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

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© 2021 InfluxData. All rights reserved. 2
• 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!