gqlgen fails when there are several @link directives

[cyrilc-pro]

What happened?

gqlgen 0.17.57 fails to run on my schema with the following stack trace:

panic: runtime error: index out of range [1] with length 0

goroutine 1 [running]:
github.com/99designs/gqlgen/api.Generate(0xc000149688, {0x0, 0x0, 0xeaf0385?})
	/<redacted>/go/pkg/mod/github.com/99designs/[email protected]/api/generate.go:41 +0x1533
main.init.func2(0xc0001c0bc0?)
	/<redacted>/go/pkg/mod/github.com/99designs/[email protected]/main.go:190 +0x9c
github.com/urfave/cli/v2.(*Command).Run(0xc00018c580, 0xc0001c0bc0, {0xc0000220f0, 0x3, 0x3})
	/<redacted>/go/pkg/mod/github.com/urfave/cli/[email protected]/command.go:276 +0x7e2
github.com/urfave/cli/v2.(*App).RunContext(0xc000140400, {0xf14baa0, 0xf4f9700}, {0xc0000220f0, 0x3, 0x3})
	/<redacted>/go/pkg/mod/github.com/urfave/cli/[email protected]/app.go:333 +0x5a5
github.com/urfave/cli/v2.(*App).Run(...)
	/<redacted>/go/pkg/mod/github.com/urfave/cli/[email protected]/app.go:307
main.main()
	/<redacted>/go/pkg/mod/github.com/99designs/[email protected]/main.go:227 +0x20b

This is caused by the use of two @link directives:

extend schema
@link(url: "https://specs.apollo.dev/federation/v2.9", import: ["@key", "@shareable", "@composeDirective"])
@link(url: "https://<readacted>.com", import: ["@owner", "@experimental"])
@composeDirective(name: "@owner")
@composeDirective(name: "@experimental")

Using multiple @link directives is required by the use of @composeDirective (following instructions from Apollo's documentation).

As a workaround, we can add the following to gqlgen's YAML configuration:

federation:
  version: 2

What did you expect?

The issue comes from the regular expression (?s)@link.*\(.*url:.*?"(.*?)"[^)]+\) that is used by gqlgen to "guess" the Apollo Federation version.

This regular expression is too "broad" and matches everything between the beginning of the first @link directive and the end of the last @link directive:

@link(url: "https://specs.apollo.dev/federation/v2.9", import: ["@key", "@shareable", "@composeDirective"])
@link(url: "https://<readacted>.com", import: ["@owner", "@experimental"])

I suggest to use a regular expression that matches the official link URL: https://specs.apollo.dev/federation/v(\d+)\.(\d+).

Minimal graphql.schema and models to reproduce

See example schema above.

versions

• go run github.com/99designs/gqlgen version? v0.17.57
• go version? go version go1.23.3 darwin/amd64