duct

duct is derived/forked from patchbay.pub. The name duct was chosen because this utility and server is meant to serve as a duct (or pipe) between utilities, and also as a sort of duct tape.

What does it do?

duct enables IFTTT-type applications. The duct server provides infinite HTTP endpoints that provide a multi-process, multi-consumer (MPMC) queue which can be used to implement powerful serverless applications - including desktop notificiations, sms notifications, job queues, web hosting, and file sharing. These applications are basically just a few lines of bash that wrap a curl command. However, duct also contains a simple IMAP/SMTP for email reading and writing that facilitates a free and easy way to do SMS notifications and webhooks.

Basics

The philosophy behind this is that the main logic happens on the local machine with small scripts. There is a server with an infinite number of virtual channels that will relay messages between the publisher and the subscriber. To subscribe to a channel you can simply make a GET request with a specified channel:

curl https://duct.schollz.com/a61b1f42

The above will block until something is published to the channel a61b1f42. You can easily publish to a channel using a POST request:

curl https://duct.schollz.com/a61b1f42 -d "hello, world"

The subscriber will immediately receive that data. If you reverse the order, then the post will block until it is received.

Pubsub mode

The default mode for publishing and subscribing is a MPMC queue, where the first to connect are able to publish/subscribe. But you can also specify publish-subscribe (pubsub) mode. In pubsub mode, the publisher will become non-blocking and their data will be transmitted to each connected subscriber. This is done using the parameter pubsub=true:

curl https://duct.schollz.com/a61b1f42?pubsub=true -d "hello, world"

Publish with GET

You can also publish with a GET request by using the parameter body=X, so that the publisher statement can be also written as:

curl https://duct.schollz.com/a61b1f42?pubsub=true&body=hello,%20world

This makes it easier to write href links that can trigger hooks.

Examples

File sharing

Change the command on the sending computer to

curl -X POST --data-binary "@test.txt" https://duct.schollz.com/test.txt

The command on the other computer remains the same as what you had

wget https://duct.schollz.com/test.txt

File sharing with end-to-end encryption + compresion

Sending:

cat file | gzip | openssl bf -pbkdf2 | curl -X POST --data-binary @- https://duct.schollz.com/00bf8a8f-ded4-48ea-9409-43796e5b9587

To receive:

curl --silent https://duct.schollz.com/00bf8a8f-ded4-48ea-9409-43796e5b9587 | openssl bf -pbkdf2 -d | gzip -d > file

Web hosting

while true; do curl -X POST https://duct.schollz.com/apps/simple_chat/chat.js --data-binary "@./apps/simple_chat/chat.js"; done

Job Queues

#!/bin/bash

# IFS determines what to split on. By default it will split on spaces. Change
# it to newlines
# See https://www.cyberciti.biz/tips/handling-filenames-with-spaces-in-bash.html
ifsbak=$IFS
IFS=$(echo -en "\n\b")

for filename in *.mp3
do
        curl https://duct.schollz.com/6903f6bb-af5d-4ed9-98e7-3cdf1b5fa386 -d $filename
done

# Need to restore IFS to its previous value
IFS=$ifsbak

And on four other computers;

#!/bin/bash

while true
do
        filename=$(curl -s https://duct.schollz.com/6903f6bb-af5d-4ed9-98e7-3cdf1b5fa386)
        if [ "$filename" != "Too Many Requests" ]
        then
                echo $filename
                ffmpeg -i "$filename" "$filename.ogg"
        else
                sleep 1
        fi
done

SMS notifications

First setup the email component of duct.

Then you can do a bash script like

#!/bin/bash

MAGIC="magic"
URL="https://duct.schollz.com/5de4210f-f835-4db2-bf42-5fe00bc0ae07"
CELLPHONE="[email protected]"
while [ 1 ]
do
X="$(curl $URL)"
if [[ $X =~ ^$MAGIC ]]; then
        Y="$(echo "$X" | sed "s/$MAGIC*//")"
        duct email --to "$CELLPHONE" --subject "notify" --body "$Y"
else
        sleep 10
fi
done

Desktop notifications

Windows

Run this PS script in the background. Follow these instructions to get this to work when you startup the computer.

$magicprefix="magic"
$url="https://duct.schollz.com/03789265-d0c0-426b-b74d-d4d5f7f63a62"
while($true)
{
    $result = Invoke-WebRequest $url
    If ($result.StatusDescription -eq "OK") {
        if ($result.Content.StartsWith("$magicprefix") -eq $true) {
            Add-Type -AssemblyName System.Windows.Forms 
            $global:balloon = New-Object System.Windows.Forms.NotifyIcon
            $path = (Get-Process -id $pid).Path
            $balloon.Icon = [System.Drawing.Icon]::ExtractAssociatedIcon($path) 
            $balloon.BalloonTipIcon = [System.Windows.Forms.ToolTipIcon]::Warning 
            $content = $result.Content.TrimStart("$magicprefix")
            $balloon.BalloonTipText = "$content"
            $balloon.BalloonTipTitle = "Attention $Env:USERNAME" 
            $balloon.Visible = $true 
            $balloon.ShowBalloonTip(5000)        
        } else {
             Start-Sleep -s 1
        }
    } else {
        Start-Sleep -s 3
    }
}

Linux

#!/bin/bash

MAGIC="magic"
URL="https://duct.schollz.com/405e3cda-7b36-4da4-9cd7-b46cab72c84b"

while [ 1 ]
do
X="$(curl $URL)"
if [[ $X =~ ^$MAGIC ]]; then
        Y="$(echo "$X" | sed "s/$MAGIC*//")"
        notify-send "$Y"
else
        sleep 10
fi
done

Email webhook

> duct email --check
{"to":"[email protected]","from":"[email protected]","date":"2019-11-27T11:44:29-08:00","subject":"my subject","body":"my body"}

You can easily use jq or similar to process and add it to some sort of hook.

License

MIT (with Copyright (c) 2019 patchbay)