"install -f" uses exec to uninstall an existing agent

changelog/fragments/1718833116-Check-for-tamper-protection-when-uninstalling.yaml

@@ -0,0 +1,35 @@
+# Kind can be one of:
+# - breaking-change: a change to previously-documented behavior
+# - deprecation: functionality that is being removed in a later release
+# - bug-fix: fixes a problem in a previous version
+# - enhancement: extends functionality but does not break or fix existing behavior
+# - feature: new functionality
+# - known-issue: problems that we are aware of in a given version
+# - security: impacts on the security of a product or a user’s deployment.
+# - upgrade: important information for someone upgrading from a prior version
+# - other: does not fit into any of the other categories
+kind: bug
+
+# Change summary; a 80ish characters long description of the change.
+summary: Check for tamper protection when install --force is used
+
+# Long description; in case the summary is not enough to describe the change
+# this field accommodate a description without length limits.
+# NOTE: This field will be rendered only for breaking-change and known-issue kinds at the moment.
+description: |
+  When using "elastic-agent install -f", the agent will exec "elastic-agent uninstall -f"
+  so that all path references are correctly loaded and tamper protection errors will cause
+  the install attempt to fail.
+
+# Affected component; a word indicating the component this changeset affects.
+component:
+
+# PR URL; optional; the PR number that added the changeset.
+# If not present is automatically filled by the tooling finding the PR where this changelog fragment has been added.
+# NOTE: the tooling supports backports, so it's able to fill the original PR number instead of the backport PR number.
+# Please provide it if you are adding a fragment for a different PR.
+#pr: https://github.com/owner/repo/1234
+
+# Issue URL; optional; the GitHub issue related to this changeset (either closes or is part of).
+# If not present is automatically filled by the tooling with the issue linked to the PR number.
+issue: https://github.com/elastic/elastic-agent/issues/4506

internal/pkg/agent/cmd/install.go

@@ -221,6 +221,24 @@ func installCmd(streams *cli.IOStreams, cmd *cobra.Command) error {
 
 	var ownership utils.FileOwner
 	cfgFile := paths.ConfigFile()
+	if status == install.Installed {
+		// Uninstall the agent
+		progBar.Describe("Uninstalling current Elastic Agent")
+		args := []string{
+			"uninstall",
+			"--force",
+		}
+		uninstall := exec.Command("elastic-agent", args...) // TODO find elastic-agent binary in $PATH
+		uninstall.Stdout = streams.Out
+		uninstall.Stderr = streams.Err
+		if err := uninstall.Start(); err != nil {
+			return fmt.Errorf("unable to start elastic-agent uninstall: %w", err)
+		}
+		if err := uninstall.Wait(); err != nil {
+			return fmt.Errorf("failed to uninstall elastic-agent: %w", err)
+		}
+		progBar.Describe("Successfully uninstalled Elastic Agent")
+	}
 	if status != install.PackageInstall {
 		ownership, err = install.Install(cfgFile, topPath, unprivileged, log, progBar, streams)
 		if err != nil {

internal/pkg/agent/install/install.go

@@ -46,26 +46,6 @@ func Install(cfgFile, topPath string, unprivileged bool, log *logp.Logger, pt *p
 		return utils.FileOwner{}, errors.New(err, "failed to discover the source directory for installation", errors.TypeFilesystem)
 	}
 
-	// We only uninstall Agent if it is currently installed.
-	status, _ := Status(topPath)
-	if status == Installed {
-		// Uninstall current installation
-		//
-		// There is no uninstall token for "install" command.
-		// Uninstall will fail on protected agent.
-		// The protected Agent will need to be uninstalled first before it can be installed.
-		pt.Describe("Uninstalling current Elastic Agent")
-		err = Uninstall(cfgFile, topPath, "", log, pt)
-		if err != nil {
-			pt.Describe("Failed to uninstall current Elastic Agent")
-			return utils.FileOwner{}, errors.New(
-				err,
-				fmt.Sprintf("failed to uninstall Agent at (%s)", filepath.Dir(topPath)),
-				errors.M("directory", filepath.Dir(topPath)))
-		}
-		pt.Describe("Successfully uninstalled current Elastic Agent")
-	}
-
 	var ownership utils.FileOwner
 	username := ""
 	groupName := ""