| Overview |  |
logger handler that sends log events to NervesHub.
A logger handler that sends log events to NervesHub.
Saves an application from calling nerves_hub_link:send_log/3 by hand, which
is the difference between a logging extension that gets used and one that is
forgotten.
logger_manager:start_link(#{
log_level => info,
logger => [
{handler, default, logger_std_h, #{}},
nh_logger:handler(#{level => info})
]
})
Handlers are given to logger_manager when it starts and there is no
add_handler/3 on AtomVM, so this is arranged by the application at startup
rather than by the agent when it connects. Nothing starts logger_manager
on AtomVM either: an application that wants logging at all has to start it,
and one that does not has no handlers for this to be added to.
Only what goes through logger. io:format/2, console:print/1 and
Elixir's IO.puts/1 write straight to the console and never reach a handler,
and a good deal of AtomVM code — including most examples — logs that way.
Elixir has no Logger on AtomVM at all: exavmlib does not ship one, so an
Elixir application calls :logger directly and is caught by the same
handler. There is nothing that can be done for IO.puts.
logger:do_log/4 accepts a list or a map and raises badarg on anything
else, so a **binary message crashes the process that logged it** before any
handler runs. That is upstream of this module and nothing here can soften
it.
It catches Elixir code in particular, where the obvious call is the one that fails:
:logger.info("started") %% badarg, a binary :logger.info(~c"started") %% fine, a charlist :logger.info(#{event => started}) %% fine, a report
Erlang code is less exposed, since a double-quoted string is already a list there.
register => Name to give
it one. Until it is registered, and after it stops, events are dropped rather
than queued: a device that cannot talk to NervesHub should not spend its
memory remembering why.
| handler/0 | Equivalent to handler(#{level => info}).
|
| handler/1 | The entry to add to logger_manager's handler list. |
| log/2 | Called by logger for each event this handler's level allows. |
| message/1 | Render a logger message as text. |
handler() -> tuple()
Equivalent to handler(#{level => info}).
handler(Config::map()) -> tuple()
The entry to add to logger_manager's handler list.
log(Event::map(), Config::map()) -> ok
Called by logger for each event this handler's level allows.
message(Other::term()) -> binary()
Render a logger message as text.
logger hands over one of three shapes, and a handler has to render all of
them or lose whichever it does not. Public so that nh_console_h renders a
line the same way this does.
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