Skip to content

Latest commit

 

History

History

reproducible-package

Folders and files

NameName
Last commit message
Last commit date

parent directory

..
app
app
 
 
Dockerfile
Dockerfile
 
 
README.md
README.md
 
 
reproducible_package.sh
reproducible_package.sh
 
 

README.md

Copyright (C) 2021, Axis Communications AB, Lund, Sweden. All Rights Reserved.

An example of how to create a reproducible ACAP application

This README file explains how to build a simple and reproducible ACAP application. It is achieved by using the containerized API and toolchain images.

Together with this README file, you should be able to find a directory called app. That directory contains the "reproducible-package" application source code which can easily be compiled and run with the help of the tools and step by step below.

The example follows the guidelines in Reproducible builds practices and the steps taken in this example are:

  • Set SOURCE_DATE_EPOCH to a specific date, in Dockerfile for standard procedure and in connection to build command acap-build if running interactively.
  • Add a code section in Makefile that if SOURCE_DATE_EPOCH is set, do set BUILD_DATE to the specified date.

N.b. These are the steps for a very basic example but might not be enough for more complex applications. See the link above for more tips on how to get your application reproducible.

Getting started

Below is the structure and scripts used in the example:

reproducible-package
├── app
│   ├── reproducible_package.c
│   ├── LICENSE
│   ├── Makefile
│   └── manifest.json
├── Dockerfile
└── README.md
  • app/reproducible_package.c - Hello World application which writes to system-log.
  • app/LICENSE - Text file which lists all open source licensed source code distributed with the application.
  • app/Makefile - Makefile containing the build and link instructions for building the ACAP application.
  • app/manifest.json - Defines the application and its configuration.
  • Dockerfile - Docker file with the specified Axis toolchain and API container to build the example specified.
  • README.md - Step by step instructions on how to run the example.

Limitations

  • The support to create reproducible packages was introduced in acap-sdk 3.4.

Build the application

The following build steps demonstrates how an application may be reproducible and not how a real application would be built.

Standing in your working directory follow the commands below:

Note

Depending on the network you are connected to, you may need to add proxy settings. The file that needs these settings is: ~/.docker/config.json. For reference please see https://docs.docker.com/network/proxy and a script for Axis devices in the ACAP documentation.

In all examples the option --no-cache is used to ensure that image is rebuilt.

Start with an ordinary build which will not give a reproducible package and copy the result from the container image to a local directory build1.

docker build --no-cache --tag rep:1 .
docker cp $(docker create rep:1):/opt/app ./build1

Now let's create a reproducible package. Set the build argument TIMESTAMP which in turn set SOURCE_DATE_EPOCH to a fix time. The chosen timestamp here is the latest commit in the current git repository. Copy the output to build2.

docker build --no-cache --build-arg TIMESTAMP="$(git log -1 --pretty=%ct)" --tag rep:2 .
docker cp $(docker create rep:2):/opt/app ./build2

Build a second reproducible application and copy the output to build3.

docker build --no-cache --build-arg TIMESTAMP="$(git log -1 --pretty=%ct)" --tag rep:3 .
docker cp $(docker create rep:3):/opt/app ./build3

Now you will have three eap-files in your working directory

reproducible-package
├── build1
│   └── reproducible_package_1_0_0_armv7hf.eap
├── build2
│   └── reproducible_package_1_0_0_armv7hf.eap
├── build3
│   └── reproducible_package_1_0_0_armv7hf.eap
  • build1/reproducible_package_1_0_0_armv7hf.eap - Application package .eap file.
  • build2/reproducible_package_1_0_0_armv7hf.eap - Reproducible application package .eap file.
  • build3/reproducible_package_1_0_0_armv7hf.eap - Reproducible application package .eap file.

Compare the files to see if they are identical or not.

cmp build1/*.eap build2/*.eap
build1/reproducible_package_1_0_0_armv7hf.eap build2/reproducible_package_1_0_0_armv7hf.eap differ: byte 13, line 1

cmp build2/*.eap build3/*.eap

All these steps are also available in a utility script

./reproducible_package.sh

Build the application interactively

To get reproducible packages running inside a container, make sure to export the environment variable before running build command.

SOURCE_DATE_EPOCH=$(git log -1 --pretty=%ct) acap-build .

N.b. To be able to use the git log as in this example you will have to run the docker container from the top directory where the .git directory is placed.

License

Apache License 2.0