PlugLoggerJson
A comprehenisve JSON logger Plug.
Dependencies
- Plug
- Poison
Elixir & Erlang Support
- The support policy is to support the last 2 major versions of Erlang and the three last minor versions of Elixir.
Installation
If available in Hex, the package can be installed as:
Add plug_logger_json to your list of dependencies in
mix.exs
:def deps do [{:plug_logger_json, “~> 0.5.0”}] end
Ensure plug_logger_json is started before your application:
def application do [applications: [:plug_logger_json]] end
Replace
Plug.Logger
withPlug.LoggerJSON, log: Logger.level
in your plug pipeline (endpoint.ex for phoenix apps)or for extra attributes (see extra attributes section)
Replace
Plug.Logger
withPlug.LoggerJSON, log: Logger.level, extra_attributes_fn: &MyPlug.extra_attributes/1
in your plug pipeline (endpoint.ex for phoenix apps)
Recommended Setup
Configure this application
Add to your
config/config.exs
orconfig/env_name.exs
ONLY if you want to filter params or headers:config :plug_logger_json, filtered_keys: [“password”, “authorization”],
Configure the logger (console)
Add to your
config/config.exs
orconfig/env_name.exs
:config :logger, :console, format: “$message\n”, level: :info, #You may want to make this an env variable to change verbosity of the logs metadata: [:request_id]
Configure the logger (file)
- Add
{:logger_file_backend, "~> 0.0.7"}
to your mix.exs - Run
mix deps.get
Add to your
config/config.exs
orconfig/env_name.exs
:config :logger, format: “$message\n”, backends: [{LoggerFileBackend, :log_file}, :console]
config :logger, :log_file, format: “$message\n”, level: :info, metadata: [:request_id], path: “log/my_pipeline.log”
- Add
Ensure you are using Plug.Parsers (Phoenix adds this to endpoint.ex by default) to parse params & req bodies
plug Plug.Parsers, parsers: [:urlencoded, :multipart, :json], pass: [“/”], json_decoder: Poison
Error Logging
In router.ex of your phoenix project or your plug pipeline
- Add
require Logger
- Add
use Plug.ErrorHandler
Add the following two private functions:
defp handle_errors(%Plug.Conn{status: 500} = conn, %{kind: kind, reason: reason, stack: stacktrace}) do Plug.LoggerJSON.log_error(kind, reason, stacktrace) send_resp(conn, 500, Poison.encode!(%{errors: %{detail: “Internal server error”}})) end
defp handleerrors(, _), do: nil
- Add
Extra Attributes
Additional data can be logged alongside the request by specifying a function to call which returns a map:
def extra_attributes(conn) do map = %{
"user_id" => get_in(conn.assigns, [:user, :user_id]), "other_id" => get_in(conn.private, [:private_resource, :id]), "should_not_appear" => conn.private[:does_not_exist]
} map |> Enum.filter(&(&1 !== nil)) |> Enum.into(%{}) end plug Plug.LoggerJSON, log: Logger.level,
extra_attributes_fn: &MyPlug.extra_attributes/1
In this example, the
:user_id
is retrieved fromconn.assigns.user.user_id
and added to the log if it exists. In the example, any values that arenil
are filtered from the map. It is a requirement that the value is serialiazable as JSON by the Poison library, otherwise an error will be raised when attempting to encode the value.
Log Verbosity
- Plug Logger JSON supports two levels of logging.
- Info / Error will log api_version, date_time, duration, log_type, method, path, request_id, & status.
- Warn / Debug log levels will include everything from info plus client_id, client_version, and params / request bodies.
Contributing
Before submitting your pull request, please run:
mix credo --strict
mix coveralls
mix dialyzer
- Update Changelog
Please squash your pull request’s commits into a single commit with a message and detailed description explaining the commit.