Add build info command and metrics

Prior to this commit the operator was unaware of its release version and other
such build information. This made tracking down issues across fleets of
instances a bit difficult.

This commit add the `version` subcommand to allow interrogating a binary and
the `redpanda_operator_build_info` metric which reports the same information
via labels on a gauge.

.goreleaser.yaml

@@ -15,6 +15,10 @@ builds:
     goarch:
       - amd64
       - arm64
+    ldflags:
+    - -X "github.com/redpanda-data/redpanda-operator/operator/cmd/version.version={{.Version}}"
+    - -X "github.com/redpanda-data/redpanda-operator/operator/cmd/version.commit={{.Commit}}"
+    - -X "github.com/redpanda-data/redpanda-operator/operator/cmd/version.buildDate={{.Date}}"
 
   - id: manager-alias
     dir: ./alias

operator/cmd/main.go

@@ -18,6 +18,7 @@ import (
 	"github.com/redpanda-data/redpanda-operator/operator/cmd/envsubst"
 	"github.com/redpanda-data/redpanda-operator/operator/cmd/run"
 	"github.com/redpanda-data/redpanda-operator/operator/cmd/syncclusterconfig"
+	"github.com/redpanda-data/redpanda-operator/operator/cmd/version"
 	"github.com/spf13/cobra"
 	ctrl "sigs.k8s.io/controller-runtime"
 )
@@ -42,6 +43,7 @@ func init() {
 		envsubst.Command(),
 		run.Command(),
 		syncclusterconfig.Command(),
+		version.Command(),
 	)
 
 	logOptions.BindFlags(rootCmd.PersistentFlags())

operator/cmd/version/version.go

@@ -0,0 +1,56 @@
+// Copyright 2024 Redpanda Data, Inc.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.md
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0
+
+package version
+
+import (
+	"runtime"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/spf13/cobra"
+	"sigs.k8s.io/controller-runtime/pkg/metrics"
+)
+
+var (
+	// these variables are set via ldflags in our goreleaser build.
+
+	version   string
+	commit    string
+	buildDate string
+)
+
+func init() {
+	buildInfoGauge := prometheus.NewGauge(prometheus.GaugeOpts{
+		Namespace: "redpanda_operator",
+		Name:      "build_info",
+		Help:      "A gauge always set to 1 that provides build information as labels.",
+		ConstLabels: prometheus.Labels{
+			"version":    version,
+			"commit":     commit,
+			"go_version": runtime.Version(),
+		},
+	})
+
+	buildInfoGauge.Set(1)
+
+	metrics.Registry.MustRegister(buildInfoGauge)
+}
+
+func Command() *cobra.Command {
+	return &cobra.Command{
+		Use:   "version",
+		Short: "print build information",
+		Run: func(cmd *cobra.Command, args []string) {
+			cmd.Printf("Version: %s\n", version)
+			cmd.Printf("Commit: %s\n", commit)
+			cmd.Printf("Go Version: %s\n", runtime.Version())
+			cmd.Printf("Build Date: %s\n", buildDate)
+		},
+	}
+}

taskfiles/goreleaser.yml

@@ -1,45 +1,8 @@
 version: '3'
 
 tasks:
-  release:
-    dir: '{{.SRC_DIR}}'
-    desc: release go binaries using the .goreleaser.yml file in given directory
-    deps:
-      - task: :k8s:generate
-    env:
-      GORELEASER_CURRENT_TAG: '{{.TAG_NAME}}'
-      GITHUB_TOKEN:
-        sh: echo "${GITHUB_TOKEN:-$GITHUB_API_TOKEN}"
-    cmds:
-      - |
-        EMPTY_NOTES="/tmp/empty_notes"
-        mkdir -p /tmp
-        echo "" >> "$EMPTY_NOTES"
-
-        goreleaser release --clean --release-notes "$EMPTY_NOTES"
-    preconditions:
-      - test -n "$GITHUB_API_TOKEN" || test -n "$GITHUB_TOKEN"
-      - test -n "{{.TAG_NAME}}"
-
-  build:
-    dir: '{{.SRC_DIR}}'
-    # A .goreleaser.yml file is required at the GO_SRC_DIR
-    desc: build go binaries with goreleaser and a given id
-    deps:
-      - task: :k8s:generate
-    env:
-      GORELEASER_CURRENT_TAG: '{{.TAG_NAME}}'
-    cmds:
-      - |
-        export PATH="{{.GORELEASER_INSTALL_DIR}}:$PATH"
-        goreleaser build --clean --id {{.GORELEASER_BUILD_ID}} {{.CLI_ARGS}}
-    preconditions:
-      - test -n "{{.GORELEASER_BUILD_ID}}"
-      - test -n "{{.TAG_NAME}}"
-
   build-operator-binaries:
     deps:
       - task: :k8s:generate
     cmds:
-      - go version
-      - 'goreleaser build --snapshot --clean'
+      - 'goreleaser build --snapshot --clean {{.CLI_ARGS}}'