Fix issue 57 - errors on VCL reload because of duplicated counters #69
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
lorenzoperi-tomtom
changed the title
| "format": "i", | ||
| "value": 0 | ||
| }, | ||
| "VBE.reload_20210114_160902_21476.default.happy": { |
There was a problem hiding this comment.
I just duplicated the VBE metrics with 2 different timestamps to simulate 2 VCL reloads.
Tests fail without the fix.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Fixes #57
Issue
The exporter fails when VCL is reloaded.
This happens because Varnish backend counters (VBE) are repeated for each reload with its timestamp:
Example:
VBE.boot.default.happyandVBE.reload_20210114_155148_19902.default.happy... thus generating duplicated metrics.
The
-p vcl_cooldown=1workaround is not good enough, because old counters are still present in varnishstat for some time (granularity is 30s, see https://varnish-cache.org/docs/6.5/reference/varnishd.html#vcl-cooldown).The result is that on each reload the exporter keeps failing for some time (1m in my tests with
-p vcl_cooldown=1, 10m without it).Solution
I propose to consider only the counters with the most recent timestamp.
I quickly calculate the most recent timestamp by checking the ".happy" counters, then I filter out the outdated counters.
Should work for any Varnish version.
Tests included.