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+title = "Posts"
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+redirect_to="/"
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diff --git a/packages/blog/content/posts/deterministic-hostnames.md b/packages/blog/content/posts/deterministic-hostnames.md
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+---
+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/packages/blog/content/posts/nohup.md b/packages/blog/content/posts/nohup.md
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+---
+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/packages/blog/content/posts/stateless-compute-networks.md b/packages/blog/content/posts/stateless-compute-networks.md
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+---
+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/packages/blog/content/posts/vim-compilers.md b/packages/blog/content/posts/vim-compilers.md
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+---
+title: "Neovim's built-in compilers"
+date: "2025-01-17"
+---
+
+Today I learned that neovim's `:make` comes with many
+[backends](https://neovim.io/doc/user/quickfix.html#_6.-selecting-a-compiler)
+already configured.
+This works for checking c/cpp and python files, among other, but I was
+most interested to see [Typst] and [Pandoc] listed as well.
+
+I was looking to add this functionality with a plugin or implementing it
+manually,
+where a document can be compiled on the fly from the editor.
+After setting `:compiler pandoc`,
+generating a pdf is done with `:make pdf`,
+with other pandoc options just appended afterwards if needed.
+
+[typst]: https://typst.app
+[pandoc]: https://github.com/jgm/pandoc