Merge pull request 'A compiled artifact names the binary a machine will run' (#157) from fix/142-a-compiled-artifact-names-its-binary into main

internal/builder/binary_name_test.go

@@ -0,0 +1,44 @@
+package builder
+
+import (
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+)
+
+// The name a machine runs a binary by is not always the name of the package that built it. The host's
+// command is cmd/mesh-host and every machine runs it as nox-mesh-host — the path it is installed at,
+// the name in its unit, and the name its launcher looks for inside a delivered version.
+//
+// A bundle carrying the package's name was delivered to a machine correctly, reported "created … 1
+// file(s)", and was invisible to the launcher (novox/hq 04-ISSUES/142). Found by reading the delivered
+// directory rather than by trusting the line that said it worked.
+
+func TestACompiledArtifactNamesTheBinaryAMachineWillRun(t *testing.T) {
+	got := binaryName(catalogue.Artifact{
+		Name: "host-arch", From: "cmd/mesh-host", Binary: "nox-mesh-host",
+	})
+	if got != "nox-mesh-host" {
+		t.Fatalf("the binary is named %q, and the launcher looks for nox-mesh-host", got)
+	}
+}
+
+func TestSayingNothingKeepsWhatTheCompilerWouldHaveChosen(t *testing.T) {
+	// go build names its output after the package, so an artifact that says nothing gets the same
+	// thing it got before this existed.
+	if got := binaryName(catalogue.Artifact{Name: "host-arch", From: "cmd/mesh-host"}); got != "mesh-host" {
+		t.Fatalf("an artifact naming no binary produced %q", got)
+	}
+	if got := binaryName(catalogue.Artifact{Name: "host-arch", From: "./cmd/agent/"}); got != "agent" {
+		t.Fatalf("a from with slashes produced %q", got)
+	}
+}
+
+func TestABundleBuiltFromTheModuleRootFallsBackToItsArtifactName(t *testing.T) {
+	// A single-command repository names no package, and `go build -o <dir>` would then write a file
+	// named after the module directory — which is not something the manifest states. The artifact's
+	// own name is what the manifest does state.
+	if got := binaryName(catalogue.Artifact{Name: "tool"}); got != "tool" {
+		t.Fatalf("a bundle built from the root produced %q", got)
+	}
+}

internal/builder/builder.go

@@ -878,7 +878,16 @@ func compile(ctx context.Context, run Runner, tree string, chain Toolchain,
 	}
 	invocation = append(invocation, chain.Compile...)
 	if chain.OutputFlag != "" {
-		invocation = append(invocation, chain.OutputFlag, out)
+		// A compiler pointed at a package is told the file to write, not the directory: the name a
+		// machine runs it by is not always the name of the package that built it. The host's command
+		// is `cmd/mesh-host` and every machine runs it as `nox-mesh-host` — so a bundle carrying the
+		// package's name lands correctly, reports success, and is invisible to whatever looks for it
+		// (novox/hq 04-ISSUES/142).
+		target := out
+		if chain.Unit == UnitPackage {
+			target = filepath.Join(out, binaryName(a))
+		}
+		invocation = append(invocation, chain.OutputFlag, target)
 	}
 	// What to compile. Named by the module rather than discovered, so adding a file does not
 	// silently change what a build produces.
@@ -1067,3 +1076,15 @@ func readBy(manifest catalogue.Manifest) []catalogue.ArtifactContext {
 	})
 	return out
 }
+
+// binaryName is what a compiled bundle's executable is called: what the artifact says, or the name of
+// the package it is built from, which is what a compiler would have chosen anyway.
+func binaryName(a catalogue.Artifact) string {
+	if name := strings.TrimSpace(a.Binary); name != "" {
+		return name
+	}
+	if from := strings.Trim(a.From, "./"); from != "" {
+		return filepath.Base(from)
+	}
+	return a.Name
+}

internal/catalogue/manifest.go

@@ -597,6 +597,16 @@ type Artifact struct {
 	// Empty for every other kind, which do not compile.
 	Language string `json:"language,omitempty"`
 
+	// Binary is what the compiled executable is called, for a bundle in a language that compiles to
+	// one. Empty means the package's own name, which is what a compiler does by default.
+	//
+	// **Because the name a machine runs it by is not always the name of the package that built it.**
+	// The host's command is `cmd/mesh-host` and every machine runs it as `nox-mesh-host` — the path
+	// it is installed at, the name in its unit, and the name its launcher looks for inside a
+	// delivered version. A bundle that carried the package's name was delivered correctly, reported
+	// success, and was invisible to the launcher (novox/hq 04-ISSUES/142).
+	Binary string `json:"binary,omitempty"`
+
 	// Entrypoints are the compiled files a tool host should load from this module, relative to the
 	// bundle's root.
 	//