docker-spk is a tool to develop sandstorm packages using Docker to build the root filesystems.

It is a work in progress, but already supports converting docker images to sandstorm packages (.spk files), and signing and populating them with metadata based on sandstorm-pkgdef.capnp.

Note that:

• It is not possible to automatically convert an arbitrary Docker image and have it work; the filesystem must be constructed to behave correctly inside Sandstorm's sandbox environment.
• Docker is only used to build the root filesystem of the app. Accordingly, Dockerfile instructions like CMD, EXPOSE, STOPSIGNAL, etc, which do not modify the image's filesystem, have no effect on the app. For other forms of customization, edit sandstorm-pkgdef.capnp.

Installing

In addition to docker-spk itself, you will also need the capnp command line tool somewhere in your $PATH; see the Cap'n Proto documentation for setup.

From Pre-Built Binaries

The releases page distributes tar archives containing x86_64 binaries of docker-spk for Linux and MacOS; extract the archive, and place the appropriate

From Source

1. Install Go 1.11 or later.
2. From the root of the source tree, run:

go build

This will create an executable ./docker-spk; place it somewhere in your $PATH.

Quick Start

First, generate a sandstorm-pkgdef.capnp in the current directory:

docker-spk init

The tool will automatically generate a keypair for your app, and save it in your keyring (by default ~/.sandstorm-keyring, but this can be overridden with the -keyring flag).

Edit the file to match your app. In particular, you will want to change the command used to launch the app, near the bottom of the file.

Then, create a Dockerfile in the current directory, which will be responsible for building the filesystem for your app. Finally, from the directory containing Dockerfile and sandstorm-pkgdef.capnp, run:

docker-spk build

This will build the docker image and then package it into a .spk file. with the name derived from the app name and version defined in sandstorm-manifest.capnp.

Alternatively, you can package an already-built docker image:

docker-spk pack -image <image-name>

...to use the image <image-name>, fetched from a running Docker daemon.

This will skip the build step and just create the .spk.

You can also use docker save to fetch the image manually and specify the file name via -imagefile:

docker save my-image > my-image.tar
docker-spk pack -imagefile my-image.tar

Examples

The examples/ directory contains some examples that may be useful in seeing how to package apps with docker-spk.

Reference

See docker-spk -h.

License

Apache 2.0, see COPYING.