How to pass variables between external plugins and system plugins?

[renshunhang]

I implemented an external plugin through Python and configured the external plugin into the route. My route also binds a custom plugin implemented in Lua. How can I get the variable values set in the Lua plugin within the Python-implemented external plugin?

[dosubot[bot]]

To pass variables from a Lua system plugin to a Python external plugin in APISIX, you should register your variable in the Lua plugin using core.ctx.register_var. This makes the variable available in the request context (ctx.var). Your Python external plugin can then explicitly request this variable by name using the ext-plugin protocol. The APISIX ext-plugin system will fetch the value from ctx.var and return it to your Python plugin when requested. There is no automatic sharing—your external plugin must request the variable by its name for each request you want to access it in. Only variables registered and available in ctx.var are accessible this way, not arbitrary Lua state or ngx.ctx fields.
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