Adding upstream version 1.34.4.

Signed-off-by: Daniel Baumann <daniel@debian.org>

docs/CUSTOMIZATION.md

@@ -0,0 +1,46 @@
+# Customization
+
+You can build customized versions of Telegraf with a specific plugin set using
+the [custom builder](/tools/custom_builder) tool or
+[build-tags](https://pkg.go.dev/cmd/go#hdr-Build_constraints).
+For build tags, the plugins can be selected either category-wise, i.e.
+`inputs`, `outputs`,`processors`, `aggregators`, `parsers`, `secretstores`
+and `serializers` or individually, e.g. `inputs.modbus` or `outputs.influxdb`.
+
+Usually the build tags correspond to the plugin names used in the Telegraf
+configuration. To be sure, check the files in the corresponding
+`plugin/<category>/all` directory. Make sure to include all parsers you intend
+to use.
+
+__Note:__ You _always_ need to include the `custom` tag when customizing the
+build as otherwise _all_ plugins will be selected regardless of other tags.
+
+## Via make
+
+When using the project's makefile, the build can be customized via the
+`BUILDTAGS` environment variable containing a __comma-separated__ list of the
+selected plugins (or categories) __and__ the `custom` tag.
+
+For example
+
+```shell
+BUILDTAGS="custom,inputs,outputs.influxdb_v2,parsers.json" make
+```
+
+will build a customized Telegraf including _all_ `inputs`, the InfluxDB v2
+`output` and the `json` parser.
+
+## Via `go build`
+
+If you wish to build Telegraf using native go tools, you can use the `go build`
+command with the `-tags` option. Specify  a __comma-separated__ list of the
+selected plugins (or categories) __and__ the `custom` tag as argument.
+
+For example
+
+```shell
+go build -tags "custom,inputs,outputs.influxdb_v2,parsers.json" ./cmd/telegraf
+```
+
+will build a customized Telegraf including _all_ `inputs`, the InfluxDB v2
+`output` and the `json` parser.