Wait for healthy containers in integration test

Rather than waiting 5 seconds and hoping for the best after we boot
docker compose, add docker healthchecks and wait for all the containers
to be healthy.

test/integration/deploy_test.rb

@@ -1,10 +1,11 @@
 require "net/http"
+require "test_helper"
 
 class DeployTest < ActiveSupport::TestCase
 
   setup do
     docker_compose "up --build --force-recreate -d"
-    sleep 5
+    wait_for_healthy
   end
 
   teardown do
@@ -20,12 +21,29 @@ class DeployTest < ActiveSupport::TestCase
   end
 
   private
-    def docker_compose(*commands)
-      system("cd test/integration && docker compose #{commands.join(" ")}")
+    def docker_compose(*commands, capture: false)
+      command = "docker compose #{commands.join(" ")}"
+      succeeded = false
+      if capture
+        result = stdouted { succeeded = system("cd test/integration && #{command}") }
+      else
+        succeeded = system("cd test/integration && #{command}")
+      end
+
+      raise "Command `#{command}` failed with error code `#{$?}`" unless succeeded
+      result
     end
 
-    def mrsk(*commands)
-      docker_compose("exec deployer mrsk #{commands.join(" ")}")
+    def deployer_exec(*commands, capture: false)
+      if capture
+        stdouted { docker_compose("exec deployer #{commands.join(" ")}") }
+      else
+        docker_compose("exec deployer #{commands.join(" ")}", capture: capture)
+      end
+    end
+
+    def mrsk(*commands, capture: false)
+      deployer_exec(:mrsk, *commands, capture: capture)
     end
 
     def assert_app_is_down
@@ -39,4 +57,12 @@ class DeployTest < ActiveSupport::TestCase
     def app_response
       Net::HTTP.get_response(URI.parse("http://localhost:12345"))
     end
+
+    def wait_for_healthy(timeout: 20)
+      timeout_at = Time.now + timeout
+      while docker_compose("ps -a | tail -n +2 | grep -v '(healthy)' | wc -l", capture: true) != "0"
+        raise "Container not healthy after #{timeout} seconds" if timeout_at < Time.now
+        sleep 0.1
+      end
+    end
 end