Add log rotation based on log size

Add new functions to logfile.go for rotating and truncating
the events log file once the log file and its contents
exceed the maximum size limit while keeping 50% of the
log file's content

Also add tests to verify log rotation and truncation

Signed-off-by: Niall Crowe <nicrowe@redhat.com>
Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>

1 files changed, 140 insertions, 0 deletions

diff --git a/libpod/events/logfile_test.go b/libpod/events/logfile_test.go
new file mode 100644
index 000000000..302533c12
--- /dev/null
+++ b/libpod/events/logfile_test.go
@@ -0,0 +1,140 @@
+package events
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestRotateLog(t *testing.T) {
+	tests := []struct {
+		// If sizeInitial + sizeContent >= sizeLimit, then rotate
+		sizeInitial uint64
+		sizeContent uint64
+		sizeLimit   uint64
+		mustRotate  bool
+	}{
+		// No rotation
+		{0, 0, 1, false},
+		{1, 1, 0, false},
+		{10, 10, 30, false},
+		{1000, 500, 1600, false},
+		// Rotation
+		{10, 10, 20, true},
+		{30, 0, 29, true},
+		{200, 50, 150, true},
+		{1000, 600, 1500, true},
+	}
+
+	for _, test := range tests {
+		tmp, err := ioutil.TempFile("", "log-rotation-")
+		require.NoError(t, err)
+		defer os.Remove(tmp.Name())
+		defer tmp.Close()
+
+		// Create dummy file and content.
+		initialContent := make([]byte, test.sizeInitial)
+		logContent := make([]byte, test.sizeContent)
+
+		// Write content to the file.
+		_, err = tmp.Write(initialContent)
+		require.NoError(t, err)
+
+		// Now rotate
+		fInfoBeforeRotate, err := tmp.Stat()
+		require.NoError(t, err)
+		isRotated, err := rotateLog(tmp.Name(), string(logContent), test.sizeLimit)
+		require.NoError(t, err)
+
+		fInfoAfterRotate, err := os.Stat(tmp.Name())
+		// Test if rotation was successful
+		if test.mustRotate {
+			// File has been renamed
+			require.True(t, isRotated)
+			require.NoError(t, err, "log file has been renamed")
+			require.NotEqual(t, fInfoBeforeRotate.Size(), fInfoAfterRotate.Size())
+		} else {
+			// File has not been renamed
+			require.False(t, isRotated)
+			require.NoError(t, err, "log file has not been renamed")
+			require.Equal(t, fInfoBeforeRotate.Size(), fInfoAfterRotate.Size())
+		}
+	}
+}
+
+func TestTruncationOutput(t *testing.T) {
+	contentBefore := `0
+1
+2
+3
+4
+5
+6
+7
+8
+9
+10
+`
+	contentAfter := `6
+7
+8
+9
+10
+`
+	// Create dummy file
+	tmp, err := ioutil.TempFile("", "log-rotation")
+	require.NoError(t, err)
+	defer os.Remove(tmp.Name())
+	defer tmp.Close()
+
+	// Write content before truncation to dummy file
+	_, err = tmp.WriteString(contentBefore)
+	require.NoError(t, err)
+
+	// Truncate the file
+	beforeTruncation, err := ioutil.ReadFile(tmp.Name())
+	require.NoError(t, err)
+	err = truncate(tmp.Name())
+	require.NoError(t, err)
+	afterTruncation, err := ioutil.ReadFile(tmp.Name())
+	require.NoError(t, err)
+
+	// Test if rotation was successful
+	require.NoError(t, err, "Log content has changed")
+	require.NotEqual(t, beforeTruncation, afterTruncation)
+	require.Equal(t, string(afterTruncation), contentAfter)
+}
+
+func TestRenameLog(t *testing.T) {
+	fileContent := `0
+1
+2
+3
+4
+5
+`
+	// Create two dummy files
+	source, err := ioutil.TempFile("", "removing")
+	require.NoError(t, err)
+	target, err := ioutil.TempFile("", "renaming")
+	require.NoError(t, err)
+
+	// Write to source dummy file
+	_, err = source.WriteString(fileContent)
+	require.NoError(t, err)
+
+	// Rename the files
+	beforeRename, err := ioutil.ReadFile(source.Name())
+	require.NoError(t, err)
+	err = renameLog(source.Name(), target.Name())
+	require.NoError(t, err)
+	afterRename, err := ioutil.ReadFile(target.Name())
+	require.NoError(t, err)
+
+	// Test if renaming was successful
+	require.Error(t, os.Remove(source.Name()))
+	require.NoError(t, os.Remove(target.Name()))
+	require.Equal(t, beforeRename, afterRename)
+}