# How to understand an error-line at docker log outout

**URL:** <https://discuss.elastic.co/t/how-to-understand-an-error-line-at-docker-log-outout/133994>\
**Category:** Logstash\
**Created:** [May 31, 2018, 7:53am UTC](https://discuss.elastic.co/t/how-to-understand-an-error-line-at-docker-log-outout/133994 "2018-05-31T07:53:55Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Robert\_D](https://avatars.discourse-cdn.com/v4/letter/r/53a042/32.png) [@Robert\_D](https://discuss.elastic.co/u/Robert_D)\
**Post date:** [May 31, 2018, 7:53am UTC](https://discuss.elastic.co/t/how-to-understand-an-error-line-at-docker-log-outout/133994/1 "2018-05-31T07:53:55Z")

</div>

I have an error like

```
logstash_1 | [2018-05-31T07:47:02,627][ERROR][logstash.pipeline] Error registering plugin {:pipeline_id=>"main", :plugin=>"#<LogStash::OutputDelegator:0x7192eb8c @namespaced_metric=#<LogStash::Instrument::NamespacedMetric:0x16868c70 @metric=#<LogStash::Instrument::Metric:0x20eea852 @collector=#<LogStash::Instrument::Collector:0x1cf4839f @agent=nil, @metric_store=#<LogStash::Instrument::MetricStore:0x4762462d @store=#<Concurrent::Map:0x00000000000fb4 entries=3 default_proc=nil>, @structured_lookup_mutex=#<Mutex:0x76e806ad>, @fast_lookup=#<Concurrent::Map:0x00000000000fb8 entries=81 default_proc=nil>>>>, @namespace_name=[:stats, :pipelines, :main, :plugins, :outputs, :\"gelf-datasync-all\"]>, @metric=#<LogStash::Instrument::NamespacedMetric:0x77807382 @metric=#<LogStash::Instrument::Metric:0x20eea852 @collector=#<LogStash::Instrument::Collector:0x1cf4839f @agent=nil, @metric_store=#<LogStash::Instrument::MetricStore:0x4762462d @store=#<Concurrent::Map:0x00000000000fb4 entries=3 default_proc=nil>, @structured_lookup_mutex=#<Mutex:0x76e806ad>, @fast_lookup=#<Concurrent::Map:0x00000000000fb8 entries=81 default_proc=nil>>>>, @namespace_name=[:stats, :pipelines, :main, :plugins, :outputs]>, @out_counter=org.jruby.proxy.org.logstash.instrument.metrics.counter.LongCounter$Proxy2 - name: out value:0, @strategy=#<LogStash::OutputDelegatorStrategies::Legacy:0x33efd32c @worker_count=1, @workers=[<LogStash::Outputs::Gelf id=>\"gelf-datasync-all\", host=>\"https://10.0.3.198\", port=>5555, protocol=>\"TCP\", enable_metric=>true, codec=><LogStash::Codecs::Plain id=>\"plain_bee72b9c-58d4-436f-a0ac-c3a2fdc9ffef\", enable_metric=>true, charset=>\"UTF-8\">, workers=>1, chunksize=>1420, sender=>\"%{host}\", level=>[\"%{severity}\", \"INFO\"], ship_metadata=>true, ship_tags=>true, ignore_metadata=>[\"@timestamp\", \"@version\", \"severity\", \"host\", \"source_host\", \"source_path\", \"short_message\"], full_message=>\"%{message}\", short_message=>\"short_message\">], @worker_queue=#<SizedQueue:0x79b79150>>, @in_counter=org.jruby.proxy.org.logstash.instrument.metrics.counter.LongCounter$Proxy2 - name: in value:0, @id=\"gelf-datasync-all\", @time_metric=org.jruby.proxy.org.logstash.instrument.metrics.counter.LongCounter$Proxy2 - name: duration_in_millis value:0, @metric_events=#<LogStash::Instrument::NamespacedMetric:0x290ce583 @metric=#<LogStash::Instrument::Metric:0x20eea852 @collector=#<LogStash::Instrument::Collector:0x1cf4839f @agent=nil, @metric_store=#<LogStash::Instrument::MetricStore:0x4762462d @store=#<Concurrent::Map:0x00000000000fb4 entries=3 default_proc=nil>, @structured_lookup_mutex=#<Mutex:0x76e806ad>, @fast_lookup=#<Concurrent::Map:0x00000000000fb8 entries=81 default_proc=nil>>>>, @namespace_name=[:stats, :pipelines, :main, :plugins, :outputs, :\"gelf-datasync-all\", :events]>, @output_class=LogStash::Outputs::Gelf>", :error=>"initialize: name or service not known", :thread=>"#<Thread:0x1662310e run>"}

```

1. How is the trace formated?
2. What is the concrete error message?

---

<div class="post-metadata">

**Author:** ![guyboertje](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/guyboertje/32/31592_2.png) [@guyboertje](https://discuss.elastic.co/u/guyboertje)\
**Post date:** [May 31, 2018, 10:18am UTC](https://discuss.elastic.co/t/how-to-understand-an-error-line-at-docker-log-outout/133994/2 "2018-05-31T10:18:03Z")

</div>

It is a bit cryptic, so I'll pluck out the important bits (reformatted).

`Error registering plugin`

```auto
<LogStash::Outputs::Gelf
  id=>"gelf-datasync-all",
  host=>"https://10.0.3.198",
  port=>5555,
  protocol=>"TCP",
  enable_metric=>true,
  codec=><LogStash::Codecs::Plain id=>"plain_bee72b9c-58d4-436f-a0ac-c3a2fdc9ffef", enable_metric=>true, charset=>"UTF-8">,
  workers=>1,
  chunksize=>1420,
  sender=>"%{host}",
  level=>["%{severity}", "INFO"],
  ship_metadata=>true,
  ship_tags=>true,
  ignore_metadata=>["@timestamp", "@version", "severity", "host", "source_host", "source_path", "short_message"],
  full_message=>"%{message}",
  short_message=>"short_message"
>

```

`@output_class=LogStash::Outputs::Gelf>`

`:error=>"initialize: name or service not known"`

**Possible resolution**  
The "error" - "initialize: name or service not known" comes from deep inside the Gelf Ruby library when the TCP socket can't be initialized.  
As you are using GELF and TCP, I doubt that you are using the `https` protocol.  
The [docs](https://www.elastic.co/guide/en/logstash-versioned-plugins/current/v3.1.7-plugins-outputs-gelf.html#v3.1.7-plugins-outputs-gelf-host) say:

**host**

- This is a required setting.
- Value type is string
- There is no default value for this setting.

Graylog2 server IP address or hostname.

Use `host=>"10.0.3.198"` in your LS config.

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [June 28, 2018, 10:18am UTC](https://discuss.elastic.co/t/how-to-understand-an-error-line-at-docker-log-outout/133994/3 "2018-06-28T10:18:04Z")

</div>

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