Provide deterministic output of linter warnings

[invidian]

Is your feature request related to a problem? Please describe.

Currently output from running the linter is sorted randomly:

1 ✗ (533ms) 18:02:25 invidian@dellxps15mateusz ~/repos/kinvolk/flatcar-linux-update-operator (invidian/more-cleanups)*$ golangci-lint run ./... | sha256sum
ce6aef0b8ed653437b2ea9b089508d17f5d9da4eb88e2cd609f008db1fb10d1d  -
0 ✓ (512ms) 18:04:04 invidian@dellxps15mateusz ~/repos/kinvolk/flatcar-linux-update-operator (invidian/more-cleanups)*$ golangci-lint run ./... | sha256sum
4514787c1974b1a875005d03b05538bbec563d4280208a5a1c5745bb4d997861  -
0 ✓ (590ms) 18:04:06 invidian@dellxps15mateusz ~/repos/kinvolk/flatcar-linux-update-operator (invidian/more-cleanups)*$ golangci-lint run ./... | sha256sum
92df4334649dee39870b22b683c9f8abec00307806def963c10668b5c48fb014  -

This makes it difficult to fix one issue, then re-run the linter as all warnings change the order.

Describe the solution you'd like

Output from golangci-lint run ./... should be the same on every invocation if source code does not change.

[bombsimon]

The linters are run in parallell which is one of the reasons golangci-lint can perform as fast as it does. Running the linters sequentially would result in a major performance impact. Depending on the amount of issues reported even waiting for all results and sorting the output could result in a hit as well.

Is this only for your personal workflow or is there some underlying reason for this I'm missing?

[invidian]

The linters are run in parallell which is one of the reasons golangci-lint can perform so fast as it does. Running the linters sequentially would result in a major performance impact. Depending on the amount of issues reported even waiting for all results and sorting the output could result in a hit as well.

Right, I don't mind running in parallel, but this should be separate from the printing part I would imagine. Can't warnings be sorted before being printed? This behavior could be hidden by a feature flag initially or if it would have some kind of performance penalty.

Is this only for your personal workflow or is there some underlying reason for this I'm missing?

This is for the personal workflow. But I think whenever it's possible, it's good to have a deterministic output from the executed commands.

[iwankgb]

I guess that sorting is doable. Perhaps not by default (it might be an issue for large amount of violations) but by enabling sorting processor. @invidian would it be good-enough-fix for you?

[invidian]

Yes, if this could be configured in .golangci.yml file, it would be awesome.

BTW, I usually run with the following configuration, which I think amplifies the need for sorting.

issues:
  max-same-issues: 0
  max-issues-per-linter: 0

If you have some hints how this could be implemented, I can have a look into it myself. I started browsing the code but passed for now not being able to follow the CLI logic.

[iwankgb]

I think I would start with, ekhm, sort_processor.go (I wasn't aware of it to be honest):

output:
  sort-results: true

[iwankgb]

The flag seems to be missing from example configuration file and the docs, I will get it added :)

[invidian]

@iwankgb awesome, it seems this config works as expected 👌

[bombsimon]

Wow! I actually remember this now when you link it but I totally forgot about it. 💯