feat: add uptime runner agent

ts/config.ts

@@ -0,0 +1,77 @@
+import type { IUptimeRunnerConfig } from './interfaces.ts';
+
+export const DEFAULT_CONFIG_PATH = '/etc/uptimerunner/config.json';
+
+export async function loadConfig(configPathArg = getConfigPath()): Promise<IUptimeRunnerConfig> {
+  const fileConfig = await readConfigFile(configPathArg);
+  const config = applyEnvironmentOverrides(fileConfig);
+  validateConfig(config);
+  return config;
+}
+
+export async function writeConfig(
+  configArg: IUptimeRunnerConfig,
+  configPathArg = getConfigPath(),
+): Promise<void> {
+  validateConfig(configArg);
+  const configDir = configPathArg.slice(0, configPathArg.lastIndexOf('/')) || '.';
+  await Deno.mkdir(configDir, { recursive: true });
+  await Deno.writeTextFile(`${configPathArg}.tmp`, `${JSON.stringify(configArg, null, 2)}\n`);
+  await Deno.rename(`${configPathArg}.tmp`, configPathArg);
+}
+
+export function getConfigPath(): string {
+  return Deno.env.get('UPTIMERUNNER_CONFIG') || DEFAULT_CONFIG_PATH;
+}
+
+export function applyEnvironmentOverrides(configArg: Partial<IUptimeRunnerConfig>) {
+  const labels = Deno.env.get('UPTIMERUNNER_LABELS');
+  const pollIntervalMs = Deno.env.get('UPTIMERUNNER_POLL_INTERVAL_MS');
+  const maxConcurrentChecks = Deno.env.get('UPTIMERUNNER_MAX_CONCURRENT_CHECKS');
+
+  return {
+    ...configArg,
+    instanceUrl: Deno.env.get('UPTIMERUNNER_INSTANCE_URL') || configArg.instanceUrl,
+    runnerId: Deno.env.get('UPTIMERUNNER_RUNNER_ID') || configArg.runnerId,
+    token: Deno.env.get('UPTIMERUNNER_TOKEN') || configArg.token,
+    labels: labels
+      ? labels.split(',').map((labelArg) => labelArg.trim()).filter(Boolean)
+      : configArg.labels,
+    pollIntervalMs: pollIntervalMs ? Number(pollIntervalMs) : configArg.pollIntervalMs,
+    maxConcurrentChecks: maxConcurrentChecks
+      ? Number(maxConcurrentChecks)
+      : configArg.maxConcurrentChecks,
+  } satisfies Partial<IUptimeRunnerConfig>;
+}
+
+export function validateConfig(
+  configArg: Partial<IUptimeRunnerConfig>,
+): asserts configArg is IUptimeRunnerConfig {
+  if (!configArg.instanceUrl) {
+    throw new Error('Missing instanceUrl. Set it in config or UPTIMERUNNER_INSTANCE_URL.');
+  }
+  if (!configArg.runnerId) {
+    throw new Error('Missing runnerId. Set it in config or UPTIMERUNNER_RUNNER_ID.');
+  }
+  if (!configArg.token) {
+    throw new Error('Missing token. Set it in config or UPTIMERUNNER_TOKEN.');
+  }
+  if (configArg.pollIntervalMs !== undefined && configArg.pollIntervalMs < 1000) {
+    throw new Error('pollIntervalMs must be at least 1000ms.');
+  }
+  if (configArg.maxConcurrentChecks !== undefined && configArg.maxConcurrentChecks < 1) {
+    throw new Error('maxConcurrentChecks must be at least 1.');
+  }
+}
+
+async function readConfigFile(configPathArg: string): Promise<Partial<IUptimeRunnerConfig>> {
+  try {
+    const configText = await Deno.readTextFile(configPathArg);
+    return JSON.parse(configText) as Partial<IUptimeRunnerConfig>;
+  } catch (error) {
+    if (error instanceof Deno.errors.NotFound) {
+      return {};
+    }
+    throw error;
+  }
+}