[Discuss] SysVinit vs. systemd

[Richard Pieri]

On 9/12/2014 12:07 PM, Mike Small wrote:
> I don't understand this at all. Aren't daemons written as daemons
> (giving up controlling terminal and whatever else within their own
> code).

"Daemonizing" in this context is the support around starting, stopping,
and querying the status of daemon programs. Like the boilerplate shell
script code that you'll find in a typical sysvinit setup.


> "systemd starts and restarts services in a consistent and isolated
> environment, not in whatever your current environment is when you run
> the start and restart commands."
> 
> Sounds like a plausible problem.

It's not. Rather, it's only a problem if you are careless about
initializing the environments for your daemons or when your daemon
programs are carelessly written. For example, daemons and daemon startup
inheriting variables from the environment (PATH and such) instead of
explicitly setting them.


> "systemd keeps track of what processes belong to a particular service,
> so it can both list all the processes that are part of a service and
> tell you what service a particular process is part of. This is a boon to
> manageability."
> 
> I can imagine this being a problem for someone doing something
> serious.

It's not. Rather, this is a straw man used to justify systemd's One and
Only True Way of system startup. In reality, either a HA service group
manager or a large-scale configuration management system will do all of
this, do it better, and be easier to manage.


> Don't understand this. What's a conditional restart and why is it
> dangerous? What's the difference between an active and passive init
> system?

It's something applicable to HA service management.

-- 
Rich P.