WIP: Configurable version and image

Replace the hard coded version and image name using git describe.

When building from tag (e.g. v0.5.1) the version (0.5.1) and the image
(quay.io/nirsof/gather:0.5.1) are injected into the executable and used
to report the version and for the --remote option.

When building without a tag, the version includes the number of commits
since the last tag, and a short git commit hash (v0.5.1-1-gcf79160).

The executable will use the image with the same version from the
registry, so we need to push the image to the registry for testing the
--remote option.

A new --version option added, reporting gather version.

A new --image option added for setting the image for the --remote
option. This is useful for testing the latest release image without
pushing the image to the registry, for testing and image from your
registry, or for using custom image on multiple clusters.

The gather script use the version option to generate
/must-gather/version file instead of the hard-coded version.

The build command is complicated now, so we use make to build the
releases. This ensures also that local builds are builds exactly like
release builds and makes it easier to debug release issues.

.github/workflows/release.yaml

@@ -12,9 +12,6 @@ permissions:
     contents: write
     packages: write
 
-env:
-  CGO_ENABLED: "0"
-
 jobs:
   release-matrix:
     name: Release binaries
@@ -35,3 +32,4 @@ jobs:
         goarch: ${{ matrix.goarch }}
         md5sum: FALSE
         compress_assets: OFF
+        build_command: make

Containerfile

@@ -14,10 +14,11 @@ RUN go mod download
 COPY cmd cmd
 COPY pkg pkg
 COPY main.go main.go
+ARG ldflags
 
 # Disable CGO to avoid dependencies on libc. Built image can be built on latest
 # Fedora and run on old RHEL.
-RUN CGO_ENABLED=0 go build
+RUN CGO_ENABLED=0 go build -ldflags "${ldflags}"
 
 FROM docker.io/library/alpine:latest
 

Makefile

@@ -4,19 +4,28 @@
 REGISTRY ?= quay.io
 REPO ?= nirsof
 IMAGE ?= gather
-TAG ?= 0.5.1
 
-image := $(REGISTRY)/$(REPO)/$(IMAGE):$(TAG)
+pkg_path := github.com/nirs/kubectl-gather/pkg/gather
+
+# 0.5.1 when building from tag (release)
+# 0.5.1-1-gcf79160 when building without tag (development)
+version := $(shell git describe --tags | sed -e 's/^v//')
+
+# The container image uses the same version. For testing the --remote option
+# you need to push the container to the registry.
+image := $(REGISTRY)/$(REPO)/$(IMAGE):$(version)
+
+ldflags := -X '$(pkg_path).Version=$(version)' -X '$(pkg_path).Image=$(image)'
 
 .PHONY: all kubectl-gather
 
 all: kubectl-gather
 
 container:
-	podman build -t $(image) .
+	podman build --tag $(image) --build-arg ldflags="$(ldflags)" .
 
 container-push: container
 	podman push $(image)
 
 kubectl-gather:
-	CGO_ENABLED=0 go build
+	CGO_ENABLED=0 go build -ldflags "$(ldflags)"

cmd/remote.go

@@ -14,8 +14,6 @@ import (
 	"time"
 )
 
-const remoteDefaultImage = "quay.io/nirsof/gather:0.5.1"
-
 func remoteGather(clusters []*clusterConfig) {
 	start := time.Now()
 
@@ -87,7 +85,7 @@ func mustGatherCommand(context string, directory string) *exec.Cmd {
 	args := []string{
 		"adm",
 		"must-gather",
-		"--image=" + remoteDefaultImage,
+		"--image=" + remoteImage,
 		"--context=" + context,
 		"--dest-dir=" + directory,
 	}

cmd/root.go

@@ -25,6 +25,7 @@ var contexts []string
 var namespaces []string
 var addons []string
 var remote bool
+var remoteImage string
 var verbose bool
 var log *zap.SugaredLogger
 
@@ -51,6 +52,7 @@ var example = `  # Gather data from all namespaces in current context in my-kube
 var rootCmd = &cobra.Command{
 	Use:     "kubectl-gather",
 	Short:   "Gather data from clusters",
+	Version: gather.Version,
 	Example: example,
 	Annotations: map[string]string{
 		cobra.CommandDisplayNameAnnotation: "kubectl gather",
@@ -84,8 +86,13 @@ func init() {
 			availableAddons()))
 	rootCmd.Flags().BoolVarP(&remote, "remote", "r", false,
 		"run on the remote clusters (requires the \"oc\" command)")
+	rootCmd.Flags().StringVar(&remoteImage, "remote-image", gather.Image,
+		"image to use when running on remote clusters")
 	rootCmd.Flags().BoolVarP(&verbose, "verbose", "v", false,
 		"be more verbose")
+
+	// Use plain machine friendly version string.
+	rootCmd.SetVersionTemplate("{{.Version}}\n")
 }
 
 func runGather(cmd *cobra.Command, args []string) {

gather

@@ -6,6 +6,7 @@
 base="/must-gather"
 
 mkdir -p "$base"
-printf "gather\n0.1.0\n" > "$base/version"
 
-/usr/bin/kubectl-gather --directory "$base" "$@"
+printf "gather\n$(kubectl-gather --version)\n" > "$base/version"
+
+kubectl-gather --directory "$base" "$@"

pkg/gather/gather.go

@@ -32,6 +32,10 @@ import (
 // TODO: Needs more testing to find the optimal value.
 const listResourcesLimit = 100
 
+// Replaced during build with actual values.
+var Version = "latest"
+var Image = "quay.io/nirsof/gather:latest"
+
 type Options struct {
 	Kubeconfig string
 	Context    string