Turn off the CGO to make it static linked

Dockerfile

@@ -6,8 +6,8 @@ FROM golang:1.15-alpine
 COPY . /go/wings/
 WORKDIR /go/wings/
 RUN apk add --no-cache upx \
- && go build -ldflags="-s -w" \
- && upx --brute wings
+    && CGO_ENABLED=0 go build -ldflags="-s -w" \
+    && upx --brute wings
 
 FROM alpine:latest
 COPY --from=0 /go/wings/wings /usr/bin/