# `lager_logstash` [](https://travis-ci.org/truqu/lager_logstash)
> Logstash backend for lager
## Configuration
Add `lager` and `lager_logstash` to `rebar.config`:
```erlang
{deps, [lager, lager_logstash]}.
```
Add configuration to `sys.config`:
```erlang
{lager, [{ handlers
, [{ lager_logstash_backend
, [ {host, "logstash_host"}
, {port, 9125}
]
}]
}]
}
```
> **Note**: Logstash requires timestamps to be in UTC. However, there is no need
> to do anything special to get this working - `lager_logstash` does the
> conversion for you.
Configure a logstash pipeline:
```
input {
udp {
codec => "json"
port => 9125
}
}
output {
...
}
```
## Supported options
| Option | Default | Acceptable values |
|-------------------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------|
| `host` (required) | / | `inet:socket_address()` or `inet:hostname()` |
| `port` (required) | / | `inet:port_number()` |
| `level` | `info` | `lager:log_level()` - including [syslog style comparison flags](https://github.com/erlang-lager/lager#syslog-style-loglevel-comparison-flags) |
| `fields` | `[]` | `[{atom(), jsx:json_term()}]` - allows specifying a bunch of extra fields to be included |
## Output format
All metadata is included as fields. Code like this:
```erlang
-module foo
-export([bar/0]).
bar () ->
lager:info([{foo, bar}], "Hello ~s", ["world"]).
```
Would result in JSON like this:
```javascript
{
"message": "Hello world",
"@timestamp": "2019-01-13T21:33:56.925Z",
"fields": {
"severity": "info",
"foo": "bar",
"application": "otp_application",
"node": "some_node@localhost",
"pid": "<0.13919.0>",
"module": "foo",
"function": "bar",
"line": "6"
}
}
```
## License
Released under the MIT license - please see the `LICENSE` file.
© 2019 - TruQu
