krust-pm - Intro

Formeley `rust-pm (available at http://crates.io), now rewritten in Kotlin

This is a pocket process manager. It is kinda imitation of python's supervisord.

Behind the scenes it uses Quasar actors and fibers to handle the whole thing.

Using it is very simple, just drop a krust-pm.toml in the same folder your krust-pm starts, and add a config like:

server_name  = "localhost"
server_port  = 4000
log_dir      = "/tmp"
debug_config = true

[[processes]]
name = "good_sleeper"
cmd = "./sleeper.py" # right now support 0 args commands
max_retries = 3 # 0 means forever
instances = 8
work_dir = "./src/main/resources"
[processes.env]
  MY_ENVAR = "test.ok"
  NACHO_KEY = "27017999929231"

[[processes]] # Process name
name = "bad_sleeper"
cmd = "./src/main/resources/bad_sleeper.py" # right now support 0 args commands
max_retries = 3 # 0 means forever

And with luck you open your browser at localhost:4000 and will see something like:

[
  {
    "name": "good_sleeper",
    "cmd": "./sleeper.py",
    "status": "Started",
    "totalInstances": 2,
    "instances": [
      {
        "id": 0,
        "currentTry": 1,
        "status": "Done"
      },
      {
        "id": 1, // inc forever per new instance scaled
        "currentTry": 1,
        "status": "Done" // or Done | Started | Running | RetriesExceeded
      }
    ]
  },
  //...
]

krust-pm start and watch the process. If it fails it starts another instance for maximum max_retries times.

REST API plus additional info

Resource	Verb	Path	Returns
root	GET	/	Json with Process details (see above). ?status=S will match S to at least one instance with the given status.
process	GET	/ps	Context for interacting with processes. See below.
process	GET	/ps/scale	Returns the number of afected instances. name=NAME is the target process, to=AMOUNT sets the number of instances of NAME to AMOUNT. You can't specify which instance will be killed.

Additional Info:

• krust-pm is designed to manage long running processes such as python process, web servers etc. But in case of any process instance finishes, it will be with status Done. All managing resources (not Java Process Management) will be hanging on the server.
• If you scale down any process, it will remove the first AMOUNT of elements of the internal list, regardless of their status.
• There is no way to get the PID of an instance.
• There is no way to specify the user that runs a command

WARN

This is an early stage project, Not used in production yet.

But if you want to try it:

1. clone the repo
2. run gradle mavenCapsule
3. fire it: java -javaagent:$PATH_TO_QUASAR_JAR -jar build/libs/krust-pm-capsule.jar

TODO

• Augment the API to support scaling processes down and up. Done
• Implement 0 max_retries to mean infinite. Done
• Allow configuration of workdir for processes. Done
• Add command line parser to specify config file. Done
• Add env per process. Done

Licensing

MIT