feat(prometheus) add wasmx metrics

changelog/unreleased/kong/prometheus-wasmx-metrics.yml

@@ -0,0 +1,3 @@
+message: Expose WasmX metrics as part of the Prometheus plugin
+type: feature
+scope: Plugin

kong/plugins/prometheus/exporter.lua

@@ -1,11 +1,14 @@
+local balancer = require "kong.runloop.balancer"
+local yield = require("kong.tools.yield").yield
+local wasm = require "kong.plugins.prometheus.wasmx"
+
+
 local kong = kong
 local ngx = ngx
 local get_phase = ngx.get_phase
 local lower = string.lower
 local ngx_timer_pending_count = ngx.timer.pending_count
 local ngx_timer_running_count = ngx.timer.running_count
-local balancer = require("kong.runloop.balancer")
-local yield = require("kong.tools.yield").yield
 local get_all_upstreams = balancer.get_all_upstreams
 if not balancer.get_all_upstreams then -- API changed since after Kong 2.5
   get_all_upstreams = require("kong.runloop.balancer.upstreams").get_all_upstreams
@@ -517,6 +520,7 @@ local function metric_data(write_fn)
   -- notify the function if prometheus plugin is enabled,
   -- so that it can avoid exporting unnecessary metrics if not
   prometheus:metric_data(write_fn, not IS_PROMETHEUS_ENABLED)
+  wasm.metric_data()
 end
 
 local function collect()

kong/plugins/prometheus/wasmx.lua

@@ -0,0 +1,165 @@
+local buffer = require "string.buffer"
+local json_safe = require "cjson.safe"
+local wasm = require "kong.runloop.wasm"
+local wasmx_shm = require "resty.wasmx.shm"
+
+
+local fmt = string.format
+local str_match = string.match
+local str_find = string.find
+local str_sub = string.sub
+local buf_new = buffer.new
+local ngx_say = ngx.say
+local table_insert = table.insert
+
+
+local _M = {}
+
+
+local function parse_key(key)
+    local name
+    local labels = {}
+
+    local header = {
+        pw = "pw.",    -- proxy-wasm metrics
+        lua = "lua.",  -- lua land metrics
+        wa = "wa."     -- internal ngx_wasm_module metrics
+    }
+
+    local is_pw = #key > #header.pw and key:sub(0, #header.pw) == header.pw
+    local is_lua = #key > #header.lua and key:sub(0, #header.lua) == header.lua
+    local is_wa = #key > #header.wa and key:sub(0, #header.wa) == header.wa
+
+    local hs = is_lua and #header.lua or #header.pw  -- wa's size == pw's size
+
+    if is_lua or is_wa then
+        name = key
+        -- label support NYI
+
+    elseif is_pw then
+        local second_dot_pos, _ = str_find(key, "%.", hs + 1)
+        local ns = str_sub(key, hs + 1, second_dot_pos - 1)
+
+        local filter_config = json_safe.decode(wasm.filters_by_name[ns].config)
+        local patterns = filter_config and filter_config.metrics.label_patterns
+
+        local first_match = #key
+
+        if patterns then
+            for _, pair in ipairs(patterns) do
+                local lkv, lv = str_match(key, pair.pattern)
+                if lkv then
+                    local lk = str_sub(lkv, 0, str_find(lkv, "="))
+                    local lk_start, _ = str_find(key, lk)
+
+                    first_match = (lk_start < first_match) and lk_start or first_match
+
+                    table_insert(labels, { pair.label, lv })
+                end
+            end
+
+            name = str_sub(key, 0, first_match - 1)
+
+        else
+            name = key
+        end
+    else
+        -- unreachable
+        error("unknown metric prefix: " .. key, 2)
+    end
+
+    name = name:gsub("%.", "_")
+
+    return name, labels
+end
+
+
+local function serialize_labels(labels)
+    local buf = buf_new()
+
+    for _, pair in ipairs(labels) do
+        buf:put(fmt('%s="%s",', pair[1], pair[2]))
+    end
+
+    local slabels = buf:get()
+
+    if #slabels > 0 then
+        return slabels:sub(0, #slabels - 1)  -- discard trailing comma
+    end
+
+    return slabels
+end
+
+
+local function serialize_metric(m)
+    local buf = buf_new()
+
+    buf:put(fmt("# HELP %s\n# TYPE %s %s", m.name, m.name, m.type))
+
+    for _, pair in ipairs(m.labels) do
+        local labels = pair[1]
+        local labeled_m = pair[2]
+        local slabels = serialize_labels(labels)
+
+        if m.type == "counter" or m.type == "gauge" then
+            if #slabels > 0 then
+                buf:put(fmt("\n%s{%s} %s", m.name, slabels, labeled_m.value))
+            else
+                buf:put(fmt("\n%s %s", m.name, labeled_m.value))
+            end
+
+        elseif m.type == "histogram" then
+            for _, bin in ipairs(labeled_m.value) do
+                local ubl = fmt('le="%s"', bin.ub)
+
+                slabels = (#slabels > 0) and (slabels .. "," .. ubl) or ubl
+
+                buf:put(fmt("\n%s{%s} %s", m.name, slabels, bin.count))
+            end
+        end
+    end
+
+    buf:put("\n")
+
+    return buf:get()
+end
+
+
+_M.metric_data = function()
+    local i = 0
+    local flush_after = 50
+    local metrics = {}
+    local parsed = {}
+    local buf = buf_new()
+
+    wasmx_shm.metrics:lock()
+
+    for key in wasmx_shm.metrics:iterate_keys() do
+        metrics[key] = wasmx_shm.metrics:get_by_name(key, { prefix = false })
+    end
+
+    wasmx_shm.metrics:unlock()
+
+    for key, m in pairs(metrics) do
+        local name, labels = parse_key(key)
+
+        parsed[name] = parsed[name] or { name = name, type = m.type, labels = {} }
+
+        table_insert(parsed[name].labels, { labels, m })
+    end
+
+    for _, metric_by_label in pairs(parsed) do
+        buf:put(serialize_metric(metric_by_label))
+
+        i = i + 1
+
+        if i % flush_after == 0 then
+            ngx_say(buf:get())
+        end
+    end
+
+    ngx_say(buf:get())
+end
+
+
+return _M

kong/runloop/wasm.lua

@@ -415,6 +415,8 @@ local function rebuild_state(db, version, old_state)
           if filter.config ~= nil and type(filter.config) ~= "string" then
             filter.config = cjson_encode(filter.config)
           end
+
+          _M.filters_by_name[filter.name].config = filter.config
         end
       end
 
@@ -778,6 +780,13 @@ local function register_property_handlers()
     return ok, value, const
   end)
 
+  properties.add_getter("kong.route_name", function(_, _, ctx)
+    local value = ctx.route and ctx.route.name
+    local ok = value ~= nil
+    local const = ok
+    return ok, value, const
+  end)
+
   properties.add_getter("kong.service.response.status", function(kong)
     return true, kong.service.response.get_status(), false
   end)
@@ -789,6 +798,13 @@ local function register_property_handlers()
     return ok, value, const
   end)
 
+  properties.add_getter("kong.service_name", function(_, _, ctx)
+    local value = ctx.service and ctx.service.name
+    local ok = value ~= nil
+    local const = ok
+    return ok, value, const
+  end)
+
   properties.add_getter("kong.version", function(kong)
     return true, kong.version, true
   end)