Merge pull request #80068 from jbedo/docker

dockerTools: fix export

nixos/tests/docker-tools.nix

@@ -378,5 +378,10 @@ import ./make-test-python.nix ({ pkgs, ... }: {
         docker.succeed(
             "docker run --rm ${examples.layeredImageWithFakeRootCommands.imageName} sh -c 'stat -c '%u' /home/jane | grep -E ^1000$'"
         )
+
+    with subtest("exportImage produces a valid tarball"):
+        docker.succeed(
+            "tar -tf ${examples.exportBash} | grep '\./bin/bash' > /dev/null"
+        )
   '';
 })

pkgs/build-support/docker/default.nix

@@ -191,13 +191,13 @@ rec {
     , postMount ? ""
     , postUmount ? ""
     }:
-    let
-      result = vmTools.runInLinuxVM (
+      vmTools.runInLinuxVM (
         runCommand name
           {
             preVM = vmTools.createEmptyImage {
               size = diskSize;
               fullName = "docker-run-disk";
+              destination = "./image";
             };
             inherit fromImage fromImageName fromImageTag;
 
@@ -278,12 +278,6 @@ rec {
 
           ${postUmount}
         '');
-    in
-    runCommand name { } ''
-      mkdir -p $out
-      cd ${result}
-      cp layer.tar json VERSION $out
-    '';
 
   exportImage = { name ? fromImage.name, fromImage, fromImageName ? null, fromImageTag ? null, diskSize ? 1024 }:
     runWithOverlay {
@@ -291,7 +285,13 @@ rec {
 
       postMount = ''
         echo "Packing raw image..."
-        tar -C mnt --hard-dereference --sort=name --mtime="@$SOURCE_DATE_EPOCH" -cf $out .
+        tar -C mnt --hard-dereference --sort=name --mtime="@$SOURCE_DATE_EPOCH" -cf $out/layer.tar .
+      '';
+
+      postUmount = ''
+        mv $out/layer.tar .
+        rm -rf $out
+        mv layer.tar $out
       '';
     };
 

pkgs/build-support/docker/examples.nix

@@ -541,4 +541,7 @@ rec {
     config.Cmd = [ "hello" ];
     includeStorePaths = false;
   };
+
+  # Example export of the bash image
+  exportBash = pkgs.dockerTools.exportImage { fromImage = bash; };
 }

pkgs/build-support/vm/default.nix

@@ -257,14 +257,23 @@ rec {
     eval "$postVM"
   '';
 
-
-  createEmptyImage = {size, fullName}: ''
-    mkdir $out
-    diskImage=$out/disk-image.qcow2
+  /*
+    A bash script fragment that produces a disk image at `destination`.
+   */
+  createEmptyImage = {
+    # Disk image size in MiB
+    size,
+    # Name that will be written to ${destination}/nix-support/full-name
+    fullName,
+    # Where to write the image files, defaulting to $out
+    destination ? "$out"
+  }: ''
+    mkdir -p ${destination}
+    diskImage=${destination}/disk-image.qcow2
     ${qemu}/bin/qemu-img create -f qcow2 $diskImage "${toString size}M"
 
-    mkdir $out/nix-support
-    echo "${fullName}" > $out/nix-support/full-name
+    mkdir ${destination}/nix-support
+    echo "${fullName}" > ${destination}/nix-support/full-name
   '';