courses I and II wired: cascade + up-down split animations, fleet-labels move in VI, the library, C-II hero + manifest

build.sh

@@ -10,11 +10,13 @@ trap 'printf "build failed at line %s\n" "$LINENO" >&2' ERR
 here="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
 cd -- "$here"
 
-for f in pilot/arc.tpl.html pilot/manifest-gitops.json pilot/manifest-supply.json \
+for f in pilot/arc.tpl.html pilot/manifest-docker.json pilot/manifest-cluster.json \
+         pilot/manifest-gitops.json pilot/manifest-supply.json \
          pilot/manifest-helm.json gsap.min.js st.min.js \
          assets/dist/course-VI-gitops.webp assets/dist/course-VII-supply-chain.webp \
          assets/dist/course-VIII-helm-press.webp assets/dist/appendix-dependency-ledger.webp \
-         assets/dist/delivery-flow.svg; do
+         assets/dist/delivery-flow.svg assets/dist/docker-layers.webp \
+         assets/dist/course-II-cluster.webp; do
   [[ -f "$f" ]] || { printf 'missing source: %s\n' "$f" >&2; exit 1; }
 done
 

pilot/arc.tpl.html

@@ -1,20 +1,114 @@
 <header class="masthead">
   <p class="eyebrow">The Exploded Cluster &middot; The Delivery Arc</p>
   <h1>The machine was the easy part.<br><em>Now watch how software reaches it.</em></h1>
-  <p class="lede">Three courses on the toolchain around the cluster: how change travels, how images
+  <p class="lede">The foundations first - what an image is, what a cluster is - then the toolchain
-    are named, and how one definition serves a fleet. Scroll, and each machine comes apart.</p>
+    that delivers to them: how change travels, how images are named, and how one definition serves
+    a fleet. Scroll, and each machine comes apart.</p>
   <p class="scrollcue" aria-hidden="true">scroll<span></span></p>
 </header>
 
 <aside class="key" aria-label="reading key">
   <p class="kt">Reading key &middot; this page stands alone - anything it leans on is listed here</p>
   <ul>
-    <li><b>C-I</b><span>Docker: an image is a stack of frozen diffs. Referenced by Course VII.</span><i>course lands here soon</i></li>
+    <li><b>C-I</b><span>Docker: an image is a stack of frozen diffs. Referenced by Course VII.</span><a href="#c1">on this page</a></li>
-    <li><b>C-II</b><span>Kubernetes: a cluster is a promise - the reconciliation loop. Referenced by Courses VI and VIII.</span><i>course lands here soon</i></li>
+    <li><b>C-II</b><span>Kubernetes: a cluster is a promise - the reconciliation loop. Referenced by Courses VI and VIII.</span><a href="#c2">on this page</a></li>
     <li><b>BLOG</b><span>Consistency by construction beats consistency by discipline - Course VIII's contexts move, lived on a real fleet.</span><a href="https://www.bztmon.com/blog/one-value-many-enforcers/">read it on bztmon.com</a></li>
   </ul>
 </aside>
 
+<!-- ============ COURSE I ============ -->
+<section class="course" id="c1" data-scene="docker" aria-labelledby="c1h">
+  <header class="chead">
+    <p class="eyebrow">Course I &middot; Docker</p>
+    <h2 id="c1h" class="thesis">An image is not a box.<br><em>It is a stack of frozen diffs.</em></h2>
+    <p class="lede">Scroll, and the thing you keep calling "a container image" comes apart in your
+      hands. Four layers. Each one only stores what changed from the layer under it - and here they
+      rise one at a time, bottom up.</p>
+  </header>
+  <div class="pin">
+    <div class="viewport">
+      <figure class="scene">
+        <img class="flat" src="__HERO_DOCKER__"
+             alt="An exploded isometric view of a container image: four stacked slabs floating
+                  apart - a heavy metal base, a circuit-etched dependency layer, a magenta-traced
+                  code layer, and a thin frosted-glass writable layer on top.">
+      </figure>
+      <ol class="legend"></ol>
+    </div>
+    <div class="bench"></div>
+  </div>
+  <div class="prose">
+    <h3>A stack of diffs wearing a name</h3>
+    <p>An image is not a copy of a machine. It is a stack of read-only layers, each recording only
+      what changed from the one beneath. The base OS is pulled once and shared by every image on
+      the host; your dependencies sit on it; your code - usually the smallest layer, always the
+      most volatile - sits above that; and the writable layer is created fresh per container and
+      thrown away when it dies. Nothing you write there survives.</p>
+    <p class="sayit">Change a layer and every layer above it must be rebuilt.</p>
+    <h3>The order is a caching decision</h3>
+    <p>The builder caches layer by layer, and a cached layer survives only while everything
+      beneath it is unchanged. Put <span class="mono">COPY . .</span> above your dependency
+      install and you have told the builder to throw the dependency cache away every time one
+      line of code changes. Dependencies first, code last - a Dockerfile is a cache policy that
+      happens to build software.</p>
+    <p class="fieldnote"><b>Field note.</b> A rebuild that takes twenty minutes and one that
+      takes twenty seconds are usually the same Dockerfile with the lines swapped.</p>
+    <p class="closeline">This stack explains the whole ecosystem above it: sharing explains why
+      pulls are fast, immutability explains why a digest can name the exact bytes (Course VII),
+      and the throwaway top layer explains why state needs volumes. One idea - frozen diffs -
+      all the way down.</p>
+    <p class="reads"><b>Pre-reads:</b> none - start here
+      &ensp;<b>Further:</b> <a href="https://docs.docker.com/get-started/">Docker get-started</a> &middot;
+      <a href="https://docs.docker.com/build/">Docker build + layers</a></p>
+  </div>
+</section>
+
+<!-- ============ COURSE II ============ -->
+<section class="course" id="c2" data-scene="cluster" aria-labelledby="c2h">
+  <header class="chead">
+    <p class="eyebrow">Course II &middot; Kubernetes</p>
+    <h2 id="c2h" class="thesis">A cluster is a promise,<br><em>not a place.</em></h2>
+    <p class="lede">You never tell Kubernetes <i>how</i> to run your app. You describe what you
+      want - declarative intent - and the cluster works, forever, to make it true. Scroll, and
+      the formation splits: the half that decides rises, the halves that run spread below.</p>
+  </header>
+  <div class="pin">
+    <div class="viewport">
+      <figure class="scene">
+        <img class="flat" src="__HERO_CLUSTER__"
+             alt="A small fleet mid-explosion: one wide command slab with a strong cyan seam
+                  hovering above a row of three identical worker blocks, all floating apart in
+                  the void.">
+      </figure>
+      <ol class="legend"></ol>
+    </div>
+    <div class="bench"></div>
+  </div>
+  <div class="prose">
+    <h3>Desired against actual, forever</h3>
+    <p>The habit underneath everything: the <b>reconciliation loop</b> - compare desired state
+      against actual state, fix the difference, repeat. That <span class="mono">kubectl apply</span>
+      didn't launch anything; it filed paperwork. The machine took it from there, and it never
+      stops taking it from there: kill a pod and it returns, not because something noticed the
+      crash but because the loop noticed the difference.</p>
+    <p class="sayit">Kubernetes doesn't run your app - it reconciles it.</p>
+    <h3>One half decides, one half runs</h3>
+    <p>The split in the scene is the split that makes everything else possible: a <b>control
+      plane</b> that decides - holds the truth, schedules, reconciles - and <b>worker nodes</b>
+      that run pods. The workers are deliberately interchangeable: identical, replaceable, cattle
+      from day one. Authority does not live where the work happens.</p>
+    <p class="fieldnote"><b>Field note.</b> If you are SSHing into nodes to "fix" things, you
+      are arm-wrestling the reconciler - and it does not get tired. Change the desired state
+      instead.</p>
+    <p class="closeline">Everything the delivery arc teaches from Course VI onward is this loop
+      wearing bigger clothes - git as the desired state, whole fleets as reconciled objects.
+      Learn the promise once; it repeats all the way up.</p>
+    <p class="reads"><b>Pre-reads:</b> C-I
+      &ensp;<b>Further:</b> <a href="https://kubernetes.io/docs/concepts/overview/">Kubernetes overview</a> &middot;
+      <a href="https://kubernetes.io/docs/concepts/architecture/">cluster architecture</a></p>
+  </div>
+</section>
+
 <!-- ============ COURSE VI ============ -->
 <section class="course" id="c6" data-scene="gitops" aria-labelledby="c6h">
   <header class="chead">
@@ -55,6 +149,15 @@
     <p class="fieldnote"><b>Field note.</b> Fighting the reconciler over SSH is arm-wrestling a
       machine that does not get tired - C-II's warning, now with a face. The fix is always
       upstream, in git.</p>
+    <h3>At fleet scale, the label is the deploy button</h3>
+    <p>Run many OpenShift clusters under a hub - RHACM, with edge clusters arriving through
+      zero-touch provisioning - and nobody applies apps to clusters by hand. Each app carries a
+      <b>Placement</b> that selects cluster <b>labels</b>; the hub matches placements against the
+      labels a cluster wears, and the chosen cluster pulls its assignment. Labelling the cluster
+      <i>is</i> the deploy action: attach the label and the app follows, remove it and the app
+      leaves. The same pull model as above, one level bigger - a cluster's labels are its
+      entitlements, reconciled like everything else.</p>
+    <p class="sayit">Label the cluster; the app follows.</p>
     <h3>The one thing git never holds</h3>
     <p>Git holds everything except secrets - a secret in git is published, forever, to everyone who
       ever clones. So the pattern splits the reference from the value: git carries an ExternalSecret
@@ -275,6 +378,40 @@
   </figure>
 </section>
 
+<section class="course" id="library" aria-labelledby="libh">
+  <header class="chead">
+    <p class="eyebrow">The library</p>
+    <h2 id="libh" class="thesis">Go to <em>the sources.</em></h2>
+    <p class="lede">Every technology this site teaches, one sentence each, official documentation
+      only.</p>
+  </header>
+  <ul class="library">
+    <li><b>Kubernetes</b><span>The container orchestrator underneath everything here: declarative
+      state, the reconciliation loop, pods, services and the machinery that keeps promises.</span>
+      <a href="https://kubernetes.io/docs/">kubernetes.io/docs</a></li>
+    <li><b>Helm</b><span>The package manager and Go-template engine that turns one chart plus a
+      per-cluster values file into the rendered manifests a cluster actually runs.</span>
+      <a href="https://helm.sh/docs/">helm.sh/docs</a></li>
+    <li><b>Red Hat OpenShift</b><span>Kubernetes as an opinionated, supported distribution -
+      SCCs, Routes and Operators, plus the fleet tooling (RHACM, zero-touch provisioning) that
+      assigns apps to clusters by label.</span>
+      <a href="https://docs.redhat.com/en/documentation/openshift_container_platform">docs.redhat.com</a></li>
+    <li><b>Argo CD</b><span>The GitOps reconciler that watches a repository and keeps the cluster
+      converged on what it finds there - the pull model that means nothing ever pushes to
+      production.</span>
+      <a href="https://argo-cd.readthedocs.io/">argo-cd.readthedocs.io</a></li>
+    <li><b>GitHub Actions</b><span>CI that builds and tests on every push - in this flow it makes
+      artefacts and proposes changes, and never holds a credential that can touch a cluster.</span>
+      <a href="https://docs.github.com/en/actions">docs.github.com/actions</a></li>
+    <li><b>Azure Key Vault</b><span>The managed vault holding secret values, so git carries only
+      references and rotation never has to become a commit.</span>
+      <a href="https://learn.microsoft.com/azure/key-vault/">learn.microsoft.com/key-vault</a></li>
+    <li><b>Azure Container Registry</b><span>The managed upstream registry CI pushes to - where
+      the digest is minted that everything downstream pins and promotes.</span>
+      <a href="https://learn.microsoft.com/azure/container-registry/">learn.microsoft.com/container-registry</a></li>
+  </ul>
+</section>
+
 <footer class="outro">
   <p>The Exploded Cluster &middot; the delivery arc &middot; every scene is one generated hero,
     sliced and scrubbed - no diagrams were harmed.</p>
@@ -318,6 +455,15 @@ b{color:var(--ink)} .mono{font-family:var(--mono);font-size:.9em;color:var(--cya
 .key a{font-family:var(--mono);font-size:.66rem;letter-spacing:.06em;white-space:nowrap}
 @media (max-width:700px){.key li{grid-template-columns:44px 1fr}.key i,.key a{grid-column:2}}
 
+.library{max-width:860px;margin:2vh auto 6vh;padding:0 24px;list-style:none;
+         display:flex;flex-direction:column;gap:12px}
+.library li{display:grid;grid-template-columns:190px 1fr auto;gap:16px;align-items:baseline;
+            border:1px solid var(--line);border-radius:8px;padding:14px 18px;background:#0a1020}
+.library b{font-family:var(--mono);font-size:.78rem;letter-spacing:.06em;color:var(--cyan)}
+.library span{font-size:.85rem;line-height:1.6;color:var(--dim)}
+.library a{font-family:var(--mono);font-size:.68rem;letter-spacing:.04em;white-space:nowrap}
+@media (max-width:760px){.library li{grid-template-columns:1fr}.library a{justify-self:start}}
+
 .blueprint{max-width:1220px;margin:2vh auto 4vh;padding:0 24px}
 .blueprint img{width:100%;height:auto;display:block;border-radius:12px}
 
@@ -384,7 +530,7 @@ body:not(.fx) .bench{display:none}
 <script>
 (() => {
   "use strict";
-  const SCENES = { gitops: __MAN_GITOPS__, supply: __MAN_SUPPLY__, helm: __MAN_HELM__ };
+  const SCENES = { docker: __MAN_DOCKER__, cluster: __MAN_CLUSTER__, gitops: __MAN_GITOPS__, supply: __MAN_SUPPLY__, helm: __MAN_HELM__ };
   const RM = matchMedia("(prefers-reduced-motion: reduce)").matches;
   const units = [];
 
@@ -419,9 +565,12 @@ body:not(.fx) .bench{display:none}
     const lis = [...u.legend.children];
     const n = lis.length;
     u.apply = t => {
+      // stagger > 0 = cascade: parts complete their travel one after another in list order
+      const sg = u.man.stagger || 0;
       u.man.parts.forEach((p, i) => {
+        const pt = sg ? Math.min(1, Math.max(0, t * (1 + sg * (n - 1)) - sg * i)) : t;
         u.slabs[i].style.transform =
-          "translate3d(" + (p.dx * (1 - t)).toFixed(3) + "%," + (p.dy * (1 - t)).toFixed(3) + "%,0)";
+          "translate3d(" + (p.dx * (1 - pt)).toFixed(3) + "%," + (p.dy * (1 - pt)).toFixed(3) + "%,0)";
       });
       u.scene.style.transform = "scale(" + (0.95 + 0.05 * t).toFixed(4) + ")";
       // the side list lights in reading order, top to bottom, as the scrub advances

pilot/assemble-arc.mjs

@@ -19,12 +19,16 @@ const i = tpl.lastIndexOf("<script>");
 const j = tpl.lastIndexOf("</script>");
 if (i < 0 || j < i) throw new Error("app script block not found");
 let app = tpl.slice(i + 8, j)
+  .replace("__MAN_DOCKER__", man("docker"))
+  .replace("__MAN_CLUSTER__", man("cluster"))
   .replace("__MAN_GITOPS__", man("gitops"))
   .replace("__MAN_SUPPLY__", man("supply"))
   .replace("__MAN_HELM__", man("helm"));
 let body = tpl.slice(0, i) + tpl.slice(j + 9);
 
 const heroes = {
+  __HERO_DOCKER__: "docker-layers.webp",
+  __HERO_CLUSTER__: "course-II-cluster.webp",
   __HERO_GITOPS__: "course-VI-gitops.webp",
   __HERO_SUPPLY__: "course-VII-supply-chain.webp",
   __HERO_HELM__: "course-VIII-helm-press.webp",

pilot/assemble-arc.py

@@ -16,9 +16,13 @@ def man(tag):
                       separators=(",", ":"))
 
 out = (ROOT / "pilot/arc.tpl.html").read_text() \
+    .replace("__MAN_DOCKER__", man("docker")) \
+    .replace("__MAN_CLUSTER__", man("cluster")) \
     .replace("__MAN_GITOPS__", man("gitops")) \
     .replace("__MAN_SUPPLY__", man("supply")) \
     .replace("__MAN_HELM__", man("helm")) \
+    .replace("__HERO_DOCKER__", b64("docker-layers.webp")) \
+    .replace("__HERO_CLUSTER__", b64("course-II-cluster.webp")) \
     .replace("__HERO_GITOPS__", b64("course-VI-gitops.webp")) \
     .replace("__HERO_SUPPLY__", b64("course-VII-supply-chain.webp")) \
     .replace("__HERO_HELM__", b64("course-VIII-helm-press.webp")) \

pilot/manifest-cluster.json

@@ -0,0 +1,439 @@
+{
+ "scene": "cluster",
+ "source": "assets/raw/course-II-cluster.jpeg",
+ "parts": [
+  {
+   "name": "command",
+   "title": "The control plane",
+   "blurb": "Decides - holds the truth, schedules, reconciles. The only authority in the room.",
+   "z": 0,
+   "points": [
+    [
+     70.1,
+     23.15
+    ],
+    [
+     70.02,
+     28.95
+    ],
+    [
+     68.86,
+     30.8
+    ],
+    [
+     63.92,
+     34.78
+    ],
+    [
+     55.0,
+     42.6
+    ],
+    [
+     51.76,
+     44.47
+    ],
+    [
+     49.56,
+     45.13
+    ],
+    [
+     47.87,
+     44.2
+    ],
+    [
+     43.26,
+     41.53
+    ],
+    [
+     32.23,
+     31.68
+    ],
+    [
+     30.85,
+     30.52
+    ],
+    [
+     29.98,
+     29.1
+    ],
+    [
+     29.83,
+     27.54
+    ],
+    [
+     30.63,
+     21.55
+    ],
+    [
+     47.43,
+     9.27
+    ],
+    [
+     49.73,
+     8.07
+    ],
+    [
+     50.71,
+     8.2
+    ],
+    [
+     68.5,
+     20.84
+    ],
+    [
+     69.3,
+     21.57
+    ]
+   ],
+   "dx": 0.0,
+   "dy": 0.0
+  },
+  {
+   "name": "worker-1",
+   "title": "Worker node",
+   "blurb": "Runs pods. Identical and replaceable by design - cattle, not pets.",
+   "z": 0,
+   "points": [
+    [
+     32.59,
+     76.73
+    ],
+    [
+     30.36,
+     76.47
+    ],
+    [
+     23.8,
+     71.93
+    ],
+    [
+     23.29,
+     71.16
+    ],
+    [
+     22.71,
+     69.64
+    ],
+    [
+     22.56,
+     68.69
+    ],
+    [
+     22.35,
+     51.98
+    ],
+    [
+     22.42,
+     49.83
+    ],
+    [
+     22.56,
+     49.04
+    ],
+    [
+     23.73,
+     46.8
+    ],
+    [
+     30.59,
+     42.2
+    ],
+    [
+     31.6,
+     41.67
+    ],
+    [
+     32.52,
+     41.8
+    ],
+    [
+     33.62,
+     42.47
+    ],
+    [
+     39.21,
+     46.19
+    ],
+    [
+     40.01,
+     47.18
+    ],
+    [
+     40.88,
+     49.36
+    ],
+    [
+     41.03,
+     52.59
+    ],
+    [
+     41.1,
+     68.65
+    ],
+    [
+     40.95,
+     69.59
+    ],
+    [
+     40.37,
+     71.1
+    ],
+    [
+     40.01,
+     71.66
+    ]
+   ],
+   "dx": 11.06,
+   "dy": -19.39
+  },
+  {
+   "name": "worker-2",
+   "title": "Worker node",
+   "blurb": "Interchangeable with its neighbours - lose one and the promise re-lands its pods elsewhere.",
+   "z": 0,
+   "points": [
+    [
+     59.78,
+     62.5
+    ],
+    [
+     59.78,
+     74.77
+    ],
+    [
+     59.7,
+     81.75
+    ],
+    [
+     59.63,
+     82.22
+    ],
+    [
+     59.56,
+     82.53
+    ],
+    [
+     58.83,
+     84.19
+    ],
+    [
+     58.54,
+     84.56
+    ],
+    [
+     52.87,
+     88.87
+    ],
+    [
+     51.1,
+     90.07
+    ],
+    [
+     50.85,
+     90.2
+    ],
+    [
+     49.12,
+     90.2
+    ],
+    [
+     48.87,
+     90.07
+    ],
+    [
+     48.29,
+     89.67
+    ],
+    [
+     41.39,
+     84.65
+    ],
+    [
+     41.1,
+     84.27
+    ],
+    [
+     40.44,
+     82.76
+    ],
+    [
+     40.3,
+     82.12
+    ],
+    [
+     40.22,
+     81.65
+    ],
+    [
+     40.15,
+     72.96
+    ],
+    [
+     40.15,
+     62.14
+    ],
+    [
+     40.22,
+     61.52
+    ],
+    [
+     40.37,
+     60.89
+    ],
+    [
+     41.02,
+     59.38
+    ],
+    [
+     41.24,
+     59.02
+    ],
+    [
+     41.53,
+     58.63
+    ],
+    [
+     45.13,
+     56.07
+    ],
+    [
+     49.37,
+     53.4
+    ],
+    [
+     49.7,
+     53.27
+    ],
+    [
+     50.28,
+     53.27
+    ],
+    [
+     50.61,
+     53.4
+    ],
+    [
+     54.86,
+     56.07
+    ],
+    [
+     58.54,
+     58.92
+    ],
+    [
+     58.76,
+     59.27
+    ],
+    [
+     59.63,
+     61.26
+    ],
+    [
+     59.7,
+     61.73
+    ]
+   ],
+   "dx": 0.28,
+   "dy": -26.71
+  },
+  {
+   "name": "worker-3",
+   "title": "Worker node",
+   "blurb": "The fleet grows by adding more of exactly this.",
+   "z": 0,
+   "points": [
+    [
+     58.9,
+     69.09
+    ],
+    [
+     58.97,
+     50.11
+    ],
+    [
+     59.19,
+     49.18
+    ],
+    [
+     60.21,
+     47.22
+    ],
+    [
+     66.51,
+     42.2
+    ],
+    [
+     67.2,
+     41.8
+    ],
+    [
+     68.05,
+     41.67
+    ],
+    [
+     68.73,
+     41.93
+    ],
+    [
+     73.28,
+     44.6
+    ],
+    [
+     76.2,
+     46.67
+    ],
+    [
+     77.22,
+     48.69
+    ],
+    [
+     77.44,
+     49.51
+    ],
+    [
+     77.58,
+     50.94
+    ],
+    [
+     77.51,
+     58.91
+    ],
+    [
+     77.36,
+     69.28
+    ],
+    [
+     77.14,
+     70.44
+    ],
+    [
+     75.71,
+     72.2
+    ],
+    [
+     70.98,
+     75.4
+    ],
+    [
+     69.0,
+     76.73
+    ],
+    [
+     67.19,
+     76.73
+    ],
+    [
+     59.92,
+     71.54
+    ],
+    [
+     59.05,
+     69.71
+    ]
+   ],
+   "dx": -11.12,
+   "dy": -19.34
+  }
+ ],
+ "stagger": 0.28
+}

pilot/manifest-docker.json

@@ -0,0 +1,183 @@
+{
+ "scene": "docker",
+ "source": "assets/dist/docker-layers.webp",
+ "stagger": 0.35,
+ "parts": [
+  {
+   "name": "base",
+   "title": "Base image",
+   "blurb": "The OS layer everything else is stacked on. Pull it once, share it across every image on the host.",
+   "z": 0,
+   "points": [
+    [
+     0,
+     55.66
+    ],
+    [
+     27.88,
+     55.66
+    ],
+    [
+     49.48,
+     75.51
+    ],
+    [
+     71.88,
+     55.6
+    ],
+    [
+     100,
+     55.6
+    ],
+    [
+     100,
+     100
+    ],
+    [
+     0,
+     100
+    ]
+   ],
+   "dx": 0.0,
+   "dy": 0.0
+  },
+  {
+   "name": "deps",
+   "title": "Dependencies",
+   "blurb": "Your packages and runtime. Change these and every layer above has to be rebuilt.",
+   "z": 0,
+   "points": [
+    [
+     0,
+     40.64
+    ],
+    [
+     28.38,
+     40.64
+    ],
+    [
+     49.76,
+     55.45
+    ],
+    [
+     71.5,
+     40.32
+    ],
+    [
+     100,
+     40.32
+    ],
+    [
+     100,
+     56.3
+    ],
+    [
+     71.88,
+     56.3
+    ],
+    [
+     49.48,
+     76.21
+    ],
+    [
+     27.88,
+     56.36
+    ],
+    [
+     0,
+     56.36
+    ]
+   ],
+   "dx": 0.0,
+   "dy": 13.49
+  },
+  {
+   "name": "code",
+   "title": "Application code",
+   "blurb": "Your actual program \u2014 usually the smallest layer, and the one that changes every single build.",
+   "z": 0,
+   "points": [
+    [
+     0,
+     26.54
+    ],
+    [
+     27.75,
+     26.54
+    ],
+    [
+     50.77,
+     40.03
+    ],
+    [
+     72.0,
+     26.17
+    ],
+    [
+     100,
+     26.17
+    ],
+    [
+     100,
+     41.02
+    ],
+    [
+     71.5,
+     41.02
+    ],
+    [
+     49.76,
+     56.15
+    ],
+    [
+     28.38,
+     41.34
+    ],
+    [
+     0,
+     41.34
+    ]
+   ],
+   "dx": 0.0,
+   "dy": 28.54
+  },
+  {
+   "name": "writable",
+   "title": "Writable layer",
+   "blurb": "Created fresh per container, thrown away when it dies. Anything written here is not in the image.",
+   "z": 0,
+   "points": [
+    [
+     0,
+     0
+    ],
+    [
+     100,
+     0
+    ],
+    [
+     100,
+     26.87
+    ],
+    [
+     72.0,
+     26.87
+    ],
+    [
+     50.77,
+     40.73
+    ],
+    [
+     27.75,
+     27.24
+    ],
+    [
+     0,
+     27.24
+    ]
+   ],
+   "dx": 0.0,
+   "dy": 40.1
+  }
+ ]
+}

pilot/manifest-supply.json

@@ -5,7 +5,7 @@
   {
    "name": "image",
    "title": "The image",
-   "blurb": "C-I's layers, shipped as one unit - the thing whose name we must say precisely.",
+   "blurb": "Course I's layers, shipped as one unit - the thing whose name we must say precisely.",
    "z": 0,
    "points": [
     [

tools/slice-arc.py

@@ -84,6 +84,8 @@ def emit(name, tag, spec):
         p["dy"] = round((ay - p["cy"]) * nest, 2)
         del p["cx"]; del p["cy"]
     man = dict(scene=tag, source=f"assets/raw/{name}", parts=parts)
+    if "stagger" in spec:
+        man["stagger"] = spec["stagger"]
     out = ROOT / "pilot" / f"manifest-{tag}.json"
     out.write_text(json.dumps(man, indent=1))
     print(f"manifest-{tag}.json: {len(parts)} parts ->",
@@ -92,7 +94,8 @@ def emit(name, tag, spec):
 if __name__ == "__main__":
     mode, scenes_json, outdir = sys.argv[1], sys.argv[2], sys.argv[3]
     scenes = json.loads(pathlib.Path(scenes_json).read_text()) if mode == "emit" else None
-    heroes = [("course-VI-gitops.jpeg", "gitops"),
+    heroes = [("course-II-cluster.jpeg", "cluster"),
+              ("course-VI-gitops.jpeg", "gitops"),
               ("course-VII-supply-chain.jpeg", "supply"),
               ("course-VIII-helm-press.jpeg", "helm")]
     for name, tag in heroes: