Syncron

Syncron is a dashboard for your cron jobs. It collects run information including environment, timings, and logs from each job and presents them in an easy to read web application.

Architecture

Syncron consists of a client and a server. The client runs on each machine you want to collect job data from. It is designed to act as a "passthrough shell"--you tell cron to use it as your shell (via the SHELL environment variable, and it runs your code collects the output and sends it off to the server. You can also run it in a client mode that doesn't try to mimic a shell.

The server is an http server. It acts as both a server for the Syncron web application to view logs and as the backend api server that the syncron clients deliver job info to. The server stores job logs on the filesystem and all other job metadata in an SQLite database.

The client and the server are compiled into the same binary. See the syncron cli reference for more information.

Despite the name and original intent, there is nothing that makes Syncron particularly tied to crontabs--it can handle any sort of repeating job that outputs to stdout/stderr.

Installing

The latest Syncron binary is available here. You can put it anywhere in the filesystem.

You do not need to (and should not) run the Syncron server as root. Instead, create a low privileged user and run Syncron as that. A typical Syncron server process might be invoked as:

/path/to/syncron serve -v --port=4567 --db=/path/to/db

The database directory must exist and be writable by the syncron process. The port is arbitrary. Syncron does not daemonize on its own and logs to stderr.

To start Syncron automatically on a systemd controlled system, put something like this in /etc/systemd/system/syncron.service (assumes a syncron user):

[Unit]
Description=Syncron Server
Wants=network.target

[Install]
WantedBy=multi-user.target

[Service]
User=syncron
WorkingDirectory=~
ExecStart=/path/to/syncron serve -v --port=4567 --db=/path/to/db
Restart=on-failure
RestartSec=2s
StandardOutput=journal
StandardError=inherit

Building From Source

If no binary is available you can build Syncron from the source.

Requirements

• A recent nightly Rust compiler
• Node and npm
• Make. I hope this is included in your OS. 🙂

Build command

To make a self contained binary in ./target/release/syncron:

make release

This will compile the rust binary, install the node modules and package up the javascript/html bits for the server portion.

To make a self contained debug version in ./target/debug/syncron:

make

When developing, usually what you want is just:

cargo build

This doesn't create a self contained binary. Instead, documentation and the front end web code and documentation will be served from the filesystem (./web and ./docs respectively). This is usually more convenient when developing the front end code or documentation since you can just reload the web browser to get any new changes instead of rebuilding the app.

Running tests

cargo test

Todo

Syncron is prerelease code at the moment. I'm personally running it "in production" on a machine but I don't fully recommend it. I've tried my best to make it robust, but use at your own risk!

Big features that are not implemented (in no particular order):

• Progress bars with timing based on previous runs
• A horizontal plot showing good/failed jobs a-la uptime robot
• Hosts (it currently works fine across hosts, but the namespace is per user instead of per host/user pair)
• Renaming jobs from the web interface
• Terminal UI a-la tig
• Pruning old job runs, with configurable retention period
• Job deletion
• Authentication (currently anyone with access to the port can do anything a client could do)
• Alerting when important jobs fail. Web hook? Slack Post? Email?

License

Copyright © 2022 David Caldwell david_syncron@porkrind.org

TLDR: GPLv3. You can redistribute the binary (or a modified version) as long as you ship the source code used to build it alongside.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.