mesh-catalog/modules/route-adapter/test/adapter.test.ts

// What ADR 0104 says holds the adapter: one route file per contribution, each named as its own, a
// file removed when its contribution goes, and every file it did not write left alone. Plus the two
// facts the file has to get right to be a route at all — the port the contributor publishes, and
// where the mesh says that contributor's machine is.

import { test } from "node:test";
import assert from "node:assert/strict";
import { mkdtemp, readdir, readFile, writeFile } from "node:fs/promises";
import { tmpdir } from "node:os";
import { join } from "node:path";

import { defaults, marker, reconcile, routesFrom, settingsFrom } from "../adapter.ts";
import type { Settings } from "../adapter.ts";

/** A dynamic directory standing in for the predecessor's, with whatever is already in it. */
async function predecessor(already: Record<string, string> = {}): Promise<Settings> {
  const dynamic = await mkdtemp(join(tmpdir(), "route-adapter-"));
  for (const [name, body] of Object.entries(already)) {
    await writeFile(join(dynamic, name), body);
  }
  return { ...defaults, dynamic };
}

/** The contributions file the mesh writes, in the shape the mesh's own proxy also reads. */
function contributed(...given: { from: string; node?: string; at?: string; name: string; port: number }[]) {
  return {
    contributions: 1,
    requirement: "route",
    given: given.map((g) => ({
      from: g.from,
      node: g.node ?? "control-node",
      at: g.at ?? "",
      values: { name: g.name, port: g.port },
    })),
  };
}

async function pass(settings: Settings, document: unknown) {
  const { routes, skipped } = routesFrom(document, settings.machine);
  assert.deepEqual(skipped, [], "a contribution was skipped that the test meant to be served");
  return reconcile(routes, settings);
}

// **One file per contribution**, named so the mesh can recognise its own — and shaped like the
// route files the predecessor already serves, down to its own certificate resolver, so a migrated
// name is served from the certificate that exists rather than one asked for at the cutover.
test("it writes one route file per contribution, in the predecessor's own shape", async () => {
  const settings = await predecessor();

  const changed = await pass(settings, contributed(
    { from: "gitea", name: "git.example", port: 2999 },
    { from: "umami", name: "stats.example", port: 3001 },
  ));

  assert.deepEqual(changed.written, ["mesh-git.example.yml", "mesh-stats.example.yml"]);
  assert.deepEqual((await readdir(settings.dynamic)).sort(),
    ["mesh-git.example.yml", "mesh-stats.example.yml"]);

  assert.equal(await readFile(join(settings.dynamic, "mesh-git.example.yml"), "utf8"), [
    marker,
    "# gitea contributed this route. It is removed when that contribution goes.",
    "http:",
    "  routers:",
    "    mesh-git-example:",
    "      entryPoints: [websecure]",
    "      rule: Host(`git.example`)",
    "      service: mesh-git-example",
    "      tls:",
    "        certResolver: le",
    "        domains:",
    "          - main: git.example",
    "  services:",
    "    mesh-git-example:",
    "      loadBalancer:",
    "        servers:",
    "          - url: http://host.docker.internal:2999",
    "",
  ].join("\n"));
});

// **A contribution that goes takes its file with it.** The contributions file is the whole truth
// about who has a route, so a module unassigned — or migrated on to the mesh's own proxy — must
// stop being served by the predecessor too. A route left behind is the stale-route fault, one
// level down.
test("it removes the file it wrote when that contribution goes", async () => {
  const settings = await predecessor();
  await pass(settings, contributed(
    { from: "gitea", name: "git.example", port: 2999 },
    { from: "umami", name: "stats.example", port: 3001 },
  ));

  const changed = await pass(settings, contributed({ from: "gitea", name: "git.example", port: 2999 }));

  assert.deepEqual(changed.removed, ["mesh-stats.example.yml"]);
  assert.deepEqual(changed.written, [], "an unchanged route was rewritten, waking the predecessor for nothing");
  assert.deepEqual(await readdir(settings.dynamic), ["mesh-git.example.yml"]);

  // And with nothing contributed at all, everything this module put there goes — which is what
  // unassigning it must mean, not "the file could not be read, so keep serving".
  const emptied = await pass(settings, contributed());
  assert.deepEqual(emptied.removed, ["mesh-git.example.yml"]);
  assert.deepEqual(await readdir(settings.dynamic), []);
});

// **The one rule that makes writing into somebody else's directory safe at all.** The mesh is a
// guest here: the predecessor's own route files, and anything else in the directory, are none of
// its business — including a file whose name happens to look like one of the mesh's but carries no
// marker of it.
test("it never touches a file it did not write", async () => {
  const predecessorsOwn = "http:\n  routers:\n    gitea-gitea:\n      rule: Host(`git.example`)\n";
  const lookalike = "# somebody else's, with a name like the mesh's\nhttp: {}\n";
  const settings = await predecessor({
    "gitea-gitea.yml": predecessorsOwn,
    "mesh-not-ours.yml": lookalike,
    "mesh-stats.example.yml": lookalike,
  });

  const changed = await pass(settings, contributed(
    { from: "gitea", name: "git.example", port: 2999 },
    { from: "umami", name: "stats.example", port: 3001 },
  ));

  // Its own file it writes; the two it did not write it leaves — one it was never asked about, and
  // one it WAS asked to write, which it refuses and says so rather than overwriting.
  assert.deepEqual(changed.written, ["mesh-git.example.yml"]);
  assert.deepEqual(changed.removed, []);
  assert.equal(changed.skipped.length, 1);
  assert.match(changed.skipped[0]!, /mesh-stats\.example\.yml is not this module's to write/);

  assert.equal(await readFile(join(settings.dynamic, "gitea-gitea.yml"), "utf8"), predecessorsOwn);
  assert.equal(await readFile(join(settings.dynamic, "mesh-not-ours.yml"), "utf8"), lookalike);
  assert.equal(await readFile(join(settings.dynamic, "mesh-stats.example.yml"), "utf8"), lookalike);

  // And a later pass that wants neither of them removes neither: removal is for files this module
  // can show it wrote, and nothing else.
  const later = await pass(settings, contributed());
  assert.deepEqual(later.removed, ["mesh-git.example.yml"]);
  assert.deepEqual((await readdir(settings.dynamic)).sort(),
    ["gitea-gitea.yml", "mesh-not-ours.yml", "mesh-stats.example.yml"]);
});

// **The port is the contributor's, not a guess.** The mesh tells a consumer the machine-side port
// it assigned (novox/hq ADR 0038), and it carries that in the contribution; the adapter's whole job
// on this axis is to put that number in the predecessor's service, unchanged.
test("the target port follows what the contributor publishes", async () => {
  const settings = await predecessor();
  await pass(settings, contributed({ from: "gitea", name: "git.example", port: 2999 }));
  assert.match(await readFile(join(settings.dynamic, "mesh-git.example.yml"), "utf8"),
    /url: http:\/\/host\.docker\.internal:2999$/m);

  // Moved to another machine port, and the route follows it on the next pass.
  const changed = await pass(settings, contributed({ from: "gitea", name: "git.example", port: 21000 }));
  assert.deepEqual(changed.written, ["mesh-git.example.yml"]);
  assert.match(await readFile(join(settings.dynamic, "mesh-git.example.yml"), "utf8"),
    /url: http:\/\/host\.docker\.internal:21000$/m);
});

// **Where the mesh says that machine is.** Empty means this one — reached from inside the
// predecessor's container by the machine's own name, not by loopback, which is `127.0.0.1` to the
// container and nothing useful. A contributor elsewhere in the mesh carries its overlay address,
// and the predecessor is sent straight there.
test("a contributor on another node is reached at the address the mesh gave it", async () => {
  const settings = await predecessor();
  await pass(settings, contributed(
    { from: "gitea", name: "git.example", port: 2999 },
    { from: "umami", node: "home-server", at: "198.51.100.7", name: "stats.example", port: 3001 },
  ));

  assert.match(await readFile(join(settings.dynamic, "mesh-git.example.yml"), "utf8"),
    /url: http:\/\/host\.docker\.internal:2999$/m);
  assert.match(await readFile(join(settings.dynamic, "mesh-stats.example.yml"), "utf8"),
    /url: http:\/\/198\.51\.100\.7:3001$/m);
});

// The node setting is the whole point of this module being assignable to more than one adopted
// machine: where the predecessor keeps its directory, which entry point and which resolver it uses
// are facts about one machine, laid over the module's defaults (novox/hq ADR 0100).
test("a node's settings are laid over the module's defaults, and nothing else changes", async () => {
  assert.deepEqual(settingsFrom(undefined), defaults);
  assert.deepEqual(settingsFrom({}), defaults);
  assert.deepEqual(settingsFrom({ dynamic: "/srv/proxy/conf.d", "certificate-resolver": "letsencrypt" }), {
    ...defaults,
    dynamic: "/srv/proxy/conf.d",
    resolver: "letsencrypt",
  });

  const settings = { ...(await predecessor()), entrypoint: "https", resolver: "letsencrypt", machine: "10.0.2.2" };
  await pass(settings, contributed({ from: "gitea", name: "git.example", port: 2999 }));
  const written = await readFile(join(settings.dynamic, "mesh-git.example.yml"), "utf8");
  assert.match(written, /entryPoints: \[https\]/);
  assert.match(written, /certResolver: letsencrypt/);
  assert.match(written, /url: http:\/\/10\.0\.2\.2:2999$/m);
});

// A contribution it cannot act on is said aloud and skipped, never guessed at — and a name that is
// not a name never becomes a path in somebody else's directory.
test("a contribution it cannot act on is skipped and named", async () => {
  const machine = defaults.machine;
  assert.deepEqual(routesFrom({ given: [{ from: "a", values: {} }] }, machine).skipped,
    ["a asked for a route and named nothing"]);
  assert.deepEqual(routesFrom({ given: [{ from: "b", values: { name: "x.example" } }] }, machine).skipped,
    ["b asked for route x.example and gave no usable port"]);
  assert.equal(routesFrom({ given: [{ from: "c", values: { name: "../../etc/x", port: 80 } }] }, machine)
    .routes.length, 0);
  assert.deepEqual(routesFrom(undefined, machine).routes, []);
});

// The directory is the predecessor's and the mesh only mounts it. Absent, there is nothing to write
// into — and writing anyway would put route files somewhere nothing reads, reporting success.
test("it refuses when the predecessor's directory is not there, and says why", async () => {
  const settings = { ...defaults, dynamic: join(await mkdtemp(join(tmpdir(), "route-adapter-")), "absent") };
  await assert.rejects(reconcile([], settings), /is not there.*`dynamic` setting.*mounts it/s);
});