Allow expressing the port to use when proxying the application

In order to properly load balance instances of a given application with
Traefik is better to configure the port used to expose the service.

Generally Traefik can deduct that based on different critieria but
fixing it is probably the most deterministic behaviour and it also
doesn't require the container to actively expose anything on the host
directly.

Author: pmarino90

.formatter.exs

@@ -10,7 +10,7 @@ locals_without_parens = [
   env: 2,
   expose_port: 2,
   proxy: 1,
-  publish_on_domain: 1
+  publish_on_domain: 2
 ]
 
 [

lib/makina/docker.ex

@@ -170,21 +170,11 @@ defmodule Makina.Docker do
       "traefik.http.middlewares.#{app_name(app)}.compress=true",
       "traefik.http.routers.#{app_name(app)}.rule=\"#{format_domains(domains)}\"",
       "traefik.http.routers.#{app_name(app)}.tls.certresolver=letsencrypt",
-      "traefik.http.services.#{app_name(app)}.loadBalancer.server.port=#{first_exposed_port(app)}"
+      "traefik.http.services.#{app_name(app)}.loadBalancer.server.port=#{app.load_balancing_port}"
     ]
   end
 
   defp format_domains(domains) when is_list(domains) do
     domains |> Enum.map_join(" || ", fn d -> "Host(\\`#{d}\\`)" end)
   end
-
-  defp first_exposed_port(%Application{exposed_ports: []}) do
-    "8080"
-  end
-
-  defp first_exposed_port(%Application{} = app) do
-    port_pair = app.exposed_ports |> List.first()
-
-    port_pair.external
-  end
 end

lib/makina/dsl/app.ex

@@ -131,6 +131,7 @@ defmodule Makina.DSL.App do
     end
   end
 
+  @publish_on_domain_opts [from_port: [type: :pos_integer, required: true]]
   @doc """
     Exposes the app on the given domain
     Can be invoked multiple times or with a list;
@@ -152,27 +153,65 @@ defmodule Makina.DSL.App do
   makina "example" do
     app name: "foo" do
 
-    publish_on_domain ["example.com", "www.example.com"]
+    publish_on_domain ["example.com", "www.example.com"], from_port: 80
 
     end
   end
   """
-  defmacro publish_on_domain(domain) when is_binary(domain) do
-    quote bind_quoted: [domain: domain] do
-      @current_application Application.put_domain(
-                             @current_application,
-                             domain
-                           )
+  defmacro publish_on_domain(domain, opts) when is_binary(domain) do
+    schema = @publish_on_domain_opts
+
+    quote bind_quoted: [domain: domain, schema: schema, opts: opts] do
+      validation = NimbleOptions.validate(opts, schema)
+
+      case validation do
+        {:ok, opts} ->
+          @current_application Application.put_domain(
+                                 @current_application,
+                                 domain
+                               )
+
+          @current_application Application.set_load_balancing_port(
+                                 @current_application,
+                                 opts[:from_port]
+                               )
+
+        {:error, error} ->
+          raise """
+            The parameters provided to the `publish_on_domain` statement are not correct:
+
+            #{Exception.message(error)}
+          """
+      end
     end
   end
 
-  defmacro publish_on_domain(domains) when is_list(domains) do
-    quote bind_quoted: [domains: domains] do
-      for d <- domains do
-        @current_application Application.put_domain(
-                               @current_application,
-                               d
-                             )
+  defmacro publish_on_domain(domains, opts) when is_list(domains) do
+    schema = @publish_on_domain_opts
+
+    quote bind_quoted: [domains: domains, opts: opts, schema: schema] do
+      validation = NimbleOptions.validate(opts, schema)
+
+      case validation do
+        {:ok, opts} ->
+          for d <- domains do
+            @current_application Application.put_domain(
+                                   @current_application,
+                                   d
+                                 )
+          end
+
+          @current_application Application.set_load_balancing_port(
+                                 @current_application,
+                                 opts[:from_port]
+                               )
+
+        {:error, error} ->
+          raise """
+            The parameters provided to the `publish_on_domain` statement are not correct:
+
+            #{Exception.message(error)}
+          """
       end
     end
   end

lib/makina/dsl/utils.ex

@@ -1,12 +1,6 @@
 defmodule Makina.DSL.Utils do
   @moduledoc false
 
-  def unset_wrapping_context() do
-    quote do
-      Module.delete_attribute(__MODULE__, :wrapping_context)
-    end
-  end
-
   def set_scope(scope) when is_list(scope) do
     for s <- scope do
       set_scope(s)

lib/makina/models/application.ex

@@ -32,7 +32,7 @@ defmodule Makina.Models.Application do
 
   alias Makina.Models.Internal
 
-  @hashable_keys ~w[name docker_image docker_registry env_vars volumes exposed_ports domains]a
+  @hashable_keys ~w[name docker_image docker_registry env_vars volumes exposed_ports domains load_balancing_port]a
 
   @derive {JSON.Encoder, []}
   defstruct __hash__: nil,
@@ -48,7 +48,8 @@ defmodule Makina.Models.Application do
             volumes: [],
             env_vars: [],
             exposed_ports: [],
-            domains: []
+            domains: [],
+            load_balancing_port: nil
 
   def new(opts) do
     app = struct(__MODULE__, opts)
@@ -99,6 +100,12 @@ defmodule Makina.Models.Application do
     set_private(app, :__hash__, hash(app))
   end
 
+  def set_load_balancing_port(%__MODULE__{} = app, port) do
+    app = %__MODULE__{app | load_balancing_port: port}
+
+    set_private(app, :__hash__, hash(app))
+  end
+
   def private_docker_registry?(%__MODULE__{docker_registry: nil}) do
     false
   end

mix.exs

@@ -4,7 +4,7 @@ defmodule Makina.MixProject do
   def project do
     [
       app: :makina,
-      version: "0.1.0",
+      version: "0.1.11",
       elixir: "~> 1.18",
       start_permanent: Mix.env() == :prod,
       deps: deps(),

test/makina/dsl_test.exs

@@ -172,6 +172,29 @@ defmodule Makina.DSLTest do
       assert port == %{internal: 80, external: 8080}
     end
 
+    test "lets the user expose an app with domains" do
+      import Makina.DSL
+
+      term =
+        makina "app-test-specify-domain" do
+          standalone do
+            app name: "test" do
+              publish_on_domain(["example.com"], from_port: 80)
+            end
+          end
+        end
+
+      module = elem(term, 1)
+      context = module.collect_context()
+
+      app = List.first(context.standalone_applications)
+
+      assert is_list(app.domains)
+
+      assert app.domains == ["example.com"]
+      assert app.load_balancing_port == 80
+    end
+
     test "raises if app block is not invoked correctly" do
       import DSL
 

test/makina/models/application_test.exs

@@ -110,15 +110,27 @@ defmodule Makina.Models.ApplicationTest do
       app = Application.new(params)
       init_hash = app.__hash__
 
-      assert app.env_vars == []
-
       app = app |> Application.put_domain("example.com")
 
       assert app.domains == ["example.com"]
       assert app.__hash__ != init_hash
     end
   end
 
+  describe "set_load_balancing_port/2" do
+    test "sets the port used by the proxy load balancer" do
+      params = [name: "foo"]
+
+      app = Application.new(params)
+      init_hash = app.__hash__
+
+      app = app |> Application.set_load_balancing_port(8080)
+
+      assert app.load_balancing_port == 8080
+      assert app.__hash__ != init_hash
+    end
+  end
+
   describe "set_private/3" do
     test "sets private fields" do
       params = [name: "foo"]
@@ -130,7 +142,8 @@ defmodule Makina.Models.ApplicationTest do
 
       assert app.__docker__ == %{
                command: [],
-               labels: []
+               labels: [],
+               networks: []
              }
 
       app = Application.set_private(app, :__scope__, [:foo])

test/makina/models/docker_test.exs

@@ -20,7 +20,7 @@ defmodule Makina.Models.DockerTest do
 
       assert is_struct(cmd, Makina.Command)
 
-      assert cmd.cmd == "docker inspect foo"
+      assert cmd.cmd == "docker inspect --type=container foo"
       assert cmd.server == server
     end
   end
@@ -129,13 +129,13 @@ defmodule Makina.Models.DockerTest do
       app =
         Application.new(name: "foo")
         |> Application.set_docker_image(name: "nginx", tag: "1.16")
-        |> Application.put_exposed_port(internal: 80, external: 8080)
         |> Application.put_domain("example.com")
+        |> Application.set_load_balancing_port(80)
 
       cmd = Docker.run(server, app)
 
       assert cmd.cmd ==
-               "docker run -d --restart unless-stopped --name foo --label org.makina.app.hash=#{app.__hash__} --label traefik.enable=true --label traefik.http.middlewares.foo.compress=true --label traefik.http.routers.foo.rule=Host\\(\\`example.com\\`\\) --label traefik.http.routers.foo.tls.certresolver=letsencrypt --label traefik.http.services.foo.loadBalancer.server.port=8080 -p 8080:80 nginx:1.16"
+               "docker run -d --restart unless-stopped --name foo --label org.makina.app.hash=#{app.__hash__} --label traefik.enable=true --label traefik.http.middlewares.foo.compress=true --label traefik.http.routers.foo.rule=\"Host(\\`example.com\\`)\" --label traefik.http.routers.foo.tls.certresolver=letsencrypt --label traefik.http.services.foo.loadBalancer.server.port=80 --network makina-web-net nginx:1.16"
     end
   end