More OG image tweaks

lib/jola_dev/og_image.ex

@@ -17,13 +17,28 @@ defmodule JolaDev.OGImage do
                 {slug, Renderer.generate_bytes(title, description)}
               end)
 
+  @default_image (
+                   {title, description} = Catalog.content_for("home")
+                   Renderer.generate_bytes(title, description)
+                 )
+
   @doc """
   Returns the public asset path for a slug's OG image. Used so the
   path scheme stays consistent.
   """
   def path_for(slug) when is_binary(slug), do: "/images/og/#{slug}.png"
 
   def image_for(slug) do
+    with :error <- image_for_slug(slug) do
+      {:ok, @default_image}
+    end
+  end
+
+  def default_image do
+    @default_image
+  end
+
+  defp image_for_slug(slug) do
     if @images do
       Map.fetch(@images, slug)
     else

lib/jola_dev_web/components/layouts/root.html.heex

@@ -27,12 +27,7 @@
     <meta property="og:type" content={if(@conn.assigns[:post], do: "article", else: "website")} />
     <meta
       property="og:image"
-      content={
-        Phoenix.VerifiedRoutes.unverified_url(
-          JolaDevWeb.Endpoint,
-          @conn.assigns[:og_image] || "/images/og-image.png"
-        )
-      }
+      content={JolaDevWeb.Helpers.OGImage.url_for(@conn)}
     />
     <meta property="og:image:type" content="image/png" />
     <meta property="og:image:width" content="1200" />
@@ -63,12 +58,7 @@
     />
     <meta
       name="twitter:image"
-      content={
-        Phoenix.VerifiedRoutes.unverified_url(
-          JolaDevWeb.Endpoint,
-          @conn.assigns[:og_image] || "/images/og-image.png"
-        )
-      }
+      content={JolaDevWeb.Helpers.OGImage.url_for(@conn)}
     />
     <meta name="twitter:image:alt" content={@conn.assigns[:page_title] || "jola.dev"} />
     <%= unless @conn.status && @conn.status >= 400 do %>
@@ -98,7 +88,7 @@
     </script>
     <link rel="icon" href="/favicon.ico" sizes="any" />
     <link rel="apple-touch-icon" href="/apple-touch-icon.png" />
-    <%= for schema <- JolaDevWeb.SEO.json_ld(@conn) do %>
+    <%= for schema <- JolaDevWeb.Helpers.SEO.json_ld(@conn) do %>
       <script type="application/ld+json">
         <%= raw(Jason.encode!(schema)) %>
       </script>

lib/jola_dev_web/controllers/blog_controller.ex

@@ -8,8 +8,7 @@ defmodule JolaDevWeb.BlogController do
       posts: posts,
       page_title: "Blog | jola.dev",
       meta_description:
-        "Blog posts by Johanna Larsson on software engineering, Elixir, and engineering leadership.",
-      og_image: JolaDev.OGImage.path_for("posts")
+        "Blog posts by Johanna Larsson on software engineering, Elixir, and engineering leadership."
     )
   end
 
@@ -27,8 +26,7 @@ defmodule JolaDevWeb.BlogController do
         tag: tag,
         noindex: true,
         page_title: "Posts tagged \"#{tag}\" | jola.dev",
-        meta_description: "Blog posts by Johanna Larsson tagged with #{tag}.",
-        og_image: JolaDev.OGImage.path_for("posts/tag/#{tag}")
+        meta_description: "Blog posts by Johanna Larsson tagged with #{tag}."
       )
     end
   end
@@ -39,8 +37,7 @@ defmodule JolaDevWeb.BlogController do
         post: post,
         related_posts: JolaDev.Blog.recent_posts(post),
         page_title: "#{post.title} | jola.dev",
-        meta_description: post.description,
-        og_image: JolaDev.OGImage.path_for("posts/#{post.id}")
+        meta_description: post.description
       )
     else
       conn

lib/jola_dev_web/controllers/page_controller.ex

@@ -8,7 +8,6 @@ defmodule JolaDevWeb.PageController do
       page_title: "Johanna Larsson — Software Engineer & Speaker",
       meta_description:
         "Johanna Larsson is a software engineer, engineering leader, writer, and speaker with many years of experience building products and leading teams.",
-      og_image: JolaDev.OGImage.path_for("home"),
       recent_posts: recent_posts
     )
   end
@@ -18,7 +17,6 @@ defmodule JolaDevWeb.PageController do
       page_title: "About | jola.dev",
       meta_description:
         "About Johanna Larsson — software engineer, engineering leader, writer, and speaker with many years of experience.",
-      og_image: JolaDev.OGImage.path_for("about"),
       page_type: :about
     )
   end
@@ -27,17 +25,15 @@ defmodule JolaDevWeb.PageController do
     render(conn, :projects,
       page_title: "Projects | jola.dev",
       meta_description:
-        "Open source projects by Johanna Larsson, including HexDiff, ElixirEvents, and more.",
-      og_image: JolaDev.OGImage.path_for("projects")
+        "Open source projects by Johanna Larsson, including HexDiff, ElixirEvents, and more."
     )
   end
 
   def talks(conn, _params) do
     render(conn, :talks,
       page_title: "Talks | jola.dev",
       meta_description:
-        "Conference talks and presentations by Johanna Larsson on Elixir, distributed systems, and engineering leadership.",
-      og_image: JolaDev.OGImage.path_for("talks")
+        "Conference talks and presentations by Johanna Larsson on Elixir, distributed systems, and engineering leadership."
     )
   end
 end

lib/jola_dev_web/helpers/og_image.ex

@@ -0,0 +1,14 @@
+defmodule JolaDevWeb.Helpers.OGImage do
+  @moduledoc """
+  Builds URLs for OG images from assigns and falls back to request_path.
+  """
+  use JolaDevWeb, :verified_routes
+
+  def url_for(%{assigns: %{post: post}}), do: build("posts/#{post.id}")
+  def url_for(%{assigns: %{tag: tag}}), do: build("posts/tag/#{tag}")
+  def url_for(%{request_path: "/"}), do: build("home")
+  def url_for(%{request_path: "/" <> rest}), do: build(rest)
+
+  defp build(slug),
+    do: unverified_url(JolaDevWeb.Endpoint, JolaDev.OGImage.path_for(slug))
+end

lib/jola_dev_web/helpers/seo.ex

@@ -1,4 +1,4 @@
-defmodule JolaDevWeb.SEO do
+defmodule JolaDevWeb.Helpers.SEO do
   @moduledoc """
   Generates JSON-LD structured data for search engines and AI systems.
   """

lib/jola_dev_web/plugs/og_image.ex

@@ -2,8 +2,7 @@ defmodule JolaDevWeb.Plugs.OGImage do
   @moduledoc """
   Serves Open Graph preview images from `JolaDev.OGImage`. Intercepts any
   `/images/og/<slug>.png` request, looks up the baked PNG bytes, and sends
-  them with appropriate cache headers. Falls through for unknown slugs so
-  Phoenix's router can render a 404.
+  them with appropriate cache headers.
   """
 
   @behaviour Plug
@@ -20,18 +19,13 @@ defmodule JolaDevWeb.Plugs.OGImage do
   def call(%Plug.Conn{request_path: "/images/og/" <> rest} = conn, _) do
     slug = String.replace_suffix(rest, ".png", "")
 
-    case JolaDev.OGImage.image_for(slug) do
-      {:ok, bytes} ->
-        conn
-        |> put_resp_content_type("image/png")
-        |> put_resp_header("cache-control", @cache_control)
-        |> send_resp(200, bytes)
-        |> halt()
-
-      :error ->
-        # Let the request fall through so Phoenix handles the 404
-        conn
-    end
+    {:ok, bytes} = JolaDev.OGImage.image_for(slug)
+
+    conn
+    |> put_resp_content_type("image/png")
+    |> put_resp_header("cache-control", @cache_control)
+    |> send_resp(200, bytes)
+    |> halt()
   end
 
   def call(conn, _), do: conn

test/jola_dev/og_image_test.exs

@@ -31,7 +31,7 @@ defmodule JolaDev.OGImageTest do
     end
 
     test "returns :error for an unknown slug" do
-      assert OGImage.image_for("no-such-page") == :error
+      assert OGImage.image_for("no-such-page") == {:ok, OGImage.default_image()}
     end
   end
 end

test/jola_dev_web/helpers/seo_test.exs

@@ -1,10 +1,12 @@
-defmodule JolaDevWeb.SEOTest do
+defmodule JolaDevWeb.Helpers.SEOTest do
   use JolaDevWeb.ConnCase, async: true
 
+  alias JolaDevWeb.Helpers.SEO
+
   describe "json_ld/1" do
     test "includes WebSite schema on all pages", %{conn: conn} do
       conn = get(conn, ~p"/")
-      schemas = JolaDevWeb.SEO.json_ld(conn)
+      schemas = SEO.json_ld(conn)
 
       website = Enum.find(schemas, &(&1["@type"] == "WebSite"))
       assert website["name"] == "jola.dev"
@@ -14,7 +16,7 @@ defmodule JolaDevWeb.SEOTest do
     test "includes BlogPosting schema on blog post pages", %{conn: conn} do
       post = List.first(JolaDev.Blog.all_posts())
       conn = get(conn, ~p"/posts/#{post.id}")
-      schemas = JolaDevWeb.SEO.json_ld(conn)
+      schemas = SEO.json_ld(conn)
 
       blog_posting = Enum.find(schemas, &(&1["@type"] == "BlogPosting"))
       assert blog_posting["headline"] == post.title
@@ -30,7 +32,7 @@ defmodule JolaDevWeb.SEOTest do
 
     test "includes ProfilePage schema on about page", %{conn: conn} do
       conn = get(conn, ~p"/about")
-      schemas = JolaDevWeb.SEO.json_ld(conn)
+      schemas = SEO.json_ld(conn)
 
       profile = Enum.find(schemas, &(&1["@type"] == "ProfilePage"))
       assert profile["mainEntity"]["@type"] == "Person"
@@ -40,21 +42,21 @@ defmodule JolaDevWeb.SEOTest do
 
     test "does not include BlogPosting on non-post pages", %{conn: conn} do
       conn = get(conn, ~p"/projects")
-      schemas = JolaDevWeb.SEO.json_ld(conn)
+      schemas = SEO.json_ld(conn)
 
       refute Enum.any?(schemas, &(&1["@type"] == "BlogPosting"))
     end
 
     test "omits BreadcrumbList on the home page", %{conn: conn} do
       conn = get(conn, ~p"/")
-      schemas = JolaDevWeb.SEO.json_ld(conn)
+      schemas = SEO.json_ld(conn)
 
       refute Enum.any?(schemas, &(&1["@type"] == "BreadcrumbList"))
     end
 
     test "includes BreadcrumbList on /about", %{conn: conn} do
       conn = get(conn, ~p"/about")
-      schemas = JolaDevWeb.SEO.json_ld(conn)
+      schemas = SEO.json_ld(conn)
 
       breadcrumb = Enum.find(schemas, &(&1["@type"] == "BreadcrumbList"))
 
@@ -77,7 +79,7 @@ defmodule JolaDevWeb.SEOTest do
     test "includes BreadcrumbList with post title on post pages", %{conn: conn} do
       post = List.first(JolaDev.Blog.all_posts())
       conn = get(conn, ~p"/posts/#{post.id}")
-      schemas = JolaDevWeb.SEO.json_ld(conn)
+      schemas = SEO.json_ld(conn)
 
       breadcrumb = Enum.find(schemas, &(&1["@type"] == "BreadcrumbList"))
       items = breadcrumb["itemListElement"]
@@ -90,7 +92,7 @@ defmodule JolaDevWeb.SEOTest do
     test "includes BreadcrumbList with tag on tag pages", %{conn: conn} do
       tag = "elixir"
       conn = get(conn, ~p"/posts/tag/#{tag}")
-      schemas = JolaDevWeb.SEO.json_ld(conn)
+      schemas = SEO.json_ld(conn)
 
       breadcrumb = Enum.find(schemas, &(&1["@type"] == "BreadcrumbList"))
       items = breadcrumb["itemListElement"]

test/jola_dev_web/plugs/og_image_test.exs

@@ -39,13 +39,13 @@ defmodule JolaDevWeb.Plugs.OGImageTest do
       assert <<137, "PNG\r\n", 26, "\n", _rest::binary>> = conn.resp_body
     end
 
-    test "falls through for an unknown OG slug", %{conn: conn} do
+    test "returns default image for an unknown OG slug", %{conn: conn} do
       original = Map.put(conn, :request_path, "/images/og/no-such-page.png")
 
       result = OGImage.call(original, [])
 
-      assert result == original
-      refute result.halted
+      assert result.status == 200
+      assert <<137, "PNG\r\n", 26, "\n", _rest::binary>> = result.resp_body
     end
 
     test "passes through for paths outside /images/og/", %{conn: conn} do