vmagent: wrong relabeling via -remoteWrite.urlRelabelConfig

[Allineer]

Describe the bug

-remoteWrite.urlRelabelConfig:

- source_labels: [job, agent]
  regex: postgres;gate
  replacement: true
  target_label: __keep

- source_labels: [__keep]
  regex: true
  action: keep

I see metrics for other jobs and agents in the database:

another -remoteWrite.urlRelabelConfig:

- source_labels: [job, agent]
  regex: extra;shkoder
  replacement: true
  target_label: __keep

- source_labels: [__keep]
  regex: true
  action: keep

Expected behavior

Correct filtering.

Version

vmagent-20200701-124503-tags-v1.37.4-0-g8da3f773a and v1.37.3

[valyala]

@Allineer , could you add {job!="victoria-metrics"} filter to the query from the first screenshot in order to see metrics for other jobs? Make sure you didn't enable self-scraping on VictoriaMetrics side with -selfScrapeInterval, because the self-scraped metrics aren't filtered by vmagent.

[Allineer]

@valyala, no other metrics atm.

self-scraping is disabled.

[Allineer]

Something new.
Third database. Postgres job is in testing stage, so it's metrics routed by vmagent only for @testing database. But..

[Allineer]

Updates:

[Allineer]

vmagent's logs:

2020-07-07T07:53:00.466Z	error	VictoriaMetrics/app/vmagent/remotewrite/client.go:237	couldn't send a block with size 19520 bytes to "http://127.0.0.1:8427/api/v1/write": write tcp4 127.0.0.1:39608->127.0.0.1:8427: write: broken pipe; re-sending the block in 2.000 seconds
2020-07-07T08:08:00.472Z	error	VictoriaMetrics/app/vmagent/remotewrite/client.go:237	couldn't send a block with size 19512 bytes to "http://127.0.0.1:8427/api/v1/write": write tcp4 127.0.0.1:43568->127.0.0.1:8427: write: broken pipe; re-sending the block in 2.000 seconds
2020-07-07T08:13:00.466Z	error	VictoriaMetrics/app/vmagent/remotewrite/client.go:237	couldn't send a block with size 19530 bytes to "http://127.0.0.1:8427/api/v1/write": write tcp4 127.0.0.1:44794->127.0.0.1:8427: write: broken pipe; re-sending the block in 2.000 seconds

I have 20-30 messages with this error daily.
:8427 is the victoria-metrics@etc instance.

[Allineer]

WOW!

[valyala]

The last graph looks really weird - scrape_samples_post_metric_relabeling metric shouldn't contain type label unless this label is explicitly added via relabeling (I assume this isn't your case according to relabeling configs posted in the initial message).

I'm still investigating this issue... It looks like some data race or improper cleanup of reused structures during relabeling.

[Allineer]

I have a really extensive promscrape config with a lot of relabeling.
And even if I assume that I add the type label as a result of erroneous relabeling, then why does it appear only twice, for a short period and without my participation?

[valyala]

@Allineer , the commit a730b3f should fix the issue. Could you try building vmagent from this commit according to these instructions and verify whether the issue is gone?

[Allineer]

@valyala

vmagent-20200712-133719-heads-master-0-ga730b3f6 (in instance with multiple -remoteWrite.urlRelabelConfig options only):

panic: interface conversion: interface {} is []prompbmarshal.TimeSeries, not *[]prompbmarshal.TimeSeries

goroutine 33 [running]:
github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite.(*remoteWriteCtx).Push(0xc000023fc0, 0xc0004fc600, 0x5, 0x8)
	/tmp/VictoriaMetrics/app/vmagent/remotewrite/remotewrite.go:218 +0x46c
github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite.Push(0xc0004d4718)
	/tmp/VictoriaMetrics/app/vmagent/remotewrite/remotewrite.go:145 +0xfb
github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape.(*scrapeWork).scrapeInternal(0xc0004d4600, 0x1734359e903, 0x0, 0xf1e8c0)
	/tmp/VictoriaMetrics/lib/promscrape/scrapework.go:230 +0x3f0
github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape.(*scrapeWork).scrapeAndLogError(0xc0004d4600, 0x1734359e903)
	/tmp/VictoriaMetrics/lib/promscrape/scrapework.go:183 +0x4d
github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape.(*scrapeWork).run(0xc0004d4600, 0xc0002d0f60)
	/tmp/VictoriaMetrics/lib/promscrape/scrapework.go:157 +0x3b7
github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape.(*scraperGroup).update.func1(0xc000092140, 0xc0004d4600, 0xc0004b1988)
	/tmp/VictoriaMetrics/lib/promscrape/scraper.go:284 +0x69
created by github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape.(*scraperGroup).update
	/tmp/VictoriaMetrics/lib/promscrape/scraper.go:282 +0x3e2

vmagent-20200708-173353-tags-v1.38.0-0-gb66c7c13a has no errors with some configs.

[valyala]

@Allineer , thanks for testing! The panic should be fixed in the commit b442a42

[Allineer]

Already testing...

[valyala]

@Allineer , FYI, all the bugfix commits mentioned in this issue have been included in v1.38.1.

[Allineer]

It's working! Thanks!