2017-09-05 20:12:11 +00:00
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# Frequently Asked Questions
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2017-12-01 19:21:39 +00:00
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### Q: How can I monitor the Docker Engine Host from within a container?
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You will need to setup several volume mounts as well as some environment
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variables:
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```
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docker run --name telegraf
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2020-01-08 18:52:58 +00:00
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-v /:/hostfs:ro
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-v /etc:/hostfs/etc:ro
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2017-12-01 19:21:39 +00:00
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-v /proc:/hostfs/proc:ro
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-v /sys:/hostfs/sys:ro
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2019-12-07 00:43:39 +00:00
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-v /var:/hostfs/var:ro
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-v /run:/hostfs/run:ro
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2017-12-01 19:21:39 +00:00
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-e HOST_ETC=/hostfs/etc
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-e HOST_PROC=/hostfs/proc
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-e HOST_SYS=/hostfs/sys
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2019-12-07 00:43:39 +00:00
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-e HOST_VAR=/hostfs/var
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-e HOST_RUN=/hostfs/run
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2017-12-01 19:21:39 +00:00
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-e HOST_MOUNT_PREFIX=/hostfs
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telegraf
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```
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2017-09-06 00:12:36 +00:00
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### Q: Why do I get a "no such host" error resolving hostnames that other
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programs can resolve?
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2017-09-05 20:12:11 +00:00
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Go uses a pure Go resolver by default for [name resolution](https://golang.org/pkg/net/#hdr-Name_Resolution).
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This resolver behaves differently than the C library functions but is more
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efficient when used with the Go runtime.
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If you encounter problems or want to use more advanced name resolution methods
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that are unsupported by the pure Go resolver, you can switch to the cgo
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resolver.
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If running manually set:
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```
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export GODEBUG=netdns=cgo
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```
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If running as a service add the environment variable to `/etc/default/telegraf`:
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```
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GODEBUG=netdns=cgo
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```
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2017-10-17 17:43:53 +00:00
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2020-01-08 18:52:58 +00:00
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### Q: How can I manage series cardinality?
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High [series cardinality][], when not properly managed, can cause high load on
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your database. Telegraf attempts to avoid creating series with high
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cardinality, but some monitoring workloads such as tracking containers are are
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inherently high cardinality. These workloads can still be monitored, but care
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must be taken to manage cardinality growth.
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You can use the following techniques to avoid cardinality issues:
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- Use [metric filtering][] options to exclude unneeded measurements and tags.
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- Write to a database with an appropriate [retention policy][].
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- Limit series cardinality in your database using the
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[max-series-per-database][] and [max-values-per-tag][] settings.
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- Consider using the [Time Series Index][tsi].
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- Monitor your databases using the [show cardinality][] commands.
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- Consult the [InfluxDB documentation][influx docs] for the most up-to-date techniques.
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[series cardinality]: https://docs.influxdata.com/influxdb/v1.7/concepts/glossary/#series-cardinality
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[metric filtering]: https://github.com/influxdata/telegraf/blob/master/docs/CONFIGURATION.md#metric-filtering
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[retention policy]: https://docs.influxdata.com/influxdb/latest/guides/downsampling_and_retention/
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[max-series-per-database]: https://docs.influxdata.com/influxdb/latest/administration/config/#max-series-per-database-1000000
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[max-values-per-tag]: https://docs.influxdata.com/influxdb/latest/administration/config/#max-values-per-tag-100000
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[tsi]: https://docs.influxdata.com/influxdb/latest/concepts/time-series-index/
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[show cardinality]: https://docs.influxdata.com/influxdb/latest/query_language/spec/#show-cardinality
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[influx docs]: https://docs.influxdata.com/influxdb/latest/
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2017-10-17 17:43:53 +00:00
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### Q: When will the next version be released?
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The latest release date estimate can be viewed on the
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[milestones](https://github.com/influxdata/telegraf/milestones) page.
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