docs(operators): write the Spark operator page

[whg517]

Summary

First real page under operators/ — it was a two-line stub. Filled following _template.md's section order, in both language trees.

Content comes from the spark-k8s-operator repository: the CRD in api/v1alpha1, the port constants in internal/util, the cleaner constraints in internal/controller/historyserver/configmap.go, and a working manifest from test/e2e/smoke/submit-task.

The most useful thing this page does

It says what the operator actually is. The repository name suggests Spark on Kubernetes generally, but the API has exactly one kind — SparkHistoryServer. There is no SparkApplication resource; the operator does not submit or schedule jobs. It manages the History Server, which reads event logs your Spark applications already write to S3.

Someone installing this expecting a job submitter would otherwise find that out the hard way.

What it covers

• The single node role
• Required clusterConfig.logFileDirectory.s3 bucket + prefix, with the full S3 setup chain (SecretClass → S3Connection → S3Bucket) taken from the e2e setup manifests
• listenerClass and what each of the three values exposes
• Ports: http 18080, metrics 18081, oidc 4180
• OIDC authentication via AuthenticationClass, and the CLIENT_ID/CLIENT_SECRET contract
• Defaults read from the CRD (productVersion: 3.5.5, repo: quay.io/zncdatadev, listenerClass: cluster-internal, replicas: 1) rather than guessed

The event log cleaner gets its own section

cleaner: true deletes old event logs from shared object storage, so only one instance may do it. The operator enforces this and rejects two configurations rather than letting cleaners race:

• cleaner on a role group with replicas > 1
• cleaner at role level when the role has more than one role group

Testing

• npm run verify exits 0 — 52 files linted with 0 errors, both locales built
• Page renders in both locales
• All relative links resolve (onBrokenLinks: 'throw') and no anchor warnings in the build log
• Resource naming in the examples checked against the e2e assert (<cluster>-<role>-<group>)

One thing worth knowing for future pages

MDX 3 parses <http://...> as a JSX tag and fails the build:

Unexpected character `/` (U+002F) before local name, expected a character that can start a name

Autolink syntax cannot be used for URLs in doc pages — use [text](url) instead. Hit this on the first build and fixed it here; noted in the commit body so the next person does not rediscover it.

Remaining stage 2 placeholders

5 left: kubernetes, kubebuilder, faq, release-notes, and database (blocked, see #38). faq and release-notes still need maintainer input rather than source research.

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