refactor: move away from monorepo setup

src/control.lua

@@ -0,0 +1,55 @@
+local metrics = require("utils.metrics")
+
+-- config
+local flush_interval_ticks = 60 -- flush every n ticks
+
+-- state
+--- @type table<number, fun()>
+local queue = {}
+
+--- @type table<number, string>
+local buffer = {}
+local last_reset = 0
+
+-- queue operations to perform for each round of metric processing
+-- that way, avoid doing too much work in a single game tick and causing UPS inconsistencies
+local function prepare_queue()
+    queue = {}
+    for _, surface in pairs(game.surfaces) do
+        for _, force in pairs(game.forces) do
+            table.insert(queue, metrics.calc_item_production_statistics(buffer, surface, force))
+            table.insert(queue, metrics.calc_fluid_production_statistics(buffer, surface, force))
+        end
+        table.insert(queue, metrics.calc_power_statistics(buffer, surface))
+    end
+end
+
+local function process_queue()
+    local entry = table.remove(queue, 1)
+    if entry then
+        entry()
+    end
+end
+
+local function tick()
+    process_queue()
+
+    if #queue == 0 and #buffer > 0 then
+        helpers.write_file("metrics.prom", table.concat(buffer, "\n"), false)
+        buffer = {}
+    end
+
+    if #queue == 0 and game.tick - last_reset >= flush_interval_ticks then
+        prepare_queue()
+        last_reset = game.tick
+    end
+end
+
+-- main tick handler
+script.on_event(defines.events.on_tick, tick)
+
+-- startup
+script.on_init(function()
+    last_reset = game.tick
+    prepare_queue()
+end)

src/data.lua

@@ -0,0 +1 @@
+require("prototypes.metrics-pole").setup()

src/info.json

@@ -0,0 +1,9 @@
+{
+    "name": "prometheus-exporter",
+    "version": "0.0.1",
+    "title": "Prometheus Exporter for Factorio",
+    "author": "Bjorn Pijnacker",
+    "factorio_version": "2.0",
+    "dependencies": ["base >= 2.0"],
+    "description": "Exports certain production and consumption metrics to Prometheus format, to be used by Prometheus/Grafana monitoring stack"
+}

src/prototypes/metrics-pole.lua

@@ -0,0 +1,62 @@
+local name = "metrics-pole"
+
+--- @class MetricsPole
+--- @field name string
+--- @field setup fun()
+local M = {
+    name = name,
+    setup = function()
+        local function tint(alpha)
+            return { r = 1, g = 0, b = 1, a = alpha }
+        end
+
+        -- POLE
+        local pole = table.deepcopy(data.raw["electric-pole"]["small-electric-pole"])
+        pole.name = name
+        pole.minable.result = name
+        pole.icons = {
+            {
+                icon = pole.icon,
+                icon_size = pole.icon_size,
+                tint = tint(0.3)
+            },
+        }
+        pole.is_military_target = false
+        pole.hidden_in_factoriopedia = true
+        pole.localised_name = "Metrics Pole"
+        pole.supply_area_distance = 0
+
+        for _, layer in pairs(pole.pictures.layers) do
+            layer.tint = tint(1)
+        end
+
+        data:extend({ pole })
+
+        -- ITEM
+        local item = table.deepcopy(data.raw["item"]["small-electric-pole"])
+        item.name = name
+        item.place_result = name
+        item.localised_name = "Metrics Pole"
+        item.icons = {
+            {
+                icon = item.icon,
+                icon_size = item.icon_size,
+                tint = tint(0.3)
+            },
+        }
+        data:extend({ item })
+
+        -- RECIPE
+        data:extend({
+            {
+                type = "recipe",
+                name = name,
+                enabled = true,
+                ingredients = { { name = "wood", amount = 1, type = "item" } },
+                results = { { name = name, type = "item", amount = 1 } }
+            }
+        })
+    end
+}
+
+return M

src/utils/metrics.lua

@@ -0,0 +1,75 @@
+local prometheus = require("utils.prometheus")
+local metrics_pole = require('prototypes.metrics-pole')
+
+local M = {}
+
+--- @param metrics_table table<number, string>
+--- @param surface LuaSurface
+--- @param force LuaForce
+--- @return fun()
+function M.calc_item_production_statistics(metrics_table, surface, force)
+    return function()
+        local item_stats = force.get_item_production_statistics(surface.name)
+        for item, count in pairs(item_stats.input_counts) do
+            table.insert(metrics_table,
+                prometheus.counter("production", "",
+                    { type = "item", surface = surface.name, force = force.name, name = item }, count))
+        end
+        for item, count in pairs(item_stats.output_counts) do
+            table.insert(metrics_table,
+                prometheus.counter("consumption", "",
+                    { type = "item", surface = surface.name, force = force.name, name = item }, count))
+        end
+    end
+end
+
+--- @param metrics_table table<number, string>
+--- @param surface LuaSurface
+--- @param force LuaForce
+--- @return fun()
+function M.calc_fluid_production_statistics(metrics_table, surface, force)
+    return function()
+        local fluid_stats = force.get_fluid_production_statistics(surface.name)
+        for item, count in pairs(fluid_stats.input_counts) do
+            table.insert(metrics_table,
+                prometheus.counter("production", "",
+                    { type = "fluid", surface = surface.name, force = force.name, name = item }, count))
+        end
+        for item, count in pairs(fluid_stats.output_counts) do
+            table.insert(metrics_table,
+                prometheus.counter("consumption", "",
+                    { type = "fluid", surface = surface.name, force = force.name, name = item }, count))
+        end
+    end
+end
+
+--- @param metrics_table table<number, string>
+--- @param surface LuaSurface
+--- @return fun()
+function M.calc_power_statistics(metrics_table, surface)
+    return function()
+        local seen = {}
+        for _, pole in pairs(surface.find_entities_filtered { name = metrics_pole.name }) do
+            if table[pole.electric_network_id] then -- deduplication
+                goto continue
+            end
+            table.insert(seen, pole.electric_network_id)
+
+            local stats = pole.electric_network_statistics
+            for name, count in pairs(stats.input_counts) do
+                table.insert(metrics_table,
+                    prometheus.counter("energy_consumption", "_joules",
+                        { surface = surface.name, network_id = pole.electric_network_id, name = name }, count))
+            end
+            for name, count in pairs(stats.output_counts) do
+                table.insert(metrics_table,
+                    prometheus.counter("energy_production", "_joules",
+                        { surface = surface.name, network_id = pole.electric_network_id, name = name }, count))
+            end
+
+            ::continue::
+        end
+    end
+end
+
+return M

src/utils/prometheus.lua

@@ -0,0 +1,17 @@
+local M = {}
+
+--- Formats a name + table of labels as a Prometheus metric
+--- @param name string
+--- @param suffix string
+--- @param labels table
+--- @param value number
+function M.counter(name, suffix, labels, value)
+    local label_parts = {}
+    for k, v in pairs(labels) do
+        table.insert(label_parts, string.format('%s="%s"', k, v))
+    end
+    local label_str = table.concat(label_parts, ",")
+    return string.format("factorio_%s_total%s{%s} %d", name, suffix, label_str, value)
+end
+
+return M