Adding upstream version 1.34.4.

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

docs/specs/tsd-002-custom-builder.md

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+# Telegraf Custom-Builder
+
+## Objective
+
+Provide a tool to build a customized, smaller version of Telegraf with only
+the required plugins included.
+
+## Keywords
+
+tool, binary size, customization
+
+## Overview
+
+The Telegraf binary continues to grow as new plugins and features are added
+and dependencies are updated. Users running on resource constrained systems
+such as embedded-systems or inside containers might suffer from the growth.
+
+This document specifies a tool to build a smaller Telegraf binary tailored to
+the plugins configured and actually used, removing unnecessary and unused
+plugins. The implementation should be able to cope with configured parsers and
+serializers including defaults for those plugin categories. Valid Telegraf
+configuration files, including directories containing such files, are the input
+to the customization process.
+
+The customization tool might not be available for older versions of Telegraf.
+Furthermore, the degree of customization and thus the effective size reduction
+might vary across versions. The tool must create a single static Telegraf
+binary. Distribution packages or containers are *not* targeted.
+
+## Prior art
+
+[PR #5809](https://github.com/influxdata/telegraf/pull/5809) and
+[telegraf-lite-builder](https://github.com/influxdata/telegraf/tree/telegraf-lite-builder/cmd/telegraf-lite-builder):
+
+- Uses docker
+- Uses browser:
+  - Generates a webpage to pick what options you want. User chooses plugins;
+    does not take a config file
+  - Build a binary, then minifies by stripping and compressing that binary
+- Does some steps that belong in makefile, not builder
+  - Special case for upx
+  - Makes gzip, zip, tar.gz
+- Uses gopkg.in?
+- Can also work from the command line
+
+[PR #8519](https://github.com/influxdata/telegraf/pull/8519)
+
+- User chooses plugins OR provides a config file
+
+[powers/telegraf-build](https://github.com/powersj/telegraf-build)
+
+- User chooses plugins OR provides a config file
+- Currently kept in separate repo
+- Undoes changes to all.go files
+
+[rawkode/bring-your-own-telegraf](https://github.com/rawkode/bring-your-own-telegraf)
+
+- Uses docker
+
+## Additional information
+
+You might be able to further reduce the binary size of Telegraf by removing
+debugging information. This is done by adding `-w` and `-s` to the linker flags
+before building `LDFLAGS="-w -s"`.
+
+However, please note that this removes information helpful for debugging issues
+in Telegraf.
+
+Additionally, you can use a binary packer such as [UPX](https://upx.github.io/)
+to reduce the required *disk* space. This compresses the binary and decompresses
+it again at runtime. However, this does not reduce memory footprint at runtime.