It seems Docker Hub is unstable now. Docker build ran into random failures when pulling golang:1.10-alpine image.
Logs:
Step 1/14 : FROM golang:1.10-alpine
1.10-alpine: Pulling from library/golang
error parsing HTTP 404 response body: invalid character ‘p’ after top-level value: “404 page not found\n”
Step 1/14 : FROM golang:1.10-alpine
unauthorized: authentication required