Merge pull request #40947 from samueldr/fix/34779

dockerTools: fixes extraCommands for mkRootLayer.

nixos/tests/docker-tools.nix

@@ -45,5 +45,11 @@ import ./make-test.nix ({ pkgs, ... }: {
       $docker->succeed("docker load --input='${pkgs.dockerTools.examples.onTopOfPulledImage}'");
       $docker->succeed("docker run --rm ontopofpulledimage hello");
       $docker->succeed("docker rmi ontopofpulledimage");
+
+      # Regression test for issue #34779
+      $docker->succeed("docker load --input='${pkgs.dockerTools.examples.runAsRootExtraCommands}'");
+      $docker->succeed("docker run --rm runasrootextracommands cat extraCommands");
+      $docker->succeed("docker run --rm runasrootextracommands cat runAsRoot");
+      $docker->succeed("docker rmi '${pkgs.dockerTools.examples.runAsRootExtraCommands.imageName}'");
     '';
 })

pkgs/build-support/docker/default.nix

@@ -352,7 +352,9 @@ rec {
     extraCommands ? ""
   }:
     # Generate an executable script from the `runAsRoot` text.
-    let runAsRootScript = shellScript "run-as-root.sh" runAsRoot;
+    let
+      runAsRootScript = shellScript "run-as-root.sh" runAsRoot;
+      extraCommandsScript = shellScript "extra-commands.sh" extraCommands;
     in runWithOverlay {
       name = "docker-layer-${name}";
 
@@ -390,7 +392,7 @@ rec {
       '';
 
       postUmount = ''
-        (cd layer; eval "${extraCommands}")
+        (cd layer; ${extraCommandsScript})
 
         echo "Packing layer..."
         mkdir $out

pkgs/build-support/docker/examples.nix

@@ -124,4 +124,16 @@ rec {
     fromImage = nixFromDockerHub;
     contents = [ pkgs.hello ];
   };
+
+  # 8. regression test for erroneous use of eval and string expansion.
+  # See issue #34779 and PR #40947 for details.
+  runAsRootExtraCommands = pkgs.dockerTools.buildImage {
+    name = "runAsRootExtraCommands";
+    contents = [ pkgs.coreutils ];
+    # The parens here are to create problematic bash to embed and eval. In case
+    # this is *embedded* into the script (with nix expansion) the initial quotes
+    # will close the string and the following parens are unexpected
+    runAsRoot = ''echo "(runAsRoot)" > runAsRoot'';
+    extraCommands = ''echo "(extraCommand)" > extraCommands'';
+  };
 }