Support replacements and customizing the core version; update readme

README.md

@@ -13,8 +13,8 @@ Stay updated, be aware of changes, and please submit feedback! Thanks!
 
 ## Requirements
 
-- Go installed
-- Go modules enabled
+- [Go installed](https://golang.org/doc/install)
+- [Go modules](https://github.com/golang/go/wiki/Modules) enabled
 
 
 ## Command usage
@@ -30,31 +30,44 @@ Install the `xcaddy` command with:
 $ go get -u github.com/caddyserver/xcaddy/cmd/xcaddy
 ```
 
+The `xcaddy` command will use the latest version of Caddy by default. You can customize this for all invocations by setting the `CADDY_VERSION` environment variable.
+
+As usual with `go` command, the `xcaddy` command will pass through the `GOOS`, `GOARCH`, and `GOARM` environment variables for cross-compilation.
+
 
 ### Custom builds
 
 Syntax:
 
 ```
-$ xcaddy build <caddy_version>
+$ xcaddy build [<caddy_version>]
     [--output <file>]
-    [--with <module[@version]>...]
+    [--with <module[@version][=replacement]>...]
 ```
 
-- `<caddy_version>` is the core Caddy version to build (required, for now).
+- `<caddy_version>` is the core Caddy version to build; defaults to `CADDY_VERSION` env variable or latest.
 - `--output` changes the output file.
 - `--with` can be used multiple times to add plugins by specifying the Go module name and optionally its version, similar to `go get`.
 
-For example:
+Examples:
 
 ```bash
-$ xcaddy build v2.0.0-rc.1 \
+$ xcaddy build \
+    --with github.com/caddyserver/ntlm-transport
+
+$ xcaddy build v2.0.1 \
     --with github.com/caddyserver/ntlm-transport@v0.1.0
+
+$ xcaddy build \
+    --with github.com/caddyserver/ntlm-transport=../../my-fork
+
+$ xcaddy build \
+    --with github.com/caddyserver/ntlm-transport=@v0.1.0=../../my-fork
 ```
 
 ### For plugin development
 
-If you run `xcaddy` from within the folder of the Caddy plugin you're working on without the `build` subcommand described above, it will build Caddy with your current module and run it, as if you manually plugged it in and ran `go run`.
+If you run `xcaddy` from within the folder of the Caddy plugin you're working on _without the `build` subcommand_, it will build Caddy with your current module and run it, as if you manually plugged it in and invoked `go run`.
 
 The binary will be built and run from the current directory, then cleaned up.
 

builder.go

@@ -42,9 +42,6 @@ type Builder struct {
 // Build builds Caddy at the configured version with the
 // configured plugins and plops down a binary at outputFile.
 func (b Builder) Build(ctx context.Context, outputFile string) error {
-	if b.CaddyVersion == "" {
-		return fmt.Errorf("CaddyVersion must be set")
-	}
 	if outputFile == "" {
 		return fmt.Errorf("output file path is required")
 	}
@@ -141,7 +138,11 @@ func newTempFolder() (string, error) {
 // of "foo" and "v2.0.0" will return "foo/v2", for use in Go imports and go commands.
 // Inputs that conflict, like "foo/v2" and "v3.1.0" are an error. This function
 // returns the input if the moduleVersion is not a valid semantic version string.
+// If moduleVersion is empty string, the input modulePath is returned without error.
 func versionedModulePath(modulePath, moduleVersion string) (string, error) {
+	if moduleVersion == "" {
+		return modulePath, nil
+	}
 	ver, err := semver.StrictNewVersion(strings.TrimPrefix(moduleVersion, "v"))
 	if err != nil {
 		// only return the error if we know they were trying to use a semantic version

cmd/xcaddy/main.go

@@ -29,6 +29,8 @@ import (
 	"github.com/caddyserver/xcaddy"
 )
 
+var caddyVersion = os.Getenv("CADDY_VERSION")
+
 func main() {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
@@ -41,16 +43,16 @@ func main() {
 		return
 	}
 
-	// TODO: the caddy version needs to be settable by the user... maybe an env var?
-	if err := runDev(ctx, "v2.0.0-rc.3", os.Args[1:]); err != nil {
+	if err := runDev(ctx, os.Args[1:]); err != nil {
 		log.Fatalf("[ERROR] %v", err)
 	}
 }
 
 func runBuild(ctx context.Context, args []string) error {
 	// parse the command line args... rather primitively
-	var caddyVersion, output string
+	var argCaddyVersion, output string
 	var plugins []xcaddy.Dependency
+	var replacements []xcaddy.Replace
 	for i := 0; i < len(args); i++ {
 		switch args[i] {
 		case "--with":
@@ -58,17 +60,20 @@ func runBuild(ctx context.Context, args []string) error {
 				return fmt.Errorf("expected value after --with flag")
 			}
 			i++
-			var mod, ver string
-			arg := args[i]
-			parts := strings.SplitN(arg, "@", 2)
-			mod = parts[0]
-			if len(parts) == 2 {
-				ver = parts[1]
+			mod, ver, repl, err := splitWith(args[i])
+			if err != nil {
+				return err
 			}
 			plugins = append(plugins, xcaddy.Dependency{
 				ModulePath: mod,
 				Version:    ver,
 			})
+			if repl != "" {
+				replacements = append(replacements, xcaddy.Replace{
+					Old: mod,
+					New: repl,
+				})
+			}
 
 		case "--output":
 			if i == len(args)-1 {
@@ -78,13 +83,18 @@ func runBuild(ctx context.Context, args []string) error {
 			output = args[i]
 
 		default:
-			if caddyVersion != "" {
-				return fmt.Errorf("missing flag; caddy version already set at %s", caddyVersion)
+			if argCaddyVersion != "" {
+				return fmt.Errorf("missing flag; caddy version already set at %s", argCaddyVersion)
 			}
-			caddyVersion = args[i]
+			argCaddyVersion = args[i]
 		}
 	}
 
+	// prefer caddy version from command line argument over env var
+	if argCaddyVersion != "" {
+		caddyVersion = argCaddyVersion
+	}
+
 	// ensure an output file is always specified
 	if output == "" {
 		if runtime.GOOS == "windows" {
@@ -98,6 +108,7 @@ func runBuild(ctx context.Context, args []string) error {
 	builder := xcaddy.Builder{
 		CaddyVersion: caddyVersion,
 		Plugins:      plugins,
+		Replacements: replacements,
 	}
 	err := builder.Build(ctx, output)
 	if err != nil {
@@ -121,7 +132,7 @@ func runBuild(ctx context.Context, args []string) error {
 	return nil
 }
 
-func runDev(ctx context.Context, caddyVersion string, args []string) error {
+func runDev(ctx context.Context, args []string) error {
 	const binOutput = "./caddy"
 
 	// get current/main module name
@@ -220,3 +231,31 @@ func trapSignals(ctx context.Context, cancel context.CancelFunc) {
 		return
 	}
 }
+
+func splitWith(arg string) (module, version, replace string, err error) {
+	const versionSplit, replaceSplit = "@", "="
+
+	parts := strings.SplitN(arg, versionSplit, 2)
+	module = parts[0]
+
+	if len(parts) == 1 {
+		parts := strings.SplitN(module, replaceSplit, 2)
+		if len(parts) > 1 {
+			module = parts[0]
+			replace = parts[1]
+		}
+	} else {
+		version = parts[1]
+		parts := strings.SplitN(version, replaceSplit, 2)
+		if len(parts) > 1 {
+			version = parts[0]
+			replace = parts[1]
+		}
+	}
+
+	if module == "" {
+		err = fmt.Errorf("module name is required")
+	}
+
+	return
+}

cmd/xcaddy/main_test.go

@@ -0,0 +1,73 @@
+package main
+
+import "testing"
+
+func TestSplitWith(t *testing.T) {
+	for i, tc := range []struct {
+		input         string
+		expectModule  string
+		expectVersion string
+		expectReplace string
+		expectErr     bool
+	}{
+		{
+			input:        "module",
+			expectModule: "module",
+		},
+		{
+			input:         "module@version",
+			expectModule:  "module",
+			expectVersion: "version",
+		},
+		{
+			input:         "module@version=replace",
+			expectModule:  "module",
+			expectVersion: "version",
+			expectReplace: "replace",
+		},
+		{
+			input:         "module=replace",
+			expectModule:  "module",
+			expectReplace: "replace",
+		},
+		{
+			input:     "=replace",
+			expectErr: true,
+		},
+		{
+			input:     "@version",
+			expectErr: true,
+		},
+		{
+			input:     "@version=replace",
+			expectErr: true,
+		},
+		{
+			input:     "",
+			expectErr: true,
+		},
+	} {
+		actualModule, actualVersion, actualReplace, actualErr := splitWith(tc.input)
+		if actualModule != tc.expectModule {
+			t.Errorf("Test %d: Expected module '%s' but got '%s' (input=%s)",
+				i, tc.expectModule, actualModule, tc.input)
+		}
+		if tc.expectErr {
+			if actualErr == nil {
+				t.Errorf("Test %d: Expected error but did not get one (input='%s')", i, tc.input)
+			}
+			continue
+		}
+		if !tc.expectErr && actualErr != nil {
+			t.Errorf("Test %d: Expected no error but got: %s (input='%s')", i, actualErr, tc.input)
+		}
+		if actualVersion != tc.expectVersion {
+			t.Errorf("Test %d: Expected version '%s' but got '%s' (input='%s')",
+				i, tc.expectVersion, actualVersion, tc.input)
+		}
+		if actualReplace != tc.expectReplace {
+			t.Errorf("Test %d: Expected module '%s' but got '%s' (input='%s')",
+				i, tc.expectReplace, actualReplace, tc.input)
+		}
+	}
+}

environment.go

@@ -126,7 +126,7 @@ func (b Builder) newEnvironment(ctx context.Context) (*environment, error) {
 
 	// pin versions by populating go.mod, first for Caddy itself and then plugins
 	log.Println("[INFO] Pinning versions")
-	err = env.execGoGet(ctx, caddyModulePath, b.CaddyVersion)
+	err = env.execGoGet(ctx, caddyModulePath, env.caddyVersion)
 	if err != nil {
 		return nil, err
 	}