feat: add new option - wait_after_healthy

This is a port of <wowu/docker-rollout#28>.

lib/docker_compizo.ex

@@ -18,7 +18,7 @@ defmodule DockerCompizo do
 
     opts = Keyword.merge(Default.options(), opts)
     compose_file = Keyword.fetch!(opts, :compose_file)
-    scale_opts = Keyword.take(opts, [:healthcheck_timeout, :no_healthcheck_timeout])
+    scale_opts = Keyword.take(opts, [:healthcheck_timeout, :no_healthcheck_timeout, :wait_after_healthy])
 
     context = %Context{
       docker_bin: System.find_executable("docker"),
@@ -98,7 +98,8 @@ defmodule DockerCompizo do
     deploy_opts = [
       is_healthcheck_supported?: is_healthcheck_supported?(context, service),
       healthcheck_timeout: Keyword.fetch!(opts, :healthcheck_timeout),
-      no_healthcheck_timeout: Keyword.fetch!(opts, :no_healthcheck_timeout)
+      no_healthcheck_timeout: Keyword.fetch!(opts, :no_healthcheck_timeout),
+      wait_after_healthy: Keyword.fetch!(opts, :wait_after_healthy)
     ]
 
     running_services = Compose.list_running_services(context)

lib/docker_compizo/default.ex

@@ -7,7 +7,16 @@ defmodule DockerCompizo.Default do
     [
       compose_file: Path.expand("compose.yaml", File.cwd!()),
       healthcheck_timeout: 60,
-      no_healthcheck_timeout: 10
+      no_healthcheck_timeout: 10,
+      # Q: Why do we need this option?
+      # A: When using a reverse proxy, such as Traefik, the reverse proxy could have their
+      #    own logic to detect containers and route traffics to new container. If we kill
+      #    the old containers immediately, it will lead to disruption of service.
+      #
+      #    Because of that, it's better to add additional timeout to destroy old containers.
+      #    This will give the new containers time to settle down, and a reverse proxy to
+      #    routes traffics to new containers.
+      wait_after_healthy: 10
     ]
   end
 end

lib/docker_compizo/strategy/blue_green.ex

@@ -7,7 +7,8 @@ defmodule DockerCompizo.Strategy.BlueGreen do
   def deploy(context, service,
         is_healthcheck_supported?: is_healthcheck_supported?,
         healthcheck_timeout: healthcheck_timeout,
-        no_healthcheck_timeout: no_healthcheck_timeout
+        no_healthcheck_timeout: no_healthcheck_timeout,
+        wait_after_healthy: wait_after_healthy
       ) do
     Helper.report("Deploying '#{service}' service with Blue/Green strategy")
 
@@ -30,6 +31,9 @@ defmodule DockerCompizo.Strategy.BlueGreen do
       Helper.report("Waiting for new containers to be healthy (timeout: #{healthcheck_timeout} seconds)")
 
       if Container.check_health_util_timeout(context, new_containers, healthcheck_timeout) do
+        Helper.report("New containers are healthy, wait #{wait_after_healthy} seconds more")
+        Process.sleep(:timer.seconds(wait_after_healthy))
+
         Helper.report("Cleaning old containers")
         Container.destroy(context, old_containers)