README ¶
What?
Piper is a https://patchbay.pub/ inspired shell tool that lets you connect separate shells together over a NATS based middleware.
You can use it to build things like network aware clipboards, notifications from servers to your desktop, ad hoc assembled work queues for doing shell based work on many cores and more.
- It has two basic modes of operation: multi consumer and multi producer or a work queue style multi producer to a load shared group of consumers
- By default, the publisher will block until there are consumers, by default it will give up after 1 hour, you can adjust this using
--timeout 5m
or by settingPIPER_TIMEOUT=5m
for example - An asynchronous mode, that avoid above blocking, is support if you have NATS JetStream
- In synchronous mode no data is stored, it's all ephemeral and the data is private to either your own NATS servers or your account on Synadia NGS (NATS as a Service). This means we won't be doing anything like serving web pages but with the shell utility scope I quite like it
- It's secure your data can not be accessed by anyone else
- Your data is compressed, NATS isn't great for large payloads but this will help a bit
Multi Producer to Multi Consumer
The n:n mode means a single producer can send a notify and any listeners on the given channel will all get the message, here are a few use cases.
Network aware speech synth
On your desktop(s) listen to messages, here using the OS X CLI tool say
that reads out whatever it receives over your speakers:
while true
do
piper listen say | xargs say
end
On any other machine:
$ ./longjob.sh ; piper say "long job completed"
Once longjob.sh
completes your speakers will say it's done.
You can also brew install terminal-notifier
and use that to get nice popups on your desktop with configurable titles, sound etc, for example instead of xargs say
you'd use terminal-notifier -title Piper -sound default
Network aware clipboard
On your desktop(s) run this:
while true
do
piper listen clipboard | pbcopy
end
Now on any other machine you can send data to your clipboard quite easily:
$ ls | piper clipboard
Multi Producer to Load shared grouped Consumers
To demonstrate the load shared group we can resize a set of png images across 2 shells, more useful utilities would be to fetch images from a s3 bucket and put smaller ones back, the requests would just be the file names or urls, but lets keep it simple:
On one shell run this:
#!/bin/bash
for filename in *.png
do
echo $filename | piper notify resize
done
On 2 other shells run this:
#!/bin/bash
while true
do
filename=$(piper listen resize --group)
base=$(basename "${filename}" .png)
echo $filename
convert -size 50%x50% "${filename}" "${base}-small.jpg"
done
Your images will now be resized using max 2 cores.
Asynchronous Mode
The examples above shows a blocking - synchronous - operation. While no persistence is needed it does mean your notifier is coupled to your listener and if either dies so does all progress.
Piper supports NATS JetStream (currently in preview) for persistence, in this case the notifier will publish data into JetStream and the listener will read from JetStream like a work queue.
If your NATS network has JetStream you can do piper setup
to configure the required settings in JetStream and pass -a
or set PIPER_ASYNC=1
in your environment. Once this is done Piper will be asynchronous.
Setup
To use it you need a NATS server, or you can sign up for a free NGS account.
You can use any NATS server, create a NATS context using nats cli:
$ nats context add piper --server example.net:4222 --credentials /some/user.creds --description "NATS Piper"
Piper will automatically use the context called piper
, you can pass --context
or set PIPER_CONTEXT
to pick another.
When in persistent mode data is kept for up to 24 hours or until any listener consumed it whichever comes first.
TODO?
- Encryption of the data
Status?
Basic features work as I want them to work, and I really like it
Contact?
R.I.Pienaar | rip@devco.net | @ripienaar
Documentation ¶
There is no documentation for this package.