Features

The SIGUSR1 signal can be now used to interrupt the interval sleep
and check for configuration changes again
Made the procd respawn parameters configurable
The agent now stores the any UCI configuration which is overwritten
by OpenWISP with the goal of restoring it if the piece of
configuration overwritten by OpenWISP is removed
Added management_interval and registration_interval options

Changes

Made configuration checksum persistent to fix 2 problems:
1. If the openwisp-config daemon is restarted (e.g. by the
  openwisp-controller via ssh) after it already downloaded the
  latest checksum but before it has applied the configuration, all
  further calls of configuration_changed() (until
  CONFIGURATION_CHECKSUM is deleted, e.g. by a reboot) will imply
  that everything is already up-to-date, although the
  configuration was never applied
2. prevents the configuration from being downloaded and written
  again after a reboot
Do not wait for management interface during registration: If
openwisp-config is not registered yet, do not wait for the
management interface to be ready because we can assume the
management interface configuration is not present yet
Increased report status retries: in some cases the report status
operation may fail because the network reload could take a few
minutes to complete (eg: in mesh networks scenarios) and therefore
the agent must be a bit more patient before giving up
Refactored init script to make it more consistent with the best
practices used in the OpenWrt community
If the agent receives 404 response from the server when downloading
the configuration checksum, after the number of attempts specified
in checksum_max_retries fail, the agent assumes the device has
been deleted from OpenWISP and exits

Use configured curl timeout values in default configuration test;
Without this fix, it's possible that the configuration test fails
while the regular checksum fetch succeeds
Ensured config download error is detected: adding the --fail flag
to curl makes it exit with a non zero exit code in case the server
respond with an HTTP status code which is not 200 OK, without this
fix, a bad response is interpreted as a valid configuration and the
agent removes the old configuration, then installs the new
configuration, which fails and the router remains with an empty
configuration, effectively causing a disruption of service
Fixed post-registration-hook logging line which was mistakenly
mentioning post-reload-hook instead of post-registration-hook
Fixed service reload handling for unnamed uci sections: the openwisp
agent modifies the configuration on first contact by rewriting all
anonymous UCI sections into na