[Templater] Template engine in bash for Openshift #openshift #bash #template #kubernetes

templater.sh

#!/bin/bash
#set -x
#bash templater.sh < oc-template.tpl.yml | oc process -f - | oc create -f -
#bash templater.sh < oc-template.tpl.yml > oc-template.yml &&  oc process -f  oc-template.yml | oc create -f -
while IFS= read -r line
do
    end_offset=${#line}
    IS_VAR=true
    # Read variable in file
    while [[ "${line:0:$end_offset}" =~ (.*)(\$\{([a-zA-Z_][a-zA-Z_0-9]*)\})(.*) ]] ; do
        IS_VAR=false
        # pre string
        PRE="${BASH_REMATCH[1]}"
        # post string
        POST="${BASH_REMATCH[4]}${line:$end_offset:${#line}}"
        # variable name
        VARNAME="${BASH_REMATCH[3]}"
        eval 'VARVAL="$(cat '$VARNAME'.yml)"'
        if [ -z "$VARVAL" ]; then
            # value is varname
            VARVAL="\${$VARNAME}"
        fi
        li=''
        while IFS= read -r linev
        do
            li="$PRE$linev$POST"
            cleaned=${li//[$'\r\n']} && cleaned=${cleaned%%*( )}
            echo -n "$cleaned"
            echo
        done < <(printf '%s\n' "$VARVAL")
        end_offset=${#PRE}
    done
    if  "$IS_VAR" = "true" ] ; then
        cleaned=${line//[$'\r\n']} && cleaned=${cleaned%%*( )}
        echo -n "$cleaned"
        echo
    fi
done < <(printf '%s\n' "$(cat; echo -n)")