Golang proxy unavailable data for some packages


I’m working on getting some metadata about Golang packages and the package itself
I’ve seen that for some packages Golang proxy doesn’t provide the data for example:

and same url with suffix .zip instead of .info

The endpoint is stating: bad request: invalid escaped version “v0.1.0-M3”

But I can see such tag is avilable on GitHub:
Release v0.1.0-M3 · eclipse-kanto/suite-connector · GitHub

Can you please help on how to solve this issue or suggest any other way to reach my goal ?

Thank you guys !

Hi @ozblumen, welcome to the forum.

It seems as if the pre-release qualifier has to follow a specific schema (even though this is not documented). When I try to access a (non-existing) “beta.1” pre-release…


…the error message is different from yours:

not found: github.com/eclipse-kanto/suite-connector@v0.1.0-beta.1: invalid version: unknown revision v0.1.0-beta.1

(This error is valid because no beta.1 exists.)

I played around with several variants and discovered that the pre-release identifier must not contain uppercase characters. (For example, ALPHA, Alpha, and alphA trigger the “invalid escaped version” error, while alpha works fine and triggers the expected “not found” error.)

I don’t know if this is a bug or by design.

It’s even a violation of the spec for semver, though they are not specific which version to follow, perhaps an earlier version was more restrictive.

A released module is published with a version number in the semantic versioning model,

Semver allows arbitrary alphanumeric labels without specifying a certain casing.

See Semantic Versioning 2.0.0 | Semantic Versioning

Good point, @NobbZ. It would then sound like a bug to me. A quick search through the issues of GitHub - golang/go: The Go programming language did not reveal anything related, however.

@christophberger & @NobbZ thanks for your comments so much !

Well I found the issue in order to know the exact URL for the info endpoint, you can run the following command: go mod download. -json <package_name>@<package_version>

And you are going to get a set of urls regarding package metadata.

So for the above case upper case letters should transform into <uppercase_letter> → !<downcase_letter>

You can also find the specs here: https://github.com/golang/go/blob/c54bc3448390d4ae4495d6d2c03c9dd4111b08f1/src/cmd/go/internal/module/module.go#L359-L417

Let me know if it works for you,

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@ozblumen That’s interesting, thanks for the pointer!

So your initial URL only needs this transformation : M → !m


…and I get a valid response back.

  "Version": "v0.1.0-M3",
  "Time": "2023-05-19T07:04:23Z",
  "Origin": {
    "VCS": "git",
    "URL": "https://github.com/eclipse-kanto/suite-connector",
    "Ref": "refs/tags/v0.1.0-M3",
    "Hash": "8ecca4f93d4b691761a5cdd3fcb1a48e07cc029d"
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It’s interesting to see how the pre-release identifier transformation impacts the URL and resolves the issue.

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