[plugins] Allow multiple plugins per repo (#1285)

## Summary

This makes 2 changes:

* Allow multiple plugins per repo using fragment syntax (similar to
nixpkgs)
* Rename default from `devbox.json` to `default.json`

## How was it tested?

example tests

examples/plugins/github-with-revision/devbox.json

@@ -11,6 +11,6 @@
     }
   },
   "include": [
-    "github:jetpack-io/devbox-plugin-example/6ea0ef9e12ab58dbbb145ca8f3a465611cb603a9"
+    "github:jetpack-io/devbox-plugin-example/6ea0ef9e12ab58dbbb145ca8f3a465611cb603a9#devbox"
   ]
 }

examples/plugins/github/devbox.json

@@ -11,6 +11,7 @@
     }
   },
   "include": [
-    "github:jetpack-io/devbox-plugin-example"
+    "github:jetpack-io/devbox-plugin-example",
+    "github:jetpack-io/devbox-plugin-example#custom-name"
   ]
 }

examples/plugins/github/test.sh

@@ -1,9 +1,12 @@
 #!/bin/bash
 
 expected="I AM SET (new value)"
-if [ "$MY_ENV_VAR" == "$expected" ]; then
+custom_expected="I AM SET TO CUSTOM (new value)"
+if [ "$MY_ENV_VAR" == "$expected" ] && [ "$MY_ENV_VAR_CUSTOM" == "$MY_ENV_VAR_CUSTOM" ]; then
   echo "Success! MY_ENV_VAR is set to '$MY_ENV_VAR'"
+  echo "Success! MY_ENV_VAR_CUSTOM is set to '$MY_ENV_VAR_CUSTOM'"
 else
   echo "MY_ENV_VAR environment variable is not set to '$expected'"
+  echo "MY_ENV_VAR MY_ENV_VAR_CUSTOM variable is not set to '$MY_ENV_VAR_CUSTOM'"
   exit 1
 fi

internal/plugin/files.go

@@ -18,7 +18,7 @@ func getConfigIfAny(pkg Includable, projectDir string) (*config, error) {
 	case *devpkg.Package:
 		return getBuiltinPluginConfig(pkg, projectDir)
 	case *githubPlugin:
-		return getConfigFromGithub(pkg, projectDir)
+		return pkg.buildConfig(projectDir)
 	case *localPlugin:
 		content, err := os.ReadFile(pkg.path)
 		if err != nil && !os.IsNotExist(err) {
@@ -60,11 +60,3 @@ func getBuiltinPluginConfig(pkg Includable, projectDir string) (*config, error)
 	}
 	return nil, nil
 }
-
-func getConfigFromGithub(pkg *githubPlugin, projectDir string) (*config, error) {
-	content, err := pkg.FileContent("devbox.json")
-	if err != nil {
-		return nil, errors.WithStack(err)
-	}
-	return buildConfig(pkg, projectDir, string(content))
-}

internal/plugin/github.go

@@ -6,6 +6,8 @@ import (
 	"net/url"
 	"strings"
 
+	"github.com/pkg/errors"
+	"github.com/samber/lo"
 	"go.jetpack.io/devbox/internal/boxcli/usererr"
 	"go.jetpack.io/devbox/internal/cuecfg"
 )
@@ -15,13 +17,17 @@ type githubPlugin struct {
 	org      string
 	repo     string
 	revision string
+	fragment string
 }
 
 // newGithubPlugin returns a plugin that is hosted on github.
-// url is of the form org/repo
-// The repo must have a devbox.json file in the root of the repo.
+// url is of the form org/repo#name
+// The repo must have a [name].json in the root of the repo. If fragment is
+// not set, it defaults to "default"
 func newGithubPlugin(url string) (*githubPlugin, error) {
-	parts := strings.Split(url, "/")
+	path, fragment, _ := strings.Cut(url, "#")
+
+	parts := strings.Split(path, "/")
 
 	if len(parts) < 2 || len(parts) > 3 {
 		return nil, usererr.New(
@@ -35,6 +41,7 @@ func newGithubPlugin(url string) (*githubPlugin, error) {
 		org:      parts[0],
 		repo:     parts[1],
 		revision: "master",
+		fragment: fragment,
 	}
 
 	if len(parts) == 3 {
@@ -75,10 +82,19 @@ func (p *githubPlugin) FileContent(subpath string) ([]byte, error) {
 	if res.StatusCode != http.StatusOK {
 		return nil, usererr.New(
 			"failed to get plugin github:%s (Status code %d). \nPlease make sure a "+
-				"devbox.json file exists in the root of the repo.",
+				"[name].json or default.json file exists in the root of the repo.",
 			p.raw,
 			res.StatusCode,
 		)
 	}
 	return io.ReadAll(res.Body)
 }
+
+func (p *githubPlugin) buildConfig(projectDir string) (*config, error) {
+	configName, _ := lo.Coalesce(p.fragment, "default")
+	content, err := p.FileContent(configName + ".json")
+	if err != nil {
+		return nil, errors.WithStack(err)
+	}
+	return buildConfig(p, projectDir, string(content))
+}