Add base path support for Next.js frontend

Add support for deploying the homepage container at a specified URL path, passed as an environment variable.

Dockerfile

@@ -23,6 +23,7 @@ WORKDIR /app
 ARG BUILDTIME
 ARG VERSION
 ARG REVISION
+ARG NEXT_PUBLIC_BASE_PATH
 
 COPY --link --from=deps /app/node_modules ./node_modules/
 COPY . .
@@ -30,7 +31,7 @@ COPY . .
 SHELL ["/bin/ash", "-xeo", "pipefail", "-c"]
 RUN npm run telemetry \
  && mkdir config \
- && NEXT_PUBLIC_BUILDTIME=$BUILDTIME NEXT_PUBLIC_VERSION=$VERSION NEXT_PUBLIC_REVISION=$REVISION npm run build
+ && NEXT_PUBLIC_BUILDTIME=$BUILDTIME NEXT_PUBLIC_VERSION=$VERSION NEXT_PUBLIC_REVISION=$REVISION NEXT_PUBLIC_BASE_PATH=$NEXT_PUBLIC_BASE_PATH npm run build
 
 # Production image, copy all the files and run next
 FROM docker.io/node:18-alpine AS runner

docker-entrypoint.sh

@@ -12,6 +12,9 @@ export PGID=${PGID:-0}
 
 export HOMEPAGE_BUILDTIME=$(date +%s)
 
+# Set the base path for the Next.js application
+export NEXT_PUBLIC_BASE_PATH=${NEXT_PUBLIC_BASE_PATH:-""}
+
 # Set privileges for /app but only if pid 1 user is root and we are dropping privileges.
 # If container is run as an unprivileged user, it means owner already handled ownership setup on their own.
 # Running chown in that case (as non-root) will cause error

next.config.js

@@ -9,6 +9,7 @@ const nextConfig = {
     unoptimized: true,
   },
   i18n,
+  basePath: process.env.NEXT_PUBLIC_BASE_PATH || '',
 };
 
 module.exports = nextConfig;