How to Convert Simple JSON to Prometheus Format

[yaohongkok]

Hello everyone. Dear @rustycl0ck and @SuperQ, hope you are doing well.

I am creating an issue because I am stuck trying to follow @rustycl0ck's suggestion. I hope someone can shed some light on this matter.

I have the following data in bad_examples/mydata1.json

{
    "name": "godlyrustyclock",
    "statusCode": "OK"
}

andbad_examples/mydata2.json

{
    "name": "godlyrustyclock",
    "statusCode": "BAD"
}

I will host this data via a python server:

$ cd bad_examples
$ python -m http.server

So, I can get my data when I do the following:

$ curl http://localhost:8000/mydata1.json
$ curl http://localhost:8000/mydata2.json

I would like convert statusCode of OK to 0 and statusCode of BAD to 1. This is my expected output:

# When statusCode is OK

hc_status{name="godlyrustyclock"} 0


# When statusCode is BAD

hc_status{name="godlyrustyclock"} 1

I am encountering some issues to achieve the above result without using our previously pull request #172.

I tried @rustycl0ck's suggestion and ended up with a simple config known as config_simple.yml stored under bad_examples/:

---
modules:
  default:
    metrics:
    - name: hc
      path: '$[?(@.statusCode == "OK"]'
      type: object
      help: Health Check
      labels:
        name: '${.name}'
      values:
        status: 0

So, I run the json exporter as:

go run main.go --config.file bad_examples/config_simple.yml

and I make the call to the exporter:

curl "http://localhost:7979/probe?module=default&target=http://localhost:8000/mydata1.json"

I get the following output:

hc_status{name=""} 0

This is the first issue I encountered.

It seems like the exporter expect the labels to be under the path and therefore it is return empty string. This is one of the reasons why our pull request #172 use the path of "$", which uses the root.

Ok, now let's expand the YML config further to be bad_examples/config.yml:

---
modules:
  default:
    metrics:
    - name: hc
      path: '$[?(@.statusCode == "OK"]'
      type: object
      help: Health Check
      labels:
        name: '${.name}'
      values:
        status: 0
    - name: hc
      path: '$[?(@.statusCode == "BAD"]'
      type: object
      help: Health Check
      labels:
        name: '${.name}'
      values:
        status: 1

Let's set up the exporter again:

go run main.go --config.file bad_examples/config.yml

Now, let's make a call to the exporter:

curl "http://localhost:7979/probe?module=default&target=http://localhost:8000/mydata1.json"

I get the following error:

An error has occurred while serving metrics:

collected metric "hc_status" { label:<name:"name" value:"" > untyped:<value:1 > } was collected before with the same name and label values

This is issue #2. I looked at the code with extra logging and I cannot really figure out what is happening.

I think the problem here is at the config.yml layer. Maybe I am not familiar enough with how to generate the right YML file. I hope someone can help me with this matter. Thank you.

Or if you see pull request #172 being helpful to solve this problem, this could be a good reason to merge the changes back into this repo.