Zero downtime redeploys

When deploying check if there is already a container with the existing
name. If there is rename it to "<version>_<random_hex_string>" to remove
the name clash with the new container we want to boot.

We can then do the normal zero downtime run/wait/stop.

While implementing this I discovered the --filter name=foo does a
substring match for foo, so I've updated those filters to do an exact
match instead.

lib/mrsk/cli/app.rb

@@ -15,22 +15,17 @@ class Mrsk::Cli::App < Mrsk::Cli::Base
             execute *MRSK.auditor(role: role).record("Booted app version #{version}"), verbosity: :debug
 
             begin
+              if capture_with_info(*MRSK.app(role: role).container_id_for_version(version)).present?
+                tmp_version = "#{version}_#{SecureRandom.hex(8)}"
+                info "Renaming container #{version} to #{tmp_version} as already deployed on #{host}"
+                execute *MRSK.auditor(role: role).record("Renaming container #{version} to #{tmp_version}"), verbosity: :debug
+                execute *MRSK.app(role: role).rename_container(version: version, new_version: tmp_version)
+              end
+
               old_version = capture_with_info(*MRSK.app(role: role).current_running_version).strip
               execute *MRSK.app(role: role).run
               sleep MRSK.config.readiness_delay
               execute *MRSK.app(role: role).stop(version: old_version), raise_on_non_zero_exit: false if old_version.present?
-
-            rescue SSHKit::Command::Failed => e
-              if e.message =~ /already in use/
-                error "Rebooting container with same version #{version} already deployed on #{host} (may cause gap in zero-downtime promise!)"
-                execute *MRSK.auditor(role: role).record("Rebooted app version #{version}"), verbosity: :debug
-
-                execute *MRSK.app(role: role).stop(version: version)
-                execute *MRSK.app(role: role).remove_container(version: version)
-                execute *MRSK.app(role: role).run
-              else
-                raise
-              end
             end
           end
         end

lib/mrsk/commands/app.rb

@@ -86,6 +86,10 @@ class Mrsk::Commands::App < Mrsk::Commands::Base
     docker :ps, "--quiet", *filter_args
   end
 
+  def container_id_for_version(version)
+    container_id_for(container_name: container_name(version))
+  end
+
   def current_running_version
     # FIXME: Find more graceful way to extract the version from "app-version" than using sed and tail!
     pipe \
@@ -108,6 +112,10 @@ class Mrsk::Commands::App < Mrsk::Commands::Base
       xargs(docker(:container, :rm))
   end
 
+  def rename_container(version:, new_version:)
+    docker :rename, container_name(version), container_name(new_version)
+  end
+
   def remove_containers
     docker :container, :prune, "--force", *filter_args
   end
@@ -126,10 +134,6 @@ class Mrsk::Commands::App < Mrsk::Commands::Base
       [ config.service, role, config.destination, version || config.version ].compact.join("-")
     end
 
-    def container_id_for_version(version)
-      container_id_for(container_name: container_name(version))
-    end
-
     def filter_args
       argumentize "--filter", filters
     end

lib/mrsk/commands/base.rb

@@ -16,7 +16,7 @@ module Mrsk::Commands
     end
 
     def container_id_for(container_name:)
-      docker :container, :ls, "--all", "--filter", "name=#{container_name}", "--quiet"
+      docker :container, :ls, "--all", "--filter", "name=^#{container_name}$", "--quiet"
     end
 
     private

lib/mrsk/commands/healthcheck.rb

@@ -43,7 +43,7 @@ class Mrsk::Commands::Healthcheck < Mrsk::Commands::Base
     end
 
     def container_id
-      container_id_for(container_name: container_name)
+      container_id_for(container_name: container_name_with_version)
     end
 
     def health_url

lib/mrsk/commands/traefik.rb

@@ -26,7 +26,7 @@ class Mrsk::Commands::Traefik < Mrsk::Commands::Base
   end
 
   def info
-    docker :ps, "--filter", "name=traefik"
+    docker :ps, "--filter", "name=^traefik$"
   end
 
   def logs(since: nil, lines: nil, grep: nil)