notes/repos-dictated-config - subversion - Git at Google

 Some thoughts on repository-dictated configuration

 Introduction
 ============
 Many software development shops of non-trivial size desire to have an enforce
 a uniform configuration environment among the various clients which commit
 to their repositories.  Although these shops my have the ability to control
 the environment on the client machines (dictating software versions, etc),
 relying up on the client for setting various configuration parameters can
 be time-consuming and problematic.

 Subversion already provides the means of enforcing much (but not all) of this
 configuration through the hook script mechanism.  What our users desire is
 some way of having the server dictate a default or recommended configuration
 to clients.  The parameters of interest typically come from the standard
 client-side config: things like global-excludes or auto-props.  Allowing the
 administrator to store a default config on the server, which then gets pushed
 to the clients, would save both time and frustration.


 Behavioral specification
 ========================
 The high-level behavior for repository-dictated configuration is relatively
 simple: the repository maintains a list of configuration parameters and
 values, and upon request, provides these to the client who then applies them
 appropriately.

 It should be noted that the configuration the server dictates is only a
 *suggestion* to the client.  Clients may choose to override the suggestion
 with a configuration of their own, so appropriate server-side enforcement
 (often via hook scripts) is still recommended.


 Server-client transmission mechanism
 ====================================
 As part of the OPTIONS request, the client will send to the server the
 sha1 hash of the version of the server-dictated config that it current has
 cached.  If the server has a different version, it will send that to the
 client in the OPTIONS response.


 Server-side storage
 ===================
 [TODO]


 Client-side storage
 ===================
 The client current maintains a global configuration file in
 ~/.subversion/config  This feature will introduce the ~/.subversion/repos/
 directory, which will hold additional subdirectories keyed on the UUID of the
 repository.  It is in this subdirectory that the cached version of the
 repository configuration will be stored.


 Configuration Hierarchy
 =======================
 [TODO]
	Some thoughts on repository-dictated configuration

	Introduction
	============
	Many software development shops of non-trivial size desire to have an enforce
	a uniform configuration environment among the various clients which commit
	to their repositories. Although these shops my have the ability to control
	the environment on the client machines (dictating software versions, etc),
	relying up on the client for setting various configuration parameters can
	be time-consuming and problematic.

	Subversion already provides the means of enforcing much (but not all) of this
	configuration through the hook script mechanism. What our users desire is
	some way of having the server dictate a default or recommended configuration
	to clients. The parameters of interest typically come from the standard
	client-side config: things like global-excludes or auto-props. Allowing the
	administrator to store a default config on the server, which then gets pushed
	to the clients, would save both time and frustration.


	Behavioral specification
	========================
	The high-level behavior for repository-dictated configuration is relatively
	simple: the repository maintains a list of configuration parameters and
	values, and upon request, provides these to the client who then applies them
	appropriately.

	It should be noted that the configuration the server dictates is only a
	suggestion to the client. Clients may choose to override the suggestion
	with a configuration of their own, so appropriate server-side enforcement
	(often via hook scripts) is still recommended.


	Server-client transmission mechanism
	====================================
	As part of the OPTIONS request, the client will send to the server the
	sha1 hash of the version of the server-dictated config that it current has
	cached. If the server has a different version, it will send that to the
	client in the OPTIONS response.


	Server-side storage
	===================
	[TODO]


	Client-side storage
	===================
	The client current maintains a global configuration file in
	~/.subversion/config This feature will introduce the ~/.subversion/repos/
	directory, which will hold additional subdirectories keyed on the UUID of the
	repository. It is in this subdirectory that the cached version of the
	repository configuration will be stored.


	Configuration Hierarchy
	=======================
	[TODO]