enhance(backend): Load settings via environment variables (#14179)

* feat(backend): Load settings via environment variables

If they're not loaded from the config file.

* chore(docker): Add hints for environment variables

It supports users to know about them.

* docs(changelog): Add the description about this change

Users can notice what's changed by this PR.

* style(backend): Fix code syntax

To pass the linter.

5 files changed, 22 insertions, 6 deletions

diff --git a/.config/docker_example.env b/.config/docker_example.env
index 4fe8e76b78..c61248da2e 100644
--- a/.config/docker_example.env
+++ b/.config/docker_example.env
@@ -1,5 +1,11 @@
+# misskey settings
+# MISSKEY_URL=https://example.tld/
+
 # db settings
 POSTGRES_PASSWORD=example-misskey-pass
+# DATABASE_PASSWORD=${POSTGRES_PASSWORD}
 POSTGRES_USER=example-misskey-user
+# DATABASE_USER=${POSTGRES_USER}
 POSTGRES_DB=misskey
+# DATABASE_DB=${POSTGRES_DB}
 DATABASE_URL="postgres://${POSTGRES_USER}:${POSTGRES_PASSWORD}@db:5432/${POSTGRES_DB}"
diff --git a/.config/docker_example.yml b/.config/docker_example.yml
index 42ac18de1b..d347882d1a 100644
--- a/.config/docker_example.yml
+++ b/.config/docker_example.yml
@@ -6,6 +6,7 @@
 #───┘ URL └─────────────────────────────────────────────────────
 
 # Final accessible URL seen by a user.
+# You can set url from an environment variable instead.
 url: https://example.tld/
 
 # ONCE YOU HAVE STARTED THE INSTANCE, DO NOT CHANGE THE
@@ -38,9 +39,11 @@ db:
   port: 5432
 
   # Database name
+  # You can set db from an environment variable instead.
   db: misskey
 
   # Auth
+  # You can set user and pass from environment variables instead.
   user: example-misskey-user
   pass: example-misskey-pass
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 83f2261c1d..14cae5d3de 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -37,6 +37,7 @@
 - Enhance: エンドポイント`gallery/posts/update`の必須項目を`postId`のみに
 - Enhance: エンドポイント`i/webhook/update`の必須項目を`webhookId`のみに
 - Enhance: エンドポイント`admin/ad/update`の必須項目を`id`のみに
+- Enhance: `default.yml`内の`url`, `db.db`, `db.user`, `db.pass`を環境変数から読み込めるように
 - Fix: チャート生成時にinstance.suspentionStateに置き換えられたinstance.isSuspendedが参照されてしまう問題を修正
 - Fix: ユーザーのフィードページのMFMをHTMLに展開するように (#14006)
 - Fix: アンテナ・クリップ・リスト・ウェブフックがロールポリシーの上限より一つ多く作れてしまうのを修正 (#14036)
diff --git a/compose_example.yml b/compose_example.yml
index 75d0d3a59c..336bd814a7 100644
--- a/compose_example.yml
+++ b/compose_example.yml
@@ -17,6 +17,8 @@ services:
     networks:
       - internal_network
       - external_network
+    # env_file:
+    #   - .config/docker.env
     volumes:
       - ./files:/misskey/files
       - ./.config:/misskey/.config:ro
diff --git a/packages/backend/src/config.ts b/packages/backend/src/config.ts
index 4cc27898be..3e5a1e81cd 100644
--- a/packages/backend/src/config.ts
+++ b/packages/backend/src/config.ts
@@ -23,7 +23,7 @@ type RedisOptionsSource = Partial<RedisOptions> & {
  * 設定ファイルの型
  */
 type Source = {
-	url: string;
+	url?: string;
 	port?: number;
 	socket?: string;
 	chmodSocket?: string;
@@ -31,9 +31,9 @@ type Source = {
 	db: {
 		host: string;
 		port: number;
-		db: string;
-		user: string;
-		pass: string;
+		db?: string;
+		user?: string;
+		pass?: string;
 		disableCache?: boolean;
 		extra?: { [x: string]: string };
 	};
@@ -202,13 +202,17 @@ export function loadConfig(): Config {
 		: { 'src/_boot_.ts': { file: 'src/_boot_.ts' } };
 	const config = yaml.load(fs.readFileSync(path, 'utf-8')) as Source;
 
-	const url = tryCreateUrl(config.url);
+	const url = tryCreateUrl(config.url ?? process.env.MISSKEY_URL ?? '');
 	const version = meta.version;
 	const host = url.host;
 	const hostname = url.hostname;
 	const scheme = url.protocol.replace(/:$/, '');
 	const wsScheme = scheme.replace('http', 'ws');
 
+	const dbDb = config.db.db ?? process.env.DATABASE_DB ?? '';
+	const dbUser = config.db.user ?? process.env.DATABASE_USER ?? '';
+	const dbPass = config.db.pass ?? process.env.DATABASE_PASSWORD ?? '';
+
 	const externalMediaProxy = config.mediaProxy ?
 		config.mediaProxy.endsWith('/') ? config.mediaProxy.substring(0, config.mediaProxy.length - 1) : config.mediaProxy
 		: null;
@@ -231,7 +235,7 @@ export function loadConfig(): Config {
 		apiUrl: `${scheme}://${host}/api`,
 		authUrl: `${scheme}://${host}/auth`,
 		driveUrl: `${scheme}://${host}/files`,
-		db: config.db,
+		db: { ...config.db, db: dbDb, user: dbUser, pass: dbPass },
 		dbReplications: config.dbReplications,
 		dbSlaves: config.dbSlaves,
 		meilisearch: config.meilisearch,