supervisor-rs

supervisor-rs used to be a manager of handle application running. supervisor-rs can start/restart/stop processing.

features:

• start different processing depend on particular yaml file when startup
• start processing when have new config in load path
• startup with particular server config
• restart processing
• stop processing

design:

1. server/client mode
2. server start -> load config files from loadpaths (if it is not quiet mode) -> do job
3. start/stop/restart/tryrestart special processing (client side)

config yaml file format:

server.yaml:

#server side config
loadpaths:
  - /tmp/client/
  - /tmp/second/path
  
mode: "full"

each command's config:

#each child config in loadpath of server config
command: /tmp/test
output:
  - stdout: aaaaaa
    mode: create

  - stderr: nnnnn
    mode: append

Usage

You can download compiled binary file directly on release tag.

Or there is a tiny install script install.sh. You may need root permission to install it. After install, it would be neat if you give soft link /usr/bin/supervisor-rs-client -> /usr/bin/supervisor-rs/supervisor-rs-client, and /usr/bin/supervisor-rs-server -> /usr/bin/supervisor-rs/supervisor-rs-server

Or you can install from cargo.io, run cargo install supervisor-rs.

Server Side

Start server side application. After compiled, run supervisor-rs-server /tmp/server.yml in shell, you can change server config yaml file to wherever you want. If no config path given, supervisor will going to find server.yml in /tmp.

After server application start, if mode is full, then all application yaml files under loadpath of server config will be ran by application. So, that's means every yaml files in there should be legal application config file, or server cannot start.

Server side's default mode is quiet, means server will record loadphths, but won't start children automatically.

Each sub-processing is named with filename of yaml file. If have multi-loadpath, make sure no yaml files have same name.

command demo:

run server with special config file: supervisor-rs-server ./test/server.yml

Client Side

Restart child processing:

supervisor-rs-client restart child0 on localhost will restart processing child0 on localhost;

supervisor-rs-client restart child0 on 198.0.0.2 will restart processing child0 on 192.0.0.2, I assume you running server side application on this host;

supervisor-rs-client restart child0 on "198.0.0.2, 198.0.0.3" will restart processing child0 on 192.0.0.2 and 192.0.0.3, I assume you running server side application on this host;

child name is not must for check/kill commands.

commands:

Startup-with feature

If server's config mode is half, server will try to startup all children in startup list when it starts.

Demo:

#server side config
loadpaths:
  - /tmp/client/
  - /tmp/second/path
  
mode: "half"
startup:
  - child1
  - child2
  - child3

server will try to start child1, child2, and child3 when it startup

QA:

Q: if child3 not exist?

A: server will going to find children in startup, if some of them not exist in loadpaths, server will skip them.

Q: what if I forget write mode to half?

A: server default mode is quiet, and startup list only used in half mode, otherwise, startup won't effect anything.

Repeat feature

if config of child has repeat field:

#file name (child name) is demo.yml
command: /tmp/test
output:
  - stdout: aaaaaa
    mode: create

  - stderr: nnnnn
    mode: append
repeat:
  action: restart
  seconds: 5 #only support seconds now
  

then, when you start it, supervisor-rs will give a timer stand by and send back command when time is up. For example, config above will run restart demo every 5 seconds.

action's values are command we using in supervisor-rs-client, so you even can stop child with repeat field. But so, supervisor-rs won't create a timer stand by.

Only start, restart, and trystart will let supervisor-rs create a timer, if repeat field exists.

If action is empty, supervisor-rs will give restart be default value. However, seconds has to have value, and it cannot be 0.

How to stop repeat

As I said above, timer be created right after child runs. So you cannot stop "next" action, but if you change child's config, like delete repeat field, then "next" action won't create a timer.

This is because all start, restart and trystart will reload config of child before it does its job.

So, what will supervisor do if child has stopped, or restart manually before timer finish its waiting and send command to supervisor again, timer isn't outdated? Timer will check if child has same processing id as when it created timer. If this check passed, timer will do its job as normal, else, timer won't do anything because child current is not child before.

Hooks feature

Each child can have two hooks, one prehook, one posthook. prehook command will run before main child start/restart. posthook will run after child stop.

If prehooks command child has anther prehook, means there is a prehooks chain, they will run one by one, and they cannot have hooks circle.

example:

command: sleep 10
hooks:
  - prehook: start child
  - posthook: start child

What if accident happens

• if supervisor-rs be killed by kill, children won't stop, they will be taken by system.
• if supervisor-rs panic, children won't stop.

Go to log to find more information if supervisor-rs-server have problem

Cross compiling

brew tap filosottile/musl-cross && brew install FiloSottile/musl-cross/musl-cross

after install musl-cross, which x86_64-linux-musl-gcc will give a result, like /usr/local/bin/x86_64-linux-musl-gcc.

give configuration in ~/.cargo/config

[target.x86_64-unknown-linux-musl]
linker = "x86_64-linux-musl-gcc"

then, cargo build --target=x86_64-unknown-linux-musl, there is no errors in my local machine.