feat: improve multiple tokens error (#2733)

Signed-off-by: Carlos A Becker <caarlos0@gmail.com>

internal/pipe/env/env.go

@@ -7,6 +7,7 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"strings"
 
 	"github.com/apex/log"
 	"github.com/goreleaser/goreleaser/internal/tmpl"
@@ -19,7 +20,13 @@ var ErrMissingToken = errors.New("missing GITHUB_TOKEN, GITLAB_TOKEN and GITEA_T
 
 // ErrMultipleTokens indicates that multiple tokens are defined. ATM only one of them if allowed.
 // See https://github.com/goreleaser/goreleaser/pull/809
-var ErrMultipleTokens = errors.New("multiple tokens defined. Only one is allowed")
+type ErrMultipleTokens struct {
+	tokens []string
+}
+
+func (e ErrMultipleTokens) Error() string {
+	return fmt.Sprintf("multiple tokens found, but only one is allowed: %s\n\nLearn more at https://goreleaser.com/errors/multiple-tokens\n", strings.Join(e.tokens, ", "))
+}
 
 // Pipe for env.
 type Pipe struct{}
@@ -61,18 +68,18 @@ func (Pipe) Run(ctx *context.Context) error {
 	gitlabToken, gitlabTokenErr := loadEnv("GITLAB_TOKEN", ctx.Config.EnvFiles.GitLabToken)
 	giteaToken, giteaTokenErr := loadEnv("GITEA_TOKEN", ctx.Config.EnvFiles.GiteaToken)
 
-	numOfTokens := 0
+	var tokens []string
 	if githubToken != "" {
-		numOfTokens++
+		tokens = append(tokens, "GITHUB_TOKEN")
 	}
 	if gitlabToken != "" {
-		numOfTokens++
+		tokens = append(tokens, "GITLAB_TOKEN")
 	}
 	if giteaToken != "" {
-		numOfTokens++
+		tokens = append(tokens, "GITEA_TOKEN")
 	}
-	if numOfTokens > 1 {
-		return ErrMultipleTokens
+	if len(tokens) > 1 {
+		return ErrMultipleTokens{tokens}
 	}
 
 	noTokens := githubToken == "" && gitlabToken == "" && giteaToken == ""

internal/pipe/env/env_test.go

@@ -120,7 +120,7 @@ func TestMultipleEnvTokens(t *testing.T) {
 		Config: config.Project{},
 	}
 	require.Error(t, Pipe{}.Run(ctx))
-	require.EqualError(t, Pipe{}.Run(ctx), ErrMultipleTokens.Error())
+	require.EqualError(t, Pipe{}.Run(ctx), "multiple tokens found, but only one is allowed: GITHUB_TOKEN, GITLAB_TOKEN, GITEA_TOKEN\n\nLearn more at https://goreleaser.com/errors/multiple-tokens\n")
 	// so the tests do not depend on each other
 	require.NoError(t, os.Unsetenv("GITHUB_TOKEN"))
 	require.NoError(t, os.Unsetenv("GITLAB_TOKEN"))

www/docs/errors/multiple-tokens.md

@@ -0,0 +1,15 @@
+# Multiple tokens found, but only one is allowed
+
+GoReleaser infers if you are using GitHub, GitLab or Gitea by which tokens are provided.
+If you have multiple tokens set, you'll get this error.
+
+Here's an example:
+
+```sh
+   ⨯ release failed after 0.02s error=gmultiple tokens found, but only one is allowed: GITHUB_TOKEN, GITLAB_TOKEN
+
+Learn more at https://goreleaser.com/errors/multiple-tokens
+```
+
+In this case, you either unset `GITHUB_TOKEN` or `GITLAB_TOKEN`.
+You can read more about it in the [SCM docs](/scm/github/).

www/mkdocs.yml

@@ -131,6 +131,7 @@ nav:
     - goreleaser jsonschema: cmd/goreleaser_jsonschema.md
 - Common errors:
   - errors/dirty.md
+  - errors/multiple-tokens.md
   - errors/no-main.md
 - deprecations.md
 - Cookbooks: