Nano template

This is a template for building your own Docker nano products using the provided Buildroot container. You can also reuse this template later to update your products after this template has received updates by merging in any changes.

Usage

Using the template is as simple as cloning this source and inserting your product's name into a few files, replacing the <product> placeholders, as outlined in the following steps.

1. Clone (git clone --recursive) this repository (forking is for updating the template itself).
2. Update settings with the name of your product.
   • NANO_IMAGE – The Buildroot image tag as listed in docker images.
   • NANO_CONTAINER – The Buildroot container name as listed in docker ps.
3. Follow the building instructions from the Buildroot repository making sure to pull your config and rootfs afterwards.
4. Add your name and email address to Dockerfile and uncomment the COPY line. Rebuild the image to ensure it still works.
5. Add your name and email address to product/Dockerfile and any other build steps required to configure your product.
6. Build your product with docker build -t nano/<product> product.
7. Test it with docker run -it --rm nano/<product> or similar.
8. Update .travis.yml test to check for the presence of your binary in the rootfs.
9. Replace this readme with the distributed one (mv README.md.dist README.md).
10. Update README.md and product/README.md so others know how to use your product.
11. Tell us! Get in touch with a member of the Docker nano team so we can add your product to the registry for others to use.

Following is information for advanced modifications that may be required.

Patching Buildroot

If you wish to make changes to Buildroot you can either copy files into place or create a patch by following the steps below. Prefer copying if you're adding new files and patching if you're changing existing files, so it's clear which changes have been made.

1. Copy the file – cp -bf file{,}.

2. Edit the file – editor file.

3. Create the patch – diff -u file{~,} > ~/buildroot/patches/my.patch. Ensure the patch name accurately describes the purpose of the patch.

4. Edit the patch header. A typical patch header may look like the following.

   --- file~    1970-01-01 00:00:00.123456789 +0000
   +++ file     1970-01-01 00:00:00.123456789 +0000
   @@ -1,0 +1,1 @@
   +foo
   

   Nano patches are applied in the context of the Buildroot source directory (~/buildroot) so if you are patching file of the foobar package then the relative path should be inserted into the patch header. The first line and time information should be removed. After editing the modified patch file may look similar to the following.

   +++ package/foobar/file
   @@ -1,0 +1,1 @@
   +foo
   

5. Copy patches back to the host – ./nano pull patches.

6. Uncomment the patching directives in the Dockerfile template.

7. Rebuild your container and ensure the patches are applied correctly.

Modifying the rootfs

If you wish to add to or overwrite files in the rootfs image simply add those files to in/rootfs_overlay and uncomment COPY in/rootfs_overlay /root/buildroot/rootfs_overlay in your Dockerfile. Buildroot is already configured to pick up files in this directory and merge them into the rootfs using the directory structure you provide in the overlay directory.

To remove files modify the post_build.sh script. The post-build script is configured to run in the context of the rootfs directory. New instructions should be appended to the existing script by modifying the Dockerfile, for example, RUN echo rm -r var/run >> buildroot/post_build.sh will remove /var/run from the rootfs. Don't forget to update .travis.bash with the same commands to modify post_build.sh.

For more information see customizing the generated target filesystem.