diff --git a/core/pkg/logbuffer/BUILD.bazel b/core/pkg/logbuffer/BUILD.bazel
new file mode 100644
index 0000000..a53cb7a
--- /dev/null
+++ b/core/pkg/logbuffer/BUILD.bazel
@@ -0,0 +1,15 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["logbuffer.go"],
+    importpath = "git.monogon.dev/source/nexantic.git/core/pkg/logbuffer",
+    visibility = ["//visibility:public"],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["logbuffer_test.go"],
+    embed = [":go_default_library"],
+    deps = ["@com_github_stretchr_testify//require:go_default_library"],
+)
diff --git a/core/pkg/logbuffer/logbuffer.go b/core/pkg/logbuffer/logbuffer.go
new file mode 100644
index 0000000..8298deb
--- /dev/null
+++ b/core/pkg/logbuffer/logbuffer.go
@@ -0,0 +1,146 @@
+// Copyright 2020 The Monogon Project Authors.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// 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 logbuffer implements a fixed-size in-memory ring buffer for line-separated logs.
+// It implements io.Writer and splits the data into lines. The lines are kept in a ring where the
+// oldest are overwritten once it's full. It allows retrieval of the last n lines. There is a built-in
+// line length limit to bound the memory usage at maxLineLength * size.
+package logbuffer
+
+import (
+	"bytes"
+	"strings"
+	"sync"
+)
+
+// LogBuffer implements a fixed-size in-memory ring buffer for line-separated logs
+type LogBuffer struct {
+	mu            sync.RWMutex
+	maxLineLength int
+	content       []Line
+	length        int
+
+	currentLineBuilder       strings.Builder
+	currentLineWrittenLength int
+}
+
+type Line struct {
+	Data           string
+	OriginalLength int
+}
+
+func New(size, maxLineLength int) *LogBuffer {
+	return &LogBuffer{
+		content:       make([]Line, size),
+		maxLineLength: maxLineLength,
+	}
+}
+
+func (b *LogBuffer) writeLimited(newData []byte) {
+	builder := &b.currentLineBuilder
+	b.currentLineWrittenLength += len(newData)
+	if builder.Len()+len(newData) > b.maxLineLength {
+		builder.Write(newData[:b.maxLineLength-builder.Len()])
+	} else {
+		builder.Write(newData)
+	}
+}
+
+func (b *LogBuffer) commitLine() {
+	b.content[b.length%len(b.content)] = Line{
+		Data:           b.currentLineBuilder.String(),
+		OriginalLength: b.currentLineWrittenLength}
+	b.length++
+	b.currentLineBuilder.Reset()
+	b.currentLineWrittenLength = 0
+}
+
+func (b *LogBuffer) Write(data []byte) (int, error) {
+	var pos int = 0
+
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	for {
+		nextNewline := bytes.IndexRune(data[pos:], '\n')
+
+		// No newline in the data, write everything to the current line
+		if nextNewline == -1 {
+			b.writeLimited(data[pos:])
+			break
+		}
+
+		// Write this line and update position
+		b.writeLimited(data[pos : pos+nextNewline])
+		b.commitLine()
+		pos += nextNewline + 1
+
+		// Data ends with a newline, stop now without writing an empty line
+		if nextNewline == len(data)-1 {
+			break
+		}
+	}
+	return len(data), nil
+}
+
+// capToContentLength caps the number of requested lines to what is actually available
+func (b *LogBuffer) capToContentLength(n int) int {
+	// If there aren't enough lines to read, reduce the request size
+	if n > b.length {
+		n = b.length
+	}
+	// If there isn't enough ringbuffer space, reduce the request size
+	if n > len(b.content) {
+		n = len(b.content)
+	}
+	return n
+}
+
+// ReadLines reads the last n lines from the buffer in chronological order. If n is bigger than the
+// ring buffer or the number of available lines only the number of stored lines are returned.
+func (b *LogBuffer) ReadLines(n int) []Line {
+	b.mu.RLock()
+	defer b.mu.RUnlock()
+
+	n = b.capToContentLength(n)
+
+	// Copy references out to keep them around
+	outArray := make([]Line, n)
+	for i := 1; i <= n; i++ {
+		outArray[n-i] = b.content[(b.length-i)%len(b.content)]
+	}
+	return outArray
+}
+
+// ReadLinesTruncated works exactly the same as ReadLines, but adds an ellipsis at the end of every
+// line that was truncated because it was over MaxLineLength
+func (b *LogBuffer) ReadLinesTruncated(n int, ellipsis string) []string {
+	// This does not use ReadLines() to prevent excessive reference copying and associated GC pressure
+	// since it could process a lot of lines.
+
+	n = b.capToContentLength(n)
+
+	outArray := make([]string, n)
+	for i := 1; i <= n; i++ {
+		line := b.content[(b.length-i)%len(b.content)]
+		if line.OriginalLength > b.maxLineLength {
+			outArray[n-i] = line.Data + ellipsis
+		} else {
+			outArray[n-i] = line.Data
+		}
+	}
+	return outArray
+}
diff --git a/core/pkg/logbuffer/logbuffer_test.go b/core/pkg/logbuffer/logbuffer_test.go
new file mode 100644
index 0000000..c38d7a6
--- /dev/null
+++ b/core/pkg/logbuffer/logbuffer_test.go
@@ -0,0 +1,94 @@
+// Copyright 2020 The Monogon Project Authors.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// 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 logbuffer
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestSingleLine(t *testing.T) {
+	buf := New(1, 16000)
+	buf.Write([]byte("Hello World\n"))
+	out := buf.ReadLines(1)
+	require.Len(t, out, 1, "Invalid number of lines read")
+	require.Equal(t, "Hello World", out[0].Data, "Read bad log line")
+	require.Equal(t, 11, out[0].OriginalLength, "Invalid line length")
+}
+
+func TestPartialWritesAndReads(t *testing.T) {
+	buf := New(2, 16000)
+	buf.Write([]byte("Hello "))
+	buf.Write([]byte("World\nTest "))
+	buf.Write([]byte("2\n"))
+
+	out := buf.ReadLines(1)
+	require.Len(t, out, 1, "Invalid number of lines for partial read")
+	require.Equal(t, "Test 2", out[0].Data, "Read bad log line")
+
+	out2 := buf.ReadLines(2)
+	require.Len(t, out2, 2, "Invalid number of lines read")
+	require.Equal(t, "Hello World", out2[0].Data, "Read bad log line")
+	require.Equal(t, "Test 2", out2[1].Data, "Read bad log line")
+}
+
+func TestBufferOverwrite(t *testing.T) {
+	buf := New(3, 16000)
+	buf.Write([]byte("Test1\nTest2\nTest3\nTest4\n"))
+
+	out := buf.ReadLines(3)
+	require.Equal(t, out[0].Data, "Test2", "Read bad log line")
+	require.Equal(t, out[1].Data, "Test3", "Read bad log line")
+	require.Equal(t, out[2].Data, "Test4", "Overwritten data is invalid")
+}
+
+func TestTooLargeRequests(t *testing.T) {
+	buf := New(1, 16000)
+	outEmpty := buf.ReadLines(1)
+	require.Len(t, outEmpty, 0, "Returned more data than there is")
+
+	buf.Write([]byte("1\n2\n"))
+	out := buf.ReadLines(2)
+	require.Len(t, out, 1, "Returned more data than the ring buffer can hold")
+}
+
+func TestSpecialCases(t *testing.T) {
+	buf := New(2, 16000)
+	buf.Write([]byte("Test1"))
+	buf.Write([]byte("\nTest2\n"))
+	out := buf.ReadLines(2)
+	require.Len(t, out, 2, "Too many lines written")
+	require.Equal(t, out[0].Data, "Test1", "Read bad log line")
+	require.Equal(t, out[1].Data, "Test2", "Read bad log line")
+}
+
+func TestLineLengthLimit(t *testing.T) {
+	buf := New(2, 6)
+
+	testStr := "Just Testing"
+
+	buf.Write([]byte(testStr + "\nShort\n"))
+
+	out := buf.ReadLines(2)
+	require.Equal(t, len(testStr), out[0].OriginalLength, "Line is over length limit")
+	require.Equal(t, "Just T", out[0].Data, "Log line not properly truncated")
+
+	out2 := buf.ReadLinesTruncated(2, "...")
+	require.Equal(t, out2[0], "Just T...", "Line is over length limit")
+	require.Equal(t, out2[1], "Short", "Truncated small enough line")
+}