Include build information and add version command (#194)

Includes relevant fields listed on
https://goreleaser.com/customization/templates/ into build artifacts.

The version command outputs the version by default:
```
$ bricks version
0.0.21-devel
```

Or all build information if `--json` is specified:
```
$ bricks version --json
{
  "ProjectName": "bricks",
  "Version": "0.0.21-devel",
  "Branch": "version-info",
  "Tag": "v0.0.20",
  "ShortCommit": "193b56b",
  "FullCommit": "193b56b0929128c0836d35e913c46fd66fa2a93c",
  "CommitTime": "2023-02-02T22:04:42+01:00",
  "Summary": "v0.0.20-5-g193b56b",
  "Major": 0,
  "Minor": 0,
  "Patch": 20,
  "Prerelease": "",
  "IsSnapshot": true,
  "BuildTime": "2023-02-02T22:07:36+01:00"
}
```

.goreleaser.yaml

@@ -9,6 +9,25 @@ builds:
     - -trimpath
   ldflags:
     - '-s -w'
+    - -X github.com/databricks/bricks/internal/build.buildProjectName={{ .ProjectName }}
+    - -X github.com/databricks/bricks/internal/build.buildVersion={{ .Version }}
+
+    # Git information
+    - -X github.com/databricks/bricks/internal/build.buildBranch={{ .Branch }}
+    - -X github.com/databricks/bricks/internal/build.buildTag={{ .Tag }}
+    - -X github.com/databricks/bricks/internal/build.buildShortCommit={{ .ShortCommit }}
+    - -X github.com/databricks/bricks/internal/build.buildFullCommit={{ .FullCommit }}
+    - -X github.com/databricks/bricks/internal/build.buildCommitTimestamp={{ .CommitTimestamp }}
+    - -X github.com/databricks/bricks/internal/build.buildSummary={{ .Summary }}
+
+    # Version information
+    - -X github.com/databricks/bricks/internal/build.buildMajor={{ .Major }}
+    - -X github.com/databricks/bricks/internal/build.buildMinor={{ .Minor }}
+    - -X github.com/databricks/bricks/internal/build.buildPatch={{ .Patch }}
+    - -X github.com/databricks/bricks/internal/build.buildPrerelease={{ .Prerelease }}
+    - -X github.com/databricks/bricks/internal/build.buildIsSnapshot={{ .IsSnapshot }}
+    - -X github.com/databricks/bricks/internal/build.buildTimestamp={{ .Timestamp }}
+
   goos:
     - windows
     - linux

cmd/version/version.go

@@ -0,0 +1,34 @@
+package version
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/databricks/bricks/cmd/root"
+	"github.com/databricks/bricks/internal/build"
+	"github.com/spf13/cobra"
+)
+
+var detail = false
+
+var versionCmd = &cobra.Command{
+	Use:  "version",
+	Args: cobra.NoArgs,
+
+	RunE: func(cmd *cobra.Command, args []string) error {
+		info := build.GetInfo()
+		if detail {
+			enc := json.NewEncoder(cmd.OutOrStdout())
+			enc.SetIndent("", "  ")
+			return enc.Encode(info)
+		}
+
+		fmt.Fprintln(cmd.OutOrStdout(), info.Version)
+		return nil
+	},
+}
+
+func init() {
+	versionCmd.Flags().BoolVar(&detail, "detail", false, "output detailed version information as JSON")
+	root.RootCmd.AddCommand(versionCmd)
+}

internal/build/info.go

@@ -0,0 +1,117 @@
+package build
+
+import (
+	"fmt"
+	"runtime/debug"
+	"strconv"
+	"sync"
+	"time"
+
+	"golang.org/x/mod/semver"
+)
+
+type Info struct {
+	ProjectName string
+	Version     string
+
+	Branch      string
+	Tag         string
+	ShortCommit string
+	FullCommit  string
+	CommitTime  time.Time
+	Summary     string
+
+	Major      int64
+	Minor      int64
+	Patch      int64
+	Prerelease string
+	IsSnapshot bool
+	BuildTime  time.Time
+}
+
+var info Info
+
+var once sync.Once
+
+// getDefaultBuildVersion uses build information stored by Go itself
+// to synthesize a build version if one wasn't set.
+// This is necessary if the binary was not built through goreleaser.
+func getDefaultBuildVersion() string {
+	bi, ok := debug.ReadBuildInfo()
+	if !ok {
+		panic("unable to read build info")
+	}
+
+	m := make(map[string]string)
+	for _, s := range bi.Settings {
+		m[s.Key] = s.Value
+	}
+
+	out := "0.0.0-dev"
+
+	// Append revision as build metadata.
+	if v, ok := m["vcs.revision"]; ok {
+		// First 12 characters of the commit SHA is plenty to identify one.
+		out = fmt.Sprintf("%s+%s", out, v[0:12])
+	}
+
+	return out
+}
+
+func initialize() {
+	// If buildVersion is empty it means the binary was NOT built through goreleaser.
+	// We try to pull version information from debug.BuildInfo().
+	if buildVersion == "" {
+		buildVersion = getDefaultBuildVersion()
+	}
+
+	// Confirm that buildVersion is valid semver.
+	// Note that the semver package requires a leading 'v'.
+	if !semver.IsValid("v" + buildVersion) {
+		panic(fmt.Sprintf(`version is not a valid semver string: "%s"`, buildVersion))
+	}
+
+	info = Info{
+		ProjectName: buildProjectName,
+		Version:     buildVersion,
+
+		Branch:      buildBranch,
+		Tag:         buildTag,
+		ShortCommit: buildShortCommit,
+		FullCommit:  buildFullCommit,
+		CommitTime:  parseTime(buildCommitTimestamp),
+		Summary:     buildSummary,
+
+		Major:      parseInt(buildMajor),
+		Minor:      parseInt(buildMinor),
+		Patch:      parseInt(buildPatch),
+		Prerelease: buildPrerelease,
+		IsSnapshot: parseBool(buildIsSnapshot),
+		BuildTime:  parseTime(buildTimestamp),
+	}
+}
+
+func GetInfo() Info {
+	once.Do(initialize)
+	return info
+}
+
+func parseInt(s string) int64 {
+	i, err := strconv.ParseInt(s, 10, 64)
+	if err != nil {
+		panic(err)
+	}
+	return i
+}
+
+func parseBool(s string) bool {
+	b, err := strconv.ParseBool(s)
+	if err != nil {
+		panic(err)
+	}
+	return b
+}
+
+func parseTime(s string) time.Time {
+	return time.Unix(parseInt(s), 0)
+}

internal/build/info_test.go

@@ -0,0 +1,9 @@
+package build
+
+import (
+	"testing"
+)
+
+func TestGetDetails(t *testing.T) {
+	GetInfo()
+}

internal/build/variables.go

@@ -0,0 +1,18 @@
+package build
+
+var buildProjectName string = "bricks"
+var buildVersion string = ""
+
+var buildBranch string = "undefined"
+var buildTag string = "undefined"
+var buildShortCommit string = "00000000"
+var buildFullCommit string = "0000000000000000000000000000000000000000"
+var buildCommitTimestamp string = "0"
+var buildSummary string = "v0.0.0"
+
+var buildMajor string = "0"
+var buildMinor string = "0"
+var buildPatch string = "0"
+var buildPrerelease string = ""
+var buildIsSnapshot string = "false"
+var buildTimestamp string = "0"

main.go

@@ -13,6 +13,7 @@ import (
 	"github.com/databricks/bricks/cmd/root"
 	_ "github.com/databricks/bricks/cmd/sync"
 	_ "github.com/databricks/bricks/cmd/test"
+	_ "github.com/databricks/bricks/cmd/version"
 )
 
 func main() {