Re: Dependencies in S6

[Crest <crest@rlwinm.de>]

On 21.10.20 12:10, Amaresh Kotekal wrote:
> Hi Team,
>
> I have some doubt on dependencies file in S6.
>
> Secnario 1:
> 1. A & B are one shot services in a s6-rc bundle. Service B is dependent on
> A. ( added in dependency file).
> 2. I think Service B will start after the completion of service A ( A then
> B, in serial manner ) is it correct ? or
> 3. Service B will start immediately after the service A as started (in a
> parallel manner) ?
>
> Secnario 2:
> 1. A is one shot service and B is a long run service. Service B is
> dependent on Service A.
> 2. Service B will start, once th service A as completed (in serial manner)
> ? or
> 3. Service B will start immediately after the service A as started (in a
> parallel manner) ?
>
> Secnario 3:
> 1. A is a long run service and B is a one shot service. Service B is
> dependent on Service A.
> 2. Service B will start immediately after the service A as started (in a
> parallel manner) ?
> 3. Do I need to use notification mechanism if I want to start service B
> after A service as reached particular point in execution
>
> Secnario 4:
> 1. A & B both are long run services. Service B is dependent on Service A.
> 2. Service B will start immediately after the service A as started (in a
> parallel manner) ?
>
> If one shot service are dependent on other one shot services. They will be
> started in serial manner one after the other ?

The s6-rc service manager is always concurrent while respecting 
dependencies. It starts all services as soon as their requirements are 
satisfied.

Having a single service depend on a single other service is just a 
special case of the more general dependency resolution s6-rc does.