Scope the tar file name more tightly

Signed-off-by: Dominic Ayre <domayre@outlook.com>

cmd/dmverity-vhd/main.go

@@ -115,7 +115,7 @@ func fetchImageLayers(ctx *cli.Context) (layers []v1.Layer, err error) {
 			}
 			defer imageTarReader.Close()
 
-			tarFile, err := os.CreateTemp("", "image-tar")
+			tarFile, err := os.CreateTemp("", "dmverity-vhd-image-tar")
 			if err != nil {
 				return nil, fmt.Errorf("failed to create tar file: %w", err)
 			}
@@ -343,7 +343,7 @@ var rootHashVHDCommand = cli.Command{
 		}
 
 		for _, file := range files {
-			if strings.HasPrefix(file.Name(), "image-tar") {
+			if strings.HasPrefix(file.Name(), "dmverity-vhd-image-tar") {
 				err := os.Remove(filepath.Join(tempDir, file.Name()))
 				if err != nil {
 					return fmt.Errorf("failed to remove file %s: %w", file.Name(), err)

docker-ubuntu.dockerfile

@@ -0,0 +1,30 @@
+# Use Ubuntu as the base image
+FROM ubuntu:latest
+
+# Avoid prompts from apt
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Update apt and install dependencies
+RUN apt-get update && apt-get install -y \
+    apt-transport-https \
+    ca-certificates \
+    curl \
+    software-properties-common
+
+# Add Docker’s official GPG key
+RUN curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add -
+
+# Add the Docker apt repository
+RUN add-apt-repository \
+   "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
+   $(lsb_release -cs) \
+   stable"
+
+# Install Docker CE
+RUN apt-get update && apt-get install -y docker-ce docker-ce-cli containerd.io
+
+# Verify installation
+RUN docker --version
+
+# Set default command
+CMD ["bash"]