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The "ServerDictatedConfiguration" page has been changed by CMichaelPilato: http://wiki.apache.org/subversion/ServerDictatedConfiguration?action=diff&rev1=16&rev2=17 Comment: Try to morph this plan per my conversation with pburba earlier. === Behavioral specification === The high-level behavior for server-dictated configuration is relatively simple: the repository maintains a list of configuration parameters and values which, as necessary, the server provides to the client. The client, then, behaves in accordance with the server-dictated configuration. - There are a number of specific bits of configuration that existing Subversion users and administrators wish to have propagated from the server to the client. There are also different scopes at which administrators might reasonably wish to apply differing defaults for these things: server-wide, repository-wide, or local to a particular directory hierarchy within a specific repository. The following is a listing of those that we know about, with some notes about scope and desired degrees of control: + There are a number of specific bits of configuration that existing Subversion users and administrators wish to have propagated from the server to the client. There are also different scopes at which administrators might reasonably wish to apply differing defaults for these things: server-wide, or local to a particular directory hierarchy within a specific repository. The following is a listing of those that we know about, with some notes about scope and desired degrees of control: ||'''Configuration''' ||'''Scope''' ||'''Enforceability''' ||'''Notes''' || - ||auto-props ||per-directory ||Enforceable via hook scripts ||Clients should be allowed to override this || + ||auto-props ||per-directory ||Enforceable via hook scripts || || - ||ignores ||per-directory ||Enforceable via hook scripts ||Client should be allowed to override this || + ||ignores ||per-directory ||Enforceable via hook scripts || || - ||use-commit-times ||per-directory ||Unenforceable ||Client should be allowed to override this || + ||use-commit-times ||per-directory ||Unenforceable || || ||log message templates ||per-directory ||Enforceable via hook scripts ||Doesn't fit the name=value configuration motif quite as readily as some of the others. Would a client need to override this? || - ||myriad authn-related stuff ||per-server ||Unenforceable ||Lack of enforceability plus relationship to security means that admins do not want the client to be able to trivially override this setting. Precise requirements TBD (is this a boolean "allow/disallow plaintext password caching", or "require X, Y or Z encrypted password stores", or ...?) || + ||store-plaintext-passwords ||per-server ||Unenforceable ||Should it be possible to override this without hacking the client? || @@ -22, +22 @@ {{{#!wiki warning The configuration the server dictates can at best be only a suggestion to the client, with well-behaving clients honoring that suggestion. As free software, though, most such clients could be modified by a malicious user to ignore server-side suggestions. Server-side enforcement of desired behaviors (where possible, and often via hook scripts) is still recommended. }}} - At least one user specifically called out the need for the server to enforce adherence to the configured behaviors ''without'' requiring hook scripts to do so. For example, if the repository has a configured auto-props list, the Subversion C code is perfectly capable of validating that incoming committed items obey those settings, failing the commit otherwise. This seems like a reasonable request so long as we permit admins to specify which of their configuration settings are "suggested" versus "required" (again, taking into account that anything unenforceable can't truly be "required"). - Subversion could recognize multiple levels of possible hierarchy in the server-side configuration: - 1. server - Settings apply for all repositories and paths therein on the server - 1. subtree within repository - Settings apply for paths at or under a given path in the repository + 1. subtree within repository - Settings apply for paths at or under a given path in the repository. This is a reasonable "phase 1" target for this feature. + 1. server - Settings apply for all repositories and paths therein on the server. We'll probably defer this to "phase 2". Admins are already used to having configuration duplicated across many repositories (hook scripts, authz files, etc.), so we suspect it's no showstopper if "server" configuration is done by ensuring that every repository is properly configured. - - And at each level, multiple degrees of insistence in the actual configuration items: - - 1. weak - The configuration value is proposed to the client, but will be overridden by any client configuration - 1. strong - The configuration value is strongly suggested by the client, and may not be overridden by well-behaved client configuration - 1. enforced - The configuration value is required and adherence to it is verified by the server logic === Server-client transmission mechanism === Over ra-neon/ra-serf, the client will send to the server the sha1 hash of the server-dictated config that it currently has cached as part of the OPTIONS request. If the server has a different version, it will send that to the client in the OPTIONS response. For ra-svn, a similar thing happens as part of the initial connection handshake/feature exchange. This is an opportunistic caching approach, keeping the client in sync with the repository configuration any time the client contacts the repository. This mechanism requires that there exist a predictable and consistent manner in which to calculate the checksum of the configuration. + We plan to introduce a new capability string ("server-config") which clients should use to announce to the server that they will honor the server's dictated configuration. Administrators may choose to use that string presence/absence in the list of capabilities passed to the start-commit hook to determine whether to allow commits from certain clients. + === Server-side storage === - ''[TODO]'' + The most logical format for server-side configuration is to again use the INI file format which is already employed for several other purposes across Subversion. And the most logical location to put those INI files is in ''${REPOS_PATH}/conf/'' somewhere. === Client-side storage === - The client current maintains a global configuration file in ~/.subversion/config This feature will introduce the ~/.subversion/repos/ directory, which will hold additional subdirectories keyed on the UUID of the repository. It is in this subdirectory that the cached version of the repository configuration will be stored. + The client current maintains a configuration in two files, ''${HOME}/.subversion/confi''g and ''${HOME}/.subversion/servers''. This feature will introduce the ''${HOME}/.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. To facilitate path-specific configuration within a repository, the typical section names of the configuration bits will be combined with the subtree path to which the options therein apply. For example: + {{{ + $ cat ${HOME}/13f79535-47bb-0310-9956-ffa450edef68/config + [miscellany:/] + enable-auto-props = no + + [miscellany:/subversion] + enable-auto-props = yes + + [auto-props:/subversion] + *.c = svn:mime-type=text/x-csrc;svn:eol-style=native;svn:keywords=Author Date Id Rev URL + *.html = svn:mime-type=text/html;; charset=UTF-8;svn:eol-style=native + + ... + $ + }}} === Configuration Hierarchy === - ''[TODO]'' + Server-dictated configuration will be the highest priority configuration recognized by well-behaved Subversion clients, exception per-use overrides (ala --config-option). Only specific options will be made available for server-dictated configuration though. Also, only certain of the server-dictated configuration options will be overridable at all. These details will be governed by hardcoded whitelists. + + So, the order in which specific configuration options will be honored where found is: + + 1. Per-use overrides (--config-option) + 1. Server-dictated configuration + 1. Per-user runtime configuration (''${HOME}/.subversion''/*) + 1. Per-machine runtime configuration (''/etc/subversion/*'') === Related Issues === * http://subversion.tigris.org/issues/show_bug.cgi?id=1974
