diff options
| author | Paul Buetow <paul@buetow.org> | 2026-02-14 23:21:56 +0200 |
|---|---|---|
| committer | Paul Buetow <paul@buetow.org> | 2026-02-14 23:21:56 +0200 |
| commit | ec46174748351390d95f2464c2e25889a98871f6 (patch) | |
| tree | 2a7a2ff7e6fd82cb5c6e4915f53d9491f34f70d2 /gemfeed | |
| parent | afdd225c06437593c5dd9450563683c8d5dc809f (diff) | |
Update content for gemtext
Diffstat (limited to 'gemfeed')
| -rw-r--r-- | gemfeed/2025-06-22-task-samurai.gmi | 1 | ||||
| -rw-r--r-- | gemfeed/2025-08-05-local-coding-llm-with-ollama.gmi | 1 | ||||
| -rw-r--r-- | gemfeed/2026-02-14-meta-slash-commands-for-prompts-and-context.gmi | 1 | ||||
| -rw-r--r-- | gemfeed/2026-02-14-til-meta-slash-commands-for-ai-workflows.gmi | 84 | ||||
| -rw-r--r-- | gemfeed/atom.xml | 460 | ||||
| -rw-r--r-- | gemfeed/index.gmi | 1 |
6 files changed, 353 insertions, 195 deletions
diff --git a/gemfeed/2025-06-22-task-samurai.gmi b/gemfeed/2025-06-22-task-samurai.gmi index 72479f74..2ab9e3d0 100644 --- a/gemfeed/2025-06-22-task-samurai.gmi +++ b/gemfeed/2025-06-22-task-samurai.gmi @@ -126,7 +126,6 @@ E-Mail your comments to `paul@nospam.buetow.org` :-) Other related posts are: -=> ./2026-02-14-til-meta-slash-commands-for-ai-workflows.gmi 2026-02-14 TIL: Meta slash-commands for reusable AI prompts and context => ./2025-08-05-local-coding-llm-with-ollama.gmi 2025-08-05 Local LLM for Coding with Ollama on macOS => ./2025-06-22-task-samurai.gmi 2025-06-22 Task Samurai: An agentic coding learning experiment (You are currently reading this) diff --git a/gemfeed/2025-08-05-local-coding-llm-with-ollama.gmi b/gemfeed/2025-08-05-local-coding-llm-with-ollama.gmi index 9a3a465c..39987dcf 100644 --- a/gemfeed/2025-08-05-local-coding-llm-with-ollama.gmi +++ b/gemfeed/2025-08-05-local-coding-llm-with-ollama.gmi @@ -421,7 +421,6 @@ E-Mail your comments to `paul@nospam.buetow.org` :-) Other related posts are: -=> ./2026-02-14-til-meta-slash-commands-for-ai-workflows.gmi 2026-02-14 TIL: Meta slash-commands for reusable AI prompts and context => ./2025-08-05-local-coding-llm-with-ollama.gmi 2025-08-05 Local LLM for Coding with Ollama on macOS (You are currently reading this) => ./2025-06-22-task-samurai.gmi 2025-06-22 Task Samurai: An agentic coding learning experiment diff --git a/gemfeed/2026-02-14-meta-slash-commands-for-prompts-and-context.gmi b/gemfeed/2026-02-14-meta-slash-commands-for-prompts-and-context.gmi index 443fbed0..0c088f04 100644 --- a/gemfeed/2026-02-14-meta-slash-commands-for-prompts-and-context.gmi +++ b/gemfeed/2026-02-14-meta-slash-commands-for-prompts-and-context.gmi @@ -213,7 +213,6 @@ Context is what the agent *knows*; commands are what the agent *does*. Both are Other related posts: -=> ./2026-02-14-til-meta-slash-commands-for-ai-workflows.gmi 2026-02-14 TIL: Meta slash-commands for reusable AI prompts and context => ./2026-02-14-meta-slash-commands-for-prompts-and-context.gmi 2026-02-14 Meta slash-commands to manage prompts and context for coding agents (You are currently reading this) => ./2026-02-02-tmux-popup-editor-for-cursor-agent-prompts.gmi 2026-02-02 A tmux popup editor for Cursor Agent CLI prompts diff --git a/gemfeed/2026-02-14-til-meta-slash-commands-for-ai-workflows.gmi b/gemfeed/2026-02-14-til-meta-slash-commands-for-ai-workflows.gmi deleted file mode 100644 index 9059b345..00000000 --- a/gemfeed/2026-02-14-til-meta-slash-commands-for-ai-workflows.gmi +++ /dev/null @@ -1,84 +0,0 @@ -# TIL: Meta slash-commands for reusable AI prompts and context - -> Published at 2026-02-14T14:00:00+02:00 - -Short post in "This week I learned" style: what I tried, why it worked, and how you can replicate it. Format: Problem → Approach → Copy/paste → Result → Gotchas. Full reference for the meta-commands lives in a separate post. - -=> ./2026-02-14-meta-slash-commands-for-prompts-and-context.gmi Full reference: Meta slash-commands to manage prompts and context for coding agents - -## TIL - -### Problem - -When I use a coding agent (Cursor Agent, Claude Code CLI, Ampcode, etc.), I repeat the same requests: "review this function," "explain this error," "add tests for this module," "format this as a blog post." Typing long prompts from scratch is tedious; ad-hoc prompts are easy to forget. I also keep pasting the same background (API conventions, project rules, infra notes) into every session so the agent doesn't guess blindly. - -### Approach - -Treat prompts and context as first-class artefacts: store them as markdown files (one per slash-command or per context) in a dotfiles repo. Use a small set of *meta* slash-commands so the agent itself creates, updates, and deletes these files from the conversation—no hand-editing. Two kinds of artefacts: - -* Commands — Reusable workflows (e.g. review-code, explain-error). Live in `commands/` as `.md` files. -* Context — Reusable background (API guidelines, runbooks, personas). Live in `context/` as `.md` files; you *load* one at session start so the agent has it in mind. - -### Copy/paste - -Minimal workflow: - -``` -/load-context api-guidelines -``` - -Then ask the agent to implement a feature or fix a bug; it already has the guidelines. - -To turn something you just did into a reusable command: - -``` -/create-command review-code -``` - -Full command reference (all meta-commands, parameters, examples): - -=> ./2026-02-14-meta-slash-commands-for-prompts-and-context.gmi Meta slash-commands — full reference - -### Result - -No more retyping long prompts; same prompt library across Cursor Agent, Claude Code CLI, OpenCode, Ampcode. Context is load-on-demand per session instead of pasting walls of text. Everything is versioned in git and synced across machines. - -### Gotchas - -* Requires an agent that supports custom slash-commands (or reading prompt files from disk). -* Context is explicit: you must run `/load-context <name>` at session start; it's not implicit like some "skills" systems. -* A flat directory of commands can grow; if it gets unwieldy, consider grouping by skill or exposing via an MCP server later. - -## Before/After - -* Before: Retyping or pasting long prompts each time; pasting API/project context into every session; prompts scattered and inconsistent across tools. -* After: `/load-context <name>` once per session; `/<command>` for repeatable tasks; commands and context in git, same library across agents. - -## Workflow recipe - -* Steps: (1) Create or update context/commands via meta-commands when you have something worth reusing. (2) Start a session → run `/load-context <name>`. (3) Use slash-commands or ask ad-hoc; agent has background and consistent prompts. -* Tools: Cursor Agent (CLI), Claude Code CLI, OpenCode, Ampcode; markdown in e.g. `~/Notes/Prompts/commands/` and `~/Notes/Prompts/context/`. -* Impact: Saves retyping and keeps prompts consistent; one-time cost is creating the first context/command with the agent. - -## Micro-template (quick reference) - -| Meta-command | Purpose | Good for | -|--------------------|--------------------------------|-------------------------------------------| -| /create-command | Create new slash-command | Turn current or recurring tasks into one | -| /update-command | Edit existing slash-command | Refine after use | -| /delete-command | Remove slash-command file | Clean up unused commands | -| /create-context | Create new context file | Capture project/infra knowledge once | -| /update-context | Edit existing context file | Keep context up to date | -| /delete-context | Remove context file | Remove outdated context | -| /load-context | Load context into conversation | Give agent background before tasks | - -Example usage: `/load-context api-guidelines`, `/create-command review-code`, `/update-command review-code`. Full details and examples in the main post linked above. - -Other related posts: - -=> ./2026-02-14-meta-slash-commands-for-prompts-and-context.gmi 2026-02-14 Meta slash-commands to manage prompts and context for coding agents -=> ./2026-02-02-tmux-popup-editor-for-cursor-agent-prompts.gmi 2026-02-02 A tmux popup editor for Cursor Agent CLI prompts - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -=> ../ Back to the main site diff --git a/gemfeed/atom.xml b/gemfeed/atom.xml index 644c9ec9..82ded3a1 100644 --- a/gemfeed/atom.xml +++ b/gemfeed/atom.xml @@ -1,6 +1,6 @@ <?xml version="1.0" encoding="utf-8"?> <feed xmlns="http://www.w3.org/2005/Atom"> - <updated>2026-02-14T23:11:16+02:00</updated> + <updated>2026-02-14T23:20:12+02:00</updated> <title>foo.zone feed</title> <subtitle>To be in the .zone!</subtitle> <link href="gemini://foo.zone/gemfeed/atom.xml" rel="self" /> @@ -253,109 +253,6 @@ mage test </content> </entry> <entry> - <title>TIL: Meta slash-commands for reusable AI prompts and context</title> - <link href="gemini://foo.zone/gemfeed/2026-02-14-til-meta-slash-commands-for-ai-workflows.gmi" /> - <id>gemini://foo.zone/gemfeed/2026-02-14-til-meta-slash-commands-for-ai-workflows.gmi</id> - <updated>2026-02-14T14:00:00+02:00</updated> - <author> - <name>Paul Buetow aka snonux</name> - <email>paul@dev.buetow.org</email> - </author> - <summary>Short post in 'This week I learned' style: what I tried, why it worked, and how you can replicate it. Format: Problem → Approach → Copy/paste → Result → Gotchas. Full reference for the meta-commands lives in a separate post.</summary> - <content type="xhtml"> - <div xmlns="http://www.w3.org/1999/xhtml"> - <h1 style='display: inline' id='til-meta-slash-commands-for-reusable-ai-prompts-and-context'>TIL: Meta slash-commands for reusable AI prompts and context</h1><br /> -<br /> -<span class='quote'>Published at 2026-02-14T14:00:00+02:00</span><br /> -<br /> -<span>Short post in "This week I learned" style: what I tried, why it worked, and how you can replicate it. Format: Problem → Approach → Copy/paste → Result → Gotchas. Full reference for the meta-commands lives in a separate post.</span><br /> -<br /> -<a class='textlink' href='./2026-02-14-meta-slash-commands-for-prompts-and-context.html'>Full reference: Meta slash-commands to manage prompts and context for coding agents</a><br /> -<br /> -<h2 style='display: inline' id='til'>TIL</h2><br /> -<br /> -<h3 style='display: inline' id='problem'>Problem</h3><br /> -<br /> -<span>When I use a coding agent (Cursor Agent, Claude Code CLI, Ampcode, etc.), I repeat the same requests: "review this function," "explain this error," "add tests for this module," "format this as a blog post." Typing long prompts from scratch is tedious; ad-hoc prompts are easy to forget. I also keep pasting the same background (API conventions, project rules, infra notes) into every session so the agent doesn't guess blindly.</span><br /> -<br /> -<h3 style='display: inline' id='approach'>Approach</h3><br /> -<br /> -<span>Treat prompts and context as first-class artefacts: store them as markdown files (one per slash-command or per context) in a dotfiles repo. Use a small set of *meta* slash-commands so the agent itself creates, updates, and deletes these files from the conversation—no hand-editing. Two kinds of artefacts:</span><br /> -<br /> -<ul> -<li>Commands — Reusable workflows (e.g. review-code, explain-error). Live in <span class='inlinecode'>commands/</span> as <span class='inlinecode'>.md</span> files.</li> -<li>Context — Reusable background (API guidelines, runbooks, personas). Live in <span class='inlinecode'>context/</span> as <span class='inlinecode'>.md</span> files; you *load* one at session start so the agent has it in mind.</li> -</ul><br /> -<h3 style='display: inline' id='copypaste'>Copy/paste</h3><br /> -<br /> -<span>Minimal workflow:</span><br /> -<br /> -<pre> -/load-context api-guidelines -</pre> -<br /> -<span>Then ask the agent to implement a feature or fix a bug; it already has the guidelines.</span><br /> -<br /> -<span>To turn something you just did into a reusable command:</span><br /> -<br /> -<pre> -/create-command review-code -</pre> -<br /> -<span>Full command reference (all meta-commands, parameters, examples):</span><br /> -<br /> -<a class='textlink' href='./2026-02-14-meta-slash-commands-for-prompts-and-context.html'>Meta slash-commands — full reference</a><br /> -<br /> -<h3 style='display: inline' id='result'>Result</h3><br /> -<br /> -<span>No more retyping long prompts; same prompt library across Cursor Agent, Claude Code CLI, OpenCode, Ampcode. Context is load-on-demand per session instead of pasting walls of text. Everything is versioned in git and synced across machines.</span><br /> -<br /> -<h3 style='display: inline' id='gotchas'>Gotchas</h3><br /> -<br /> -<ul> -<li>Requires an agent that supports custom slash-commands (or reading prompt files from disk).</li> -<li>Context is explicit: you must run <span class='inlinecode'>/load-context <name></span> at session start; it's not implicit like some "skills" systems.</li> -<li>A flat directory of commands can grow; if it gets unwieldy, consider grouping by skill or exposing via an MCP server later.</li> -</ul><br /> -<h2 style='display: inline' id='beforeafter'>Before/After</h2><br /> -<br /> -<ul> -<li>Before: Retyping or pasting long prompts each time; pasting API/project context into every session; prompts scattered and inconsistent across tools.</li> -<li>After: <span class='inlinecode'>/load-context <name></span> once per session; <span class='inlinecode'>/<command></span> for repeatable tasks; commands and context in git, same library across agents.</li> -</ul><br /> -<h2 style='display: inline' id='workflow-recipe'>Workflow recipe</h2><br /> -<br /> -<ul> -<li>Steps: (1) Create or update context/commands via meta-commands when you have something worth reusing. (2) Start a session → run <span class='inlinecode'>/load-context <name></span>. (3) Use slash-commands or ask ad-hoc; agent has background and consistent prompts.</li> -<li>Tools: Cursor Agent (CLI), Claude Code CLI, OpenCode, Ampcode; markdown in e.g. <span class='inlinecode'>~/Notes/Prompts/commands/</span> and <span class='inlinecode'>~/Notes/Prompts/context/</span>.</li> -<li>Impact: Saves retyping and keeps prompts consistent; one-time cost is creating the first context/command with the agent.</li> -</ul><br /> -<h2 style='display: inline' id='micro-template-quick-reference'>Micro-template (quick reference)</h2><br /> -<br /> -<span>| Meta-command | Purpose | Good for |</span><br /> -<span>|--------------------|--------------------------------|-------------------------------------------|</span><br /> -<span>| /create-command | Create new slash-command | Turn current or recurring tasks into one |</span><br /> -<span>| /update-command | Edit existing slash-command | Refine after use |</span><br /> -<span>| /delete-command | Remove slash-command file | Clean up unused commands |</span><br /> -<span>| /create-context | Create new context file | Capture project/infra knowledge once |</span><br /> -<span>| /update-context | Edit existing context file | Keep context up to date |</span><br /> -<span>| /delete-context | Remove context file | Remove outdated context |</span><br /> -<span>| /load-context | Load context into conversation | Give agent background before tasks |</span><br /> -<br /> -<span>Example usage: <span class='inlinecode'>/load-context api-guidelines</span>, <span class='inlinecode'>/create-command review-code</span>, <span class='inlinecode'>/update-command review-code</span>. Full details and examples in the main post linked above.</span><br /> -<br /> -<span>Other related posts:</span><br /> -<br /> -<a class='textlink' href='./2026-02-14-meta-slash-commands-for-prompts-and-context.html'>2026-02-14 Meta slash-commands to manage prompts and context for coding agents</a><br /> -<a class='textlink' href='./2026-02-02-tmux-popup-editor-for-cursor-agent-prompts.html'>2026-02-02 A tmux popup editor for Cursor Agent CLI prompts</a><br /> -<br /> -<span>E-Mail your comments to <span class='inlinecode'>paul@nospam.buetow.org</span> :-)</span><br /> -<br /> -<a class='textlink' href='../'>Back to the main site</a><br /> - </div> - </content> - </entry> - <entry> <title>Meta slash-commands to manage prompts and context for coding agents</title> <link href="gemini://foo.zone/gemfeed/2026-02-14-meta-slash-commands-for-prompts-and-context.gmi" /> <id>gemini://foo.zone/gemfeed/2026-02-14-meta-slash-commands-for-prompts-and-context.gmi</id> @@ -591,7 +488,6 @@ mage test <br /> <span>Other related posts:</span><br /> <br /> -<a class='textlink' href='./2026-02-14-til-meta-slash-commands-for-ai-workflows.html'>2026-02-14 TIL: Meta slash-commands for reusable AI prompts and context</a><br /> <a class='textlink' href='./2026-02-14-meta-slash-commands-for-prompts-and-context.html'>2026-02-14 Meta slash-commands to manage prompts and context for coding agents (You are currently reading this)</a><br /> <a class='textlink' href='./2026-02-02-tmux-popup-editor-for-cursor-agent-prompts.html'>2026-02-02 A tmux popup editor for Cursor Agent CLI prompts</a><br /> <br /> @@ -7711,7 +7607,6 @@ content = "{CODE}" <br /> <span>Other related posts are:</span><br /> <br /> -<a class='textlink' href='./2026-02-14-til-meta-slash-commands-for-ai-workflows.html'>2026-02-14 TIL: Meta slash-commands for reusable AI prompts and context</a><br /> <a class='textlink' href='./2025-08-05-local-coding-llm-with-ollama.html'>2025-08-05 Local LLM for Coding with Ollama on macOS (You are currently reading this)</a><br /> <a class='textlink' href='./2025-06-22-task-samurai.html'>2025-06-22 Task Samurai: An agentic coding learning experiment</a><br /> <br /> @@ -10785,7 +10680,6 @@ http://www.gnu.org/software/src-highlite --> <br /> <span>Other related posts are:</span><br /> <br /> -<a class='textlink' href='./2026-02-14-til-meta-slash-commands-for-ai-workflows.html'>2026-02-14 TIL: Meta slash-commands for reusable AI prompts and context</a><br /> <a class='textlink' href='./2025-08-05-local-coding-llm-with-ollama.html'>2025-08-05 Local LLM for Coding with Ollama on macOS</a><br /> <a class='textlink' href='./2025-06-22-task-samurai.html'>2025-06-22 Task Samurai: An agentic coding learning experiment (You are currently reading this)</a><br /> <br /> @@ -18418,4 +18312,356 @@ http://www.gnu.org/software/src-highlite --> </div> </content> </entry> + <entry> + <title>KISS high-availability with OpenBSD</title> + <link href="gemini://foo.zone/gemfeed/2024-04-01-KISS-high-availability-with-OpenBSD.gmi" /> + <id>gemini://foo.zone/gemfeed/2024-04-01-KISS-high-availability-with-OpenBSD.gmi</id> + <updated>2024-03-30T22:12:56+02:00</updated> + <author> + <name>Paul Buetow aka snonux</name> + <email>paul@dev.buetow.org</email> + </author> + <summary>I have always wanted a highly available setup for my personal websites. I could have used off-the-shelf hosting solutions or hosted my sites in an AWS S3 bucket. I have used technologies like (in unsorted and slightly unrelated order) BGP, LVS/IPVS, ldirectord, Pacemaker, STONITH, scripted VIP failover via ARP, heartbeat, heartbeat2, Corosync, keepalived, DRBD, and commercial F5 Load Balancers for high availability at work. </summary> + <content type="xhtml"> + <div xmlns="http://www.w3.org/1999/xhtml"> + <h1 style='display: inline' id='kiss-high-availability-with-openbsd'>KISS high-availability with OpenBSD</h1><br /> +<br /> +<span class='quote'>Published at 2024-03-30T22:12:56+02:00</span><br /> +<br /> +<span>I have always wanted a highly available setup for my personal websites. I could have used off-the-shelf hosting solutions or hosted my sites in an AWS S3 bucket. I have used technologies like (in unsorted and slightly unrelated order) BGP, LVS/IPVS, ldirectord, Pacemaker, STONITH, scripted VIP failover via ARP, heartbeat, heartbeat2, Corosync, keepalived, DRBD, and commercial F5 Load Balancers for high availability at work. </span><br /> +<br /> +<span>But still, my personal sites were never highly available. All those technologies are great for professional use, but I was looking for something much more straightforward for my personal space - something as KISS (keep it simple and stupid) as possible.</span><br /> +<br /> +<span>It would be fine if my personal website wasn't highly available, but the geek in me wants it anyway.</span><br /> +<br /> +<span class='quote'>PS: ASCII-art below reflects an OpenBSD under-water world with all the tools available in the base system.</span><br /> +<br /> +<pre> +Art by Michael J. Penick (mod. by Paul B.) + ACME-sky + __________ + / nsd tower\ ( + /____________\ (\) awk-ward + |:_:_:_:_:_| )) plant + |_:_,--.:_:| dig-bubble (\// ) + |:_:|__|_:_| relayd-castle _ ) )) (( + _ |_ _ :_:| _ _ _ (_) (((( /)\` + | |_| |_| | _| | |_| |_| | o \\)) (( ( + \_:_:_:_:/|_|_|_|\:_:_:_:_/ . (( )))) + |_,-._:_:_:_:_:_:_:_.-,_| )) ((// + |:|_|:_:_:,---,:_:_:|_|:| ,-. )/ + |_:_:_:_,'puffy `,_:_:_:_| _ o ,;'))(( + |:_:_:_/ _ | _ \_:_:_:| (_O (( )) +_____|_:_:_| (o)-(o) |_:_:_|--'`-. ,--. ksh under-water (((\'/ + ', ;|:_:_:| -( .-. )- |:_:_:| ', ; `--._\ /,---.~ goat \`)) +. ` |_:_:_| \`-'/ |_:_:_|. ` . ` /()\.__( ) .,-----'`-\(( sed-root + ', ;|:_:_:| `-' |:_:_:| ', ; ', ; `--'| \ ', ; ', ; ',')).,-- +. ` MJP ` . ` . ` . ` . httpd-soil ` . . ` . ` . ` . ` . ` + ', ; ', ; ', ; ', ; ', ; ', ; ', ; ', ; ', ; ', ; ', ; ', ; ', ; ', ; + +</pre> +<br /> +<h2 style='display: inline' id='table-of-contents'>Table of Contents</h2><br /> +<br /> +<ul> +<li><a href='#kiss-high-availability-with-openbsd'>KISS high-availability with OpenBSD</a></li> +<li>⇢ <a href='#my-auto-failover-requirements'>My auto-failover requirements</a></li> +<li>⇢ <a href='#my-ha-solution'>My HA solution</a></li> +<li>⇢ ⇢ <a href='#only-openbsd-base-installation-required'>Only OpenBSD base installation required</a></li> +<li>⇢ ⇢ <a href='#fairly-cheap-and-geo-redundant'>Fairly cheap and geo-redundant</a></li> +<li>⇢ ⇢ <a href='#failover-time-and-split-brain'>Failover time and split-brain</a></li> +<li>⇢ ⇢ <a href='#failover-support-for-multiple-protocols'>Failover support for multiple protocols</a></li> +<li>⇢ ⇢ <a href='#let-s-encrypt-tls-certificates'>Let's encrypt TLS certificates</a></li> +<li>⇢ ⇢ <a href='#monitoring'>Monitoring</a></li> +<li>⇢ ⇢ <a href='#rex-automation'>Rex automation</a></li> +<li>⇢ <a href='#more-ha'>More HA</a></li> +</ul><br /> +<h2 style='display: inline' id='my-auto-failover-requirements'>My auto-failover requirements</h2><br /> +<br /> +<ul> +<li>Be OpenBSD-based (I prefer OpenBSD because of the cleanliness and good documentation) and rely on as few external packages as possible. </li> +<li>Don't rely on the hottest and newest tech (don't want to migrate everything to a new and fancier technology next month already!).</li> +<li>It should be reasonably cheap. I want to avoid paying a premium for floating IPs or fancy Elastic Load Balancers.</li> +<li>It should be geo-redundant. </li> +<li>It's fine if my sites aren't reachable for five or ten minutes every other month. Due to their static nature, I don't care if there's a split-brain scenario where some requests reach one server and other requests reach another server.</li> +<li>Failover should work for both HTTP/HTTPS and Gemini protocols. My self-hosted MTAs and DNS servers should also be highly available.</li> +<li>Let's Encrypt TLS certificates should always work (before and after a failover).</li> +<li>Have good monitoring in place so I know when a failover was performed and when something went wrong with the failover.</li> +<li>Don't configure everything manually. The configuration should be automated and reproducible.</li> +</ul><br /> +<h2 style='display: inline' id='my-ha-solution'>My HA solution</h2><br /> +<br /> +<h3 style='display: inline' id='only-openbsd-base-installation-required'>Only OpenBSD base installation required</h3><br /> +<br /> +<span>My HA solution for Web and Gemini is based on DNS (OpenBSD's <span class='inlinecode'>nsd</span>) and a simple shell script (OpenBSD's <span class='inlinecode'>ksh</span> and some little <span class='inlinecode'>sed</span> and <span class='inlinecode'>awk</span> and <span class='inlinecode'>grep</span>). All software used here is part of the OpenBSD base system and no external package needs to be installed - OpenBSD is a complete operating system.</span><br /> +<br /> +<a class='textlink' href='https://man.OpenBSD.org/nsd.8'>https://man.OpenBSD.org/nsd.8</a><br /> +<a class='textlink' href='https://man.OpenBSD.org/ksh'>https://man.OpenBSD.org/ksh</a><br /> +<a class='textlink' href='https://man.OpenBSD.org/awk'>https://man.OpenBSD.org/awk</a><br /> +<a class='textlink' href='https://man.OpenBSD.org/sed'>https://man.OpenBSD.org/sed</a><br /> +<a class='textlink' href='https://man.OpenBSD.org/dig'>https://man.OpenBSD.org/dig</a><br /> +<a class='textlink' href='https://man.OpenBSD.org/ftp'>https://man.OpenBSD.org/ftp</a><br /> +<a class='textlink' href='https://man.OpenBSD.org/cron'>https://man.OpenBSD.org/cron</a><br /> +<br /> +<span>I also used the <span class='inlinecode'>dig</span> (for DNS checks) and <span class='inlinecode'>ftp</span> (for HTTP/HTTPS checks) programs. </span><br /> +<br /> +<span>The DNS failover is performed automatically between the two OpenBSD VMs involved (my setup doesn't require any quorum for a failover, so there isn't a need for a 3rd VM). The <span class='inlinecode'>ksh</span> script, executed once per minute via CRON (on both VMs), performs a health check to determine whether the current master node is available. If the current master isn't available (no HTTP response as expected), a failover is performed to the standby VM: </span><br /> +<br /> +<!-- Generator: GNU source-highlight 3.1.9 +by Lorenzo Bettini +http://www.lorenzobettini.it +http://www.gnu.org/software/src-highlite --> +<pre><i><font color="silver">#!/bin/ksh</font></i> + +ZONES_DIR=/var/nsd/zones/master/ +DEFAULT_MASTER=fishfinger.buetow.org +DEFAULT_STANDBY=blowfish.buetow.org + +determine_master_and_standby () { + <b><u><font color="#000000">local</font></u></b> master=$DEFAULT_MASTER + <b><u><font color="#000000">local</font></u></b> standby=$DEFAULT_STANDBY + + . + . + . + + <b><u><font color="#000000">local</font></u></b> -i health_ok=<font color="#000000">1</font> + <b><u><font color="#000000">if</font></u></b> ! ftp -<font color="#000000">4</font> -o - https://$master/index.txt | grep -q <font color="#808080">"Welcome to $master"</font>; <b><u><font color="#000000">then</font></u></b> + echo <font color="#808080">"https://$master/index.txt IPv4 health check failed"</font> + health_ok=<font color="#000000">0</font> + <b><u><font color="#000000">elif</font></u></b> ! ftp -<font color="#000000">6</font> -o - https://$master/index.txt | grep -q <font color="#808080">"Welcome to $master"</font>; <b><u><font color="#000000">then</font></u></b> + echo <font color="#808080">"https://$master/index.txt IPv6 health check failed"</font> + health_ok=<font color="#000000">0</font> + <b><u><font color="#000000">fi</font></u></b> + <b><u><font color="#000000">if</font></u></b> [ $health_ok -eq <font color="#000000">0</font> ]; <b><u><font color="#000000">then</font></u></b> + <b><u><font color="#000000">local</font></u></b> tmp=$master + master=$standby + standby=$tmp + <b><u><font color="#000000">fi</font></u></b> + + . + . + . +} +</pre> +<br /> +<span>The failover scripts looks for the <span class='inlinecode'> ; Enable failover</span> string in the DNS zone files and swaps the <span class='inlinecode'>A</span> and <span class='inlinecode'>AAAA</span> records of the DNS entries accordingly:</span><br /> +<br /> +<!-- Generator: GNU source-highlight 3.1.9 +by Lorenzo Bettini +http://www.lorenzobettini.it +http://www.gnu.org/software/src-highlite --> +<pre>fishfinger$ grep failover /var/nsd/zones/master/foo.zone.zone + <font color="#000000">300</font> IN A <font color="#000000">46.23</font>.<font color="#000000">94.99</font> ; Enable failover + <font color="#000000">300</font> IN AAAA 2a03:<font color="#000000">6000</font>:6f67:<font color="#000000">624</font>::<font color="#000000">99</font> ; Enable failover +www <font color="#000000">300</font> IN A <font color="#000000">46.23</font>.<font color="#000000">94.99</font> ; Enable failover +www <font color="#000000">300</font> IN AAAA 2a03:<font color="#000000">6000</font>:6f67:<font color="#000000">624</font>::<font color="#000000">99</font> ; Enable failover +standby <font color="#000000">300</font> IN A <font color="#000000">23.88</font>.<font color="#000000">35.144</font> ; Enable failover +standby <font color="#000000">300</font> IN AAAA 2a01:4f8:c17:20f1::<font color="#000000">42</font> ; Enable failover +</pre> +<br /> +<!-- Generator: GNU source-highlight 3.1.9 +by Lorenzo Bettini +http://www.lorenzobettini.it +http://www.gnu.org/software/src-highlite --> +<pre>transform () { + sed -E <font color="#808080">'</font> +<font color="#808080"> /IN A .*; Enable failover/ {</font> +<font color="#808080"> /^standby/! {</font> +<font color="#808080"> s/^(.*) 300 IN A (.*) ; (.*)/</font>\1<font color="#808080"> 300 IN A '</font>$(cat /var/nsd/run/master_a)<font color="#808080">' ; </font>\3<font color="#808080">/;</font> +<font color="#808080"> }</font> +<font color="#808080"> /^standby/ {</font> +<font color="#808080"> s/^(.*) 300 IN A (.*) ; (.*)/</font>\1<font color="#808080"> 300 IN A '</font>$(cat /var/nsd/run/standby_a)<font color="#808080">' ; </font>\3<font color="#808080">/;</font> +<font color="#808080"> }</font> +<font color="#808080"> }</font> +<font color="#808080"> /IN AAAA .*; Enable failover/ {</font> +<font color="#808080"> /^standby/! {</font> +<font color="#808080"> s/^(.*) 300 IN AAAA (.*) ; (.*)/</font>\1<font color="#808080"> 300 IN AAAA '</font>$(cat /var/nsd/run/master_aaaa)<font color="#808080">' ; </font>\3<font color="#808080">/;</font> +<font color="#808080"> }</font> +<font color="#808080"> /^standby/ {</font> +<font color="#808080"> s/^(.*) 300 IN AAAA (.*) ; (.*)/</font>\1<font color="#808080"> 300 IN AAAA '</font>$(cat /var/nsd/run/standby_aaaa)<font color="#808080">' ; </font>\3<font color="#808080">/;</font> +<font color="#808080"> }</font> +<font color="#808080"> }</font> +<font color="#808080"> / ; serial/ {</font> +<font color="#808080"> s/^( +) ([0-9]+) .*; (.*)/</font>\1<font color="#808080"> '</font>$(date +%s)<font color="#808080">' ; </font>\3<font color="#808080">/;</font> +<font color="#808080"> }</font> +<font color="#808080"> '</font> +} +</pre> +<br /> +<span>After the failover, the script reloads <span class='inlinecode'>nsd</span> and performs a sanity check to see if DNS still works. If not, a rollback will be performed:</span><br /> +<br /> +<!-- Generator: GNU source-highlight 3.1.9 +by Lorenzo Bettini +http://www.lorenzobettini.it +http://www.gnu.org/software/src-highlite --> +<pre><i><font color="silver">#! Race condition !#</font></i> + +<b><u><font color="#000000">if</font></u></b> [ -f $zone_file.bak ]; <b><u><font color="#000000">then</font></u></b> + mv $zone_file.bak $zone_file +<b><u><font color="#000000">fi</font></u></b> + +cat $zone_file | transform > $zone_file.new.tmp + +grep -v <font color="#808080">' ; serial'</font> $zone_file.new.tmp > $zone_file.new.noserial.tmp +grep -v <font color="#808080">' ; serial'</font> $zone_file > $zone_file.old.noserial.tmp + +echo <font color="#808080">"Has zone $zone_file changed?"</font> +<b><u><font color="#000000">if</font></u></b> diff -u $zone_file.old.noserial.tmp $zone_file.new.noserial.tmp; <b><u><font color="#000000">then</font></u></b> + echo <font color="#808080">"The zone $zone_file hasn't changed"</font> + rm $zone_file.*.tmp + <b><u><font color="#000000">return</font></u></b> <font color="#000000">0</font> +<b><u><font color="#000000">fi</font></u></b> + +cp $zone_file $zone_file.bak +mv $zone_file.new.tmp $zone_file +rm $zone_file.*.tmp +echo <font color="#808080">"Reloading nsd"</font> +nsd-control reload + +<b><u><font color="#000000">if</font></u></b> ! zone_is_ok $zone; <b><u><font color="#000000">then</font></u></b> + echo <font color="#808080">"Rolling back $zone_file changes"</font> + cp $zone_file $zone_file.invalid + mv $zone_file.bak $zone_file + echo <font color="#808080">"Reloading nsd"</font> + nsd-control reload + zone_is_ok $zone + <b><u><font color="#000000">return</font></u></b> <font color="#000000">3</font> +<b><u><font color="#000000">fi</font></u></b> + +<b><u><font color="#000000">for</font></u></b> cleanup <b><u><font color="#000000">in</font></u></b> invalid bak; <b><u><font color="#000000">do</font></u></b> + <b><u><font color="#000000">if</font></u></b> [ -f $zone_file.$cleanup ]; <b><u><font color="#000000">then</font></u></b> + rm $zone_file.$cleanup + <b><u><font color="#000000">fi</font></u></b> +<b><u><font color="#000000">done</font></u></b> + +echo <font color="#808080">"Failover of zone $zone to $MASTER completed"</font> +<b><u><font color="#000000">return</font></u></b> <font color="#000000">1</font> +</pre> +<br /> +<span>A non-zero return code (here, 3 when a rollback and 1 when a DNS failover was performed) will cause CRON to send an E-Mail with the whole script output.</span><br /> +<br /> +<span>The authorative nameserver for my domains runs on both VMs, and both are configured to be a "master" DNS server so that they have their own individual zone files, which can be changed independently. Otherwise, my setup wouldn't work. The side effect is that under a split-brain scenario (both VMs cannot see each other), both would promote themselves to master via their local DNS entries. More about that later, but that's fine in my use case.</span><br /> +<br /> +<span>Check out the whole script here:</span><br /> +<br /> +<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/frontends/scripts/dns-failover.ksh'>dns-failover.ksh</a><br /> +<br /> +<h3 style='display: inline' id='fairly-cheap-and-geo-redundant'>Fairly cheap and geo-redundant</h3><br /> +<br /> +<span>I am renting two small OpenBSD VMs: One at OpenBSD Amsterdam and the other at Hetzner Cloud. So, both VMs are hosted at another provider, in different IP subnets, and in different countries (the Netherlands and Germany).</span><br /> +<br /> +<a class='textlink' href='https://OpenBSD.Amsterdam'>https://OpenBSD.Amsterdam</a><br /> +<a class='textlink' href='https://www.Hetzner.cloud'>https://www.Hetzner.cloud</a><br /> +<br /> +<span>I only have a little traffic on my sites. I could always upload the static content to AWS S3 if I suddenly had to. But this will never be required.</span><br /> +<br /> +<span>A DNS-based failover is cheap, as there isn't any BGP or fancy load balancer to pay for. Small VMs also cost less than millions.</span><br /> +<br /> +<h3 style='display: inline' id='failover-time-and-split-brain'>Failover time and split-brain</h3><br /> +<br /> +<span>A DNS failover doesn't happen immediately. I've configured a DNS TTL of <span class='inlinecode'>300</span> seconds, and the failover script checks once per minute whether to perform a failover or not. So, in total, a failover can take six minutes (not including other DNS caching servers somewhere in the interweb, but that's fine - eventually, all requests will resolve to the new master after a failover).</span><br /> +<br /> +<span>A split-brain scenario between the old master and the new master might happen. That's OK, as my sites are static, and there's no database to synchronise other than HTML, CSS, and images when the site is updated.</span><br /> +<br /> +<h3 style='display: inline' id='failover-support-for-multiple-protocols'>Failover support for multiple protocols</h3><br /> +<br /> +<span>With the DNS failover, HTTP, HTTPS, and Gemini protocols are failovered. This works because all domain virtual hosts are configured on either VM's <span class='inlinecode'>httpd</span> (OpenBSD's HTTP server) and <span class='inlinecode'>relayd</span> (it's also part of OpenBSD and I use it to TLS offload the Gemini protocol). So, both VMs accept requests for all the hosts. It's just a matter of the DNS entries, which VM receives the requests.</span><br /> +<br /> +<a class='textlink' href='https://man.OpenBSD.org/httpd.8'>https://man.OpenBSD.org/httpd.8</a><br /> +<a class='textlink' href='https://man.OpenBSD.org/relayd.8'>https://man.OpenBSD.org/relayd.8</a><br /> +<br /> +<span>For example, the master is responsible for the <span class='inlinecode'>https://www.foo.zone</span> and <span class='inlinecode'>https://foo.zone</span> hosts, whereas the standby can be reached via <span class='inlinecode'>https://standby.foo.zone</span> (port 80 for plain HTTP works as well). The same principle is followed with all the other hosts, e.g. <span class='inlinecode'>irregular.ninja</span>, <span class='inlinecode'>paul.buetow.org</span> and so on. The same applies to my Gemini capsules for <span class='inlinecode'>gemini://foo.zone</span>, <span class='inlinecode'>gemini://standby.foo.zone</span>, <span class='inlinecode'>gemini://paul.buetow.org</span> and <sp |