Maxwell MorrisandClaude Sonnet 5
110bd97cca
Every node is now both control plane and worker, giving real tolerance for losing any single machine (etcd quorum needs 3, not 1). A Talos VIP gives the cluster one stable address regardless of which node answers. Also pre-installs Longhorn for replicated storage, backed by a Talos UserVolume on each node's second disk (>=900GB, non-system) rather than the default path — mirroring the pattern from the homescale repo. Docs renumbered to make room for 06-longhorn.md; checklist, glossary, network map, and CLAUDE.md's guided-bootstrap instructions updated to match, including asking the user for node IPs, VIP, and disk info before generating any Talos config. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
95 lines
3.6 KiB
Markdown
95 lines
3.6 KiB
Markdown
# 07 — Your first change
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Everything so far proved Argo CD can deploy what's in Git. This doc proves
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the part that actually matters day to day: changing what's in Git and
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watching the cluster follow, with no `kubectl apply` from you at all.
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## Steps
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1. Open [`apps/demo/configmap.yaml`](../apps/demo/configmap.yaml) and edit
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the HTML — change the `<h1>` text to something of your own.
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2. Commit and push, exactly like any other Git change:
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```sh
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git add apps/demo/configmap.yaml
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git commit -m "Personalize the demo page"
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git push
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```
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3. By default, Argo CD polls Git every three minutes, so your change will
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show up on its own — but you can force it immediately:
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```sh
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argocd app sync demo
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```
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4. Watch it happen:
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```sh
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argocd app get demo
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```
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You'll see Argo CD detect that the live ConfigMap no longer matches
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Git, and correct it.
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5. Refresh `http://<your-demo-app-IP>` (the MetalLB address you gave it in
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[`docs/05-metallb.md`](05-metallb.md)). Your new text should be there. Note
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that nginx itself never restarted — Kubernetes noticed the mounted
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ConfigMap changed and updated the file inside the running Pod's
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filesystem automatically. (This is specific to volume-mounted
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ConfigMaps; not every kind of change is this seamless — a change to the
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Deployment's image, for instance, does trigger a Pod restart, by
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design.)
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Give it up to a minute if the page doesn't look different yet.
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`argocd app get demo` shows the *ConfigMap object* updating right away,
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but kubelet — the agent on the node that actually keeps a Pod's mounted
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files in sync — only re-checks mounted ConfigMaps on its own periodic
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cycle, not instantly. A blank refresh isn't a sign anything's wrong;
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give it a moment and refresh again.
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## What just proved itself
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You changed a file, pushed it, and never touched the cluster directly. That
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gap between "commit" and "running" being closed automatically, without you
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doing the applying, *is* GitOps. Everything from here on — every future app
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you add — works exactly this way: edit, commit, push, done.
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## Try triggering self-healing
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Optional, but worth seeing once. Reintroduce drift by hand:
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```sh
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kubectl -n demo patch configmap demo-page --type merge \
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-p '{"data":{"index.html":"<h1>hand-edited, not from Git</h1>"}}'
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```
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Watch the ConfigMap *object* itself, not the browser, for this one — it's
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the more reliable way to see the timing: Argo CD's self-heal typically
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reverts a hand-edit within a second or two, which is faster than kubelet's
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own mount-sync cycle usually gets around to reflecting a change in the
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served page at all (see the note above). Check the object directly:
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```sh
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kubectl -n demo get configmap demo-page -o jsonpath='{.data.index\.html}'
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```
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Run that once right after the `patch` above and you may catch your
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hand-edited text; run it again a couple of seconds later and it'll already
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be back to what's in Git — with no action from you. That's `selfHeal:
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true` from `apps/demo.yaml` in action. See
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[`docs/00-what-is-all-this.md`](00-what-is-all-this.md#the-reconciliation-loop)
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for the loop that just ran.
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> **Ask Claude:** "if selfHeal is on, how would I ever safely debug
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> something by changing it live in the cluster first?" — a real question
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> people run into once this clicks, and worth understanding before you hit
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> it for real.
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## Checklist
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- [ ] Edited `apps/demo/configmap.yaml`, committed, pushed
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- [ ] Saw the change reflected in `argocd app get demo`
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- [ ] Saw the new text in the browser
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- [ ] (Optional) Watched self-healing revert a hand-made change
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Continue to [`docs/08-adding-new-apps.md`](08-adding-new-apps.md) to add
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something of your own.
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