diagnostics creates the necessary folder for -f argumen (elastic#3340)

- makes diagnostics command to create the necessary folders when a custom path is provided by the '-f' flag.
 - refactors the diagnosticCmd splitting it into smaller functions
 - add test  createFile
 - rename logs_test.go createFile function to createFileEmpty so its name wont collide with the newly created 'createFile' function.
add license headaer

changelog/fragments/1693544911-Diagnostics-command-creates-necessary-folders-for--f-flag.yaml

@@ -0,0 +1,32 @@
+# 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: Diagnostics command creates necessary folders for -f flag
+
+# 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:
+
+# Affected component; a word indicating the component this changeset affects.
+component: diagnostics command
+
+# 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/owner/repo/1234

internal/pkg/agent/cmd/diagnostics.go

@@ -8,6 +8,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"path"
 	"time"
 
 	"github.com/elastic/elastic-agent/pkg/control/v2/client"
@@ -39,25 +40,46 @@ func newDiagnosticsCommand(_ []string, streams *cli.IOStreams) *cobra.Command {
 }
 
 func diagnosticCmd(streams *cli.IOStreams, cmd *cobra.Command) error {
-	fileName, _ := cmd.Flags().GetString("file")
-	if fileName == "" {
+	filepath, _ := cmd.Flags().GetString("file")
+	if filepath == "" {
 		ts := time.Now().UTC()
-		fileName = "elastic-agent-diagnostics-" + ts.Format("2006-01-02T15-04-05Z07-00") + ".zip" // RFC3339 format that replaces : with -, so it will work on Windows
+		filepath = "elastic-agent-diagnostics-" + ts.Format("2006-01-02T15-04-05Z07-00") + ".zip" // RFC3339 format that replaces : with -, so it will work on Windows
 	}
 
 	ctx := handleSignal(context.Background())
 
+	// 1st create the file to store the diagnostics, if it fails, anything else
+	// is pointless.
+	f, err := createFile(filepath)
+	if err != nil {
+		return fmt.Errorf("could not create diagnostics file %q: %w", filepath, err)
+	}
+	defer f.Close()
+
+	cpuProfile, _ := cmd.Flags().GetBool("cpu-profile")
+	agentDiag, unitDiags, compDiags, err := collectDiagnostics(ctx, streams, cpuProfile)
+	if err != nil {
+		return fmt.Errorf("failed collecting diagnostics: %w", err)
+	}
+
+	if err := diagnostics.ZipArchive(streams.Err, f, agentDiag, unitDiags, compDiags); err != nil {
+		return fmt.Errorf("unable to create archive %q: %w", filepath, err)
+	}
+	fmt.Fprintf(streams.Out, "Created diagnostics archive %q\n", filepath)
+	fmt.Fprintln(streams.Out, "***** WARNING *****\nCreated archive may contain plain text credentials.\nEnsure that files in archive are redacted before sharing.\n*******************")
+	return nil
+}
+
+func collectDiagnostics(ctx context.Context, streams *cli.IOStreams, cpuProfile bool) ([]client.DiagnosticFileResult, []client.DiagnosticUnitResult, []client.DiagnosticComponentResult, error) {
 	daemon := client.New()
 	err := daemon.Connect(ctx)
 	if err != nil {
-		return fmt.Errorf("failed to connect to daemon: %w", err)
+		return nil, nil, nil, fmt.Errorf("failed to connect to daemon: %w", err)
 	}
 	defer daemon.Disconnect()
 
-	fetchCPU, _ := cmd.Flags().GetBool("cpu-profile")
-
-	additionalDiags := []cproto.AdditionalDiagnosticRequest{}
-	if fetchCPU {
+	var additionalDiags []cproto.AdditionalDiagnosticRequest
+	if cpuProfile {
 		// console will just hang while we wait for the CPU profile; print something so user doesn't get confused
 		fmt.Fprintf(streams.Out, "Creating diagnostics archive, waiting for CPU profile...\n")
 		additionalDiags = []cproto.AdditionalDiagnosticRequest{cproto.AdditionalDiagnosticRequest_CPU}
@@ -79,19 +101,24 @@ func diagnosticCmd(streams *cli.IOStreams, cmd *cobra.Command) error {
 	}
 
 	if len(compDiags) == 0 && len(unitDiags) == 0 && len(agentDiag) == 0 {
-		return fmt.Errorf("no diags could be fetched")
+		return nil, nil, nil, fmt.Errorf("no diags could be fetched")
 	}
 
-	f, err := os.Create(fileName)
-	if err != nil {
-		return fmt.Errorf("error creating .zip file: %w", err)
+	return agentDiag, unitDiags, compDiags, nil
+}
+
+func createFile(filepath string) (*os.File, error) {
+	// Ensure all the folders on filepath exist as os.Create does not do so.
+	// 0777 is the same permission, before unmask, os.Create uses.
+	dir := path.Dir(filepath)
+	if err := os.MkdirAll(dir, 0777); err != nil {
+		return nil, fmt.Errorf("could not create folders to save diagnostics on %q: %w",
+			dir, err)
 	}
-	defer f.Close()
 
-	if err := diagnostics.ZipArchive(streams.Err, f, agentDiag, unitDiags, compDiags); err != nil {
-		return fmt.Errorf("unable to create archive %q: %w", fileName, err)
+	f, err := os.Create(filepath)
+	if err != nil {
+		return nil, fmt.Errorf("error creating .zip file: %w", err)
 	}
-	fmt.Fprintf(streams.Out, "Created diagnostics archive %q\n", fileName)
-	fmt.Fprintln(streams.Out, "***** WARNING *****\nCreated archive may contain plain text credentials.\nEnsure that files in archive are redacted before sharing.\n*******************")
-	return nil
+	return f, nil
 }

internal/pkg/agent/cmd/diagnostics_test.go

@@ -0,0 +1,51 @@
+// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+// or more contributor license agreements. Licensed under the Elastic License;
+// you may not use this file except in compliance with the Elastic License.
+
+package cmd
+
+import (
+	"os"
+	"path"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_createFile(t *testing.T) {
+	dir := t.TempDir()
+	existingFile := "existingfile.zip"
+	f, err := os.Create(path.Join(dir, "existingFile"))
+	require.NoErrorf(t, err, "could not create file %q", path.Join(dir, "existingFile"))
+	err = f.Close()
+	require.NoError(t, err, "could not close file")
+
+	testCases := []struct {
+		name     string
+		filePath string
+	}{
+		{
+			name:     "ExistingFile",
+			filePath: path.Join(dir, existingFile),
+		},
+		{
+			name:     "NewFile",
+			filePath: path.Join(dir, "newfile.zip"),
+		},
+		{
+			name:     "NonexistentFolders",
+			filePath: path.Join(dir, "nonexistent", "folders", "file.zip"),
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			file, err := createFile(tc.filePath)
+			require.NoError(t, err, "failed creating diagnostics file %q",
+				tc.filePath)
+			defer func() {
+				file.Close()
+			}()
+		})
+	}
+}

internal/pkg/agent/cmd/logs_test.go

@@ -38,10 +38,10 @@ func TestGetLogFilenames(t *testing.T) {
 	t.Run("returns the correct sorted filelist", func(t *testing.T) {
 		dir := t.TempDir()
 
-		createFile(t, dir, file2)
-		createFile(t, dir, file)
-		createFile(t, dir, file1)
-		createFile(t, dir, file3)
+		createFileEmpty(t, dir, file2)
+		createFileEmpty(t, dir, file)
+		createFileEmpty(t, dir, file1)
+		createFileEmpty(t, dir, file3)
 
 		names, err := getLogFilenames(dir)
 		require.NoError(t, err)
@@ -62,14 +62,14 @@ func TestGetLogFilenames(t *testing.T) {
 		prevDayFile2 := "elastic-agent-20230529-2.ndjson"
 		prevDayFile3 := "elastic-agent-20230529-3.ndjson"
 
-		createFile(t, dir, file2)
-		createFile(t, dir, file)
-		createFile(t, dir, prevDayFile1)
-		createFile(t, dir, file1)
-		createFile(t, dir, prevDayFile)
-		createFile(t, dir, prevDayFile2)
-		createFile(t, dir, file3)
-		createFile(t, dir, prevDayFile3)
+		createFileEmpty(t, dir, file2)
+		createFileEmpty(t, dir, file)
+		createFileEmpty(t, dir, prevDayFile1)
+		createFileEmpty(t, dir, file1)
+		createFileEmpty(t, dir, prevDayFile)
+		createFileEmpty(t, dir, prevDayFile2)
+		createFileEmpty(t, dir, file3)
+		createFileEmpty(t, dir, prevDayFile3)
 
 		names, err := getLogFilenames(dir)
 		require.NoError(t, err)
@@ -99,7 +99,7 @@ func TestGetLogFilenames(t *testing.T) {
 
 	t.Run("does not return non-log entries", func(t *testing.T) {
 		dir := t.TempDir()
-		createFile(t, dir, "excluded")
+		createFileEmpty(t, dir, "excluded")
 
 		names, err := getLogFilenames(dir)
 		require.NoError(t, err)
@@ -109,7 +109,7 @@ func TestGetLogFilenames(t *testing.T) {
 
 	t.Run("returns a list of one", func(t *testing.T) {
 		dir := t.TempDir()
-		createFile(t, dir, file1)
+		createFileEmpty(t, dir, file1)
 
 		names, err := getLogFilenames(dir)
 		require.NoError(t, err)
@@ -539,7 +539,7 @@ func generateLines(prefix string, start, end int) string {
 	return b.String()
 }
 
-func createFile(t *testing.T, dir, name string) {
+func createFileEmpty(t *testing.T, dir, name string) {
 	createFileContent(t, dir, name, nil)
 }