From 704b7e93310a099844d28646f9f0f8111d775133 Mon Sep 17 00:00:00 2001
From: Ken <ken@open.gov.sg>
Date: Mon, 16 Dec 2024 18:58:40 +0800
Subject: [PATCH] feat: expose .well-known

---
 .ebextensions/01env-file-aws-ssm.config       |  1 +
 .../config/features/formsg-sdk-jwks.config.ts | 17 +++++++++++++
 src/app/loaders/express/index.ts              |  8 +++----
 src/app/routes/.well-known/index.ts           | 24 +++++++++++++++++++
 4 files changed, 46 insertions(+), 4 deletions(-)
 create mode 100644 src/app/config/features/formsg-sdk-jwks.config.ts
 create mode 100644 src/app/routes/.well-known/index.ts

diff --git a/.ebextensions/01env-file-aws-ssm.config b/.ebextensions/01env-file-aws-ssm.config
index a7f16a54ad..d9bbde264e 100644
--- a/.ebextensions/01env-file-aws-ssm.config
+++ b/.ebextensions/01env-file-aws-ssm.config
@@ -46,6 +46,7 @@ files:
         aws ssm get-parameter --name "${ENV_TYPE}-verified-fields" --with-decryption --region $AWS_REGION | jq -r '.Parameter.Value' >> $TARGET_DIR/.env
         aws ssm get-parameter --name "${ENV_TYPE}-webhook-verified-content" --with-decryption --region $AWS_REGION | jq -r '.Parameter.Value' >> $TARGET_DIR/.env
         aws ssm get-parameter --name "${ENV_TYPE}-wogaa" --with-decryption --region $AWS_REGION | jq -r '.Parameter.Value' >> $TARGET_DIR/.env
+        aws ssm get-parameter --name "/${ENV_TYPE}/formsg-sdk/jwks" --region $AWS_REGION | jq -r '.Parameter.Value' >> $TARGET_DIR/.env
         aws ssm get-parameter --name "${ENV_SITE_NAME}-sgid" --with-decryption --region $AWS_REGION | jq -r '.Parameter.Value' >> $TARGET_DIR/.env
         aws ssm get-parameter --name "${ENV_SITE_NAME}-payment" --with-decryption --region $AWS_REGION | jq -r '.Parameter.Value' >> $TARGET_DIR/.env
         aws ssm get-parameter --name "${ENV_SITE_NAME}-cron-payment" --with-decryption --region $AWS_REGION | jq -r '.Parameter.Value' >> $TARGET_DIR/.env
diff --git a/src/app/config/features/formsg-sdk-jwks.config.ts b/src/app/config/features/formsg-sdk-jwks.config.ts
new file mode 100644
index 0000000000..7c7f996a05
--- /dev/null
+++ b/src/app/config/features/formsg-sdk-jwks.config.ts
@@ -0,0 +1,17 @@
+import convict, { Schema } from 'convict'
+
+type FormSgSdkJwks = {
+  publicJwks: string
+}
+
+const formSgSdkJwksSchema: Schema<FormSgSdkJwks> = {
+  publicJwks: {
+    doc: 'JSON Web Key Set for FormSG SDK',
+    format: String,
+    default: null, // required field
+    env: 'FORMSG_SDK_PUBLIC_JWKS',
+  },
+}
+export const formSgSdkJwksConfig = convict(formSgSdkJwksSchema)
+  .validate({ allowed: 'strict' })
+  .getProperties()
diff --git a/src/app/loaders/express/index.ts b/src/app/loaders/express/index.ts
index abfeada8b8..b7c9647bb6 100644
--- a/src/app/loaders/express/index.ts
+++ b/src/app/loaders/express/index.ts
@@ -12,6 +12,7 @@ import * as IntranetMiddleware from '../../modules/intranet/intranet.middleware'
 import { MYINFO_ROUTER_PREFIX } from '../../modules/myinfo/myinfo.constants'
 import { MyInfoRouter } from '../../modules/myinfo/myinfo.routes'
 import { SgidRouter } from '../../modules/sgid/sgid.routes'
+import { WellKnownRouter } from '../../routes/./.well-known'
 import { ApiRouter } from '../../routes/api'
 import { LegacyRedirectRouter } from '../../routes/legacy-redirect'
 import { SpOidcJwksRouter } from '../../routes/singpass'
@@ -123,6 +124,8 @@ const loadExpressApp = async (connection: Connection) => {
   app.use('/sgid', SgidRouter)
   app.use(MYINFO_ROUTER_PREFIX, MyInfoRouter)
 
+  app.use('/.well-known', WellKnownRouter)
+
   // Legacy frontend routes which may still be in use
   app.use(LegacyRedirectRouter)
 
@@ -135,10 +138,7 @@ const loadExpressApp = async (connection: Connection) => {
 
   // If requests for known static asset patterns were not served by
   // the static handlers above, middleware should try to fetch from s3 static bucket or else return 404s
-  app.get(
-    /^\/(public|static|\.well-known)\//,
-    catchNonExistentStaticRoutesMiddleware,
-  )
+  app.get(/^\/(public|static)\//, catchNonExistentStaticRoutesMiddleware)
 
   // Requests for root files (e.g. /robots.txt or /favicon.ico) that were
   // not served statically above will also return 404
diff --git a/src/app/routes/.well-known/index.ts b/src/app/routes/.well-known/index.ts
new file mode 100644
index 0000000000..eadd2b6277
--- /dev/null
+++ b/src/app/routes/.well-known/index.ts
@@ -0,0 +1,24 @@
+import { Router } from 'express'
+
+import { formSgSdkJwksConfig } from '../../config/features/formsg-sdk-jwks.config'
+import { createLoggerWithLabel } from '../../config/logger'
+
+export const WellKnownRouter = Router()
+
+const logger = createLoggerWithLabel(module)
+/**
+ * Returns the FormSG's public json web key set (JWKS) for communication with FormSG SDK
+ * @route GET /.well-known/formsg/jwks.json
+ * @returns 200
+ */
+WellKnownRouter.get('/formsg/jwks.json', (req, res) => {
+  logger.info({
+    message: 'Admin attempting to make changes',
+    meta: {
+      action: 'formsg/jwks.json',
+      publicJwks: formSgSdkJwksConfig.publicJwks,
+    },
+  })
+
+  return res.send(formSgSdkJwksConfig.publicJwks)
+})