Detect ImageMagick and add to Docker images

Dockerfile

@@ -64,7 +64,7 @@ RUN mix release
 # the compiled release and other runtime necessities
 FROM ${RUNNER_IMAGE}
 
-RUN apt-get update -y && apt-get install -y curl libstdc++6 openssl locales ghostscript default-jre libreoffice-java-common \
+RUN apt-get update -y && apt-get install -y curl libstdc++6 openssl locales ghostscript imagemagick default-jre libreoffice-java-common \
   && apt-get install -y libreoffice --no-install-recommends && apt-get clean && rm -f /var/lib/apt/lists/*_*
 # RUN apk add --no-cache curl libstdc++ openssl ncurses ghostscript openjdk11-jre
 

Dockerfile.dev

@@ -37,6 +37,7 @@ RUN apt-get update && apt-get install -y \
     libtool \
     openjdk-11-jdk \
     ghostscript \
+    imagemagick \
     libreoffice \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*

lib/claper/tasks/converter.ex

@@ -8,6 +8,8 @@ defmodule Claper.Tasks.Converter do
   alias Claper.Presentations.PresentationFile
   alias Porcelain.Result
 
+  @imagemagick_commands ~w(magick convert convert-im6.q16)
+
   @doc """
   Convert the presentation file to images.
   We use original hash :erlang.phash2(code-name) where the files are uploaded to send it to another folder with a new hash. This last stored in db.
@@ -157,17 +159,14 @@ defmodule Claper.Tasks.Converter do
 
     files = Path.wildcard("#{path}/*.jpg")
 
-    if Enum.empty?(files) do
-      {:error, :missing_slides}
-    else
+    with [_ | _] <- files,
+         {:ok, imagemagick_command} <- get_imagemagick_command() do
       result =
         Enum.reduce_while(files, :ok, fn file, _acc ->
           thumb_path = Path.join(thumbs_dir, Path.basename(file))
 
-          # Generate thumbnail with 200px width, maintaining aspect ratio
-          # Using "magick" for ImageMagick v7+ compatibility
           case Porcelain.exec(
-                 "magick",
+                 imagemagick_command,
                  [
                    file,
                    "-resize",
@@ -187,6 +186,16 @@ defmodule Claper.Tasks.Converter do
       end
 
       result
+    else
+      [] -> {:error, :missing_slides}
+      {:error, _reason} = error -> error
+    end
+  end
+
+  defp get_imagemagick_command do
+    case Enum.find(@imagemagick_commands, &System.find_executable/1) do
+      nil -> {:error, :missing_imagemagick}
+      command -> {:ok, command}
     end
   end
 

test/claper/tasks/converter_test.exs

@@ -0,0 +1,104 @@
+defmodule Claper.Tasks.ConverterTest do
+  use ExUnit.Case, async: false
+
+  import ExUnit.CaptureIO
+
+  alias Claper.Presentations.PresentationFile
+  alias Claper.Tasks.Converter
+
+  describe "regenerate_thumbnails/1" do
+    test "uses convert when magick is unavailable" do
+      storage_dir = unique_tmp_dir()
+      hash = "convert-fallback"
+      slide_dir = Path.join([storage_dir, "uploads", hash])
+      bin_dir = Path.join(storage_dir, "bin")
+
+      File.mkdir_p!(slide_dir)
+      File.write!(Path.join(slide_dir, "1.jpg"), "slide")
+      File.mkdir_p!(bin_dir)
+      write_fake_imagemagick(bin_dir, "convert")
+
+      put_local_storage_config(storage_dir)
+      put_path(bin_dir)
+
+      presentation_file = %PresentationFile{hash: hash, length: 1}
+
+      output =
+        capture_io(fn -> assert :ok = Converter.regenerate_thumbnails(presentation_file) end)
+
+      assert output =~ "Generated 1 thumbnails"
+      assert File.read!(Path.join([slide_dir, "thumbs", "1.jpg"])) == "fake-thumbnail"
+    end
+
+    test "returns a clear error when ImageMagick is unavailable" do
+      storage_dir = unique_tmp_dir()
+      hash = "missing-imagemagick"
+      slide_dir = Path.join([storage_dir, "uploads", hash])
+      empty_bin_dir = Path.join(storage_dir, "empty-bin")
+
+      File.mkdir_p!(slide_dir)
+      File.write!(Path.join(slide_dir, "1.jpg"), "slide")
+      File.mkdir_p!(empty_bin_dir)
+
+      put_local_storage_config(storage_dir)
+      put_path(empty_bin_dir)
+
+      assert {:error, :missing_imagemagick} =
+               Converter.regenerate_thumbnails(%PresentationFile{hash: hash, length: 1})
+    end
+  end
+
+  defp write_fake_imagemagick(bin_dir, command) do
+    path = Path.join(bin_dir, command)
+
+    File.write!(path, """
+    #!/bin/sh
+    last=""
+
+    for arg in "$@"; do
+      last="$arg"
+    done
+
+    printf fake-thumbnail > "$last"
+    """)
+
+    File.chmod!(path, 0o755)
+  end
+
+  defp put_local_storage_config(storage_dir) do
+    previous_storage_dir = Application.get_env(:claper, :storage_dir)
+    previous_presentations = Application.get_env(:claper, :presentations)
+
+    Application.put_env(:claper, :storage_dir, storage_dir)
+
+    Application.put_env(
+      :claper,
+      :presentations,
+      Keyword.merge(previous_presentations || [], storage: "local")
+    )
+
+    on_exit(fn ->
+      File.rm_rf!(storage_dir)
+      Application.put_env(:claper, :storage_dir, previous_storage_dir)
+      Application.put_env(:claper, :presentations, previous_presentations)
+    end)
+  end
+
+  defp put_path(path) do
+    previous_path = System.get_env("PATH")
+
+    System.put_env("PATH", path)
+
+    on_exit(fn ->
+      if previous_path do
+        System.put_env("PATH", previous_path)
+      else
+        System.delete_env("PATH")
+      end
+    end)
+  end
+
+  defp unique_tmp_dir do
+    Path.join(System.tmp_dir!(), "claper-converter-test-#{System.unique_integer([:positive])}")
+  end
+end