K6 module

[pablochacin]

What does this PR do?

Implements a module for running k6.

Why is it important?

K6 is a well-known tool for testing. This module allows the reuse of existing k6 test scripts in tests using TestContainers. This is particularly interesting when implementing e2e tests.

Note to reviewers

There are a few things I'm not totally satisfied with in its present form, and I would like to address in future iterations:

• The test script passed to k6 is presently dfined as an option (WithTestScript), but it reality a "mandatory option" and if not specified, the test execution will fail. I considered adding it as an argument to the RunContainer function, but this seems not to be how other modules work.

RunContainer(ctx context.Context, string script, options....)

• Specifying a build cache also requires running the container with the AsUser option to give it access to the cache directory. This is required because the image runs with its own user and mounting a local directory would fail with an access error. Maybe there's an alternative way to do this. For example, if instead of using a local directory, the cache is passed as a volume, this wouldn't be a problem. But requiring the user to create a docker volume before the test seems a little overkill.

Edit: I found a way to mount a regular directory in the image without requiring specifying an user.

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[mdelapenya]

Hey @pablochacin great job with the module! Thank you so much!!

I added a few comments regarding some leftovers from previous runs, as @mmorel-35 pointed out (thank you), so let's remove the examples/k6 files and references.

I have one question regarding the test execution, probably caused by my total inexperience in the k6 project, so sorry about it if it's a dumb question: I can imagine the JS script will try to connect to an application to perform some load, right? Should the k6 module provide a way to connect to that app, or it's not needed? ATM I cannot picture how the script interacts with the app under test.

[pablochacin]

Hi @mdelapenya @mmorel-35 I'm adding a module and the example for that module.
Should I submit them separately? For me, it makes more sense to add both, as the example is part of the documentation.

[pablochacin]

I have one question regarding the test execution, probably caused by my total inexperience in the k6 project, so sorry about it if it's a dumb question: I can imagine the JS script will try to connect to an application to perform some load, right? Should the k6 module provide a way to connect to that app, or it's not needed? ATM I cannot picture how the script interacts with the app under test.

@mdelapenya yes, that is the case. In general, the scripts use an environment variable to get the address of the target application. I was planning to add an example for this.

[mdelapenya]

Hi @mdelapenya @mmorel-35 I'm adding a module and the example for that module. Should I submit them separately? For me, it makes more sense to add both, as the example is part of the documentation.

Oh I see now. Then the docs are not clear enough. Our bad.

Please add an examples_test.go file (IIRC the generator should create it) in the k6 module dir, including the ExampleRunContainer function.

TBH I'm thinking about removing everything under examples, as they are just plain code snippets to copy paste, probably causing more confusion than benefits. Since we added testable examples support I think they are not needed anymore.

[pablochacin]

Oh I see now. Then the docs are not clear enough. Our bad.

This PR is still a draft. The documentation and examples are still a work in progress.

TBH I'm thinking about removing everything under examples,

Then it makes sense to remove the examples. I will put all of them under the module's examples_test.go.

[pablochacin]

@mdelapenya I don't really understand this linter message. Could you please help me point out the issue? 🙏

Running [/home/runner/golangci-lint-1.54.1-linux-amd64/golangci-lint run --out-format=github-actions --path-prefix=modules/k6 --verbose] in [/home/runner/work/testcontainers-go/testcontainers-go/modules/k6] ...
Error: File is not gci-ed with --skip-generated -s standard -s default -s prefix(github.com/testcontainers) (gci)
Error: File is not gci-ed with --skip-generated -s standard -s default -s prefix(github.com/testcontainers) (gci)
Error: File is not gci-ed with --skip-generated -s standard -s default -s prefix(github.com/testcontainers) (gci)

[pablochacin]

It is weird that running the linter locally is not catching any of these errors. I'm not sure what I'm doing wrong.

I'm running it from my module's root directory (modules/k6) using the following command that is generating the output shown below

make lint 
golangci-lint run --out-format=github-actions --path-prefix=. --verbose -c /home/pablo/go/src/github.com/testcontainers/testcontainers-go/.golangci.yml --fix
INFO [config_reader] Used config file .golangci.yml 
INFO [lintersdb] Active 12 linters: [errcheck errorlint gci gocritic gofumpt gosimple govet ineffassign misspell staticcheck typecheck unused] 
INFO [loader] Go packages loading at mode 575 (files|name|compiled_files|deps|types_sizes|exports_file|imports) took 339.074702ms 
INFO [runner/filename_unadjuster] Pre-built 0 adjustments in 25.921286ms 
INFO [linters_context/goanalysis] analyzers took 0s with no stages 
INFO [runner] fixer took 0s with no stages        
INFO [runner] Issues before processing: 97, after processing: 0 
INFO [runner] Processors filtering stat (out/in): skip_files: 97/97, autogenerated_exclude: 97/97, identifier_marker: 97/97, cgo: 97/97, filename_unadjuster: 97/97, skip_dirs: 97/97, path_prettifier: 97/97, exclude: 97/97, exclude-rules: 4/97, nolint: 0/4 
INFO [runner] processing took 8.156372ms with stages: nolint: 4.288631ms, identifier_marker: 2.089663ms, exclude-rules: 601.775µs, path_prettifier: 569.636µs, autogenerated_exclude: 463.261µs, skip_dirs: 72.157µs, fixer: 40.755µs, cgo: 15.52µs, filename_unadjuster: 7.481µs, max_same_issues: 1.853µs, source_code: 740ns, skip_files: 705ns, diff: 605ns, exclude: 600ns, severity-rules: 545ns, uniq_by_line: 505ns, path_shortener: 497ns, max_from_linter: 442ns, sort_results: 423ns, max_per_file_from_linter: 292ns, path_prefixer: 286ns 
INFO [runner] linters took 585.581845ms with stages: goanalysis_metalinter: 577.308068ms 
INFO File cache stats: 0 entries of total size 0B 
INFO Memory: 11 samples, avg is 56.1MB, max is 88.5MB 
INFO Execution took 961.363062ms  

Something that I don't understand is this message because I don't see any change in any file after running the command.

INFO [runner] Issues before processing: 97, after processing: 0

[mmorel-35]

@pablochacin ,

can you remove --path-prefix=. and see how it goes ?

[pablochacin]

can you remove --path-prefix=. and see how it goes ?

Same 😞 I mean, no changes.

[mmorel-35]

When I try it on codespaces from artemis module's where I have created a deliberated issue

/workspaces/testcontainers-go/modules/artemis $ make lint
golangci-lint run --out-format=github-actions --path-prefix=. --verbose -c /workspaces/testcontainers-go/.golangci.yml --fix
INFO [config_reader] Used config file ../../.golangci.yml
INFO [lintersdb] Active 11 linters: [errcheck errorlint gci gocritic gofumpt gosimple govet ineffassign misspell staticcheck unused] 
INFO [loader] Go packages loading at mode 575 (types_sizes|files|imports|name|compiled_files|deps|exports_file) took 245.382898ms 
INFO [runner/filename_unadjuster] Pre-built 0 adjustments in 511.104µs 
INFO [linters_context/goanalysis] analyzers took 0s with no stages 
INFO [runner] Fix issue &result.Issue{FromLinter:"gci", Text:"File is not `gci`-ed with --skip-generated -s standard -s default -s prefix(github.com/testcontainers)", Severity:"", SourceLines:[]string{"\t\"github.com/docker/go-connections/nat\""}, Replacement:(*result.Replacement)(0xc00114a6f0), Pkg:(*packages.Package)(0xc000f9f500), LineRange:(*result.Range)(nil), Pos:token.Position{Filename:"artemis.go", Offset:0, Line:7, Column:0}, HunkPos:0, ExpectNoLint:false, ExpectedNoLintLinter:""} with range {7 7} 
INFO [runner] fixer took 1.232051ms with stages: all: 1.232051ms 
INFO [runner] Issues before processing: 3, after processing: 0 
INFO [runner] Processors filtering stat (out/in): source_code: 1/1, path_shortener: 1/1, filename_unadjuster: 3/3, autogenerated_exclude: 3/3, exclude: 3/3, nolint: 1/1, uniq_by_line: 1/1, diff: 1/1, identifier_marker: 3/3, max_same_issues: 1/1, severity-rules: 1/1, cgo: 3/3, path_prettifier: 3/3, skip_files: 3/3, skip_dirs: 3/3, max_from_linter: 1/1, fixer: 0/1, exclude-rules: 1/3, max_per_file_from_linter: 1/1 
INFO [runner] processing took 1.745278ms with stages: fixer: 1.258429ms, nolint: 198.761µs, identifier_marker: 92.634µs, exclude-rules: 66.093µs, path_prettifier: 52.589µs, autogenerated_exclude: 43.16µs, source_code: 15.779µs, skip_dirs: 11.432µs, path_shortener: 1.483µs, cgo: 1.172µs, max_same_issues: 772ns, filename_unadjuster: 561ns, uniq_by_line: 391ns, exclude: 371ns, sort_results: 301ns, max_from_linter: 280ns, severity-rules: 280ns, skip_files: 260ns, max_per_file_from_linter: 230ns, diff: 170ns, path_prefixer: 130ns 
INFO [runner] linters took 457.480433ms with stages: goanalysis_metalinter: 455.644814ms 
INFO File cache stats: 1 entries of total size 3.0KiB 
INFO Memory: 9 samples, avg is 52.1MB, max is 84.7MB 
INFO Execution took 707.979266ms

See the relative path to the "Used config file ../../.golangci.yml" is different from your output. Any reason ?

[mdelapenya]

When I fetched the PR before 420041c, I saw errors in the command output with the same lines that GH added as comments in the PR.

Basically saving the k6.go file on my VSCode fixed it, as it ran the automatic format for Go.

[pablochacin]

Hi I'm submitting this first version of the k6 module. Thanks, @mdelapenya and @mmorel-35 for your reviews of the draft. I marked all your suggested changes as resolved to facilitate processing any new comments.

[pablochacin]

Update: Just after submitting the PR, I realized there is a way to specify the cache dir without requiring the user. I would prefer to make the changes in this PR because it really improves the user experience. What do you think?

Update: My comment above was premature. Further testing has shown the result is not as expected. So please ignore this. Sorry for the noise.

[pablochacin]

Hi. What is the preferred way to update a PR when it is out-of-date with the base branch? merge commit or rebase?

[mmorel-35]

I would recommend with rebase when it's possible.

[mdelapenya]

I would recommend with rebase when it's possible.

I usually use the merge commit strategy, as I see it more convenient regarding keeping the git history and commit IDs. I understand that rebasing is "cleaner" in terms of git history, but at the same time, moves the pointer of when the first commit was created, probably removing context about that time: e.g. at the time the PR was created, a dependency was not updated yet, therefore the new module could not include it.

Said that, I'd be very happy in a change to rebase strategy if there are advantages that I'm not aware of, so please help me with that if you consider rebasing is better.

[mdelapenya]

I think we are super close to be ready. Only concerned about the usage of Mounts Vs Files (see comments), which we should explain in our docs in a better way.

Other than that, once addressed, we are ready to go

Thank you for your time here!

[mdelapenya]

Thanks for this loong but properly discussed PR.

LGTM