Cloudflare Prometheus Exporter

src/lib/config.ts

@@ -0,0 +1,93 @@
+import z from "zod";
+
+/**
+ * Application configuration parsed from environment variables.
+ */
+export type AppConfig = {
+	readonly excludeHost: boolean;
+	readonly httpStatusGroup: boolean;
+	readonly metricsDenylist: ReadonlySet<string>;
+	readonly cfAccounts: ReadonlySet<string> | null;
+	readonly cfZones: ReadonlySet<string> | null;
+	readonly cfFreeTierAccounts: ReadonlySet<string>;
+	readonly metricsPath: string;
+	readonly disableUi: boolean;
+	readonly disableConfigApi: boolean;
+};
+
+/**
+ * Parses comma-separated string into Set, trimming whitespace.
+ * Returns empty Set for empty/undefined input.
+ *
+ * @param value Comma-separated string or undefined.
+ * @returns Set of trimmed non-empty strings.
+ */
+function parseCommaSeparated(value: string | undefined): Set<string> {
+	if (!value || value.trim() === "") {
+		return new Set();
+	}
+	return new Set(
+		value
+			.split(",")
+			.map((s) => s.trim())
+			.filter((s) => s.length > 0),
+	);
+}
+
+/**
+ * Optional environment variables not defined in wrangler.jsonc vars.
+ */
+type OptionalEnvVars = {
+	METRICS_DENYLIST?: string;
+	CF_ACCOUNTS?: string;
+	CF_ZONES?: string;
+	CF_FREE_TIER_ACCOUNTS?: string;
+};
+
+/**
+ * Parses application configuration from environment variables.
+ * Uses Zod for type coercion with sensible defaults.
+ *
+ * @param env Worker environment bindings.
+ * @returns Parsed application configuration.
+ */
+export function parseConfig(env: Env): AppConfig {
+	const optionalEnv = env as Env & OptionalEnvVars;
+
+	const excludeHost = z.coerce.boolean().catch(false).parse(env.EXCLUDE_HOST);
+	const httpStatusGroup = z.coerce
+		.boolean()
+		.catch(false)
+		.parse(env.CF_HTTP_STATUS_GROUP);
+	const metricsPath = z
+		.string()
+		.min(1)
+		.catch("/metrics")
+		.parse(env.METRICS_PATH);
+	const disableUi = z.coerce.boolean().catch(false).parse(env.DISABLE_UI);
+	const disableConfigApi = z.coerce
+		.boolean()
+		.catch(false)
+		.parse(env.DISABLE_CONFIG_API);
+
+	const metricsDenylist = parseCommaSeparated(optionalEnv.METRICS_DENYLIST);
+	const cfAccountsRaw = parseCommaSeparated(optionalEnv.CF_ACCOUNTS);
+	const cfAccounts = cfAccountsRaw.size > 0 ? cfAccountsRaw : null;
+	const cfZonesRaw = parseCommaSeparated(optionalEnv.CF_ZONES);
+	const cfZones = cfZonesRaw.size > 0 ? cfZonesRaw : null;
+	const cfFreeTierAccounts = parseCommaSeparated(
+		optionalEnv.CF_FREE_TIER_ACCOUNTS,
+	);
+
+	return {
+		excludeHost,
+		httpStatusGroup,
+		metricsDenylist,
+		cfAccounts,
+		cfZones,
+		cfFreeTierAccounts,
+		metricsPath,
+		disableUi,
+		disableConfigApi,
+	};
+}