我试图通过http从openhab解析一个XML文件到InfluxDB 2.1.1版本，但服务重新启动，并显示以下错误消息：
panic: runtime error: invalid memory address or nil pointer dereference
以下是完整输出：
Feb 09 22:36:00 hostname.lan telegraf[2172922]: 2022-02-09T21:36:00Z I! Starting Telegraf 1.21.3
Feb 09 22:36:00 hostname.lan telegraf[2172922]: 2022-02-09T21:36:00Z I! Loaded inputs: http
Feb 09 22:36:00 hostname.lan telegraf[2172922]: 2022-02-09T21:36:00Z I! Loaded aggregators:
Feb 09 22:36:00 hostname.lan telegraf[2172922]: 2022-02-09T21:36:00Z I! Loaded processors:
Feb 09 22:36:00 hostname.lan telegraf[2172922]: 2022-02-09T21:36:00Z I! Loaded outputs: influxdb_v2
Feb 09 22:36:00 hostname.lan telegraf[2172922]: 2022-02-09T21:36:00Z I! Tags enabled:
Feb 09 22:36:00 hostname.lan telegraf[2172922]: 2022-02-09T21:36:00Z I! [agent] Config: Interval:10s, Quiet:false, Hostname:"", Flush Interval:10s
Feb 09 22:36:10 hostname.lan telegraf[2172922]: panic: runtime error: invalid memory address or nil pointer dereference
Feb 09 22:36:10 hostname.lan telegraf[2172922]: [signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x94622a]
Feb 09 22:36:10 hostname.lan telegraf[2172922]: goroutine 42 [running]:
Feb 09 22:36:10 hostname.lan telegraf[2172922]: github.com/antchfx/xpath.eqFunc({0x5835860, 0xc00062f520}, {0x42f49a0, 0x831bd20}, {0x42fa9e0, 0xc00100a330})
Feb 09 22:36:10 hostname.lan telegraf[2172922]: /go/pkg/mod/github.com/antchfx/xpath@v1.2.0/operator.go:220 +0x8a
Feb 09 22:36:10 hostname.lan telegraf[2172922]: github.com/antchfx/xpath.(*logicalQuery).Evaluate(0xc001000b70, {0x5835860, 0xc00062f520})
Feb 09 22:36:10 hostname.lan telegraf[2172922]: /go/pkg/mod/github.com/antchfx/xpath@v1.2.0/query.go:724 +0x91
Feb 09 22:36:10 hostname.lan telegraf[2172922]: github.com/antchfx/xpath.(*logicalQuery).Select(0xc000ea1928, {0x5835860, 0xc00062f520})
Feb 09 22:36:10 hostname.lan telegraf[2172922]: /go/pkg/mod/github.com/antchfx/xpath@v1.2.0/query.go:711 +0x57
Feb 09 22:36:10 hostname.lan telegraf[2172922]: github.com/antchfx/xpath.(*NodeIterator).MoveNext(0xc00062f520)
Feb 09 22:36:10 hostname.lan telegraf[2172922]: /go/pkg/mod/github.com/antchfx/xpath@v1.2.0/xpath.go:86 +0x38
Feb 09 22:36:10 hostname.lan telegraf[2172922]: github.com/antchfx/xmlquery.QuerySelectorAll(0xc000b28d80, 0xc00062f460)
Feb 09 22:36:10 hostname.lan telegraf[2172922]: /go/pkg/mod/github.com/antchfx/xmlquery@v1.3.9/query.go:116 +0x13a
Feb 09 22:36:10 hostname.lan telegraf[2172922]: github.com/antchfx/xmlquery.QueryAll(0xc000ea1a18, {0xc000d3f0c1, 0x1457f})
Feb 09 22:36:10 hostname.lan telegraf[2172922]: /go/pkg/mod/github.com/antchfx/xmlquery@v1.3.9/query.go:98 +0x52
Feb 09 22:36:10 hostname.lan telegraf[2172922]: github.com/influxdata/telegraf/plugins/parsers/xpath.(*xmlDocument).QueryAll(0xc0006f9c80, {0x48daca0, 0xc000b28d80}, {0xc000d3f0c1, 0xc0006f9cd0})
Feb 09 22:36:10 hostname.lan telegraf[2172922]: /go/src/github.com/influxdata/telegraf/plugins/parsers/xpath/xml_document.go:18 +0x45
Feb 09 22:36:10 hostname.lan telegraf[2172922]: github.com/influxdata/telegraf/plugins/parsers/xpath.(*Parser).Parse(0xc000b28a00, {0xc000f12000, 0x1457f, 0x18000})
Feb 09 22:36:10 hostname.lan telegraf[2172922]: /go/src/github.com/influxdata/telegraf/plugins/parsers/xpath/parser.go:96 +0x2b1
Feb 09 22:36:10 hostname.lan telegraf[2172922]: github.com/influxdata/telegraf/plugins/inputs/http.(*HTTP).gatherURL(0xc000632000, {0x5960588, 0xc0000ad620}, {0xc000d3f001, 0x34})
Feb 09 22:36:10 hostname.lan telegraf[2172922]: /go/src/github.com/influxdata/telegraf/plugins/inputs/http/http.go:235 +0x80d
Feb 09 22:36:10 hostname.lan telegraf[2172922]: github.com/influxdata/telegraf/plugins/inputs/http.(*HTTP).Gather.func1({0xc000d3f001, 0x34})
Feb 09 22:36:10 hostname.lan telegraf[2172922]: /go/src/github.com/influxdata/telegraf/plugins/inputs/http/http.go:144 +0x9e
Feb 09 22:36:10 hostname.lan telegraf[2172922]: created by github.com/influxdata/telegraf/plugins/inputs/http.(*HTTP).Gather
Feb 09 22:36:10 hostname.lan telegraf[2172922]: /go/src/github.com/influxdata/telegraf/plugins/inputs/http/http.go:142 +0x188
Feb 09 22:36:10 hostname.lan systemd[1]: telegraf.service: Main process exited, code=exited, status=2/INVALIDARGUMENT
Feb 09 22:36:10 hostname.lan systemd[1]: telegraf.service: Failed with result 'exit-code'.
Feb 09 22:36:10 hostname.lan systemd[1]: telegraf.service: Service RestartSec=100ms expired, scheduling restart.
Feb 09 22:36:10 hostname.lan systemd[1]: telegraf.service: Scheduled restart job, restart counter is at 24.
Feb 09 22:36:10 hostname.lan systemd[1]: Stopped The plugin-driven server agent for reporting metrics into InfluxDB.
在这里你可以看到我的配置文件以及我想要插入的XML层次结构：
[global_tags]
[agent]
interval = "10s"
round_interval = true
metric_batch_size = 1000
metric_buffer_limit = 10000
collection_jitter = "0s"
flush_interval = "10s"
flush_jitter = "0s"
precision = ""
debug = false
quiet = false
omit_hostname = true
[[outputs.influxdb_v2]]
urls = ["http://hostname.lan:8086"]
token = "..."
organization = "Home"
bucket = "SmartHome"
[[inputs.http]]
urls = [
"http://openhab.lan/addons/xmlapi/statelist.cgi"
]
data_format = "xml"
tagexclude = ["url", "host"]
[[inputs.http.xml]]
# <stateList>
# ...
# <device name="Hygrometer_LR" ise_id="1555" unreach="false" sticky_unreach="false" config_pending="false">
# <channel name="Hygrometer_LR:0" ise_id="1556" index="0" visible="" operate="">
# ...
# </channel>
# <channel name="HM-WDS40-TH-I-2 OEQ0161025:1" ise_id="1576" index="1" visible="true" operate="true">
# <datapoint name="BidCos-RF.OEQ0161025:1.TEMPERATURE" type="TEMPERATURE" ise_id="1578" value="21.700000" valuetype="4" valueunit="°C" timestamp="1644441533" operations="5"/>
# <datapoint name="BidCos-RF.OEQ0161025:1.HUMIDITY" type="HUMIDITY" ise_id="1577" value="65" valuetype="16" valueunit="%" timestamp="1644441533" operations="5"/>
# </channel>
# </device>
# ...
# </stateList>
metric_name = "'hygrometer'"
metric_selection = "/stateList/device/@name=Hygrometer_LR/channel/@ise_id=1576"
timestamp = "datapoint/@type=TEMPERATURE/@timestamp"
timestamp_format = "unix"
[[inputs.http.xml.tags]]
room = "LR"
[[inputs.http.xml.fields]]
humidity = "number(datapoint/@type=HUMIDITY/@value)"
temperature = "number(datapoint/@type=TEMPERATURE/@value)"
InfluxDB和Telegraf都作为服务在CentOS8上运行。
以及来自URL的文件信息：
# file /tmp/statelist.cgi
/tmp/statelist.cgi: XML 1.0 document, ISO-8859 text, with very long lines, with no line terminators
我从inlfuxdb社区得到了正确的答案：
[[inputs.http.xpath]]
metric_name = "'hygrometer'"
metric_selection = "/stateList/device[@name='Hygrometer_LR']/channel[@ise_id='1576']"
timestamp = "datapoint[@type='TEMPERATURE']/@timestamp"
timestamp_format = "unix"
[inputs.http.xpath.tags]
room = "string(../@name)"
[inputs.http.xpath.fields]
humidity = "number(datapoint[@type='HUMIDITY']/@value)"
temperature = "number(datapoint[@type='TEMPERATURE']/@value)"