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On Fri, Oct 31, 2014 at 2:27 PM, Rich Freeman <rich0@g.o> wrote: |
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> On Fri, Oct 31, 2014 at 1:34 PM, Tom H <tomh0665@×××××.com> wrote: |
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>> Is "After" really necessary as an option? I've never come across a |
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>> service that uses "After" without a "Requires" or a Wants" but I've |
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>> never taken the time to look. |
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> |
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> Hmm, I found After more common that Wants, but maybe I only look at |
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> units that have problems. :) |
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LOL. Which supports the thesis that "After" might not be a useful |
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setting within a service unit. But it's just occured to me that target |
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units use "After" without "Requires" or "Wants", for example |
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network-online.target has "After=network.target". |
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> I think the intent is to handle optional dependencies, but in practice |
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> I don't know that it works well. It would almost be better to have |
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> some kind of cluster config file that specifies all the actual |
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> dependencies (possibly including cross-host) and have it spit out all |
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> the unit dependencies automatically. That is a bit much to ask for |
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> now, and probably a bit much for somebody who just wants their laptop |
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> to launch kde after all their mounts are ready. |
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Optional dependencies are handled by "Wants" like openrc's "use". |
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IIUC you're referring to a BSD-like rc daemon config file. WOuldn't |
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that have to be maintained by a sysadmin rather than by a package |
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maintainer? |
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> Specifying After vs Wants separately does make sense. Dependency |
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> doesn't have to imply sequential. |
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Do you have an example of a service that uses "After=" but doesn't |
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need a "Requires=" or a "Wants="? I'm either being unimaginative or |
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plain dumb, but I can't think of any. I wonder whether, if Lennart and |
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co removed "After=" from service units and turned "Requires=" into the |
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equivakent of the current "Requires=" and "After=" setup, someone |
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would raise a storm over the change because it would've broken |
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something. |