export a variable from a json payload

export_payload_var.sh

set -eu

# shortcut for getting payload values
function export_payload_var() {
    name="$1"
    pattern="$2"
    value=$(jq -r "$pattern" "${PAYLOAD}")
    if [[ "$value" == "null" ]]; then
        echo "Could not find pattern '$pattern' in payload '${PAYLOAD}'"
        exit 1
    fi
    echo export "$name"="$value"
}

export_pipeline_var GCP_PROJECT '.data.project_id'