Enable packaging of curl|bash and other wild stuff.

For #1853

lib/fpm/package/curlbash.rb

@@ -0,0 +1,34 @@
+
+class FPM::Package::CurlBash < FPM::Package
+
+  option "--container-image", "IMAGE", "The container image to use when running the command", :default => "ubuntu:latest"
+
+  option "--setup", "SHELL COMMANDS", "Commands to run but not to include in the resulting package. For example, 'apt-get update' or other setup.", :multivalued => true
+
+  def input(command)
+    name = "whatever-#{$$}"
+
+    content = template("curlbash.erb").result(binding)
+    containerfile = build_path("Containerfile")
+    File.write(containerfile, content)
+
+    safesystem("podman", "image", "build", "-t", name, build_path)
+
+    # Convert the container to a image layer tarball.
+    changes_tar = build_path("changes.tar")
+    safesystem("podman", "save", name, "-o", changes_tar)
+
+    last_layer = nil
+    execmd(["podman", "inspect", name], :stdin => false, :stdout =>true) do |stdout|
+      inspection = JSON.parse(stdout.read)
+      stdout.close
+      last_layer = inspection[0]["RootFS"]["Layers"][-1]
+    end
+
+    layerdir = build_path("layers")
+    safesystem("podman", "save", "--format", "docker-dir", "--output", layerdir, name)
+
+    # Extract the last layer to the staging_path for packaging.
+    safesystem("tar", "-C", staging_path, "-xf", build_path(File.join("layers", last_layer.gsub(/^sha256:/, ""))))
+  end
+end

templates/curlbash.erb

@@ -0,0 +1,7 @@
+FROM <%= attributes[:curlbash_container_image] %>
+
+<% attributes[:curlbash_setup_list].each do |step| %>
+RUN <%= step %>
+<% end %>
+
+RUN <%= command %>