kapply

#!/bin/bash

set -e

TMPFILE=kapply-tmp${RANDOM}
CMD="apply"
OBJECT=""
VERBOSE=""
BLANKMISSING=""

while [[ "$1" == "-"* ]]; do
    case "$1" in
    -t)  TESTRUN="true" ;;
	-b)  BLANKMISSING="true" ;;
	-c)  CMD="create"  ;;
    -p)  CMD="path"
         OBJECT="$2"
         shift ;;
    -v)  VERBOSE="true" ;;
    *) echo "Uknown option '$1'" ; exit 1 ;;
    esac
    shift
done

while [[ -n "${1}" ]]; do
    file="${1}"
    shift

    rm -f "${TMPFILE}"
    IFS=''
    cat "${file}" | while read line ; do
	    pos=0
        while [[ "${line:pos}" == *"\${"* && "$line" == *"}"* ]]; do
            pre=$(echo "$line" | sed "s/\([^\$]*\)\${\([^}]*\)}\(.*\)/\1/")
            var=$(echo "$line" | sed "s/\([^\$]*\)\${\([^}]*\)}\(.*\)/\2/")
            rest=$(echo "$line" | sed "s/\([^\$]*\)\${\([^}]*\)}\(.*\)/\3/")

			save_var="${var}"
            # .file.property
            if [[ "$var" == "."* ]]; then
                if [[ "${var:1}" == *"."* ]]; then
                    file=$(echo "${var}" | sed "s/^\(.[^.]*\).*$/\1/")
                    var=$(echo "${var}" | sed "s/^\(.[^.]*\)\.\(.*\)$/\2/")
                    var=$(cat "${file}" | grep "^${var}=" | sed "s/^[^=]*=//")
                else
                    var=$(cat "${var}")
                fi
            else
                # var == env var name
                if [[ "${!var}" == "" ]]; then
                    var=$(cat .env | grep "^${var}=" | sed "s/^[^=]*=//")
                else
                    var=${!var} # Use env var named "${var}"'s value
                fi
            fi

			if [[ "${var}" == "" && -z "${BLANKMISSING}" ]]; then
			  var='${'${save_var}'}'
			fi

            line="$pre$var" #$rest"
			pos=${#line}   # Don't reparse what we just added
			line="$line$rest"
        done
        echo "$line" >> "${TMPFILE}"
    done

    # echo "> ${file}"
    ( [[ -n "$VERBOSE" ]] || [[ -n "$TESTRUN" ]] ) && cat "${TMPFILE}"
    if [[ -n "$TESTRUN" ]]; then
        # cat "${TMPFILE}"
        true
    elif [[ "$CMD" == "apply" || "$CMD" == "create" ]]; then
        kubectl $CMD -f "${TMPFILE}"
    else
        kubectl patch $OBJECT --type=json -p "$(cat ${TMPFILE})"
    fi
    rm -f "${TMPFILE}"
done