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kong.ctx

Contextual data for the current request.

kong.ctx.shared

A table that has the same lifetime as the current request. This table is shared between all plugins. It can be used to share data between several plugins in a given request.

This table is only relevant in the context of a request and cannot be accessed from the top-level chunk of Lua modules. Instead, it can only be accessed in request phases, which are represented by the rewrite, access, header_filter, response, body_filter, log, and preread phases of the plugin interfaces. Accessing this table in those functions (and their callees) is fine.

Values inserted in this table by a plugin are visible by all other plugins. Be careful when interacting with values in this table, as a naming conflict could result in the overwrite of data.

Phases

• rewrite, access, header_filter, response, body_filter, log, preread

Usage

-- Two plugins A and B, and if plugin A has a higher priority than B's
-- (it executes before B):

-- plugin A handler.lua
function plugin_a_handler:access(conf)
  kong.ctx.shared.foo = "hello world"

  kong.ctx.shared.tab = {
    bar = "baz"
  }
end

-- plugin B handler.lua
function plugin_b_handler:access(conf)
  kong.log(kong.ctx.shared.foo) -- "hello world"
  kong.log(kong.ctx.shared.tab.bar) -- "baz"
end

kong.ctx.plugin

A table that has the same lifetime as the current request. Unlike kong.ctx.shared, this table is not shared between plugins. Instead, it is only visible for the current plugin instance. For example, if several instances of the Rate Limiting plugin are configured on different Services, each instance has its own table for every request.

Because of its namespaced nature, this table is safer for a plugin to use than kong.ctx.shared since it avoids potential naming conflicts, which could lead to several plugins unknowingly overwriting each other’s data.

This table is only relevant in the context of a request and cannot be accessed from the top-level chunk of Lua modules. Instead, it can only be accessed in request phases, which are represented by the rewrite, access, header_filter, body_filter, log, and preread phases of the plugin interfaces. Accessing this table in those functions (and their callees) is fine.

Values inserted in this table by a plugin are visible in successful phases of this plugin’s instance only.

Phases

• rewrite, access, header_filter, response, body_filter, log, preread

Usage

-- plugin handler.lua

-- For example, if a plugin wants to
-- save some value for post-processing during the `log` phase:

function plugin_handler:access(conf)
  kong.ctx.plugin.val_1 = "hello"
  kong.ctx.plugin.val_2 = "world"
end

function plugin_handler:log(conf)
  local value = kong.ctx.plugin.val_1 .. " " .. kong.ctx.plugin.val_2

  kong.log(value) -- "hello world"
end