procfusion
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linkdd
Very simple process manager written in Rust for your Docker images
ProcFusion
Very simple process manager for your Docker images.
Introduction
One container, one application. That is the mantra we should follow when designing a container based application.
However, one application can sometimes be split into multiple processes. When that is the case, it can become challenging to manage those processes within a Docker image.
Solutions like supervisord can help, but they come with their own quirks, for example:
- supervisord restart the child processes by default
- supervisord logs the child process's stdout/stderr to a file by default
- when redirected to stdout/stderr instead, the logs are mixed and not easily filterable
Also, requiring Python in your Docker container can be a huge overhead, especially if your application is not written in Python.
ProcFusion aims to solve this.
Features
- start each child process in a process group
- if SIGINT/SIGTERM/SIGHUP is sent to ProcFusion, it forwards it to each child process
- if a process exits (normally or not), ProcFusion sends SIGTERM to every other child process, and exits with the exited process's exit code
- prefix stdout/stderr of each process with a deterministic label
Comparison
| Feature | ProcFusion | Supervisord | s6-overlay | dumb-init |
|---|---|---|---|---|
| Process Groups | :white_check_mark: | :white_check_mark: | :white_check_mark: | :white_check_mark: |
| Forward signals | :white_check_mark: | :white_check_mark: | :white_check_mark: | :white_check_mark: |
| Multiple children | :white_check_mark: | :white_check_mark: | :white_check_mark: | :x: |
| Dependency management | :x: | :x: | :white_check_mark: | :x: |
| Logs prefixing | :white_check_mark: | :x: | :x: | :x: |
| Configuration | TOML | INI-like | Service files | Command-line or as shebang |
| Language (not that it matters) | Rust | Python | Shell | C |
Installation
$ cargo install --git https://github.com/linkdd/procfusion
Or download the archive from the latest release.
Usage
ProcFusion expects its configuration as a TOML file:
[processes.foo]
command = "while true; do echo foo; sleep 1; done"
shell = "/bin/sh" # Wraps command in '/bin/sh -c'
directory = "/tmp" # Optional, defaults to $PWD
[processes.bar]
command = "while true; do echo bar; sleep 2; done"
shell = "/bin/sh"
[processes.baz]
command = "for i in 1 2; do echo baz; sleep 3; done; exit 1"
shell = "/bin/sh"
Then run:
$ procfusion path/to/config.toml
The example above will have the following output:
proc.foo[stdout] | foo: hello
proc.bar[stdout] | bar
proc.baz[stdout] | baz
proc.foo[stdout] | foo: hello
proc.bar[stdout] | bar
proc.foo[stdout] | foo: hello
proc.baz[stdout] | baz
proc.foo[stdout] | foo: hello
proc.bar[stdout] | bar
proc.foo[stdout] | foo: hello
proc.foo[stdout] | foo: hello
controller[stdout] | time=2024-05-15T12:18:50.247868783Z message="baz exited with exit status: 1"
controller[stdout] | time=2024-05-15T12:18:50.248983822Z message="bar exited with signal: 15 (SIGTERM)"
controller[stdout] | time=2024-05-15T12:18:50.249275312Z message="foo exited with signal: 15 (SIGTERM)"
NB: Environment variables are inherited from the ProcFusion process.
License
This software is distributed under the terms of the MIT License.
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