An external plugin allows Telegraf to collect metrics from external programs. This presentation demonstrates how to create an external plugin by printing 3D data from an Octoprint server. It discusses the basics of external plugins, provides a simple example using Bash, and walks through building a plugin for Octoprint using Go. The presentation concludes by discussing how to create plugins in other languages like Rust and ideas for other external plugins.

1. Presented by: Sebastian Spaink
Layer by Layer:
Printing your own external
input plugin for Telegraf

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• My Name: Sebastian Spaink
• Team: Data Acquisition
• Quarantine Craft: 3D printing
| Introduction
3D printed Gopher!

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• Share how AWESOME external plugins are in Telegraf!
• Give you the knowledge you need to make your own!
| Goal?

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1. What and Why of external plugins
2. Show basic example
3. Walkthrough practical example
4. How to start with a new language?
| Overview

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● Telegraf: The plugin-driven agent for collecting & reporting metrics
● Hundreds of internal plugins included!
| Overview of Telegraf and its plugins

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Definition: An external plugin is a program outside of Telegraf that
can communicate and be run by a Telegraf plugin called execd
● There is a execd plugin for: input, processor, output
● Communicates through STDOUT with supported data format
External Plugins:
https:/
/github.com/influxdata/telegraf/blob/master/EXTERNAL_PLUGINS.md
| What is an external plugin?

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• Benefits:
– Create a plugin that covers your unique use case
– Begin using it immediately
– Write it in any language, not limited to Go
| Why would you want to make one?
For example a external plugin written in Python:
• https:/
/github.com/jhpope/smc_ipmi

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| Keep it simple, a basic example
Straight from the README:
https:/
/github.com/influxdata/telegraf/tree/master/pl
ugins/inputs/execd#daemon-written-in-bash-using-st
din-signaling
A simple bash script that blocks, waiting for
input from STDIN, incrementing a counter.
Done. You have an external plugin!

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| Configure it with Telegraf
Telegraf Config

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PLACEHOLDER FOR OUTPUT
ANIMATION

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| Signals accepted by execd plugin
● "none" : Do not signal anything. (Recommended for service
inputs) The process must output metrics by itself.
● "STDIN" : Send a newline on STDIN. (Recommended for gather
inputs)
● “SIGHUP" : Send a HUP signal. Not available on Windows. (not
recommended)
● "SIGUSR1" : Send a USR1 signal. Not available on Windows.
● "SIGUSR2" : Send a USR2 signal. Not available on Windows.

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| Getting started with a practical example
● Octoprint: open source 3D printer controller application,
which provides a web interface for the connected printers
● Information you can get:
○ Printing state: paused or ready
○ Current temperature of nozzle/printing bed
● All you need is an API to make an input plugin!

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| Easy start to an external plugin, the Go Shim
● The Telegraf execd Go shim is a great way to start!
● A scaffolding created to make plugins as if they were in Telegraf
○ Provides same structures used in the internal project
○ Provides logic to interact with the execd plugin

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| Go Shim Versus Execd Plugin
● Go Shim: A utility tool to help start external plugins
● Execd Plugin: A Telegraf plugin to manage external plugins
Go Shim Execd Plugin Telegraf

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Get the main.go from the examples/cmd directory and
place it in your project.
Then you just need to edit the file to import the package
containing your plugin code, such as so:
| Quick step overview to use Go shim
Reference link:
https:/
/github.com/influxdata/telegraf/tree/master/plugins/common/shim

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| Gather the data
Screenshot #1 Screenshot #2

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| Custom configuration
● Optionally, you can create a separate config file for your
external plugin
● It is required this config is completely separate from the main
config and lives in another directory

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| Configuring the Octoprint plugin with Telegraf
1. Build the external plugin you’ve made to an executable binary
2. Then update the main Telegraf config such as below:
Note: The signal is set to “none” instead of “STDIN”
● The execd Go shim has a default polling interval of 1 second
○ can be adjusted by passing the flag poll_interval

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PLACEHOLDER FOR ANIMATION

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| Temperature data!
Nozzle
Build Plate

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| Extend Octoprint with plugins!
● Not Telegraf plugins, but different plugins!
● Display Layer Progress
○ https:/
/plugins.octoprint.org/plugins/DisplayLayerProgress/
● Filament Manager
○ https:/
/plugins.octoprint.org/plugins/filamentmanager/

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| Display Layer Progress
● This plugin displays the current layer being printed!
● Fun to know and helpful!

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| Display Layer Progress
● New API endpoint: /plugin/DisplayLayerProgress/values

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| Filament Manager
● To get the filament data we need a postgres database!

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| Filament Manager

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| Demo Time!

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PLACEHOLDER FOR ANIMATION

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| End result!

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| Overview Components
inputs.execd outputs.influxdb_v2
Octoprint external plugin
Telegraf
API
Display Layer
Progress API
Filament
Manager
Postgres DB
Octoprint
InfluxDB 2.0

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| Try it for yourself!
● Source Code: https:/
/github.com/sspaink/octoprint-telegraf-plugin
● Feel free to make a pull request with changes!

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| Creating your own plugin
● With the structure defined, the rest is just regular fun coding!
● Tip: Following the plugin guidelines are a great way to work!
○ when external, they are more “guidelines” then actual rules…
Guidelines:
● https:/
/github.com/influxdata/telegraf/blob/master/docs/INPUTS.md
● https:/
/github.com/influxdata/telegraf/blob/master/docs/PROCESSORS.md
● https:/
/github.com/influxdata/telegraf/blob/master/docs/OUTPUTS.md

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• No shim?!?! What to do!
• Let’s try to re-implement the octoprint plugin in Rust!
| What if I want to use a different language?

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| Let’s try to implement octoprint plugin in Rust!
Output in influxdb line protocol
Loop in one second intervals
Set configuration
Gather data

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| demo placeholder

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| What about outputs and processors?
Output Example: https:/
/github.com/morfien101/telegraf-output-kinesis
Processor Example: https:/
/github.com/a-bali/telegraf-geoip

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• Filter issues/pr’s by the label external plugin
• Suid input plugin: https:/
/github.com/influxdata/telegraf/pull/7597
• Libvirt input plugin: https:/
/github.com/influxdata/telegraf/issues/690
• Jira input plugin: https:/
/github.com/influxdata/telegraf/pull/4944
| Need ideas?

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Thank you for watching! I hope you learned something.
I look forward to seeing any external plugins you might make!
If you do make one, please share it by making a pull request to
update the EXTERNAL_PLUGINS.md doc in the Telegraf project!