nerves_runtime v0.6.5 Nerves.Runtime.LogTailer
Collects operating system-level messages from /dev/log
and /proc/kmsg
,
forwarding them to Logger
with an appropriate level to match the syslog
priority parsed out of the message.
You can disable this feature (e.g. for testing) by configuring the following option:
# config.exs
config :nerves_runtime, enable_syslog: false
Link to this section Summary
Functions
Returns a specification to start this module under a supervisor
Invoked when the server is started. start_link/3
or start/3
will
block until it returns
Parse out the syslog facility, severity, and message (including the timestamp and host) from a syslog-formatted string
type
must be :syslog
or :kmsg
to indicate which log to tail with this
process. They’re managed by separate processes, both to isolate failures and
to simplify the handling of messages being sent back from the ports
Link to this section Types
Link to this section Functions
Returns a specification to start this module under a supervisor.
See Supervisor
.
Invoked when the server is started. start_link/3
or start/3
will
block until it returns.
args
is the argument term (second argument) passed to start_link/3
.
Returning {:ok, state}
will cause start_link/3
to return
{:ok, pid}
and the process to enter its loop.
Returning {:ok, state, timeout}
is similar to {:ok, state}
except handle_info(:timeout, state)
will be called after timeout
milliseconds if no messages are received within the timeout.
Returning {:ok, state, :hibernate}
is similar to
{:ok, state}
except the process is hibernated before entering the loop. See
c:handle_call/3
for more information on hibernation.
Returning :ignore
will cause start_link/3
to return :ignore
and the
process will exit normally without entering the loop or calling c:terminate/2
.
If used when part of a supervision tree the parent supervisor will not fail
to start nor immediately try to restart the GenServer
. The remainder of the
supervision tree will be (re)started and so the GenServer
should not be
required by other processes. It can be started later with
Supervisor.restart_child/2
as the child specification is saved in the parent
supervisor. The main use cases for this are:
- The
GenServer
is disabled by configuration but might be enabled later. - An error occurred and it will be handled by a different mechanism than the
Supervisor
. Likely this approach involves callingSupervisor.restart_child/2
after a delay to attempt a restart.
Returning {:stop, reason}
will cause start_link/3
to return
{:error, reason}
and the process to exit with reason reason
without
entering the loop or calling c:terminate/2
.
Callback implementation for GenServer.init/1
.
Parse out the syslog facility, severity, and message (including the timestamp and host) from a syslog-formatted string.
type
must be :syslog
or :kmsg
to indicate which log to tail with this
process. They’re managed by separate processes, both to isolate failures and
to simplify the handling of messages being sent back from the ports.