Move OpenAuditLogFileUntilSuccess to new helpers package (#31)

This function is relevant also outside of the `ginaudit` package, so
let's make it available through a new package.

Signed-off-by: Juan Antonio Osorio <[email protected]>

docs/middleware.md

@@ -25,7 +25,7 @@ It is often the case that one must not start to process events until the audit l
 capabilities are set up. For this, the following pattern is suggested:
 
 ```golang
-fd, err := ginaudit.OpenAuditLogFileUntilSuccess(auditLogPath)
+fd, err := helpers.OpenAuditLogFileUntilSuccess(auditLogPath)
 if err != nil {
     panic(err)
 }
@@ -36,7 +36,7 @@ defer fd.Close()
 mdw := ginaudit.NewJSONMiddleware("my-test-component", fd)
 ```
 
-The function `ginaudit.OpenAuditLogFileUntilSuccess` attempts to open the audit log
+The function `helpers.OpenAuditLogFileUntilSuccess` attempts to open the audit log
 file, and will block until it's available. This file may be created beforehand or it
 may be created by another process e.g. a sidecar container. It opens the file with
 `O_APPEND` which enables atomic writes as long as the audit events are less than 4096 bytes.

ginaudit/mdw.go

@@ -19,9 +19,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
-	"os"
 	"sync"
-	"time"
 
 	"github.com/gin-gonic/gin"
 	"github.com/prometheus/client_golang/prometheus"
@@ -35,34 +33,6 @@ type Middleware struct {
 	eventTypeMap sync.Map
 }
 
-const (
-	ownerGroupAccess = 0o640
-	retryInterval    = 100 * time.Millisecond
-)
-
-// OpenAuditLogFileUntilSuccess attempts to open a file for writing audit events until
-// it succeeds.
-// It assumes that audit events are less than 4096 bytes to ensure atomicity.
-// it takes a writer for the audit log.
-func OpenAuditLogFileUntilSuccess(path string) (*os.File, error) {
-	for {
-		// This is opened with the O_APPEND option to ensure
-		// atomicity of writes. This is important to ensure
-		// we can concurrently write to the file and not block
-		// the server's main loop.
-		fd, err := os.OpenFile(path, os.O_WRONLY|os.O_APPEND, ownerGroupAccess)
-		if err != nil {
-			if os.IsNotExist(err) {
-				time.Sleep(retryInterval)
-				continue
-			}
-			// Not being able to write audit log events is a fatal error
-			return nil, err
-		}
-		return fd, nil
-	}
-}
-
 // NewMiddleware returns a new instance of audit Middleware.
 func NewMiddleware(component string, aew *auditevent.EventWriter) *Middleware {
 	return &Middleware{

ginaudit/mdw_test.go

@@ -29,7 +29,6 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"os"
-	"path/filepath"
 	"regexp"
 	"strings"
 	"sync"
@@ -319,68 +318,6 @@ func TestParallelCallsToMiddleware(t *testing.T) {
 	}
 }
 
-func TestOpenAuditLogFileUntilSuccess(t *testing.T) {
-	t.Parallel()
-
-	var wg sync.WaitGroup
-	wg.Add(1)
-
-	tmpdir := t.TempDir()
-	tmpfile := filepath.Join(tmpdir, "audit.log")
-
-	go func() {
-		defer wg.Done()
-		time.Sleep(time.Second)
-		fd, err := os.OpenFile(tmpfile, os.O_RDONLY|os.O_CREATE, 0o600)
-		require.NoError(t, err)
-		err = fd.Close()
-		require.NoError(t, err)
-	}()
-
-	fd, err := ginaudit.OpenAuditLogFileUntilSuccess(tmpfile)
-	require.NoError(t, err)
-	require.NotNil(t, fd)
-
-	err = fd.Close()
-	require.NoError(t, err)
-
-	// We wait so we don't leak file descriptors
-	wg.Wait()
-
-	err = os.Remove(tmpfile)
-	require.NoError(t, err)
-}
-
-func TestOpenAuditLogFileError(t *testing.T) {
-	t.Parallel()
-
-	var wg sync.WaitGroup
-	wg.Add(1)
-
-	tmpdir := t.TempDir()
-	tmpfile := filepath.Join(tmpdir, "audit.log")
-
-	go func() {
-		defer wg.Done()
-		time.Sleep(time.Second)
-		// This file is read only
-		fd, err := os.OpenFile(tmpfile, os.O_RDONLY|os.O_CREATE, 0o500)
-		require.NoError(t, err)
-		err = fd.Close()
-		require.NoError(t, err)
-	}()
-
-	fd, err := ginaudit.OpenAuditLogFileUntilSuccess(tmpfile)
-	require.Error(t, err)
-	require.Nil(t, fd)
-
-	// We wait so we don't leak file descriptors
-	wg.Wait()
-
-	err = os.Remove(tmpfile)
-	require.NoError(t, err)
-}
-
 func TestCantRegisterMultipleTimesToSamePrometheus(t *testing.T) {
 	t.Parallel()
 

helpers/helpers.go

@@ -0,0 +1,49 @@
+/*
+Copyright 2022 Equinix, Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package helpers
+
+import (
+	"os"
+	"time"
+)
+
+const (
+	ownerGroupAccess = 0o640
+	retryInterval    = 100 * time.Millisecond
+)
+
+// OpenAuditLogFileUntilSuccess attempts to open a file for writing audit events until
+// it succeeds.
+// It assumes that audit events are less than 4096 bytes to ensure atomicity.
+// it takes a writer for the audit log.
+func OpenAuditLogFileUntilSuccess(path string) (*os.File, error) {
+	for {
+		// This is opened with the O_APPEND option to ensure
+		// atomicity of writes. This is important to ensure
+		// we can concurrently write to the file and not block
+		// the server's main loop.
+		fd, err := os.OpenFile(path, os.O_WRONLY|os.O_APPEND, ownerGroupAccess)
+		if err != nil {
+			if os.IsNotExist(err) {
+				time.Sleep(retryInterval)
+				continue
+			}
+			// Not being able to write audit log events is a fatal error
+			return nil, err
+		}
+		return fd, nil
+	}
+}

helpers/helpers_test.go

@@ -0,0 +1,90 @@
+/*
+Copyright 2022 Equinix, Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package helpers_test
+
+import (
+	"os"
+	"path/filepath"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/metal-toolbox/auditevent/helpers"
+)
+
+func TestOpenAuditLogFileUntilSuccess(t *testing.T) {
+	t.Parallel()
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+
+	tmpdir := t.TempDir()
+	tmpfile := filepath.Join(tmpdir, "audit.log")
+
+	go func() {
+		defer wg.Done()
+		time.Sleep(time.Second)
+		fd, err := os.OpenFile(tmpfile, os.O_RDONLY|os.O_CREATE, 0o600)
+		require.NoError(t, err)
+		err = fd.Close()
+		require.NoError(t, err)
+	}()
+
+	fd, err := helpers.OpenAuditLogFileUntilSuccess(tmpfile)
+	require.NoError(t, err)
+	require.NotNil(t, fd)
+
+	err = fd.Close()
+	require.NoError(t, err)
+
+	// We wait so we don't leak file descriptors
+	wg.Wait()
+
+	err = os.Remove(tmpfile)
+	require.NoError(t, err)
+}
+
+func TestOpenAuditLogFileError(t *testing.T) {
+	t.Parallel()
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+
+	tmpdir := t.TempDir()
+	tmpfile := filepath.Join(tmpdir, "audit.log")
+
+	go func() {
+		defer wg.Done()
+		time.Sleep(time.Second)
+		// This file is read only
+		fd, err := os.OpenFile(tmpfile, os.O_RDONLY|os.O_CREATE, 0o500)
+		require.NoError(t, err)
+		err = fd.Close()
+		require.NoError(t, err)
+	}()
+
+	fd, err := helpers.OpenAuditLogFileUntilSuccess(tmpfile)
+	require.Error(t, err)
+	require.Nil(t, fd)
+
+	// We wait so we don't leak file descriptors
+	wg.Wait()
+
+	err = os.Remove(tmpfile)
+	require.NoError(t, err)
+}

internal/testtools/testtools.go

@@ -30,7 +30,7 @@ import (
 
 	"github.com/stretchr/testify/require"
 
-	"github.com/metal-toolbox/auditevent/ginaudit"
+	"github.com/metal-toolbox/auditevent/helpers"
 )
 
 const (
@@ -63,7 +63,7 @@ func SetPipeReader(t *testing.T, namedPipe string) <-chan io.WriteCloser {
 	t.Helper()
 	rchan := make(chan io.WriteCloser)
 	go func(c chan<- io.WriteCloser) {
-		fd, err := ginaudit.OpenAuditLogFileUntilSuccess(namedPipe)
+		fd, err := helpers.OpenAuditLogFileUntilSuccess(namedPipe)
 		require.NoError(t, err)
 		c <- fd
 	}(rchan)