Improved deployer version mismatch error.

Recall that when a deployer deploys a binary, it first extracts the
deployer API version from the binary and checks that its deployer API
version is compatible. Before this PR, the resulting error message
looked like this:

```
version mismatch: deployer's deployer API version v0.17.0 is
incompatible with app' deployer API version v0.14.0
```

Now, it looks like this:

```
ERROR: The binary you're trying to deploy ("collatz") was built with
github.com/ServiceWeaver/weaver module version v0.17.0 (deployer API
version v0.14.0). However, the 'weaver multi' binary you're using was built
with weaver module version v0.17.0 (deployer API version v0.15.0). These
versions are incompatible.

We recommend updating both the weaver module your application is built with and
updating the 'weaver multi' command by running the following.

    go get github.com/ServiceWeaver/weaver@latest
    go install github.com/ServiceWeaver/weaver/cmd/weaver@latest

Then, re-build your code and re-run 'weaver multi deploy'. If the problem
persists, please file an issue at https://github.com/ServiceWeaver/weaver/issues.
```

This PR also makes the multi and ssh deployers check these versions
earlier, before trying to deploy anything.

See #431 for a similar PR.

godeps.txt

@@ -609,6 +609,7 @@ github.com/ServiceWeaver/weaver/internal/tool/multi
     github.com/ServiceWeaver/weaver/runtime/protos
     github.com/ServiceWeaver/weaver/runtime/retry
     github.com/ServiceWeaver/weaver/runtime/tool
+    github.com/ServiceWeaver/weaver/runtime/version
     github.com/google/uuid
     go.opentelemetry.io/otel/sdk/trace
     golang.org/x/exp/maps
@@ -661,11 +662,13 @@ github.com/ServiceWeaver/weaver/internal/tool/ssh
     github.com/ServiceWeaver/weaver/internal/tool/config
     github.com/ServiceWeaver/weaver/internal/tool/ssh/impl
     github.com/ServiceWeaver/weaver/runtime
+    github.com/ServiceWeaver/weaver/runtime/bin
     github.com/ServiceWeaver/weaver/runtime/codegen
     github.com/ServiceWeaver/weaver/runtime/colors
     github.com/ServiceWeaver/weaver/runtime/logging
     github.com/ServiceWeaver/weaver/runtime/protos
     github.com/ServiceWeaver/weaver/runtime/tool
+    github.com/ServiceWeaver/weaver/runtime/version
     github.com/google/uuid
     golang.org/x/exp/maps
     io

internal/tool/multi/deploy.go

@@ -24,16 +24,19 @@ import (
 	"net/http"
 	"os"
 	"os/signal"
+	"path/filepath"
 	"syscall"
 
 	"github.com/ServiceWeaver/weaver/internal/status"
 	"github.com/ServiceWeaver/weaver/internal/tool/config"
 	"github.com/ServiceWeaver/weaver/runtime"
+	"github.com/ServiceWeaver/weaver/runtime/bin"
 	"github.com/ServiceWeaver/weaver/runtime/codegen"
 	"github.com/ServiceWeaver/weaver/runtime/colors"
 	"github.com/ServiceWeaver/weaver/runtime/logging"
 	"github.com/ServiceWeaver/weaver/runtime/retry"
 	"github.com/ServiceWeaver/weaver/runtime/tool"
+	"github.com/ServiceWeaver/weaver/runtime/version"
 	"github.com/google/uuid"
 )
 
@@ -84,6 +87,37 @@ func deploy(ctx context.Context, args []string) error {
 	}
 	multiConfig.App = appConfig
 
+	// Check version compatibility.
+	versions, err := bin.ReadVersions(appConfig.Binary)
+	if err != nil {
+		return fmt.Errorf("read versions: %w", err)
+	}
+	if versions.DeployerVersion != version.DeployerVersion {
+		// Try to relativize the binary, defaulting to the absolute path if
+		// there are any errors..
+		binary := appConfig.Binary
+		if cwd, err := os.Getwd(); err == nil {
+			if rel, err := filepath.Rel(cwd, appConfig.Binary); err == nil {
+				binary = rel
+			}
+		}
+		return fmt.Errorf(`ERROR: The binary you're trying to deploy (%q) was built with
+github.com/ServiceWeaver/weaver module version %s (deployer API
+version %s). However, the 'weaver multi' binary you're using was built
+with weaver module version %s (deployer API version %s). These
+versions are incompatible.
+
+We recommend updating both the weaver module your application is built with and
+updating the 'weaver multi' command by running the following.
+
+    go get github.com/ServiceWeaver/weaver@latest
+    go install github.com/ServiceWeaver/weaver/cmd/weaver@latest
+
+Then, re-build your code and re-run 'weaver multi deploy'. If the problem
+persists, please file an issue at https://github.com/ServiceWeaver/weaver/issues.`,
+			binary, versions.ModuleVersion, versions.DeployerVersion, version.ModuleVersion, version.DeployerVersion)
+	}
+
 	// Create the deployer.
 	deploymentId := uuid.New().String()
 	d, err := newDeployer(ctx, deploymentId, multiConfig)

internal/tool/ssh/deploy.go

@@ -35,11 +35,13 @@ import (
 	"github.com/ServiceWeaver/weaver/internal/tool/config"
 	"github.com/ServiceWeaver/weaver/internal/tool/ssh/impl"
 	"github.com/ServiceWeaver/weaver/runtime"
+	"github.com/ServiceWeaver/weaver/runtime/bin"
 	"github.com/ServiceWeaver/weaver/runtime/codegen"
 	"github.com/ServiceWeaver/weaver/runtime/colors"
 	"github.com/ServiceWeaver/weaver/runtime/logging"
 	"github.com/ServiceWeaver/weaver/runtime/protos"
 	"github.com/ServiceWeaver/weaver/runtime/tool"
+	"github.com/ServiceWeaver/weaver/runtime/version"
 )
 
 const (
@@ -92,6 +94,37 @@ func deploy(ctx context.Context, args []string) error {
 		App: app,
 	}
 
+	// Check version compatibility.
+	versions, err := bin.ReadVersions(app.Binary)
+	if err != nil {
+		return fmt.Errorf("read versions: %w", err)
+	}
+	if versions.DeployerVersion != version.DeployerVersion {
+		// Try to relativize the binary, defaulting to the absolute path if
+		// there are any errors..
+		binary := app.Binary
+		if cwd, err := os.Getwd(); err == nil {
+			if rel, err := filepath.Rel(cwd, app.Binary); err == nil {
+				binary = rel
+			}
+		}
+		return fmt.Errorf(`ERROR: The binary you're trying to deploy (%q) was built with
+github.com/ServiceWeaver/weaver module version %s (deployer API
+version %s). However, the 'weaver ssh' binary you're using was built
+with weaver module version %s (deployer API version %s). These
+versions are incompatible.
+
+We recommend updating both the weaver module your application is built with and
+updating the 'weaver ssh' command by running the following.
+
+    go get github.com/ServiceWeaver/weaver@latest
+    go install github.com/ServiceWeaver/weaver/cmd/weaver@latest
+
+Then, re-build your code and re-run 'weaver ssh deploy'. If the problem
+persists, please file an issue at https://github.com/ServiceWeaver/weaver/issues.`,
+			binary, versions.ModuleVersion, versions.DeployerVersion, version.ModuleVersion, version.DeployerVersion)
+	}
+
 	// Retrieve the list of locations to deploy.
 	locs, err := getLocations(config)
 	if err != nil {

runtime/bin/bin.go

@@ -29,19 +29,19 @@ import (
 	"github.com/ServiceWeaver/weaver/runtime/version"
 )
 
-// deployerVersion exists to embed the deployer API version into a Service
-// Weaver binary. We split declaring and assigning version to prevent the
-// compiler from erasing it.
+// versionData exists to embed the weaver module version and deployer API
+// version into a Service Weaver binary. We split declaring and assigning
+// versionData to prevent the compiler from erasing it.
 //
 //nolint:unused
-var deployerVersion string
+var versionData string
 
 func init() {
-	// NOTE that deployerVersion must be assigned a string constant that
-	// reflects the values of version.DeployerMajor and version.DeployerMinor.
-	// If the string is not a constant---if we try to use fmt.Sprintf, for
+	// NOTE that versionData must be assigned a string constant that reflects
+	// the values of version.ModuleVersion and version.DeployerVersion. If the
+	// string is not a constant---if we try to use fmt.Sprintf, for
 	// example---it will not be embedded in a Service Weaver binary.
-	deployerVersion = "⟦wEaVeRdEpLoYeRvErSiOn:v0.14.0⟧"
+	versionData = "⟦wEaVeRvErSiOn:module=v0.17.0;deployer=v0.14.0⟧"
 }
 
 // rodata returns the read-only data section of the provided binary.
@@ -112,37 +112,49 @@ func ReadListeners(file string) ([]codegen.ComponentListeners, error) {
 	return codegen.ExtractListeners(data), nil
 }
 
-// ReadDeployerVersion reads the deployer API version from the specified binary.
-func ReadDeployerVersion(filename string) (version.SemVer, error) {
+type Versions struct {
+	ModuleVersion   version.SemVer // see version.ModuleVersion
+	DeployerVersion version.SemVer // see version.DeployerVersion
+}
+
+// ReadVersions reads the module version and deployer API version from the
+// specified binary.
+func ReadVersions(filename string) (Versions, error) {
 	data, err := rodata(filename)
 	if err != nil {
-		return version.SemVer{}, err
+		return Versions{}, err
 	}
-	return extractDeployerVersion(data)
+	return extractVersions(data)
 }
 
-// extractDeployerVersion returns the deployer API version embedded in data.
-func extractDeployerVersion(data []byte) (version.SemVer, error) {
-	re := regexp.MustCompile(`⟦wEaVeRdEpLoYeRvErSiOn:v([0-9]*?)\.([0-9]*?)\.([0-9]*?)⟧`)
+// extractVersions returns the module version and deployer API version embedded
+// in data.
+func extractVersions(data []byte) (Versions, error) {
+	re := regexp.MustCompile(`⟦wEaVeRvErSiOn:module=v([0-9]*?)\.([0-9]*?)\.([0-9]*?);deployer=v([0-9]*?)\.([0-9]*?)\.([0-9]*?)⟧`)
 	m := re.FindSubmatch(data)
 	if m == nil {
-		return version.SemVer{}, fmt.Errorf("embedded deployer API version not found")
+		return Versions{}, fmt.Errorf("embedded versions not found")
 	}
-	major, minor, patch := string(m[1]), string(m[2]), string(m[3])
 
-	v := version.SemVer{}
-	var err error
-	v.Major, err = strconv.Atoi(major)
-	if err != nil {
-		return version.SemVer{}, fmt.Errorf("invalid embedded deployer API major %q: %w", major, err)
-	}
-	v.Minor, err = strconv.Atoi(minor)
-	if err != nil {
-		return version.SemVer{}, fmt.Errorf("invalid embedded deployer API minor %q: %w", minor, err)
-	}
-	v.Patch, err = strconv.Atoi(patch)
-	if err != nil {
-		return version.SemVer{}, fmt.Errorf("invalid embedded deployer API patch %q: %w", patch, err)
+	v := Versions{}
+	for _, segment := range []struct {
+		name string
+		data []byte
+		dst  *int
+	}{
+		{"module major version", m[1], &v.ModuleVersion.Major},
+		{"module minor version", m[2], &v.ModuleVersion.Minor},
+		{"module patch version", m[3], &v.ModuleVersion.Patch},
+		{"deployer major version", m[4], &v.DeployerVersion.Major},
+		{"deployer minor version", m[5], &v.DeployerVersion.Minor},
+		{"deployer patch version", m[6], &v.DeployerVersion.Patch},
+	} {
+		s := string(segment.data)
+		x, err := strconv.Atoi(s)
+		if err != nil {
+			return Versions{}, fmt.Errorf("invalid embedded %s %q: %w", segment.name, s, err)
+		}
+		*segment.dst = x
 	}
 	return v, nil
 }

runtime/bin/bin_test.go

@@ -121,20 +121,26 @@ func TestReadListeners(t *testing.T) {
 	}
 }
 
-func TestExtractDeployerVersion(t *testing.T) {
-	for _, want := range []version.SemVer{
-		{Major: 0, Minor: 0, Patch: 0},
-		{Major: 10, Minor: 10, Patch: 10},
-		{Major: 123, Minor: 4567, Patch: 891011},
+func TestExtractVersion(t *testing.T) {
+	for _, want := range []Versions{
+		{
+			ModuleVersion:   version.SemVer{Major: 1, Minor: 2, Patch: 3},
+			DeployerVersion: version.SemVer{Major: 4, Minor: 5, Patch: 6},
+		},
+		{
+			ModuleVersion:   version.SemVer{Major: 100, Minor: 100, Patch: 234},
+			DeployerVersion: version.SemVer{Major: 0, Minor: 567, Patch: 8910},
+		},
 	} {
-		t.Run(want.String(), func(t *testing.T) {
+		name := fmt.Sprintf("%s-%s", want.ModuleVersion, want.DeployerVersion)
+		t.Run(name, func(t *testing.T) {
 			// Embed the version string inside a big array of bytes.
 			var bytes [10000]byte
-			embedded := fmt.Sprintf("⟦wEaVeRdEpLoYeRvErSiOn:%s⟧", want)
+			embedded := fmt.Sprintf("⟦wEaVeRvErSiOn:module=%s;deployer=%s⟧", want.ModuleVersion, want.DeployerVersion)
 			copy(bytes[1234:], []byte(embedded))
 
 			// Extract the version string.
-			got, err := extractDeployerVersion(bytes[:])
+			got, err := extractVersions(bytes[:])
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -162,12 +168,15 @@ func TestReadVersion(t *testing.T) {
 			}
 
 			// Read version.
-			got, err := ReadDeployerVersion(binary)
+			got, err := ReadVersions(binary)
 			if err != nil {
 				t.Fatal(err)
 			}
-			if got != version.DeployerVersion {
-				t.Fatalf("bad dipe version: got %s, want %s", got, version.DeployerVersion)
+			if got.ModuleVersion != version.ModuleVersion {
+				t.Fatalf("bad module version: got %s, want %s", got.ModuleVersion, version.ModuleVersion)
+			}
+			if got.DeployerVersion != version.DeployerVersion {
+				t.Fatalf("bad deployer version: got %s, want %s", got.DeployerVersion, version.DeployerVersion)
 			}
 		})
 	}