# git submodule init and redundant data in .gitmodules/.git/config 7 messages from 2007-08-15 to 2007-08-17. Participants: martin f krafft, Sven Verdoolaege, Josef Weidendorfer, Lars Hjemli. Thread: https://gitlist.dev/t/9538 ## martin f krafft, 2007-08-15 16:20 Subject: git submodule init and redundant data in .gitmodules/.git/config Message-ID: <20070815162005.GA18463@piper.oerlikon.madduck.net> URL: https://gitlist.dev/e/20070815162005.GA18463%40piper.oerlikon.madduck.net ``` Hi, I am starting to learn submodules and hit the first state of confusion when I encountered git-submodule init: After git-submodule add, I find in my repository a .gitmodules file as well as the newly-cloned submodule. I can call git-submodule status on it to get the HEAD hash. The .gitmodules file has a stanza for each submodule, linking remote url to local path, e.g.: [submodule "foo"] path = foo url = ../foo.git The manpage then talks about git-submodule init: init Initialize the submodules, i.e. register in .git/config each submodule name and url found in .gitmodules. The key used in .git/config is submodule.$name.url. This command does not alter existing information in .git/config. When I run git-submodule init, the following stanza gets added to .git/config: [submodule "foo"] url = ../foo.git Unless I call init, I cannot use git-submodule update. But looking at the two stanzas, it strikes me that the remote url of the submodule is duplicated and detached, creating redundant data which may become desynchronised. Why is this? What is the reason for git-submodule init and moving the data to .git/config? Thanks, -- martin; (greetings from the heart of the sun.) \____ echo mailto: !#^."<*>"|tr "<*> mailto:" net@madduck "it is only the modern that ever becomes old-fashioned." -- oscar wilde spamtraps: madduck.bogus@madduck.net ``` ## Sven Verdoolaege, 2007-08-15 16:38 Subject: Re: git submodule init and redundant data in .gitmodules/.git/config Message-ID: <20070815163822.GC1070MdfPADPa@greensroom.kotnet.org> URL: https://gitlist.dev/e/20070815163822.GC1070MdfPADPa%40greensroom.kotnet.org In-Reply-To: <20070815162005.GA18463@piper.oerlikon.madduck.net> ``` On Wed, Aug 15, 2007 at 06:20:05PM +0200, martin f krafft wrote: > But looking at the two stanzas, it strikes me that the remote url of > the submodule is duplicated and detached, creating redundant data > which may become desynchronised. > > Why is this? > > What is the reason for git-submodule init and moving the data to > .git/config? The (most appropriate) URL from which to get updates of a submodule may be different for different people and therefore has to be stored in .git/config. It was then decided that the default value for this URL should be stored in .gitmodules. git submodule init simply initializes the URL using this default value. You are free to not call git submodule init and set a (more) appropriate URL manually. skimo ``` ## martin f krafft, 2007-08-15 22:29 Subject: using .gitmodule as default (was: git submodule init and redundant data in .gitmodules/.git/config) Message-ID: <20070815222907.GA7395@piper.oerlikon.madduck.net> URL: https://gitlist.dev/e/20070815222907.GA7395%40piper.oerlikon.madduck.net In-Reply-To: <20070815163822.GC1070MdfPADPa@greensroom.kotnet.org> ``` also sprach Sven Verdoolaege [2007.08.15.1838 +0200]: > The (most appropriate) URL from which to get updates of a submodule > may be different for different people and therefore has to be stored > in .git/config. It was then decided that the default value > for this URL should be stored in .gitmodules. git submodule init > simply initializes the URL using this default value. You are free > to not call git submodule init and set a (more) appropriate URL manually. Ah. I shall prepare a patch against the manpage to make this more clear then. Thanks for your explanation. I have one open question though: why require init? It makes perfect sense to allow for a local override, but unless I need to override it, git-submodule update should really just keep using the default, which it does not as far as I can tell from my tests: piper:/tmp/cdt.tfd29893/co/a> git submodule update piper:/tmp/cdt.tfd29893/co/a> git-submodule init Submodule 'b' (/tmp/cdt.tfd29893/repos/b.git) registered for path 'b' piper:/tmp/cdt.tfd29893/co/a> git submodule update Initialized empty Git repository in /tmp/cdt.tfd29893/co/a/b/.git/ 0 blocks Submodule path 'b': checked out '0c1403bc9e13480e70745b70f79ffb00deb25a8d' Is there a reason for this or should I try to create a patch, which would make git-submodule consult .gitmodules in addition to config.submodules for all modules not found in config.submodules. Now if I may go a step further, I'll claim that init is a misnomer, really. Instead, I would suggest to rename it. Here are some thoughts: - config there is already git-config, and just like git-svn reuses e.g. rebase, this would keep the taxonomy compact - cpconf it does copy the configuration, after all - override not sure, since it doesn't actually override anything, but sets it all up for the user to be able to override the config - instconf install or instantiate the configuration - localise overloaded word, but it'd be localising configuration in some ways - localconf hinting at making the configuration local Comments welcome, -- martin; (greetings from the heart of the sun.) \____ echo mailto: !#^."<*>"|tr "<*> mailto:" net@madduck man muss noch chaos in sich haben um einen tanzenden stern zu gebähren. -- friedrich nietzsche spamtraps: madduck.bogus@madduck.net ``` ## Josef Weidendorfer, 2007-08-16 13:53 Subject: Re: using .gitmodule as default (was: git submodule init and redundant data in .gitmodules/.git/config) Message-ID: <200708161553.10991.Josef.Weidendorfer@gmx.de> URL: https://gitlist.dev/e/200708161553.10991.Josef.Weidendorfer%40gmx.de In-Reply-To: <20070815222907.GA7395@piper.oerlikon.madduck.net> ``` On Thursday 16 August 2007, martin f krafft wrote: > also sprach Sven Verdoolaege [2007.08.15.1838 +0200]: > > The (most appropriate) URL from which to get updates of a submodule > > may be different for different people and therefore has to be stored > > in .git/config. It was then decided that the default value > > for this URL should be stored in .gitmodules. git submodule init > > simply initializes the URL using this default value. You are free > > to not call git submodule init and set a (more) appropriate URL manually. > > Ah. I shall prepare a patch against the manpage to make this more > clear then. Thanks for your explanation. > > I have one open question though: why require init? It makes perfect > sense to allow for a local override, but unless I need to override > it, git-submodule update should really just keep using the default, The information in .gitmodules is only a default value for the URL, and not to be actually used. The URL in the config has to exist and will be used for updating. So the config value is not about overriding anything, but is required information. The URL should not depend on the current revision you have checked out at the moment; otherwise, if the default URL in .gitmodules changed at some point in the history, and you check out some earlier commit in the superproject, the update of the submodule would not work: the submodule project still resides on the new URL, regardless of the old information in .gitmodules at the time of the old commit. Josef ``` ## martin f krafft, 2007-08-16 14:21 Subject: Re: using .gitmodule as default (was: git submodule init and redundant data in .gitmodules/.git/config) Message-ID: <20070816142133.GA26013@piper.oerlikon.madduck.net> URL: https://gitlist.dev/e/20070816142133.GA26013%40piper.oerlikon.madduck.net In-Reply-To: <200708161553.10991.Josef.Weidendorfer@gmx.de> ``` also sprach Josef Weidendorfer [2007.08.16.1553 +0200]: > The information in .gitmodules is only a default value for the > URL, and not to be actually used. The URL in the config has to > exist and will be used for updating. So the config value is not > about overriding anything, but is required information. It's not required for git-submodule status. > The URL should not depend on the current revision you have checked > out at the moment; otherwise, if the default URL in .gitmodules > changed at some point in the history, and you check out some > earlier commit in the superproject, the update of the submodule > would not work: the submodule project still resides on the new > URL, regardless of the old information in .gitmodules at the time > of the old commit. Fair point. Thanks, -- martin; (greetings from the heart of the sun.) \____ echo mailto: !#^."<*>"|tr "<*> mailto:" net@madduck "heuristic is computer science jargon for 'doesn't actually work.'" -- charlie reiman spamtraps: madduck.bogus@madduck.net ``` ## Josef Weidendorfer, 2007-08-16 16:39 Subject: Re: using .gitmodule as default (was: git submodule init and redundant data in .gitmodules/.git/config) Message-ID: <200708161839.52749.Josef.Weidendorfer@gmx.de> URL: https://gitlist.dev/e/200708161839.52749.Josef.Weidendorfer%40gmx.de In-Reply-To: <20070816142133.GA26013@piper.oerlikon.madduck.net> ``` On Thursday 16 August 2007, martin f krafft wrote: > also sprach Josef Weidendorfer [2007.08.16.1553 +0200]: > > The information in .gitmodules is only a default value for the > > URL, and not to be actually used. The URL in the config has to > > exist and will be used for updating. So the config value is not > > about overriding anything, but is required information. > > It's not required for git-submodule status. This can show uninitialized submodules, so that's fine. As the URL in .gitmodules is only an initial default, it probably could be optional: if you work on a supermodule with a submodule of your own, it is easily possible that you have no idea about what a reasonable default of a submodule URL should be at the time you do the first supermodule commit. It makes no sense to have to provide a bogus URL there. Josef ``` ## Lars Hjemli, 2007-08-17 07:14 Subject: Re: using .gitmodule as default (was: git submodule init and redundant data in .gitmodules/.git/config) Message-ID: <8c5c35580708170014i5af2da62w1dbcbad71430e26@mail.gmail.com> URL: https://gitlist.dev/e/8c5c35580708170014i5af2da62w1dbcbad71430e26%40mail.gmail.com In-Reply-To: <20070815222907.GA7395@piper.oerlikon.madduck.net> ``` On 8/16/07, martin f krafft wrote: > I have one open question though: why require init? The purpose of 'init' is to inform git-submodule about which submodules you want to checkout. E.g. for a project with submodules in directories 'a', 'b' and 'c', you could do $ git submodule init b c $ git submodule update This would only fetch/checkout the submodules in direcotories 'b' and 'c', while 'git submodule status' would still inform you that there is actually three submodules available. Note: If you wanted to initialize all three submodules at once, you could simply do $ git submodule init -- larsh ```