fix: validate and respect oidc validation settings

app/utils/config/headplane.ts

@@ -10,6 +10,7 @@ import { parse } from 'yaml'
 
 import { IntegrationFactory, loadIntegration } from '~/integration'
 import { HeadscaleConfig, loadConfig } from '~/utils/config/headscale'
+import { testOidc } from '~/utils/oidc'
 import log from '~/utils/log'
 
 export interface HeadplaneContext {
@@ -157,6 +158,7 @@ async function checkOidc(config?: HeadscaleConfig) {
 	let client = process.env.OIDC_CLIENT_ID
 	let secret = process.env.OIDC_CLIENT_SECRET
 	let method = process.env.OIDC_CLIENT_SECRET_METHOD ?? 'client_secret_basic'
+	let skip = process.env.OIDC_SKIP_CONFIG_VALIDATION === 'true'
 
 	log.debug('CTXT', 'Checking OIDC environment variables')
 	log.debug('CTXT', 'Issuer: %s', issuer)
@@ -171,6 +173,14 @@ async function checkOidc(config?: HeadscaleConfig) {
 	}
 
 	if (issuer && client && secret) {
+		if (!skip) {
+			log.debug('CTXT', 'Validating OIDC configuration from environment variables')
+			testOidc(issuer, client, secret)
+		} else {
+			log.debug('CTXT', 'OIDC_SKIP_CONFIG_VALIDATION is set')
+			log.debug('CTXT', 'Skipping OIDC configuration validation')
+		}
+
 		return {
 			issuer,
 			client,
@@ -214,6 +224,15 @@ async function checkOidc(config?: HeadscaleConfig) {
 		return
 	}
 
+	if (config.oidc.only_start_if_oidc_is_available) {
+		log.debug('CTXT', 'Validating OIDC configuration from headscale config')
+		testOidc(issuer, client, secret)
+		return
+	} else {
+		log.debug('CTXT', 'OIDC validation is disabled in headscale config')
+		log.debug('CTXT', 'Skipping OIDC configuration validation')
+	}
+
 	return {
 		issuer,
 		client,

app/utils/oidc.ts

@@ -17,6 +17,7 @@ import {
 
 import { post } from '~/utils/headscale'
 import { commitSession, getSession } from '~/utils/sessions'
+import log from '~/utils/log'
 
 import { HeadplaneContext } from './config/headplane'
 
@@ -169,3 +170,30 @@ export async function finishOidc(oidc: OidcConfig, req: Request) {
 		},
 	})
 }
+
+// Runs at application startup to validate the OIDC configuration
+export async function testOidc(issuer: string, client: string, secret: string) {
+	const oidcClient = {
+		client_id: client,
+		client_secret: secret,
+		token_endpoint_auth_method: 'client_secret_post',
+	} satisfies Client
+
+	const issuerUrl = new URL(issuer)
+
+	try {
+		log.debug('OIDC', 'Checking OIDC well-known endpoint')
+		const response = await discoveryRequest(issuerUrl)
+		const processed = await processDiscoveryResponse(issuerUrl, response)
+		if (!processed.authorization_endpoint) {
+			log.debug('OIDC', 'No authorization endpoint found on the OIDC provider')
+			return false
+		}
+
+		log.debug('OIDC', 'Found auth endpoint: %s', processed.authorization_endpoint)
+		return true
+	} catch (e) {
+		log.debug('OIDC', 'Validation failed: %s', e.message)
+		return false
+	}
+}