#!/usr/bin/env sh
set -eu

OPTIONS_FILE=/data/options.json
UPSTREAM_URL=$(jq -r '.upstream_url // empty' "$OPTIONS_FILE")

case "$UPSTREAM_URL" in
  http://*|https://*) ;;
  *)
    echo "upstream_url must start with http:// or https://" >&2
    exit 1
    ;;
esac

UPSTREAM_URL=${UPSTREAM_URL%/}

cat > /etc/nginx/conf.d/default.conf <<EOF
server {
    listen 8099;
    server_name _;

    location / {
        proxy_pass ${UPSTREAM_URL};
        proxy_http_version 1.1;
        proxy_set_header Host \$proxy_host;
        proxy_set_header X-Real-IP \$remote_addr;
        proxy_set_header X-Forwarded-For \$proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Host \$host;
        proxy_set_header X-Forwarded-Proto \$scheme;
        proxy_set_header X-Ingress-Path \$http_x_ingress_path;
        proxy_set_header Upgrade \$http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_redirect off;
    }
}
EOF

exec nginx -g 'daemon off;'