𝐤𝐮𝐫𝐯 is a process manager, mainly for Node.js and Python applications. It's written in Rust. It daemonizes your apps so that they can run in the background. It also restarts them if they crash.

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Why 𝐤𝐮𝐫𝐯?

So, why the name 𝐤𝐮𝐫𝐯? Well, it means "basket" in many languages I don't speak, like Norwegian (but it sounded cool 😄). Think of 𝐤𝐮𝐫𝐯 as a basket for your apps. In kurv, we call each deployed app as an egg. So, let's go and collect some eggs 🥚 in your basket 🧺.

Installation

Note

𝐤𝐮𝐫𝐯 can run either as a server or as a CLI client, using the same binary.

The server is responsible for managing the eggs, while the client is used to interact with the server and tell it what to do or ask it for information.

Download binaries

Download the latest release from GitHub.

crates.io

You can also install it from crates.io using cargo:

cargo install kurv

Usage

Start the server

To get the server rolling, type:

kurv server

Important

• 𝐤𝐮𝐫𝐯 will create a file called .kurv where it will store the current state of the server. The file will be created in the same directory where the binary is located or in the path specified by the KURV_HOME_KEY environment variable.

• since 𝐤𝐮𝐫𝐯 can be used both as a server and as a client, if you want to run it as a server, you need to set the KURV_SERVER environment to true. This is just a safety measure to prevent you from running the server when you actually want to run the client. To bypass this, you can use the --force flag (kurv server --force)

Collect some 🥚

To deploy/start/daemonize an app (collect an egg), do:

kurv collect <egg-cfg-path>

The path should point to a YAML file that contains the configuration for the egg.

It should look something like this:

name: fastapi # the name of the egg / should be unique
command: poetry # the command/program to run
args: # the arguments to pass to the command
    - run
    - serve
cwd: /home/user/my-fastapi-app # the working directory in which the command will be run
env: # the environment variables to pass to the command
    FASTAPI_PORT: 8080

This will run the command poetry run serve in /home/user/my-fastapi-app with the environment variable FASTAPI_PORT set to 8080.

If for some reason, the command/program crashes or exits, 𝐤𝐮𝐫𝐯 will revive it!

Show me my eggs

If you want a summary of the current state of your eggs, run:

$ kurv list

🥚 eggs snapshot

╭───┬───────┬───────────┬─────────┬───┬────────╮
│ # │ pid   │ name      │ status  │ ↺ │ uptime │
├───┼───────┼───────────┼─────────┼───┼────────┤
│ 1 │ 35824 │ fastapi   │ running │ 0 │   1s   │
│ 2 │ 0     │ fastapi-2 │ stopped │ 0 │   -    │
╰───┴───────┴───────────┴─────────┴───┴────────╯

For details on a specific egg:

$ kurv egg <egg:name|id|pid>

This will show you the egg's configuration, process details, etc.

Stop an egg

To halt an egg without removing it:

$ kurv stop <egg:name|id|pid>

This will stop the process but keep its configuration in the basket in case you want to start it again later.

Remove an egg

To actually remove an egg, run:

$ kurv remove <egg:name|id|pid>

It will stop the process and remove the egg from the basket.

Restart

If you need the process to be restarted, run:

$ kurv restart <egg:name|id|pid>

🔌 Plugins

Want to extend 𝐤𝐮𝐫𝐯 with your own tools? Kurv support plugins! They're special eggs that 𝐤𝐮𝐫𝐯 automatically discovers and manages.

How it works

1. Drop an executable starting with kurv- in <KURV_HOME>/plugins/
2. Make it respond to --kurv-cfg with JSON config, same as an egg config
3. Restart 𝐤𝐮𝐫𝐯 server
4. That's it! The plugin is now running 🎉

View your plugins:

$ kurv plugins # list all plugins

Plugins can be started, stopped, and restarted just like regular eggs, but they can't be removed (stop kurv and delete the executable instead).

To do list

𝐤𝐮𝐫𝐯 is still under development. Here are some of the things I'm planning to add:

• Simple password protection
• Scheduled egg runs: allow eggs to not be long-running processes, but instead run at specific times or intervals (cron-like). This might be implemented as a plugin "kurv-cron".
• Remotely manage eggs
• SSL support
• More tests

Plugins / extensions

Since 𝐤𝐮𝐫𝐯 is a process manager, we can easily extend its functionality by adding plugin eggs (simple eggs managed by 𝐤𝐮𝐫𝐯 itself that provide additional functionality).

Here are some ideas I have for plugins:

• Web UI
• Log Viewer (kurv tail <egg> (livestream) and kurv logs <egg> --lines N (last N lines))
• Log Rotation

Plugin system improvements

• Command-based plugins: allow plugins to register custom commands that can be run using kurv <plugin-command> [args...] (requires ability to register not-long-running eggs that run a command and exit, instead of being daemonized)

Inspiration

pm2

Inspired by the robust process manager, pm2, my goal with 𝐤𝐮𝐫𝐯 was to create a lightweight alternative. Not that pm2 is a resource hog, but I found myself in a server with extremely limited resources. Plus, I was itching for an excuse to dive into Rust, and voila, 𝐤𝐮𝐫𝐯 was born.

eggsecutor

Derived from eggsecutor, 𝐤𝐮𝐫𝐯 adopted the whimsical term "eggs" to represent deployed applications.

pueue

Insights from pueue were instrumental in helping me understand how to manage processes in Rust.

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With 🧉 from Argentina 🇦🇷