Add cpuCount configuration option

Implement the `cpuCount` (`APPSIGNAL_CPU_COUNT` environment variable)
configuration option for the AppSignal for Node.js integration.

.changesets/implement-cpu-count-configuration-option.md

@@ -5,6 +5,5 @@ type: "add"
 
 Implement CPU count configuration option. Use it to override the auto-detected, cgroups-provided number of CPUs that is used to calculate CPU usage percentages.
 
-To set it, use the `APPSIGNAL_CPU_COUNT` environment variable, the `cpu_count`
-configuration option in the Ruby, Elixir or Python integrations, the `cpuCount` attribute in the Node.js instrumentation, or the `cpu_count` configuration option in the stand-alone agent TOML configuration file.
+To set it, use the `cpuCount` configuration option, or the `APPSIGNAL_CPU_COUNT` environment variable.
 

src/__tests__/config.test.ts

@@ -129,11 +129,15 @@ describe("Configuration", () => {
       process.env["APPSIGNAL_ENABLE_STATSD"] = "true"
       process.env["APPSIGNAL_ENABLE_HOST_METRICS"] = "false"
       process.env["APPSIGNAL_DNS_SERVERS"] = "8.8.8.8,8.8.4.4"
+      process.env["APPSIGNAL_CPU_COUNT"] = "1.5"
+
       const envOptions = {
         enableStatsd: true,
         enableHostMetrics: false,
-        dnsServers: ["8.8.8.8", "8.8.4.4"]
+        dnsServers: ["8.8.8.8", "8.8.4.4"],
+        cpuCount: 1.5
       }
+
       const expectedConfig = {
         ...expectedDefaultConfig,
         ...envOptions
@@ -319,6 +323,7 @@ describe("Configuration", () => {
       expect(env("_APPSIGNAL_APP_NAME")).toBeUndefined()
       expect(env("_APPSIGNAL_BIND_ADDRESS")).toBeUndefined()
       expect(env("_APPSIGNAL_CA_FILE_PATH")).toMatch(/cert\/cacert\.pem$/)
+      expect(env("_APPSIGNAL_CPU_COUNT")).toBeUndefined()
       expect(env("_APPSIGNAL_DNS_SERVERS")).toBeUndefined()
       expect(env("_APPSIGNAL_ENABLE_HOST_METRICS")).toEqual("true")
       expect(env("_APPSIGNAL_ENABLE_OPENTELEMETRY_HTTP")).toEqual("true")
@@ -367,6 +372,7 @@ describe("Configuration", () => {
           name,
           active: true,
           bindAddress: "0.0.0.0",
+          cpuCount: 1.5,
           pushApiKey,
           dnsServers: ["8.8.8.8", "8.8.4.4"],
           enableHostMetrics: false,
@@ -397,6 +403,7 @@ describe("Configuration", () => {
         expect(env("_APPSIGNAL_ACTIVE")).toEqual("true")
         expect(env("_APPSIGNAL_APP_NAME")).toEqual(name)
         expect(env("_APPSIGNAL_BIND_ADDRESS")).toEqual("0.0.0.0")
+        expect(env("_APPSIGNAL_CPU_COUNT")).toEqual("1.5")
         expect(env("_APPSIGNAL_DNS_SERVERS")).toEqual("8.8.8.8,8.8.4.4")
         expect(env("_APPSIGNAL_ENABLE_HOST_METRICS")).toEqual("false")
         expect(env("_APPSIGNAL_ENABLE_OPENTELEMETRY_HTTP")).toEqual("false")

src/config.ts

@@ -11,7 +11,8 @@ import {
   BOOL_KEYS,
   STRING_KEYS,
   LIST_KEYS,
-  LIST_OR_BOOL_KEYS
+  LIST_OR_BOOL_KEYS,
+  FLOAT_KEYS
 } from "./config/configmap"
 
 /**
@@ -214,6 +215,18 @@ export class Configuration {
       }
     })
 
+    FLOAT_KEYS.forEach(k => {
+      const current = process.env[k]
+
+      if (current) {
+        const parsed = parseFloat(current)
+
+        if (!isNaN(parsed)) {
+          conf[ENV_TO_KEY_MAPPING[k]] = parsed
+        }
+      }
+    })
+
     return conf
   }
 

src/config/configmap.ts

@@ -6,6 +6,7 @@ export const ENV_TO_KEY_MAPPING: Record<string, keyof AppsignalOptions> = {
   APPSIGNAL_APP_NAME: "name",
   APPSIGNAL_BIND_ADDRESS: "bindAddress",
   APPSIGNAL_CA_FILE_PATH: "caFilePath",
+  APPSIGNAL_CPU_COUNT: "cpuCount",
   APPSIGNAL_DISABLE_DEFAULT_INSTRUMENTATIONS: "disableDefaultInstrumentations",
   APPSIGNAL_DNS_SERVERS: "dnsServers",
   APPSIGNAL_ENABLE_HOST_METRICS: "enableHostMetrics",
@@ -46,6 +47,7 @@ export const PRIVATE_ENV_MAPPING: Record<string, keyof AppsignalOptions> = {
   _APPSIGNAL_APP_NAME: "name",
   _APPSIGNAL_BIND_ADDRESS: "bindAddress",
   _APPSIGNAL_CA_FILE_PATH: "caFilePath",
+  _APPSIGNAL_CPU_COUNT: "cpuCount",
   _APPSIGNAL_DNS_SERVERS: "dnsServers",
   _APPSIGNAL_ENABLE_HOST_METRICS: "enableHostMetrics",
   _APPSIGNAL_ENABLE_OPENTELEMETRY_HTTP: "enableOpentelemetryHttp",
@@ -80,6 +82,7 @@ export const JS_TO_RUBY_MAPPING: Record<keyof AppsignalOptions, string> = {
   bindAddress: "bind_address",
   pushApiKey: "push_api_key",
   caFilePath: "ca_file_path",
+  cpuCount: "cpu_count",
   disableDefaultInstrumentations: "disable_default_instrumentations",
   dnsServers: "dns_servers",
   enableHostMetrics: "enable_host_metrics",
@@ -163,3 +166,5 @@ export const LIST_KEYS: string[] = [
 export const LIST_OR_BOOL_KEYS: string[] = [
   "APPSIGNAL_DISABLE_DEFAULT_INSTRUMENTATIONS"
 ]
+
+export const FLOAT_KEYS: string[] = ["APPSIGNAL_CPU_COUNT"]

src/config/options.ts

@@ -4,6 +4,7 @@ export type AppsignalOptions = {
   active: boolean
   bindAddress: string
   caFilePath: string
+  cpuCount: number
   disableDefaultInstrumentations: DefaultInstrumentationName[] | boolean
   dnsServers: string[]
   enableHostMetrics: boolean