Add version flag and installation of specific version

Dockerfile

@@ -6,7 +6,7 @@ COPY go.sum .
 RUN go mod download
 COPY . .
 ARG VERSION=unknown
-RUN CGO_ENABLED=1 go build -mod=readonly -ldflags "-X main.version=$VERSION" -o coroot-node-agent .
+RUN CGO_ENABLED=1 go build -mod=readonly -ldflags "-X 'github.com/coroot/coroot-node-agent/flags.Version=${VERSION}'" -o coroot-node-agent .
 
 FROM registry.access.redhat.com/ubi9/ubi
 

flags/flags.go

@@ -1,6 +1,7 @@
 package flags
 
 import (
+	"fmt"
 	"os"
 	"strings"
 
@@ -39,6 +40,9 @@ var (
 
 	ScrapeInterval = kingpin.Flag("scrape-interval", "How often to gather metrics from the agent").Default("15s").Envar("SCRAPE_INTERVAL").Duration()
 	WalDir         = kingpin.Flag("wal-dir", "Path to where the agent stores data (e.g. the metrics Write-Ahead Log)").Default("/tmp/coroot-node-agent").Envar("WAL_DIR").String()
+
+	agentVersion = kingpin.Flag("version", "Print version and exit").Default("false").Bool()
+	Version      = "unknown"
 )
 
 func GetString(fl *string) string {
@@ -56,6 +60,11 @@ func init() {
 	kingpin.HelpFlag.Short('h').Hidden()
 	kingpin.Parse()
 
+	if *agentVersion {
+		fmt.Println("Version:", Version)
+		os.Exit(0)
+	}
+
 	if *CollectorEndpoint != nil {
 		u := *CollectorEndpoint
 		if *MetricsEndpoint == nil {

install.sh

@@ -10,7 +10,7 @@ fi
 
 BIN_DIR=/usr/bin
 SYSTEMD_DIR=/etc/systemd/system
-VERSION=
+VERSION="latest"
 SYSTEM_NAME=coroot-node-agent
 SYSTEMD_SERVICE=${SYSTEM_NAME}.service
 UNINSTALL_SH=${BIN_DIR}/${SYSTEM_NAME}-uninstall.sh
@@ -26,9 +26,17 @@ info()
 fatal()
 {
     echo '[ERROR] ' "$@" >&2
+    show_help
     exit 1
 }
 
+show_help() {
+    echo "Usage: $0 [options]"
+    echo "Options:"
+    echo "  -h, --help                        Show this help message and exit"
+    echo "  -v v1.22.2, --version v1.22.2     Specify the version to install (default: latest)"
+}
+
 verify_system() {
     if [ -x /bin/systemctl ] || type systemctl > /dev/null 2>&1; then
         return
@@ -84,20 +92,24 @@ setup_tmp() {
 }
 
 get_release_version() {
-    info "Finding the latest release"
-    latest_release_url=${GITHUB_URL}/latest
-    case $DOWNLOADER in
-        curl)
-            VERSION=$(curl -w '%{url_effective}' -L -s -S ${latest_release_url} -o /dev/null | sed -e 's|.*/||')
-            ;;
-        wget)
-            VERSION=$(wget -SqO /dev/null ${latest_release_url} 2>&1 | grep -i Location | sed -e 's|.*/||')
-            ;;
-        *)
-            fatal "Incorrect downloader executable '$DOWNLOADER'"
-            ;;
-    esac
-    info "The latest release is ${VERSION}"
+    if [ "$VERSION" = "latest" ]; then
+        info "Finding the latest release"
+        latest_release_url=${GITHUB_URL}/latest
+        case $DOWNLOADER in
+            curl)
+                VERSION=$(curl -w '%{url_effective}' -L -s -S ${latest_release_url} -o /dev/null | sed -e 's|.*/||')
+                ;;
+            wget)
+                VERSION=$(wget -SqO /dev/null ${latest_release_url} 2>&1 | grep -i Location | sed -e 's|.*/||')
+                ;;
+            *)
+                fatal "Incorrect downloader executable '$DOWNLOADER'"
+                ;;
+        esac
+        info "The latest release is ${VERSION}"
+    else
+        info "Using specified version ${VERSION}"
+    fi
 }
 
 download_binary() {
@@ -136,7 +148,6 @@ download() {
     setup_binary
 }
 
-
 create_uninstall() {
     info "Creating uninstall script ${UNINSTALL_SH}"
     $SUDO tee ${UNINSTALL_SH} >/dev/null << EOF
@@ -229,7 +240,6 @@ systemd_start() {
     $SUDO systemctl restart ${SYSTEM_NAME}
 }
 
-
 service_enable_and_start() {
     systemd_enable
 
@@ -244,6 +254,22 @@ service_enable_and_start() {
     return 0
 }
 
+while [ $# -gt 0 ]; do
+    case "$1" in
+        -h|--help)
+            show_help
+            exit 0
+            ;;
+        -v|--version)
+            VERSION="$2"
+            shift 2
+            ;;
+        *)
+            fatal "Unknown option: $1"
+            ;;
+    esac
+done
+
 {
     verify_system
     download

main.go

@@ -26,7 +26,7 @@ import (
 )
 
 var (
-	version = "unknown"
+	version = flags.Version
 )
 
 const minSupportedKernelVersion = "4.16"