Preserve important stuff across mender updates.

This is mostly symlinking stuff into the /data partition.

systemd is assumed/required.

• Generate SSH keys and store in /data
• Generate SSL keys and store in /data
• systemd-hostnamed mapped to /data
• systemd-networkd mapped to /data
• read-only-rootfs is enabled by default. There is no good reason not to use it.

/etc/hostname is symlinked to MENDER/CONST_CONF_HOSTNAME_CONF_DATA_DIR.

When the new hostname file changes, systemd-hostnamed-watcher.service applies the hostname via hostnamectl.

All systemd.netowrk files (*.network) are installed into MENDER/CONST_CONF_NETWORK_CONF_DATA_DIR (/data partition).

This directory is mounted/merged (overlayfs) at /etc/systemd/network, allowing dynamic and persistent network changes with a read-only filesystem.

When one of the systemd.network files change, systemd-networkd-watcher.service restarts systemd-networkd via systemctl to apply changes.

/var/log/journal is symlinked to MENDER/CONST_CONF_JOURNALD_LOG_DATA_DIR. This allows journald logs to persist boots (via the /data partition).

This layer only installs zdefault.network, a catchall that sets the interface to unmanaged. This is so unused interfaces do not cause systemd to report failed services.

To add custom systemd.network files, append systemd-conf_%.bbappend to extend FILESEXTRAPATHS:prepend. They are expected to be located at:

${WORKDIR}/network/*.network
${WORKDIR}/network/${MACHINE}/*.network

Any found will be added automatically.

Otherwise dynamically create files at runtime.

This layer depends on:

URI: git://git.openembedded.org/bitbake

URI: git://git.openembedded.org/openembedded-core
layers: meta
branch: master

URI: https://github.com/mendersoftware/meta-mender.git
layers: meta-mender-core
branch: master

URI: https://github.com/coreycothrum/meta-bitbake-variable-substitution.git
layers: meta-bitbake-variable-substitution
branch: master

In order to use this layer, the build system must be aware of it.

Assuming this layer exists at the top-level of the yocto build tree; add the location of this layer to bblayers.conf, along with any additional layers needed:

BBLAYERS ?= "                                       \
  /path/to/yocto/meta                               \
  /path/to/yocto/meta-poky                          \
  /path/to/yocto/meta-yocto-bsp                     \
  /path/to/yocto/meta-mender/meta-mender-core       \
  /path/to/yocto/meta-bitbake-variable-substitution \
  /path/to/yocto/meta-mender-const-conf             \
  "

Alternatively, run bitbake-layers to add:

$ bitbake-layers add-layer /path/to/yocto/meta-mender-const-conf

The following definitions should be added to local.conf or custom_machine.conf

require conf/include/mender-const-conf.inc

Alternatively, a kas file has been provided to help with setup/config. Include kas/kas.yml from this layer in the top level kas file. E.g.:

header:
  version : 1
  includes:
    - repo: meta-mender-const-conf
      file: kas/kas.yml

Please submit any patches against this layer via pull request.

Commits must be signed off.

Use conventional commits.

This layer will remain compatible with the latest YOCTO LTS. This mirrors what meta-mender does.