task stops with unsupported type error

[jszzang]

Snap daemon version (use snapteld -v):
snapteld version master-0bf590e

Environment:

• Cloud provider or hardware configuration: cloud
• OS (e.g. from /etc/os-release):centos 7
• Kernel (e.g. uname -a): Linux d-thms-os03 3.10.0-327.36.3.el7.x86_64
• Relevant tools (e.g. plugins used with Snap):
  facter, tag, mysql
• Others (e.g. deploying with Ansible):

What happened:
cannot publish to mysql. task stops with following error message.

[[37mDEBU[[0m[2017-07-05T15:43:40+09:00] time="2017-07-05T15:43:40+09:00" level=info msg="Error: Cannot convert incoming data to string, err=Unsupported type bool (currently supported data type: string, []string, int, []int, uint, []uint, uint64, []uint64, float64, []float64, or nil)"
[[37m_module[[0m=plugin-exec [[37mio[[0m=stderr [[37mplugin[[0m=mysql
[[31mERRO[[0m[2017-07-05T15:43:40+09:00] error with publisher job [[31m_module[[0m=scheduler-job [[31mblock[[0m=run [[31merror[[0m=Publish call error:
Unsupported type bool (currently supported data type: string, []string, int, []int, uint, []uint, uint64, []uint64, float64, []float64, or nil) [[31mjob-type[[0m=publisher [[31mplugin-config[[0m=map[password:{Value:tidc} port:{Value:3306} tablename:{Value:snap_metrics} username:{Value:tidc} database:{Value:tidc_vm} hostname:{Value:113.217.254.155}] [[31mplugin-name[[0m=mysql [[31mplugin-version[[0m=-1
[[33mWARN[[0m[2017-07-05T15:43:40+09:00] Publish job failed [[33m_block[[0m=submit-publish-job [[33m_module[[0m=scheduler-workflow [[33mparent-node-type[[0m=processor [[33mpublish-name[[0m=mysql [[33mpublish-version[[0m=-1 [[33mtask-id[[0m=dae9a749-78bf-4fdf-b003-7d05b4db4a7b [[33mtask-name[[0m=Task-dae9a749-78bf-4fdf-b003-7d05b4db4a7b
[[37mDEBU[[0m[2017-07-05T15:43:40+09:00] Batch submission complete [[37m_block[[0m=work-jobs [[37m_module[[0m=scheduler-workflow [[37mcount-process-nodes[[0m=0 [[37mcount-publish-nodes[[0m=1 [[37mparent-node-type[[0m=processor [[37mtask-id[[0m=dae9a749-78bf-4fdf-b003-7d05b4db4a7b [[37mtask-name[[0m=Task-dae9a749-78bf-4fdf-b003-7d05b4db4a7b
[[37mDEBU[[0m[2017-07-05T15:43:40+09:00] Batch submission complete [[37m_block[[0m=work-jobs [[37m_module[[0m=scheduler-workflow [[37mcount-process-nodes[[0m=1 [[37mcount-publish-nodes[[0m=0 [[37mparent-node-type[[0m=collector [[37mtask-id[[0m=dae9a749-78bf-4fdf-b003-7d05b4db4a7b [[37mtask-name[[0m=Task-dae9a749-78bf-4fdf-b003-7d05b4db4a7b
[[33mWARN[[0m[2017-07-05T15:43:40+09:00] Task failed [[33m_block[[0m=spin [[33m_module[[0m=scheduler-task [[33mconsecutive failure limit[[0m=10 [[33mconsecutive failures[[0m=1 [[33merror[[0m=Publish call error: Unsupported type bool (currently supported data type: string, []string, int, []int, uint, []uint, uint64, []uint64, float64, []float64, or nil) [[33mtask-id[[0m=dae9a749-78bf-4fdf-b003-7d05b4db4a7b [[33mtask-name[[0m=Task-dae9a749-78bf-4fdf-b003-7d05b4db4a7b
[[37mDEBU[[0m[2017-07-05T15:43:40+09:00] task spin loop [[37m_module[[0m=scheduler-task
[[37mDEBU[[0m[2017-07-05T15:43:40+09:00] event received [[37m_block[[0m=handle-events [[37m_module[[0m=scheduler-events [[37mevent-namespace[[0m=Scheduler.MetricsCollected [[37mmetric-count[[0m=62 [[37mtask-id[[0m=dae9a749-78bf-4fdf-b003-7d05b4db4a7b
[[37mDEBU[[0m[2017-07-05T15:43:40+09:00] Ping received [[37m_module[[0m=plugin-exec [[37mio[[0m=stderr [[37mplugin[[0m=tag
[[37mDEBU[[0m[2017-07-05T15:43:40+09:00] Heartbeat received at: 2017-07-05 15:43:40.610643066 +0900 KST [[37m_module[[0m=plugin-exec [[37mio[[0m=stdout [[37mplugin[[0m=facter
[[34mINFO[[0m[2017-07-05T15:43:44+09:00] grpc: addrConn.resetTransport failed to create client transport: connection error: desc = "transport: dial tcp 127.0.0.1:44103: getsockopt: connection refused"; Reconnecting to {"127.0.0.1:44103" }

What you expected to happen:
publish facter data w/o error

Steps to reproduce it (as minimally and precisely as possible):

1. load plugins (facter/tag/mysql)
2. create task w/ following file

{
    "version": 1,
    "schedule": {
        "type": "simple",
        "interval": "20s"
    },
    "workflow": {
        "collect": {
            "metrics": {
                "/intel/facter/dmi/bios/release_date": {},
                "/intel/facter/dmi/bios/vendor": {},
                "/intel/facter/dmi/bios/version": {},
                "/intel/facter/dmi/manufacturer": {},
                "/intel/facter/dmi/product/name": {},
                "/intel/facter/dmi/product/serial_number": {},
                "/intel/facter/dmi/product/uuid": {},
                "/intel/facter/is_virtual": {},
                "/intel/facter/kernel": {},
                "/intel/facter/kernelmajversion": {},
                "/intel/facter/kernelrelease": {},
                "/intel/facter/kernelversion": {},
                "/intel/facter/networking/domain": {},
                "/intel/facter/networking/fqdn": {},
                "/intel/facter/networking/hostname": {},
                "/intel/facter/networking/interfaces/eth0/ip": {},
                "/intel/facter/networking/interfaces/eth0/mac": {},
                "/intel/facter/networking/interfaces/eth0/netmask": {},
                "/intel/facter/os/architecture": {},
                "/intel/facter/os/family": {},
                "/intel/facter/os/hardware": {},
                "/intel/facter/os/name": {},
                "/intel/facter/os/release/full": {},
                "/intel/facter/os/release/major": {},
                "/intel/facter/os/release/minor": {}
            },
        "process": [
        {
            "plugin_name": "tag",
            "config": {
                "tags": "datacenter:tmp"
            },
                "publish": [
                {
                        "plugin_name": "mysql",
                        "config": {
                                "username": "myid",
                                "password": "mypass",
                                "hostname": "1xx.xxx.xxx.xxx",
                                "port": "3306",
                                "database": "idc",
                                "tablename": "snap_metrics"
                        }
                }
                ]

        }
        ]
        }
    }
}

Anything else do we need to know (e.g. issue happens only occasionally):