Don't use ENV for branch value

Dockerfile

@@ -63,7 +63,7 @@ ARG COMMIT_SHA="" \
     BRANCH=""
 
 # Put COMMIT_SHA in a file, since Docker managers like Portainer will not use updated ENVs
-RUN echo $COMMIT_SHA > commit-sha.txt
+RUN echo $COMMIT_SHA > commit-sha.txt && echo $BRANCH > branch.txt
 
 LABEL org.opencontainers.image.title="epicgames-freegames-node" \ 
     org.opencontainers.image.url="https://github.com/claabs/epicgames-freegames-node" \

src/version.ts

@@ -4,13 +4,18 @@ import { config } from './common/config/index.js';
 import L from './common/logger.js';
 
 const PROJECT_NAME = 'epicgames-freegames-node';
-const { BRANCH, DISTRO } = process.env;
-let { COMMIT_SHA } = process.env;
+const { DISTRO } = process.env;
+let { COMMIT_SHA, BRANCH } = process.env;
 try {
   COMMIT_SHA = readFileSync('./commit-sha.txt', { encoding: 'utf-8' }).trim();
 } catch (error) {
   L.debug('Fallback to environment variable commit SHA');
 }
+try {
+  BRANCH = readFileSync('./branch.txt', { encoding: 'utf-8' }).trim();
+} catch (error) {
+  L.debug('Fallback to environment variable branch');
+}
 
 export async function checkForUpdate(): Promise<void> {
   L.info({ COMMIT_SHA, BRANCH, DISTRO }, `Started ${PROJECT_NAME}`);