bc9a71e111
This was primarily intended to consume InfluxDB-style expvars,
particularly InfluxDB's `/debug/vars` endpoint.
That endpoint follows a structure like
```json
{
"httpd::8086": {
"name": "httpd",
"tags": {
"bind": ":8086"
},
"values": {
"pointsWrittenOK": 33756,
"queryReq": 19,
"queryRespBytes": 26973,
"req": 428,
"writeReq": 205,
"writeReqBytes": 3939161
}
}
}
```
There are an arbitrary number of top-level keys in the JSON response at
the configured URLs, and this plugin will iterate through all of their
values looking for objects with keys "name", "tags", and "values"
indicating a metric to be consumed by telegraf.
Running this on current master of InfluxDB, I am able to record nearly
the same information that is normally stored in the `_internal`
database; the only measurement missing from `_internal` is `runtime`,
which is present in expvars under the "memstats" key but does not follow
the expvar format and so is not consumed in this plugin.
```
$ influx -database=telegraf -execute 'SHOW FIELD KEYS FROM /expvar/'
name: expvar_influxdb_engine
----------------------------
fieldKey
blksWrite
blksWriteBytes
blksWriteBytesC
pointsWrite
pointsWriteDedupe
name: expvar_influxdb_httpd
---------------------------
fieldKey
pingReq
pointsWrittenOK
queryReq
queryRespBytes
req
writeReq
writeReqBytes
name: expvar_influxdb_shard
---------------------------
fieldKey
fieldsCreate
seriesCreate
writePointsOk
writeReq
name: expvar_influxdb_subscriber
--------------------------------
fieldKey
pointsWritten
name: expvar_influxdb_wal
-------------------------
fieldKey
autoFlush
flushDuration
idleFlush
memSize
metaFlush
pointsFlush
pointsWrite
pointsWriteReq
seriesFlush
name: expvar_influxdb_write
---------------------------
fieldKey
pointReq
pointReqLocal
req
subWriteOk
writeOk
```
|
||
|---|---|---|
| .. | ||
| README.md | ||
| expvar.go | ||
| expvar_test.go | ||
README.md
expvar plugin
The expvar plugin collects InfluxDB-style expvar data from JSON endpoints.
With a configuration of:
[plugins.expvar]
[[plugins.expvar.services]]
name = "produce"
urls = [
"http://127.0.0.1:8086/debug/vars",
"http://192.168.2.1:8086/debug/vars"
]
And if 127.0.0.1 responds with this JSON:
{
"k1": {
"name": "fruit",
"tags": {
"kind": "apple"
},
"values": {
"inventory": 371,
"sold": 112
}
},
"k2": {
"name": "fruit",
"tags": {
"kind": "banana"
},
"values": {
"inventory": 1000,
"sold": 403
}
}
}
And if 192.168.2.1 responds like so:
{
"k3": {
"name": "transactions",
"tags": {},
"values": {
"total": 100,
"balance": 184.75
}
}
}
Then the collected metrics will be:
expvar_produce_fruit,expvar_url='http://127.0.0.1:8086/debug/vars',kind='apple' inventory=371.0,sold=112.0
expvar_produce_fruit,expvar_url='http://127.0.0.1:8086/debug/vars',kind='banana' inventory=1000.0,sold=403.0
expvar_produce_transactions,expvar_url='http://192.168.2.1:8086/debug/vars' total=100.0,balance=184.75
There are two important details to note about the collected metrics:
-
Even though the values in JSON are being displayed as integers, the metrics are reported as floats. JSON encoders usually don't print the fractional part for round floats. Because you cannot change the type of an existing field in InfluxDB, we assume all numbers are floats.
-
The top-level keys' names (in the example above,
"k1","k2", and"k3") are not considered when recording the metrics.