_non_zero_exit: false
+            execute *KAMAL.proxy.remove_container
+
+            info "Starting kamal-proxy on #{host}..."
+            execute *KAMAL.proxy.run
+
+            KAMAL.roles_on(host).select(&:running_proxy?).each do |role|
+              app = KAMAL.app(role: role, host: host)
+
+              version = capture_with_info(*app.current_running_version, raise_on_non_zero_exit: false).strip
+              endpoint = capture_with_info(*app.container_endpoint(version: version)).strip
+              raise Kamal::Cli::BootError, "Failed to get endpoint for #{role} on #{host}, is the app container running?" if endpoint.empty?
+
+              info "Deploying #{endpoint} for role `#{role}` on #{host}..."
+              execute *KAMAL.proxy.deploy(role.container_prefix, target: endpoint)
+            end
+          end
+          run_hook "post-proxy-reboot", hosts: host_list
+        end
+      end
+    end
+  end
+
   desc "details", "Show details about proxy container from servers"
   def details
     on(KAMAL.proxy_hosts) { |host| puts_by_host host, capture_with_info(*KAMAL.proxy.info), type: "Proxy" }

lib/kamal/commands/proxy.rb

@@ -26,8 +26,8 @@ class Kamal::Commands::Proxy < Kamal::Commands::Base
     docker :container, :start, container_name
   end
 
-  def stop
-    docker :container, :stop, container_name
+  def stop(name: container_name)
+    docker :container, :stop, name
   end
 
   def start_or_run
@@ -60,12 +60,12 @@ class Kamal::Commands::Proxy < Kamal::Commands::Base
     ).join(" "), host: host
   end
 
-  def remove_container
-    docker :container, :prune, "--force", "--filter", container_filter
+  def remove_container(filter: container_filter)
+    docker :container, :prune, "--force", "--filter", filter
   end
 
-  def remove_image
-    docker :image, :prune, "--all", "--force", "--filter", image_filter
+  def remove_image(filter: image_filter)
+    docker :image, :prune, "--all", "--force", "--filter", filter
   end
 
   private

test/cli/proxy_test.rb

@@ -87,6 +87,28 @@ class CliProxyTest < CliTestCase
     end
   end
 
+  test "update" do
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with(:docker, :container, :ls, "--all", "--filter", "name=^app-web-123$", "--quiet", "|", :xargs, :docker, :inspect, "--format", "'{{.NetworkSettings.IPAddress}}{{range $k, $v := .NetworkSettings.Ports}}{{printf \":%s\" $k}}{{break}}{{end}}'", "|", :sed, "-e", "'s/\\/tcp$//'")
+      .returns("172.1.0.2:80")
+      .at_least_once
+
+    SSHKit::Backend::Abstract.any_instance.expects(:capture_with_info)
+      .with { |*args| args[0..1] == [ :sh, "-c" ] }
+      .returns("123")
+      .at_least_once
+
+    run_command("update", "-y").tap do |output|
+      assert_match "docker container stop traefik", output
+      assert_match "docker container prune --force --filter label=org.opencontainers.image.title=traefik", output
+      assert_match "docker image prune --all --force --filter label=org.opencontainers.image.title=traefik", output
+      assert_match "docker container stop kamal-proxy", output
+      assert_match "docker container prune --force --filter label=org.opencontainers.image.title=kamal-proxy", output
+      assert_match "docker run --name kamal-proxy --detach --restart unless-stopped --publish 80:80 --publish 443:443 --volume /var/run/docker.sock:/var/run/docker.sock --volume kamal-proxy:/root/.config/kamal-proxy --log-opt max-size=\"10m\" #{Kamal::Configuration::Proxy::DEFAULT_IMAGE}", output
+      assert_match "docker exec kamal-proxy kamal-proxy deploy app-web --target \"172.1.0.2:80\"", output
+    end
+  end
+
   private
     def run_command(*command)
       stdouted { Kamal::Cli::Proxy.start([ *command, "-c", "test/fixtures/deploy_with_accessories.yml" ]) }