log2stderr_with_loglevel_support.bash

# Borrowed to someone, but I don't remember who it was, sorry :(
# Print message $2 with log-level $1 to STDERR, colorized if terminal
# log DEBUG "DOCKER_HOST ${DOCKER_HOST}"
log() {
    local level=${1?}
    shift
    local code= line="[$(date '+%F %T')] $level: $*"
    if [ -t 2 ]
    then
        case "$level" in
	        INFO) code=36 ;;
	        DEBUG) code=35 ;;
	        WARN) code=33 ;;
	        ERROR) code=31 ;;
	        *) code=37 ;;
        esac
        echo -e "\e[${code}m${line}\e[0m"
    else
        echo "$line"
    fi >&2
}