gelato v0.3.0 Gelato View Source

Gelato is a opinionated logger backend helper library to log events with telemetry attached.

It is to be configured in config.exs in the following way:

config :gelato,
  uri: "http://127.0.0.1:9200",
  events: [:app, :lib],
  handler: :elastic

config :logger,
  backends: [Gelato.Logger.Backend],
  level: :debug

and might be used normally as a usual logger backend

Logger.info "users", name: "John", reference: "U-123456789"

Basically, it logs the payload with the telemetry attached to the configured ElasticSearch instance. The telemetry includes some process information by default, besides monotonic time and some additional parameters.

The process info data might be altered or switched off by passing :process_info keyword parameter in call to Logger.log/3. true value (default) would collect and store the current process info; any other value would be passed through as is.

level parameter is one of :debug | :info | :warn | :error
message is mapped to ElasticSearch index when passed; possible values must be configured in config.exs file in the list of telemetry events
payload is a keyword list to be passed to Elastic

Also it supports benchmarking with Elixir.Gelato.bench/4. The latter will execute the block passed to the function, surrounded with two calls to Logger.log/3 to collect some additional info about this particular block execution.

By default all the logger methods would attach process_info to the events sent to Elastic to alter / discard this pass process_info: SOMETHING to the call to all the exported functions’ payload. Unless SOMETHING is true, this value will be used instead of real process info.

Link to this section Summary

Functions

bench(level, tag \\ nil, entity, payload_and_do_block)

Similar to Logger.log/3 but accepts a block.

defdelegatelog(fun, opts)

Defines a function that delegates to another module and wraps the delegated call into Gelato.bench/4. Similar to Kernel.defdelegate/2.

Link to this section Functions

bench(level, tag \\ nil, entity, payload_and_do_block)

(macro)

bench(
  level :: Logger.level(),
  tag :: atom(),
  entity :: entity(),
  payload_and_do_block :: keyword()
) :: any()

Similar to Logger.log/3 but accepts a block.

The block will be executed, surrounded by calls to log and the telemetry data will be accumulated in the latter call.

defdelegatelog(fun, opts)

(macro)

Defines a function that delegates to another module and wraps the delegated call into Gelato.bench/4. Similar to Kernel.defdelegate/2.

Functions defined with defdelegatelog/2 are public and can be invoked from outside the module they’re defined in, as if they were defined using def/2.

Options

:to — the module to dispatch to.
:as — the function to call on the target given in :to. This parameter is optional and defaults to the name being delegated (fun).
:level — the level to be used for wrapping logging, default :info
:tag — the tag to be used as an index in the target Elastic call. Default: "default".
:entity — additional key to simplify search in Elastic logs. Usually it specifies a business entity, loke :user, or :order. Default: nil.

Examples

defmodule MyList do
  defdelegatelog reverse(list), to: Enum
end
MyList.reverse([1, 2, 3])
#   Logger.log is called under the hood with telemetry metrics attached
#=> [3, 2, 1]
#   Logger.log is called under the hood with telemetry metrics attached