feat: create user guide section

* new User Guide section
* compile-kernel page
* build-initramfs page

Signed-off-by: RedbeanGit <dubois.julien.mail@gmail.com>

package.json

@@ -22,6 +22,7 @@
     "@ianvs/prettier-plugin-sort-imports": "4.1.0",
     "@next/eslint-plugin-next": "13.5.4",
     "@types/node": "18.11.10",
+    "@types/react": "^18.2.31",
     "@typescript-eslint/eslint-plugin": "6.7.4",
     "@typescript-eslint/parser": "6.7.4",
     "autoprefixer": "^10.4.16",

pages/docs/_meta.json

@@ -1,7 +1,5 @@
 {
-  "-- Getting Started --": {
-    "type": "separator",
-    "title": "Getting Started"
-  },
-  "index": "Introduction"
+  "index": "Introduction",
+  "getting-started": "Getting Started",
+  "user-guide": "User Guide"
 }

pages/docs/getting-started/_meta.json

@@ -0,0 +1 @@
+{}

pages/docs/user-guide/_meta.json

@@ -0,0 +1,4 @@
+{
+  "compile-kernel": "Compiling the Kernel",
+  "build-initramfs": "Build initramfs"
+}

pages/docs/user-guide/build-initramfs.mdx

@@ -0,0 +1,115 @@
+import Image from 'next/image';
+import Link from 'next/link';
+import InitramfsComponentsImage from '../../../public/images/schemas/initramfs-components.png';
+
+# Building initramfs
+
+Requirements:
+
+- [Rust toolchain](https://www.rust-lang.org/fr/learn/get-started)
+
+## Introduction
+
+Lambdo uses custom initramfs builded from Docker images. You can build it by
+yourself or use prebuilt one.
+
+## Lambdo initramfs structure
+
+Lambdo initramfs contains at least 3 components:
+
+- **init** - init process which starts all other processes.
+- **agent** - agent process which is responsible for communication with Lambdo
+  API.
+- **config.yaml** - configuration file which contains all necessary
+  configuration for Lambdo agent (see
+  [Configuration documentation](/docs/reference/configuration)).
+
+<div className="col-span-2 flex items-center justify-center py-2">
+  <Image
+    src={InitramfsComponentsImage}
+    alt="Initramfs components"
+    width={500}
+    height={500}
+  />
+</div>
+
+## Preparation
+
+Create an empty directory for initramfs:
+
+```bash copy
+mkdir initramfs
+```
+
+Clone `lambdo` repository:
+
+```bash copy
+git clone https://github.com/faast-rt/lambdo.git
+```
+
+## Build Lambdo agent
+
+Build Lambdo agent and move it to initramfs directory:
+
+```bash copy
+cd lambdo/agent
+cargo build --release
+cd ../..
+mv lambdo/target/release/agent initramfs
+```
+
+## Write init script
+
+You can write your own script or use example one (must be named `init`):
+
+```bash copy filename="initramfs/init"
+#! /bin/sh
+mount -t devtmpfs dev /dev
+mount -t proc proc /proc
+mount -t sysfs sysfs /sys
+ip link set up dev lo
+
+exec /agent --config /config.yaml
+
+exit
+poweroff -f
+```
+
+> **Note 1:** Your init script must be executable.
+
+> **Note 2:** Your init script must start agent process.
+
+## Write configuration file
+
+You can write your own configuration file or use example one (must be named
+`config.yaml`):
+
+```yaml copy filename="initramfs/config.yaml"
+apiVersion: lambdo.io/v1alpha1
+kind: AgentConfig
+serial:
+  path: /dev/pts/6
+  baudRate: 9600
+```
+
+## Build initramfs by yourself
+
+Build initramfs tool and move it to initramfs directory:
+
+```bash copy
+cd lambdo/initramfs
+cargo build --release
+cd ../..
+mv lambdo/target/release/initramfs initramfs
+```
+
+Run initramfs tool (replace `node:20-alpine` with the image of the language you
+want):
+
+```bash copy
+cd initramfs
+./initramfs --image node:20-alpine
+```
+
+**The image built here is stored at
+`initramfs/initramfs-library-node-20-alpine.img`.**

pages/docs/user-guide/compile-kernel.mdx

@@ -0,0 +1,49 @@
+# Compiling Linux kernel
+
+Lambdo uses a Linux kernel compiled from source. This is a guide to compile the
+kernel.
+
+## Install dependencies
+
+#### Debian/Ubuntu
+
+```bash copy filename="bash"
+sudo apt update
+sudo apt install git build-essential bc flex bison
+```
+
+#### Fedora/RHEL/CentOS
+
+```bash copy filename="bash"
+sudo dnf install git gcc make xz bc flex bison diffutils
+```
+
+#### Arch Linux
+
+```bash copy filename="bash"
+sudo pacman -Syu
+sudo pacman -S git gcc make xz bc flex bison diffutils
+```
+
+## Build the kernel
+
+Clone the Linux kernel official repository:
+
+```bash copy filename="bash"
+git clone https://github.com/torvalds/linux.git
+```
+
+Generate the default configuration:
+
+```bash copy filename="bash"
+cd linux
+sudo make tinyconfig
+```
+
+Compile the kernel:
+
+```bash copy filename="bash"
+KCFLAGS="-Wa,-mx86-used-note=no" sudo make bzImage -j `nproc`
+```
+
+**The image is located at `arch/x86/boot/compressed/vmlinux.bin`**