Auto Load ChefDK when in a Chef cookbook directory (when a .chedk file is present). You only need one of the files depending on the shell you use.

.bash_chefdk

# For BASH users
# If you use BASH as your main shell, then add these lines to the end our source from a seperate file.
# It will make it so it loads the ChefDK automatically when you enter the chef cookbook directory or
# directory whose ancestor is a cookbook directory and unload the ChefDK when you leave the cookbook directory.
# If you want to force load the ChefDK environment you should:
#     load_chefdk 1
#
# Then to force unload:
#     unload_chefdk 1

### For working with the ChefDK (with rvm)
function parent_dir() {
    path=$PWD

    if [ "$#" -eq 1 ]; then path=$1; fi

    regex='(.+)(/.+$)'
    [[ $path =~ $regex ]]

    if [ -z "${BASH_REMATCH[1]}" ]; then
        echo '/'
    else
        echo "${BASH_REMATCH[1]}"
    fi
}

function check_for_chefdk_marker() {
    cwd=$PWD

    while [ "$cwd" != '/' ]; do
        [ -f "${cwd}/.chefdk" ] && return 0
        cwd=$(parent_dir "$cwd")
    done

    return 1
}

function __autoload_chefdk() {
    if check_for_chefdk_marker; then
        load_chefdk
    elif [ "$CHEFDK_FORCE_LOADED" != "1" ]; then
        unload_chefdk
    fi
}

# Force load pass any value after it. You'll need to force unload if you want
# unload the chefdk.
function load_chefdk() {
    if [ "$CHEFDK" != "1" ]; then
        old_path="$PATH"
        old_gem_home="$GEM_HOME"
        old_gem_path="$GEM_PATH"
        old_gem_root="$GEM_ROOT"

        eval "$(chef shell-init bash)"
        if [ "$?" -eq 0 ]; then
            if [ "$#" -eq 1 ]; then export CHEFDK_FORCE_LOADED=1; fi

            export CHEFDK_OLD_PATH="$old_path"
            export CHEFDK_OLD_GEM_HOME="$old_gem_home"
            export CHEFDK_OLD_GEM_PATH="$old_gem_path"
            export CHEFDK_OLD_GEM_ROOT="$old_gem_root"
            export CHEFDK=1

            echo "ChefDK loaded."
        fi
    fi
}

# To fore unload, pass any argument to the function.
function unload_chefdk() {
    if [ "$CHEFDK" == "1" ]; then
        if [ "$#" -eq 1 ]; then export CHEFDK_FORCE_LOADED=0; fi

        if [ -n "$CHEFDK_OLD_PATH" ]; then export PATH="$CHEFDK_OLD_PATH"; fi
        if [ -n "$CHEFDK_OLD_GEM_HOME" ]; then export GEM_HOME="$CHEFDK_OLD_GEM_HOME"; else unset GEM_HOME; fi
        if [ -n "$CHEFDK_OLD_GEM_PATH" ]; then export GEM_PATH="$CHEFDK_OLD_GEM_PATH"; else unset GEM_PATH; fi
        if [ -n "$CHEFDK_OLD_GEM_ROOT" ]; then export GEM_ROOT="$CHEFDK_OLD_GEM_ROOT"; else unset GEM_ROOT; fi

        unset CHEFDK_OLD_PATH
        unset CHEFDK_OLD_GEM_HOME
        unset CHEFDK_OLD_GEM_PATH
        unset CHEFDK_OLD_GEM_ROOT
        unset CHEFDK

        echo 'Unloaded ChefDK.'
    fi
}


# So that it autoloads by itself
PROMPT_COMMAND=__autoload_chefdk

.zshrc_chefdk

# For ZSH users
# Add this to your .zshrc or a source it from a seperate file.It will make it so it loads
# the ChefDK automatically when you enter the chef cookbook directory or directory whose ancestor
# is a cookbook directory and unload the ChefDK when you leave the cookbook directory.
# If you want to force load the ChefDK environment you should:
# load_chefdk 1
#
# Then to force unload:
# unload_chefdk 1

# For working with the ChefDK
function parent_dir() {
    path=$PWD

    if [ "$#" -eq 1 ]; then path=$1; fi

    regex='(.+)(/.+$)'
    [[ $path =~ $regex ]]

    if [ -z "${match[1]}" ]; then
        echo '/'
    else
        echo "${match[1]}"
    fi

    unset match
}
function check_for_chefdk_marker() {
    cwd=$PWD

    while [ "$cwd" != '/' ]; do
        [ -f "${cwd}/.chefdk" ] && return 0
        cwd=$(parent_dir "$cwd")
    done

    return 1
}

function __autoload_chefdk() {
    if check_for_chefdk_marker; then
        load_chefdk
    elif [ "$CHEFDK_FORCE_LOADED" != "1" ]; then
        unload_chefdk
    fi
}

# Force load pass any value after it. You'll need to force unload if you want
# unload the chefdk.
function load_chefdk() {
    if [ "$CHEFDK" != "1" ]; then
        old_path=$PATH
        old_gem_home=$GEM_HOME
        old_gem_path=$GEM_PATH
        old_gem_root=$GEM_ROOT

        eval "$(chef shell-init bash)"
        if [ "$?" -eq 0 ]; then
            if [ "$#" -eq 1 ]; then export CHEFDK_FORCE_LOADED=1; fi

            export CHEFDK_OLD_PATH=$old_path
            export CHEFDK_OLD_GEM_HOME=$old_gem_home
            export CHEFDK_OLD_GEM_PATH=$old_gem_path
            export CHEFDK_OLD_GEM_ROOT=$old_gem_root
            export CHEFDK=1

            echo "ChefDK loaded."
        fi
    fi
}

# To fore unload, pass any argument to the function.
function unload_chefdk() {
    if [ "$CHEFDK" = "1" ]; then
        if [ "$#" -eq 1 ]; then export CHEFDK_FORCE_LOADED=0; fi

        if [ -n "$CHEFDK_OLD_PATH" ]; then export PATH="$CHEFDK_OLD_PATH"; fi
        if [ -n "$CHEFDK_OLD_GEM_HOME" ]; then export GEM_HOME="$CHEFDK_OLD_GEM_HOME"; else unset GEM_HOME; fi
        if [ -n "$CHEFDK_OLD_GEM_PATH" ]; then export GEM_PATH="$CHEFDK_OLD_GEM_PATH"; else unset GEM_PATH; fi
        if [ -n "$CHEFDK_OLD_GEM_ROOT" ]; then export GEM_ROOT="$CHEFDK_OLD_GEM_ROOT"; else unset GEM_ROOT; fi

        unset CHEFDK_OLD_PATH
        unset CHEFDK_OLD_GEM_HOME
        unset CHEFDK_OLD_GEM_PATH
        unset CHEFDK_OLD_GEM_ROOT
        unset CHEFDK

        echo 'Unloaded ChefDK.'
    fi
}

# Add this after the chefdk functions to your .zshrc
function chpwd() {
    __autoload_chefdk
}