15 files changed, 385 insertions, 0 deletions
diff --git a/mod/web/blog/.gitignore b/mod/web/blog/.gitignore
new file mode 100644
index 0000000..decc3f8
--- /dev/null
+++ b/mod/web/blog/.gitignore
@@ -0,0 +1,2 @@
+public/
+nohup.out
diff --git a/mod/web/blog/config.toml b/mod/web/blog/config.toml
new file mode 100644
index 0000000..69c389b
--- /dev/null
+++ b/mod/web/blog/config.toml
@@ -0,0 +1,8 @@
+base_url = "https://4kb.net"
+build_search_index = false
+compile_sass = false
+generate_feeds = true
+minify_html = true
+
+[markdown]
+highlight_code = false
diff --git a/mod/web/blog/content/log/_index.md b/mod/web/blog/content/log/_index.md
new file mode 100644
index 0000000..10f2311
--- /dev/null
+++ b/mod/web/blog/content/log/_index.md
@@ -0,0 +1,7 @@
++++
+title = "Log"
+sort_by = "date"
+template = "blog.html"
+page_template = "post.html"
+description = "notes too short to post"
++++
diff --git a/mod/web/blog/content/log/deterministic-hostnames.md b/mod/web/blog/content/log/deterministic-hostnames.md
new file mode 100644
index 0000000..43dc7d8
--- /dev/null
+++ b/mod/web/blog/content/log/deterministic-hostnames.md
@@ -0,0 +1,80 @@
+---
+title: "Deterministic and unique network hostnames"
+date: "2024-11-10"
+---
+
+As part of building out a Kubernetes cluster, I wanted to build and distribute a
+single OS image to create stateless worker nodes. Using network booting, and
+some clever tricks to differentiate nodes, we can create a scaleable and
+efficient farm of workers for a cluster that don't even need disks.
+
+The idea came from a plan to build a cluster using the
+[compute blade](https://computeblade.com/), and a few Raspberry Pi SBCs I
+already own. Running the cluster from an SD card is not recommended due to the
+not-so-great reliability of the flash used by most manufacturers, so I wanted to
+try PXE booting each Pi to save money rather than purchasing an SSD for each
+one. The compute blades do support an NVMe disk, but I plan to use those for a
+storage cluster later, so they need to remain empty.
+
+## Base image
+
+Alpine Linux has been my preferred server OS for a long time. It provides a very
+lightweight base system, and bundles an excellent bootstrapping system,
+[apkovl](https://wiki.alpinelinux.org/wiki/Alpine_local_backup), that allows the
+user to save a set of customisations to an system as an overlay to a stock
+Alpine live image. In other words, we can create our image once, save the
+changes as an `apkovl.tar.gz` file, and apply the same changes to a base system
+on boot. This file can even be provided as a
+[kernel parameter](https://wiki.alpinelinux.org/wiki/PXE_boot#Guide_to_options)
+and will be fetched from a remote webserver automatically!
+
+Since the image and configuration will be shipped to the node via the network,
+an added benefit of using Alpine is its tiny space consumption. I'm not using
+enough nodes for this to really matter, but it's a cool optimization regardless.
+
+## Differentiating the nodes
+
+One of the main goals of this project is that there should be no persistent
+storage required outside the boot image itself. Since every node will download
+and generate the same root file-system on startup, the first problem that arises
+is how the nodes will identify themselves both on the network and the cluster,
+given that it's not possible to name them ahead of time. In other words, any
+given node has to generate a unique hostname that won't collide with other
+workers, and that will be the same each time that node boots.
+
+Since these nodes will not have a predefined name, we have to rely on
+characteristics of the hardware to differentiate each one. The hardware MAC
+address is perfect for this, since it's unique to to each node and will not be
+wiped away after the node reboots. On a system like Linux that exposes its
+hardware through a _sysfs_, we can find a file containing the address at
+`/sys/class/net/eth0/address`. I don't really like the idea of attaching the
+literal MAC address of the node to its network hostname, since it's a security
+risk, and a bit too verbose. Instead, we can transform it into something safer
+using a `sha1sum`, which is already present on our Alpine base system:
+
+```console
+sha1sum /sys/class/net/eth0/address | head -c 6 | awk '{print "worker-" $0}'
+```
+
+### Applying the new name
+
+Ideally, the node should apply its generated hostname before reaching out for an
+address over DHCP or joining the cluster. We can make sure it happens before any
+traffic is sent out by adding a `pre-up` command to the right interface in
+`/etc/network/interfaces`:
+
+```
+
+...
+
+auto eth0
+iface eth0 inet dhcp
+    pre-up sha1sum /sys/class/net/eth0/address | head -c 6 | awk '{print "worker-" $0}' > /etc/hostname
+
+...
+```
+
+The VM I tested with looks outputs `worker-e2fae8`. Pretty clean result, and if
+you want to know the physical node that maps to each hostname, you can take note
+of the MAC address beforehand and generate the same hash on another computer to
+match them up.
diff --git a/mod/web/blog/content/log/nohup.md b/mod/web/blog/content/log/nohup.md
new file mode 100644
index 0000000..64f7983
--- /dev/null
+++ b/mod/web/blog/content/log/nohup.md
@@ -0,0 +1,26 @@
+---
+title: "Spawning background processes"
+date: "2024-11-17"
+---
+
+Working in a terminal,
+I often pair my editor with a background process watching files.
+Before reaching for terminal multiplexers,
+see if you can get away with simple tty job control.
+Spawn the background process,
+still attached to the terminal instance:
+
+```
+program args &
+```
+
+Also redirect its output to a file,
+for when the process writes to the tty from the background:
+
+```
+nohup program args &
+```
+
+Extra reading:
+
+- <https://jvns.ca/blog/2024/07/03/reasons-to-use-job-control/>
diff --git a/mod/web/blog/content/posts/_index.md b/mod/web/blog/content/posts/_index.md
new file mode 100644
index 0000000..1f4024a
--- /dev/null
+++ b/mod/web/blog/content/posts/_index.md
@@ -0,0 +1,8 @@
++++
+title = "Posts"
+sort_by = "date"
+template = "blog.html"
+page_template = "post.html"
++++
+
+Longer form writing.
diff --git a/mod/web/blog/content/posts/stateless-compute-networks.md b/mod/web/blog/content/posts/stateless-compute-networks.md
new file mode 100644
index 0000000..bac9e5d
--- /dev/null
+++ b/mod/web/blog/content/posts/stateless-compute-networks.md
@@ -0,0 +1,41 @@
+---
+title: "On stateless compute networks"
+date: "2024-11-10"
+draft: true
+---
+
+On the topic of distributed systems and clustering,
+I am quite invested in the idea of compute nodes that rely entirely on the network for configuration.
+Arbitrary nodes can join a pre-existing cluster,
+offering their CPU time and memory for computation without relying on any pre-existing configuration on the node itself.
+In other words, any computer could pick up work,
+only needing power and a network connection to the cluster.
+
+Perhaps this eventually leads into a "self-healing" cluster where only one node is manually bootstrapped,
+which then serves a _configuration endpoint_ for other stateless nodes to reach out to for their instructions,
+which they will then also serve once they are themselves ready.
+
+Early revisions of these notes mention Kubernetes,
+but I am also trying to achieve similar results with NixOS on a custom project.
+In any case, these are my ever-updating notes towards a general implementation of a stateless distributed systems architecture.
+
+## Self healing cluster
+
+Assuming control of an external DHCP server,
+a self healing Kubernetes cluster would be feasible,
+with the PXE boot artifacts supplied by the cluster itself.
+That is, as long as one node is running the pod hosting the artifacts on a given endpoint,
+other nodes can boot those artifacts and join the cluster,
+thereby being able to host the artifacts as well.
+
+## Configuration endpoint
+
+The nodes shouldn't require a disk installed to be able to join the network.
+Rather, the lofty goal of zero-configuration compute nodes passes the job of node initialization to the supporting network.
+This is accomplished with PXE boot instructions supplied over DHCP.
+
+I delegate the following tasks to a single node in the subnet:
+
+- Gateway: Optional outbound connections if required
+- DHCP server: Cluster IPAM
+- TFTP and HTTP server: Serves iPXE firmware and kernel/initrd artifacts
diff --git a/mod/web/blog/default.nix b/mod/web/blog/default.nix
new file mode 100644
index 0000000..5d76e7a
--- /dev/null
+++ b/mod/web/blog/default.nix
@@ -0,0 +1,15 @@
+{ pkgs, ... }: pkgs.stdenvNoCC.mkDerivation {
+  pname = "4kb.net";
+  version = "1.0";
+  src = ./.;
+
+  nativeBuildInputs = with pkgs; [
+    zola
+  ];
+
+  buildPhase = "zola build";
+  installPhase = ''
+    mkdir -p $out
+    cp -r public/* $out/
+  '';
+}
diff --git a/mod/web/blog/static/avatar.png b/mod/web/blog/static/avatar.png
new file mode 100644
index 0000000..91357dc
--- /dev/null
+++ b/mod/web/blog/static/avatar.png
diff --git a/mod/web/blog/static/style.css b/mod/web/blog/static/style.css
new file mode 100644
index 0000000..fdfd692
--- /dev/null
+++ b/mod/web/blog/static/style.css
@@ -0,0 +1,85 @@
+:root {
+  --bg: #181616;
+  --fg: #c5c9c5;
+  --link: #76946a;
+  --linkhover: #98bb6c;
+}
+
+html {
+  scroll-behavior: smooth;
+  color-scheme: dark;
+}
+
+body {
+  font-family: serif;
+  padding: 0 0.75em;
+  max-width: 42em;
+  margin: auto;
+  background: var(--bg);
+  color: var(--fg);
+}
+
+p {
+  line-height: 1.3em;
+}
+
+th,
+td {
+  padding: 0.2em 0.4em;
+  border: thin solid;
+}
+
+table {
+  border: thin solid;
+  border-collapse: collapse;
+}
+
+article {
+  padding-top: 1em;
+}
+
+footer {
+  margin: 3em auto;
+  text-align: center;
+}
+
+a,
+a:link {
+  color: var(--link);
+}
+
+a:hover {
+  color: var(--linkhover);
+}
+
+a[href^="http"]:where(:not([href*="4kb.net/"]))::after {
+  content: " \21e2";
+}
+
+article img {
+  display: block;
+  margin: 0 auto;
+  max-width: 80%;
+  height: auto;
+  object-fit: contain;
+}
+
+nav {
+  margin-top: 1em;
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  font-family: monospace;
+  font-weight: bold;
+  gap: 8px;
+}
+
+nav div {
+  display: flex;
+  gap: 10px;
+}
+
+pre {
+  padding: 1em;
+  overflow-x: scroll;
+}
diff --git a/mod/web/blog/templates/404.html b/mod/web/blog/templates/404.html
new file mode 100644
index 0000000..a4669df
--- /dev/null
+++ b/mod/web/blog/templates/404.html
@@ -0,0 +1,9 @@
+{% extends "base.html" %}
+
+{% block content %}
+<head>
+  <title>Error 404!</title>
+</head>
+
+404!
+{% endblock content %}
diff --git a/mod/web/blog/templates/base.html b/mod/web/blog/templates/base.html
new file mode 100644
index 0000000..6757d02
--- /dev/null
+++ b/mod/web/blog/templates/base.html
@@ -0,0 +1,26 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <link href="/style.css" rel="stylesheet" />
+    <link rel="preload" href="style.css" as="style" />
+    <title>{% block title %}4kb.net{% endblock title %}</title>
+  </head>
+  <body>
+    <nav>
+      <span>4kb.net</span>
+      <div>
+        <a href="/">Home</a>
+        <a href="/posts">Posts</a>
+        <a href="/log">Log</a>
+      </div>
+    </nav>
+    <hr />
+    <main>{% block content %} {% endblock %}</main>
+    <footer>
+      <hr />
+      <span>&#x00a9; 2024 Kleidi Bujari</span>
+    </footer>
+  </body>
+</html>
diff --git a/mod/web/blog/templates/blog.html b/mod/web/blog/templates/blog.html
new file mode 100644
index 0000000..6c92a07
--- /dev/null
+++ b/mod/web/blog/templates/blog.html
@@ -0,0 +1,22 @@
+{% extends "base.html" %}
+
+{% block content %}
+
+<head>
+  <title>4kb.net</title>
+</head>
+
+<h2>{{ section.title }}</h2>
+
+{{ section.content | safe }}
+
+<ul>
+  {% for page in section.pages %}
+    <li>
+    <span>[{{ page.date }}]</span>
+    <a href="{{ page.permalink | safe }}">{{ page.title }}</a>
+    </li>
+  {% endfor %}
+</ul>
+
+{% endblock content %}
diff --git a/mod/web/blog/templates/index.html b/mod/web/blog/templates/index.html
new file mode 100644
index 0000000..74e9a0f
--- /dev/null
+++ b/mod/web/blog/templates/index.html
@@ -0,0 +1,44 @@
+{% extends "base.html" %} {% block content %}
+
+<h2>welcome!</h2>
+
+<p>
+  I'm a computer engineering undergrad studying in Toronto. This is my personal
+  site where I sometimes publish long form posts on topics I'm interested in, or
+  short "logs" for information I want to remember.
+</p>
+
+<span>Find me on:</span>
+<ul>
+  <li>email: <a href="mailto:mail@4kb.net">mail@4kb.net</a></li>
+  <li>github: <a href="https://github.com/kbujari">kbujari</a></li>
+</ul>
+
+<!--<h3>Recent Posts</h3>-->
+<!---->
+<!--{% set section = get_section(path="posts/_index.md") %}-->
+<!---->
+<!--<ul>-->
+<!--  {% for page in section.pages | slice(end=4) %}-->
+<!--    <li>-->
+<!--    <span>[{{ page.date }}]</span>-->
+<!--    <a href="{{ page.permalink | safe }}">{{ page.title }}</a>-->
+<!--    </li>-->
+<!--  {% endfor %}-->
+<!--</ul>-->
+
+<h3>Recent Logs</h3>
+
+{% set section = get_section(path="log/_index.md") %}
+
+<ul>
+  {% for page in section.pages | slice(end=4) %}
+    <li>
+    <span>[{{ page.date }}]</span>
+    <a href="{{ page.permalink | safe }}">{{ page.title }}</a>
+    </li>
+  {% endfor %}
+</ul>
+
+
+{% endblock content %}
diff --git a/mod/web/blog/templates/post.html b/mod/web/blog/templates/post.html
new file mode 100644
index 0000000..b1981e4
--- /dev/null
+++ b/mod/web/blog/templates/post.html
@@ -0,0 +1,12 @@
+{% extends "base.html" %}
+{% block title%}
+  {{ page.title }} - {{ super() }}
+{% endblock title %}
+
+{% block content %}
+
+<h1 style="text-align: center; margin-top: 1em;">{{ page.title }}</h1>
+<article>
+  {{ page.content | safe }}
+</article>
+{% endblock content %}