/api/prom/push produce error 400 with 'unexpected IDENTIFIER'

[mailtosmyk]

Describe the bug
When trying to submit stream thru api endpoint "/api/prom/push" loki return error code 400 with not helpful message "parse error at line 1, col 1: syntax error: unexpected IDENTIFIER"

To Reproduce
1 clone grafana/loki from https://github.com/grafana/loki
2 Run docker-compose up
3 Using chrome plugin ARC create POST request with based on documentation from https://github.com/grafana/loki/blob/v1.3.0/docs/api.md#get-lokiapiv1labels:

URL: http://localhost:3100/api/prom/push
Body content: application/json
body: {"streams":[{"labels":"cat","entries":[{"ts":"2018-12-18T08:28:06.801064-04:00","line":"fizzbuzz"}]}]}

CURL output:
c:\test\loki\production\loki-mixin>curl -H "Content-Type: application/json" -X POST "http://localhost:3100/api/prom/push" -d "{"streams": [{ "labels": "cats", "entries": [{ "ts": "2018-12-18T08:28:06.801064-04:00", "line": "fizzbuzz" }] }]}"
parse error at line 1, col 1: syntax error: unexpected IDENTIFIER

4 Loki server return "parse error at line 1, col 1: syntax error: unexpected IDENTIFIER"

Expected behavior
HTTP status code 2XX or better explanation what is missing/incorrect

Environment:

• Infrastructure: laptop, windows 10, docker-compose
• Deployment tool: docker-compose

[cyriltovena]

The error should be better, the label field is incorrect. See https://github.com/grafana/loki/blob/master/docs/api.md#examples-8

Also I recommend you to use the v1 API see the link above.

[talham7391]

I can take a look at this!

[cyriltovena]

Sure I'll feed you with more info on how to on Monday!

[Pixelstudio]

Hi,
Iv encoured the same error using the following json, im using the new api : loki/api/v1/push

{"streams": [{ "labels": "{foo="bar"}", "entries": [{ "ts": "2018-12-18T08:28:06.801064-04:00", "line": "fizzbuzz" }] }]}

The error is :
parse error at line 1, col 2: syntax error: unexpected }, expecting IDENTIFIER

[cyriltovena]

I’m sorry you’re encountering this again, the v1 api has a different label format.

See https://github.com/grafana/loki/blob/master/docs/api.md#examples-4

Basically now it’s a map before it was a string.

[cyriltovena]

@talham7391 It's happening here: https://github.com/grafana/loki/blob/master/pkg/distributor/validator.go#L60

I would change add more context to the error. Something like

return httpgrpc.Errorf(http.StatusBadRequest, fmt.Errorf("error parsing labels: %v", err.Error()))

[talham7391]

Okay great, will push a PR soon!