Mender is an open source over-the-air (OTA) software updater for embedded Linux devices. Mender comprises a client running at the embedded device, as well as a server that manages deployments across many devices.

Embedded product teams often end up creating homegrown updaters at the last minute due to the need to fix bugs in field-deployed devices. However, the most important requirement for an embedded update process is robustness, for example loss of power at any time should not brick a device. This creates a challenge given the time constraints to develop and maintain a homegrown updater.

Mender aims to address this challenge with a robust and easy to use updater for embedded Linux devices, which is open source and available to anyone.

Robustness is ensured with atomic image-based deployments using a dual A/B rootfs partition layout. This makes it always possible to roll back to a working state, even when losing power at any time during the update process.

Ease of use is addressed with an intuitive UI, comprehensive documentation, a meta layer for the Yocto Project for easy integration into existing environments, and high quality software (see the test coverage badge).

This repository contains the Mender client updater, which can be run in standalone mode (manually triggered through its command line interface) or managed mode (connected to the Mender server).

Mender not only provides the client-side updater, but also the backend and UI for managing deployments as open source. The Mender server is designed as a microservices architecture and comprises several repositories.

To start using Mender, we recommend that you begin with the Getting started section in the Mender documentation.

In order to support rollback, the Mender client depends on integration with U-Boot and the partition layout. It is therefore most easily built as part of your Yocto Project image by using the meta layer for the Yocto Project.

We welcome and ask for your contribution. If you would like to contribute to Mender, please read our guide on how to best get started contributing code or documentation.

Mender is licensed under the Apache License, Version 2.0. See LICENSE for the full license text.

We take security very seriously. If you come across any issue regarding security, please disclose the information by sending an email to [email protected]. Please do not create a new public issue. We thank you in advance for your cooperation.

• C compiler
• Go compiler
• liblzma-dev package

If no LZMA Artifact compression support if desired, you can ignore the liblzma-dev package dependency and substitute the make commands in the instructions below for:

make TAGS=nolzma

To install Mender on a device from source, please run the following commands inside the cloned repository:

make
sudo make install

Installing this way does not offer a complete system updater. For this you need additional integration steps. However, it is possible to use Update Modules and update other parts of the system.

In order to connect to a Mender server, you either need to get a Hosted Mender account, or set up a server environment. If you are setting up a demo environment, you will need to put the support/demo.crt file into /etc/mender/server.crt on the device and add the configuration line below to /etc/mender/mender.conf after the installation steps above:

  "ServerCertificate": "/etc/mender/server.crt"

Keep in mind that /etc/mender/mender.conf will be overwritten if you rerun the sudo make install command.

Important: demo.crt is not a secure certificate, and should only be used for demo purposes, never in production.

• C cross-compiler for the target platform
• Go compiler

Download the cross-compiler required for your device. Then add the cross-compiler bin/ subfolder in your path and set the CC variable accordingly using the commands:

export PATH=$PATH:<path_to_my_cross_compiler>/bin
export CC=<cross_compiler_prefix>

For intance, to cross-compiling for Raspberry Pi:

git clone https://github.com/raspberrypi/tools.git
export PATH="$PATH:$(pwd)/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin"
export CC=arm-linux-gnueabihf-gcc

Donwload, extract, compile, and install liblzma with the following commands:

wget -q https://tukaani.org/xz/xz-5.2.4.tar.gz
tar -xzf xz-5.2.4.tar.gz
cd xz-5.2.4
./configure --host=<target-arch> --prefix=$(pwd)/install
make
make install

Where target-arch should match your device toolchain, for example arm-linux-gnueabihf

Export an env variable for later use:

export LIBLZMA_INSTALL_PATH=$(pwd)/install

Now, to cross-compile Mender, run the following commands inside the cloned repository:

make CGO_CFLAGS="-I${LIBLZMA_INSTALL_PATH}/include" CGO_LDFLAGS="-L${LIBLZMA_INSTALL_PATH}/lib" \
CGO_ENABLED=1 GOOS=linux GOARCH=<arch>

Where arch is the target architecture (for example arm). See all possible values for GOARCH in the source code. Also note that for arm architecture you also need to specify which family to compile for with GOARM; for more information see this link

You can deploy the mender client file tree in a custom directory in order to send it to your device afterwards. To deploy all mender client files in a custom directory, run the command:

make prefix=<custom-dir> install

Where custom-dir is the destination folder for your file tree

Finally, copy this file tree into your target's device rootfs. You can do it remotely using SSH, for example.

See also Installation notes

Once installed, Mender can be enabled by executing:

systemctl enable mender && systemctl start mender

• Join the Mender Hub discussion forum
• Follow us on Twitter. Please feel free to tweet us questions.
• Fork us on Github
• Create an issue in the bugtracker
• Email us at [email protected]
• Connect to the #mender IRC channel on Freenode

Mender was created by the team at Northern.tech AS, with many contributions from the community. Thanks everyone!

Mender is sponsored by Northern.tech AS.