janhoy commented on a change in pull request #531: URL: https://github.com/apache/solr/pull/531#discussion_r786305409
########## File path: dev-docs/plugins-modules-packages.adoc ########## @@ -0,0 +1,129 @@ += Plugins, Modules and Packages +:toc: left + +This document discusses how developers can group features into Plugins, Modules and Packages. + +== Definitions + +=== Plugin + +A plugin is a low level class that implements a certain Lucene or Solr interface, such as +`QParserPlugin`, `AuthPlugin`, `UpdateRequestProcessor`, `QueryResponseWriter` etc. +See ref guide page https://solr.apache.org/guide/solr-plugins.html[Solr Plugins] for details. + +=== Module + +Earlier referred to as "Contrib". This is a well-defined piece of functionality that is +separate from solr-core and produces a separate `.jar` file in the build. Modules help +keep the solr-core small and lean and also reduces risk by including only needed java classes +on the class-path. A module can contain multiple Plugins. + +=== Package + +A Package is some server-side functionality for Solr that is provisioned with a `manifest.json` +to enable discovering and loading through https://solr.apache.org/guide/package-manager.html[Solr's package manager]. Packages are loaded from a "package repository" which is +simply a json file on a HTTP server. Packages can be maintained by 3rd party devs and hosted on +GitHub, like https://github.com/yasa-org/yasa[YASA], +https://github.com/rohitbemax/dataimporthandler[DataImportHandler], +https://github.com/erikhatcher/solr-velocity[Velocity] and +https://github.com/cominvent/request-sanitizer-component[RequestSanitizerComponent]. +But the Solr project is also working on packaging our own (1st party) modules as packages, +and host them either inside the binary tarball distribution of Solr or later also in the +ASF download repos. + +== Dev guide for creating modules + +=== When to create a module + +Any functionality added to Solr that is not obviously useful for all Solr users and that +spans more than a single source file, should be considered for a new module. + +=== Module layout + +Modules consist of a `solr-<moduleName>-X.Y.Z.jar` artifact as often also a set of dependency +`.jar` files that it needs to work (but not jars that are otherwise default a part of Solr). + +Module sources live in the `solr/modules/` folder in the checkout, and have their own gradle +build file. See "Bootstrapping" paragraph on how to scaffold a new module. + +The layout of modules in the binary distribution is produced by the gradle build and is +as follows: +``` +<install-dir>/modules/<moduleName>/ + +-- README.md + +-- lib/ + +-- solr-<moduleName>-X.Y.Z.jar + +-- dependency-1.jar + +-- other-dependency.jar +``` + +=== Bootstrapping a new module + +It is not hard to create a new module. You can do it by hand, or you can run the helper tool: + +```bash +dev-tools/scripts/scaffoldNewModule.py <short-name> <full name> <one line description> +``` + +Once you have the scaffold, start creating classes, or move out classes from solr-core. +Solr-core and test-framework are added as dependencies by default, and you can add custom +dependencies as necessary. Those will automatically end up in `<moduleName>/lib` in the +binary distro. + +=== Module naming + +As the number of modules grow, we should strive to keep naming logical. The proposal is to +structure module name as `<type>-<name>`. + +Types can be: + +* `analysis-` - for fieldTypes, tokenizers, token filters (lucene level) +* `update-` - for UpdateRequestHandlers, UpdateRequestProcessors and other indexing related +* `search-` - for QParser, ResponseWriters, SearchHandler, SearchComponent +* `auth-` - for Authentication and Autorization +* `backup-`- for backup repositories +* ...more here... + +Examples: + +* `search-clustering` +* `update-extraction` +* `backup-gcs` + +== Dev guide for turning a module into a package + +=== Adding a manifest + +Create a file `<my-module>/src/main/resources/manifest.json`. It contents should be at a +minimum as below. + +```json +{ + "version-constraint": "9", + "plugins": [ + { + "name": "update-extraction", + "setup-command": { + "path": "/api/collections/${collection}/config", + "payload": {"add-requesthandler": {"name": "${NAME}", "class": "update-extraction:org.apache.solr.handler.extraction.ExtractingRequestHandler"}}, + "method": "POST" + }, + "uninstall-command": { + "path": "/api/collections/${collection}/config", + "payload": {"delete-requesthandler": "${NAME}"}, + "method": "POST" + } + } + ], + "parameter-defaults": { + "NAME": "/update/extract" + } +} +``` + +Version constraint must follow SemVer expression syntax, `9` means it is +compatible with any 9.x version of Solr. It is dangerous to assume compatibility with future versions, and for 1st party modules, we release them with every minor version, so consider +using e.g. `9.1`, which will be compatible with all bugfix 9.1 releases. + +TODO: Move some content from https://solr.apache.org/guide/8_11/package-manager-internals.html Review comment: I just linked to that page for now. Can do some restructuring later. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
