rset(1) : pln(5)

Features

Lightweight	Execution start in < 0.5 seconds, task completion in as little as 1 second.
Real-time Status	Standard output and error messages are piped in from target hosts without buffering.
Simple	The standard tool chain can be mastered in 1 hour. All of the key operational paradigms are covered in the man pages ( rset(1), pln(5), rinstall(1), rsub(1) ).
Extensible	Add capabilities by dropping scripts, executable, or data files into a directory that is shipped to each host.
Portable	No dependencies for target BSD, Mac, and Linux machines; even Busybox on Alpine is enough.
Language Independent	Shell scripts are most common, but any interpreter that can read on STDIN can be used (Ruby, Python, Perl, ...)
Secure	Content visible to each host is explicitly specified in the routes file. Remote hosts can only request public data (source tarballs, packages, etc.)
Sequential	All actions are executed in the exact order they were written. The dry-run feature highlights which hosts and labels will be executed.
Predictable	Configuration and data are always located relative to the top-level routes file.

Overview

rset(1) stages configuration files and sequentially executes script fragments on remote hosts

# routes.pln

execute_with=sudo
interpreter=/bin/bash

10.10.0.20: mail/
→    www.pln

10.10.0.21: mail/
→    www.pln

pln(5) is a tab-indented format for embedding scripting languages to be executed in the order they were written

# www.pln
interpreter=/bin/ksh -x

packages:
→    pkg_add -I ruby
→    ln -sf /usr/local/bin/{ruby32,ruby}
→    ln -sf /usr/local/bin/{irb32,irb}

services:
→    ./rinstall mail/smtpd_relay.conf /etc/mail/smtpd.conf \
→        && rcctl restart smtpd

# vim:noexpandtab:syntax=sh:ts=4

The minimal directory layout for the example above is

├── _rutils
│   └── renv
│   ├── rinstall
│   └── rsub
├── _sources
├── mail
│   └── smtpd_relay.conf
├── www.pln
└── routes.pln

• _rutils contains utilities to be shipped to the staging directory on every remote host. rinstall and rsub are installed automatically, and provide an easy means of installing and modifying files. renv provides an interface for setting session-level environment variables.
• _sources is a directory made available by a built-in web server, typically larger files that rinstall can fetch on demand.
• In this example mail is also replicated to a temporary staging directory on the remote host since it was listed for export in routes.pln
• routes.pln lists each host to manage along with the rules to run for each.

Formulas

The following formulas are examples illustrate some of the ways in which pln(5) files can be written to configure services on OpenBSD. The same concepts apply equally well on other platforms.

PicOS Switches and Routers
Juniper Switches and Routers
OpenSMPTD Relay
Login Message
Let's Encrypt
WordPress
WireGuard
Multiple Platforms
Minio Lab
Check and Install
Metabase
Add/Modify Users

Security Model

For the most part rset(1) does not trust the remote hosts it manages, and takes several steps to prevent an attacker from reading configuration intended for another host.

1. Files and directories intended only for specific hosts are explicitly listed for each host. Only the contents of _rutils directory is copied implicitly to all hosts.
2. Scripts embedded in pln(5) files are not copied, they are piped to the interpreter over SSH. This ensures that temporary files are never left behind containing sensitive information.

Several measures are also taken to prevent the compromise of the host running rset

1. Large files are serviced by a local web server, miniquark(1), which only serves content under _sources.
2. On OpenBSD, pledge(2) is used to eliminate write access to system resources and to sandbox the http server.