how to use ready-notification funciton?

[lfxx]

Hello.I try to use ready-notification funtion.But it is not working.Can you post a demo config here?it would be nicer if you can eleborate this function more clear.at this time,i think it has the following usage:
For example, there are two services, A and B, with B depending on A. I wish to set a variable such that when A changes it, it implies that A has fully started, and at that point, B is started.
am i right?

[lfxx]

Urgent on this issue.Anyone come to help me out,thanks!

[mobin-2008]

Hello. What did you expect from ready-notification? It designed to help daemons to notify supervisor about they're ready for actual functionality.
From dinit-service(5) man-page:

ready-notification = {pipefd:fd-number | pipevar:env-var-name}
Specifies the mechanism, if any, by which a process service will notify that it is ready (successfully started). If not specified, a process service is considered started as soon as it has begun execution. The two options are:

pipefd:fd-number — the service will write a message to the specified file descriptor, which dinit sets up as the write end of a pipe before execution. This mechanism is compatible with the S6 supervision suite.

pipevar:env-var-name — the service will write a message to file descriptor identified using the contents of the specified environment variable, which will be set by dinit before execution to a file descriptor (chosen arbitrarily) attached to the write end of a pipe.

[davmac314]

Example setting:

ready-notification = fd:3

This would set allow the service process to signal readiness by writing to file descriptor number 3.

For example, there are two services, A and B, with B depending on A. I wish to set a variable such that when A changes it, it implies that A has fully started, and at that point, B is started.

This is roughly what readiness notification is for, yes (if the variable is internal to dinit). When the process for service A indicates readiness, then service A is considered started and then the service B process can be started.

[lfxx]

for example,now i has
A setting:
ready-notification = pipevar:worker_status
B setting:
depends-ms=A
A has a python demo:

import time
import os
time.sleep(5)
os.environ.setdefault("worker_status","ok")

use dinit -d dinit_config/ B can not start B service.How should i do?just want to know how to change the var worker_status
i will make my question more clear.
My user case is start A is time consuming.i want to do a funtion test after A start,if pass,then change the var worker_status to indicate A is ready.Then we can start B to receive request.Has dinit supported this now?
@mobin-2008 @davmac314

[SolitudeSF]

pipevar writes file descriptor number to the variable you provided. you dont need to write to the variable, you need to read it, and write a byte to the file descriptor it specifies.

[lfxx]

sorry.but i still don't understand.Could you please post a demo code here,thank you very much!i don't how to obtain the specific file descriptor in python.is this function just for c++ or c?

[lfxx]

finally,i use fd=os.fdopen(3, 'w') open the file descriptor successfully.

[davmac314]

If worker_status contains 3, then that is correct approach, yes.

[davmac314]

(or if you are using the example setting I provided above.)