# Better Stack Erlang logging

## Start logging in 3 steps

Collect logs from your Erlang application.

### 1. Install

Add [betterstack_logger](https://github.com/silviucpp/betterstack_logger) to your project dependencies using Rebar or Mix.

[code-tabs]
```erlang
[label rebar.config]
{deps, [betterstack_logger]}.
```
```elixir
[label mix.exs]
def deps do
  [
    {:betterstack_logger, "~> 1.0"}
  ]
end
```
[/code-tabs]

### 2. Setup

Configure `betterstack_logger` in your application's configuration file,or add it programmatically via Logger API:

[code-tabs]
```erlang
[label sys.config]
[
  {betterstack_logger, [
      {logger, [
          {handler, betterstack_logs, betterstack_logger, #{
              level => info,
              config => #{
                  http_pool_options => [
                      {timeout, 15000},
                      {max_connections, 10}
                  ],
                  betterstack_host => <<"https://$INGESTING_HOST">>,
                  betterstack_source_token => <<"$SOURCE_TOKEN">>,
                  extra_fields => [
                      {<<"_env">>, <<"prod">>}
                  ],
                  upload_batch_max_size => 50,
                  upload_batch_inteval_ms => 5000,
                  upload_failed_retry_count => 3,
                  upload_failed_retry_delay_ms => 1000
              },
              formatter => {
                  logger_formatter, #{
                      single_line => true,
                      template => [pid, " ", mfa,":",line, " => ", msg],
                      time_offset => "Z"
                  }
              },
              filters => [
                  %{remote_group_leader, {fun logger_filters:remote_gl/2, stop}},
                  %{progress, {fun logger_filters:progress/2, stop}},
                  %{sasl, {fun logger_filters:domain/2, {stop, sub, [otp, sasl]}}}
              ]
          }}
      ]}
  ]}
].
```
```erlang
[label call logger:add_handler in your start module]
logger:add_handler(my_handler, betterstack_logs, #{
    level => info,
    config => #{
        http_pool_options => [
            {timeout, 15000},
            {max_connections, 10}
        ],
        betterstack_host => <<"https://$INGESTING_HOST">>,
        betterstack_source_token => <<"$SOURCE_TOKEN">>,
        extra_fields => [
            {<<"_env">>, <<"prod">>}
        ],
        upload_batch_max_size => 50,
        upload_batch_inteval_ms => 5000,
        upload_failed_retry_count => 3,
        upload_failed_retry_delay_ms => 1000
    },
    formatter => {
        logger_formatter, #{
            single_line => true,
            template => [pid, " ", mfa,":",line, " => ", msg],
            time_offset => "Z"
        }
    },
    filters => [
        %{remote_group_leader, {fun logger_filters:remote_gl/2, stop}},
        %{progress, {fun logger_filters:progress/2, stop}},
        %{sasl, {fun logger_filters:domain/2, {stop, sub, [otp, sasl]}}}
    ]
}).
```
[/code-tabs]

[warning]
#### Using the logger as default handler is not supported.
To avoid cyclic dependency, it's not currently possible to set `betterstack_logger` as `default` handler via `sys.config`.
[/warning]

### 3. Start logging 🎉

Use the Erlang `logger` module as usual. Your log events will be sent to Better Stack automatically.

```erlang
[label Example usage]
logger:info("Application started successfully."),
logger:error("Failed to connect to database."),
logger:debug("Debugging value: ~p", [Value]).
```

You should see your logs in [Better Stack → Live tail](https://telemetry.betterstack.com/team/0/tail ";_blank").

---

Huge thanks to [Silviu Caragea](https://github.com/silviucpp) who maintains the [betterstack_logger](https://github.com/silviucpp/betterstack_logger) library as an MIT-licenced open-source! ❤️

## Need help?

Please reach out to us at [hello@betterstack.com](mailto:hello@betterstack.com).  
We're happy to help! 🙏

## Additional information

Ensure your application terminates gracefully, giving the logger enough time to finish sending logs to BetterStack.

Use `init:stop()` to end your application properly.

Avoid using `erlang:halt()`, as it terminates all processes immediately and may drop your logs.