fix(plugins): load wasm filter plugins before external plugins #13931
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note: I removed the cherry-pick label in favor of manually cherry-picking this into the in-progress branch in EE land: |
In 4059a31 (#13843) we added a plugin-like interface for Wasm filters. We now have 3 sources for plugins: Lua, External, and Wasm Filters. When a plugin is enabled or configured, the plugin system follows a resolution order for looking up the plugin handler and schema: 1. Lua => `require kong.plugins.<name>.{handler,schema}` 2. External => `kong.runloop.plugin_servers.load_{handler,schema}(<name>)` 3. Wasm Filters => `kong.runloop.wasm.plugins.load_{handler,schema}(<name>)` When a user configures Kong with a "bad" entry in `pluginserver_names` (read: a plugin server that is not actually installed), step #2 of the plugin resolution process throws an exception, because the external plugin subsystem attempts to query a plugin server that does not exist. Importantly, *this exception is not encountered when the user has only configured/enabled Lua plugins,* because we never reach beyond step #1 of the plugin resolution process. A side effect of adding the Wasm filter plugin interface is that discovered Wasm filters are added to the global plugins table (`kong.configuration.loaded_plugins`) when Wasm is enabled. This means that, if Wasm is enabled, and any Wasm filters are installed, we _always_ step through step #2 of the plugin resolution process, triggering an exception if the user has any badly-configured plugin server. A future change will likely render this scenario unreachable by performing deeper validation of `pluginserver_names` at startup. For now, a simple fix is just to change the resolution order such that Wasm filters are loaded _before_ we query the external plugin subsystem: 1. Lua 2. Wasm Filters 3. External
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I'm going to wait to merge this until after the EE PR is green just to ensure there are no other fixes needed here. |
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Summary
In 4059a31 (#13843) we added a plugin-like interface for Wasm filters.
We now have 3 sources for plugins: Lua, External, and Wasm Filters. When a plugin is enabled or configured, the plugin system follows a resolution order for looking up the plugin handler and schema:
require kong.plugins.<name>.{handler,schema}kong.runloop.plugin_servers.load_{handler,schema}(<name>)kong.runloop.wasm.plugins.load_{handler,schema}(<name>)When a user configures Kong with a "bad" entry in
pluginserver_names(read: a plugin server that is not actually installed), step #2 of the plugin resolution process throws an exception, because the external plugin subsystem attempts to query a plugin server that does not exist. Importantly, this exception is not encountered when the user has only configured/enabled Lua plugins, because we never reach beyond step #1 of the plugin resolution process.A side effect of adding the Wasm filter plugin interface is that discovered Wasm filters are added to the global plugins table (
kong.configuration.loaded_plugins) when Wasm is enabled. This means that, if Wasm is enabled, and any Wasm filters are installed, we always step through step #2 of the plugin resolution process, triggering an exception if the user has any badly-configured plugin server.A future change will likely render this scenario unreachable by performing deeper validation of
pluginserver_namesat startup. For now, a simple fix is just to change the resolution order such that Wasm filters are loaded before we query the external plugin subsystem:Checklist
A changelog file has been created(this fixes an unreleased bug)There is a user-facing docs PRIssue reference
KAG-5911