zenrun

#! /usr/bin/env bash
##############################################################################
# 
# Copyright (C) Zenoss, Inc. 2014, all rights reserved.
# 
# This content is made available according to terms specified in
# License.zenoss under the directory where your Zenoss product is installed.
# 
##############################################################################


# This script runs custom commands passed in to the container from the host.
#
# Error Codes:
#    255 - BADPARAM     Bad params
#    254 - NOTFOUND     Script not found
#    253 - INVALID      Invalid script
#    252 - NOCOMMIT     NOCOMMIT environment variable was set
#
# Each script follows a specific design template.
#
# Example:
#   #! /bin/bash
#
#   # Default action for undefined program calls
#   __DEFAULT__() {
#       /bin/helloworld $@
#   }
#
#   # ---
#   # Transaction-based commands
#   # ---
#
#   # Usage: zenrun /bin/helloworld savestate
#   savestate() {
#       /bin/helloworld $@
#       return $?
#   }

# Parse the arguments
# Usage: zenrun PROGRAM [ARGS]
if [[ $# -lt 1 ]]; then
    echo -e "Missing program argument" >&2
    exit 255
fi

DESIRED_USER=${DESIRED_USER:-"zenoss"}
if [[ "$(whoami)" != "$DESIRED_USER" ]]; then
    exec su - "$DESIRED_USER" -c "DESIRED_USER=$DESIRED_USER NOCOMMIT=$NOCOMMIT $0 $*"
fi

RUNPATH=${RUNPATH:-$(dirname $0)/zenrun.d}
PROGRAM=$1
shift

# Load the program
RC=nil
if [[ -r $RUNPATH/$PROGRAM ]]; then
    source $RUNPATH/$PROGRAM
elif [[ -r $PROGRAM ]]; then
    source $PROGRAM
elif which $PROGRAM > /dev/null ; then
    $PROGRAM "$@"
    RC="$?"
else
    echo -e "Program not found: $PROGRAM" >&2
    exit 254
fi

# Look up the command and run
declare -f __DEFAULT__ &> /dev/null
defaultExists=$?
if [[ $RC != nil ]]; then
    : # Already have return code; do nothing
elif [[ $defaultExists=0 && -z "$1" ]]; then
    __DEFAULT__
    RC="$?"
elif declare -f -- "$1" &> /dev/null; then
    "$@"
    RC="$?"
elif [[ $defaultExists=0 ]]; then
    __DEFAULT__ "$@"
    RC="$?"
else
    echo -e "Missing __DEFAULT__ declaration in $PROGRAM" >&2
    exit 253
fi

if ${NOCOMMIT:-false} ; then
    echo Command definition deliberately disables container commit.
    exit 252
fi

exit "$RC"