terdut-operator/DESIGN.md

terdut-operator design

This is the design reference for implementing terdut-operator. It exists so implementation can start from settled decisions instead of re-litigating them mid-PR. It is deliberately more detailed than the README; the README stays as the short pitch and now points here instead of carrying open questions.

Written against terdut-server as of the Postgres-only, per-team-resources version (teams, escalation policies, dead man's switches and integrations are all rows scoped to a team, managed over internal/api/* — not env/config-file driven; see that repo's charts/terdut-server for the current deploy story this operator supersedes).

1. Goals & non-goals

Goal: let a terdut-server install — the server itself, its teams, their escalation policies, dead man's switches and alert-source integrations — be fully described as Kubernetes objects and managed through gitops, following controller-runtime / Kubebuilder conventions.

Non-goals (v1):

• Not a general-purpose Postgres operator. It consumes a database that either the Zalando postgres-operator or something else already provides.
• Not managing Alertmanager itself, or the routing rules that decide which alerts reach which integration webhook — only the terdut-server side (creating the integration and handing back its URL/key).
• Not OLM packaging. Plain Kubebuilder manifests + Helm chart for install, matching how terdut-server itself ships.
• Cross-namespace references are limited to exactly one edge: TerdutTeam.spec.serverRef may name a TerdutServer in a different namespace, gated by that TerdutServer's own spec.allowedTeams consent field (§4.1, §4.2) — this is the multi-tenant shape the operator exists for (one platform team owns a TerdutServer; other teams self-service a TerdutTeam against it without needing write access to the server's namespace). Every other reference (teamRef on the escalation rule/dead-man-switch/alert-source CRDs) stays same-namespace-as-its-TerdutTeam only, in v1 — those manage a specific team's own resources and are expected to live alongside it.
• No validating/mutating admission webhooks in v1. CEL validation rules on the CRDs (OpenAPI x-kubernetes-validations) cover what they can; anything that needs a live look at another object (e.g. "does this teamRef exist") is a status condition, not an admission rejection — keeps v1 to a controller-only deployment with no cert-manager/webhook dependency.

2. The README's open questions, resolved

How do team-crd connect with server-crd?

Explicit spec.serverRef: {name, namespace} on TerdutTeam — same reasoning as before (explicit, greppable, trivially validated), but namespace is deliberately part of the reference: one team can run and own a TerdutServer, and other teams — in their own namespaces, without any write access to the server-owning team's namespace — self-service a TerdutTeam against it. namespace defaults to the TerdutTeam's own namespace when omitted, so the common single-tenant case (serverRef: {name: terdut}) is unchanged.

This cross-namespace edge needs the target namespace's explicit consent — otherwise any namespace in the cluster could point a TerdutTeam at someone else's TerdutServer and have the operator provision a team + credentials against it, which is a namespace-boundary violation, not a gitops convenience. Kubernetes has two established patterns for this kind of consent, and Gateway API itself uses both, for two different relationships:

• ReferenceGrant (used for a Route reaching into an arbitrary Service/Secret): a separate object, living in the target namespace, enumerating exact {fromNamespace, fromKind} → {toKind, toName} pairs. No wildcard, no selector — every permitted namespace is spelled out.
• An inline field on the parent (used for a ListenerSet attaching to a shared Gateway, GA since Gateway API v1.5): the parent carries spec.allowedListeners.namespaces: {from: None|Same|All|Selector, selector} directly, no separate CRD.

TerdutTeam attaching to a shared TerdutServer is structurally the second case, not the first — a bounded set of expected children attaching to a parent they were deliberately made shareable, not an arbitrary backend reference — so this design follows the ListenerSet precedent: TerdutServer.spec.allowedTeams (§4.1), no extra CRD. §4.2 covers how TerdutTeam resolves against it. No other reference in this design (teamRef on the child CRDs) crosses a namespace boundary, so this is the only place cross-namespace consent is needed at all (§1, §5, §6, §9).

How does escalationrules, switches and alertsources connect to a team?

Explicit spec.teamRef: {name} on each of TerdutEscalationRule, TerdutDeadmanSwitch, TerdutAlertSource — same reasoning, and it mirrors terdut-server's own data model, where every one of these rows carries a team_id foreign key already. A matcher/selector on TerdutTeam would be inventing a second source of truth for an association the server already models as a plain reference.

Support for both postgres-operator (Zalando) and bring-your-own, how do we design that to be user friendly?

TerdutServer.spec.database is a oneOf, mirroring the chart's existing database.dsn / database.passwordSecret contract (see §8):

• dsn + passwordSecretRef — bring-your-own, exactly today's chart inputs.
• postgresClusterRef — points at a Zalando postgresql.acid.zalan.do CR; the operator derives the DSN and resolves the generated credentials Secret itself (see §8). CloudNativePG support is a natural follow-up using the same shape and is called out as deferred (§13), not designed in detail now.

3. API group, versions, CRD catalog

• Group: terdut.ryuvia.com, version: v1alpha1 (matches the ryuvia.com domain terdut-server already uses; bump to v1beta1/v1 per the normal Kubernetes API graduation criteria once the shapes below have proven stable against a real install).
• Module: git.ryuvia.com/niklas/terdut-operator, scaffolded with Kubebuilder (controller-runtime), matching terdut-server's Go toolchain and house style.

Kind	Scope	Purpose
TerdutServer	Namespaced	One terdut-server install: Deployment, Service, database wiring, bootstrap, operator credentials, cross-namespace team consent.
TerdutTeam	Namespaced	One team on a TerdutServer, possibly in another namespace: name, OIDC group mapping.
TerdutEscalationRule	Namespaced	A team's escalation policy (levels, targets, repeat).
TerdutDeadmanSwitch	Namespaced	One dead man's switch on a team.
TerdutAlertSource	Namespaced	One alert-ingest integration on a team (currently: Alertmanager webhook).

4. Per-CRD spec

4.1 TerdutServer

apiVersion: terdut.ryuvia.com/v1alpha1
kind: TerdutServer
metadata:
  name: terdut
  namespace: oncall
spec:
  image:
    repository: git.ryuvia.com/niklas/terdut-server
    tag: v0.9.3
  replicas: 1                      # terdut-server is not horizontally-scale-tested; keep the field, default 1
  networking:
    hostname: terdut.example.com
    servicePort: 8080
    gatewayListener: ""            # same semantics as chart's networking.listener
  database:
    dsn: "postgres://terdut@terdut-postgres:5432/terdut?sslmode=require"   # mutually exclusive with postgresClusterRef
    passwordSecretRef: {name: terdut.terdut-postgres.credentials.postgresql.acid.zalan.do, key: password}
    # --- OR ---
    postgresClusterRef: {name: terdut-postgres}   # Zalando `postgresql` CR in the same namespace
  sweeper:
    staleAfter: 6h
    archiveAfter: 168h
  deadman:
    matchers: "alertname=Watchdog"
    timeout: 15m
    severity: critical
  notify:
    ntfyURL: "http://ntfy.ntfy.svc.cluster.local"
    fallbackTopic: ""
    repeatEvery: 15m
    tokenSecretRef: {name: "", key: token}
  oidc:
    enabled: false
    issuer: ""
    clientID: ""
    clientSecretRef: {name: "", key: client-secret}
    name: SSO
    scopes: "openid profile email"
    allowedGroups: []
    adminGroup: ""
    sessionMaxAge: 12h
  passwordLogin: true
  # Consent for TerdutTeams in OTHER namespaces to set serverRef at this
  # TerdutServer. Same-namespace TerdutTeams never need this. Modeled on
  # Gateway API's Gateway.spec.allowedListeners.namespaces (the ListenerSet
  # attachment pattern, not ReferenceGrant — see §2 for why).
  allowedTeams:
    namespaces:
      from: None        # None (default) | Same | All | Selector
      # selector:       # required, and only meaningful, when from: Selector
      #   matchLabels:
      #     terdut.ryuvia.com/allowed: "true"
status:
  conditions: [...]                 # Ready, DatabaseReady, Bootstrapped
  observedGeneration: 3
  serviceName: terdut
  operatorCredentialsSecretRef: {name: terdut-operator-credentials}  # see §6

Field-for-field this is the chart's values.yaml reshaped as a spec — the operator absorbs the chart's Deployment/Service/bootstrap-job templates, so existing installs have a direct mapping when migrating (see §10).

spec.database fields are +kubebuilder:validation:XValidation guarded to be mutually exclusive (dsn xor postgresClusterRef); mirrors the chart's "chart provisions no database" stance — this operator provisions no database either, only wires up one that exists.

spec.allowedTeams.namespaces.from defaults to None, matching allowedListeners's own default — a fresh TerdutServer accepts no cross-namespace TerdutTeam until its owner opts in, same-namespace TerdutTeams are unaffected either way. Selector deliberately has no per-name allowlist (no "and only these teams") — namespace-level consent is the right granularity here, same reasoning as ListenerSet: the namespace is the tenancy boundary, not the object.

4.2 TerdutTeam

spec:
  serverRef:
    name: terdut
    namespace: platform-oncall      # optional; defaults to this TerdutTeam's own namespace.
                                     # Cross-namespace requires that TerdutServer's spec.allowedTeams
                                     # (§4.1) to admit this namespace — otherwise Ready: False, reason: RefNotPermitted.
  displayName: "Platform"          # -> POST /api/teams {"name": ...}; server assigns the ID
  oidc:
    memberGroup: "terdut-platform-members"
    ownerGroup: "terdut-platform-owners"
status:
  conditions: [...]
  teamID: 42                       # the server-side ID; needed by every child object's controller
  observedGeneration: 1

Team membership (which users belong, team_members) is explicitly not modeled as a CRD field in v1: terdut-server already manages membership via OIDC group sync at login for SSO installs, and manual membership for password-login installs is a people-management action, not infrastructure — forcing it through gitops would mean a human's team change goes through a PR review. Flagged in §13 as revisitable if a real gitops-membership need shows up.

4.3 TerdutEscalationRule

spec:
  teamRef: {name: platform-team}
  repeatCount: 2
  fallbackTopic: "platform-oncall"
  levels:
    - timeout: 5m
      targets:
        - kind: oncall            # "oncall" or "user"
        - kind: user
          username: alice         # resolved to a user ID by the controller at apply time
    - timeout: 15m
      targets:
        - kind: oncall
status:
  conditions: [...]
  observedGeneration: 1

One TerdutEscalationRule per team — the server itself models a policy as one row (escalation_policies) with an owned list of levels, so a one-CRD-to-one-policy mapping (not one-CRD-per-level) matches the server's own aggregate and lets the whole thing be reconciled with the single PUT /api/teams/{teamID}/escalation the API actually exposes (see §5).

4.4 TerdutDeadmanSwitch

spec:
  teamRef: {name: platform-team}
  name: "prod-watchdog"
  matcher: "alertname=Watchdog,cluster=prod"
  timeout: 15m
  severity: critical
status:
  conditions: [...]
  switchID: 7

4.5 TerdutAlertSource

spec:
  teamRef: {name: platform-team}
  kind: alertmanager
  name: "prod-alertmanager"
status:
  conditions: [...]
  integrationID: 3
  webhookURLSecretRef: {name: prod-alertmanager-terdut-webhook}   # url + key, never in status/spec

The integration key is shown by the API exactly once, at creation (Integration.Key/URL in terdut-server's own model) — never re-readable, same shape as the bootstrap admin key. The controller writes it straight into a generated, owner-referenced Secret on the create it caused and never logs or stores it anywhere else; the CR's status carries only the Secret reference, matching how e.g. cert-manager's Certificate exposes spec.secretName rather than the key material itself.

4.6 Cross-namespace consent: TerdutServer.spec.allowedTeams

No separate CRD — the consent lives on TerdutServer itself (§4.1), following Gateway API's Gateway.spec.allowedListeners (ListenerSet attachment) rather than its ReferenceGrant, since a TerdutTeam attaching to a shared TerdutServer is the same shape of relationship: a bounded set of expected children attaching to a parent explicitly designed to be shared, not an arbitrary cross-namespace backend reference (see §2 for the full comparison of both patterns).

• from: None (default) — no cross-namespace TerdutTeam may resolve a serverRef into this TerdutServer. Same-namespace TerdutTeams are always allowed regardless of this field.
• from: Same — equivalent to None in effect (same-namespace is already unrestricted) but kept for parity with the upstream enum and to make the policy self-documenting in a diff.
• from: All — any namespace in the cluster may reference in. Appropriate for a genuinely shared, cluster-wide TerdutServer; the audit trail is "check allowedTeams plus who has RBAC to create a TerdutTeam anywhere," which is materially weaker than Selector.
• from: Selector — only namespaces matching spec.allowedTeams.namespaces.selector (a standard metav1.LabelSelector over Namespace objects, exactly like allowedListeners's own selector) may reference in. This is the recommended mode for the platform-team-owns-a-shared-server scenario this design targets: label the consuming namespaces once (e.g. terdut.ryuvia.com/allowed-server: platform-oncall/terdut) and new namespaces opt in by carrying the label, without editing the TerdutServer again.
• A TerdutTeam's controller re-evaluates allowedTeams on every reconcile before it will resolve a cross-namespace serverRef — for Selector, this means a Get on its own Namespace object plus reading the target TerdutServer's spec, not a List across the cluster. Same-namespace serverRef never consults this field at all.
• Narrowing or clearing allowedTeams (or unlabeling a namespace, under Selector) is a live revocation: the next reconcile of any TerdutTeam it used to authorize finds itself no longer permitted, flips Ready: False, reason: RefNotPermitted, and — deliberately — does not delete the team server-side on revocation alone; it stops reconciling further changes until access is restored or the TerdutTeam CR itself is deleted (whose finalizer still needs the credentials Secret described in §6 to clean up, so blocking new changes rather than forcing an immediate, possibly credential-less deletion is the safer failure mode).

5. Reconciliation semantics

terdut-server's REST surface (internal/api/router.go) does not give every resource a full update verb, so reconciliation strategy is per-resource:

Resource	Verbs available	Strategy
Team	POST create, PUT rename, DELETE, PUT oidc-groups	Real update-in-place: diff spec vs. last-applied, PUT the changed pieces.
Escalation policy	GET/PUT whole-policy	Update-in-place: PUT the full desired policy every reconcile that finds drift; cheap because whole-policy is small and already loaded whole server-side.
Dead man's switch	POST create, DELETE — no PUT	Delete-and-recreate on any spec diff other than name. The controller diffs against status (which mirrors what was last successfully applied) rather than re-reading the server every reconcile, to avoid a spurious recreate from field reordering.
Integration (alert source)	POST create, PATCH rename, DELETE	Rename via PATCH; any other spec change (kind) is delete-and-recreate, which rotates the webhook key — called out loudly in the CRD's field docs and in a Warning event, since it breaks whatever sends to the old URL/key until the new Secret is picked up.

General rules for every controller:

• Idempotent create: before POSTing, check status.<serverSideID> is unset; if the server already has a same-named object from a previous partial reconcile (e.g. after a crash between POST and status-write), treat a 409/name-conflict as "adopt" — GET-by-name and populate status, rather than erroring forever. terdut-server's list endpoints in each of these areas return objects by name, so this is a straightforward correlation.
• Periodic resync in addition to watch-triggered reconciles (Kubebuilder default RequeueAfter on success, e.g. every 5–10 minutes) to catch drift from someone changing state directly against the server's API/UI, since gitops correctness means the CR wins, not "first write wins".
• Finalizers on every CRD that has a server-side counterpart, so deletion calls the corresponding DELETE before the Kubernetes object disappears. Failure to delete server-side (e.g. server unreachable) blocks finalizer removal and surfaces as a Degraded condition + event, rather than silently orphaning a row.
• Owner chain for status resolution, not API calls: TerdutTeam's controller does not call any other controller; every child CRD's controller independently resolves its own teamRef → TerdutTeam.status.teamID and serverRef chain down to TerdutServer.status.operatorCredentialsSecretRef, the way any two independent controller-runtime reconcilers would. If the referenced parent isn't Ready yet, the child requeues with backoff and reports Ready: False, reason: WaitingForTeam — no cross-controller RPC.
• Cross-namespace serverRef is re-checked every reconcile, not just at creation: TerdutTeam's controller reads the target TerdutServer's spec.allowedTeams (and, under Selector, a Get on its own Namespace object for labels) on every pass before touching a cross-namespace TerdutServer — revocation (§4.6) takes effect on the team's very next reconcile, not just when the CR is first applied.

6. Bootstrap & authentication to terdut-server's API

terdut-server has no first-class "service account" token type — API keys belong to a real user row (api_keys.user_id). The chart's current answer is a one-shot Job that calls POST /api/bootstrap, gets a one-time admin key back, and stores it in a Secret (bootstrap-job.yaml). The operator absorbs this rather than shelling out to curl:

1. Confirmed against source (internal/api/users.go's handleBootstrap): /api/bootstrap is single-shot per install, not per identity — it gates on SELECT COUNT(*) FROM users, so any call once one user exists 403s regardless of who's asking, exactly as charts/terdut-server's own bootstrap-job.yaml already assumes (403 → "already bootstrapped, nothing to do", exit 0). This rules out the two-identity plan this section originally described: there is no way for the operator to get its own bootstrap identity once the chart (or a human) has already bootstrapped the server. The operator's real first-reconcile flow has to be: call /api/bootstrap only if nothing has bootstrapped yet (an empty-DB fresh install with no chart bootstrap job enabled), and otherwise obtain its credential through a dedicated, repeatable service-account endpoint — see the note at the end of this section. This also surfaces an unhandled race worth designing around explicitly once §10 is settled: if both the chart's bootstrap Job and this controller call /api/bootstrap against the same fresh install, exactly one gets the 201 and the other must treat 403 as "someone else already bootstrapped, go get my own credential the other way" rather than as an error.
2. The returned API key is written to a generated Secret (<name>-operator-credentials), owner-referenced to the TerdutServer, referenced back from status.operatorCredentialsSecretRef.
3. Every other same-namespace controller (EscalationRule, DeadmanSwitch, AlertSource, and any same-namespace TerdutTeam) reads that Secret directly to call the API — never its own credentials.
4. Cross-namespace TerdutTeam never reads the source Secret directly. Granting arbitrary consuming namespaces get/list/watch on a Secret in the server's namespace would mean any future workload in that namespace with Secret-read RBAC could be pointed at it too — allowedTeams (§4.1, §4.6) only authorizes the TerdutTeam kind to resolve a reference, not "read this Secret". Instead, the TerdutServer controller (which already holds the real credentials, and whose ServiceAccount is the only thing with legitimate cross-namespace write access — see §9) watches TerdutTeam objects across the cluster for ones that both name it and pass its allowedTeams check, and mirrors a copy of the credentials Secret into each such namespace on demand — not proactively into every namespace a Selector/All policy could admit, only into ones an actual permitted TerdutTeam currently references. The mirror is named <serverRef.name>.<serverRef.namespace>-terdut-credentials, owned not by an OwnerReference (those can't cross namespaces) but tracked in the TerdutServer's status and cleaned up once no permitted TerdutTeam in that namespace references it any more (revoked allowedTeams, or the last referencing TerdutTeam deleted). The remote TerdutTeam's controller reads only this local mirror, never the original.
   • This is one shared mirrored Secret per (server, consuming namespace) pair, not one per TerdutTeam — terdut-server's own API key isn't team-scoped (§13), so there is nothing finer to hand out; "scoped" here means scoped by namespace boundary, not by team permission. This is the design's real weak point, not the mirroring mechanism itself: the RBAC argument above (mirror rather than grant broad cross-namespace Secret-read) is sound on its own terms, but every mirrored copy is still server-admin-equivalent regardless of which team's namespace it lands in — allowedTeams gates whether a namespace may attach a TerdutTeam at all, it does nothing to bound what that namespace's copy of the credential can then do to every other team on the same server. This goes away, mirroring included, once team-scoped service- account tokens exist (see the note below): mint one key per TerdutTeam, directly into its own namespace, owner-referenced to the CR. No mirror, no shared-per-namespace blast radius — a leaked Secret compromises exactly one team.
5. Rotation: the key is a bearer credential with no expiry modeled server-side today. This section's original plan — delete the Secret + the api_keys row, let the controller re-bootstrap — does not work: deleting an api_keys row doesn't reduce users to zero, so the next /api/bootstrap call still 403s (see point 1 above). Until terdut-server grows a real credential-issuance endpoint, there is no working rotation story here at all; do not implement this as written.
6. This entire section is a stand-in for a real scoped service-account token type, and more than a nice-to-have: it's the dependency that makes points 1 and 5 above actually resolvable. Recommended shape (raised as a terdut-server feature request, tracked in §13): a POST /api/service-accounts (instance-scoped, admin-only, safely callable repeatedly — unlike /api/bootstrap) to create the operator's own identity and mint its first key, POST /api/service-accounts/{id}/keys to rotate without recreating the account, and GET /api/service-accounts?name= so a 403 from a stale lookup resolves to "fetch my existing account" instead of an unhandled error. Team-scoped accounts (rather than the one instance-scoped operator identity) are what let point 4 above mint a key per TerdutTeam instead of mirroring. Until this lands server-side, treat this section's bootstrap flow as v1-blocking, not v1-shippable — see §10's note on sequencing.

7. Ownership, status, garbage collection

• Every generated object (Deployment, Service, credentials Secret, webhook Secret) carries a metav1.OwnerReference to the CR that caused it, in the same namespace — standard GC, no finalizer needed for these (only for the server-side REST resources, per §5).
• Status conditions follow the standard metav1.Condition shape with at least Ready on every kind, plus kind-specific ones (TerdutServer: DatabaseReady, Bootstrapped; children: Synced).
• status.observedGeneration on every kind, bumped only after a successful reconcile against that generation's spec — the standard way a client (or kubectl wait) tells "applied" from "seen".
• No cluster-scoped aggregation object (e.g. no cluster-wide "all servers" status) in v1 — kubectl get terdutservers -A is the aggregate view.

8. Postgres integration

Mirrors the chart's existing two-path contract (values.yaml database.dsn/passwordSecret), because that contract is already documented and tested operationally:

• Bring-your-own: spec.database.dsn (no password) + spec.database.passwordSecretRef — the operator sets PGPASSWORD on the Deployment's container env from that Secret, exactly like the chart does today, and does nothing else. No connectivity check beyond what the Deployment's own readiness probe already gives.
• Zalando postgres-operator: spec.database.postgresClusterRef names a postgresql.acid.zalan.do CR in the same namespace. The controller:
  • Reads that CR's status for the primary Service name/port to build the DSN host — <cluster>.<namespace>.svc:5432 — and database name convention.
  • Resolves the generated credentials Secret (<user>.<cluster>.credentials.postgresql.acid.zalan.do) the same way the chart's comment already documents, and wires it in as PGPASSWORD the same way.
  • Watches that Secret (not just the postgresql CR) so a credential rotation triggers a requeue — the chart today requires a manual pod restart for this; the operator can at least detect and report it via a condition even if restarting on rotation is left as a §13 follow-up rather than done automatically (a rolling restart on credential change is a behavior change worth its own design pass, not folded in here).
  • Requires read RBAC on postgresql.acid.zalan.do (optional CRD — the operator's ClusterRole/Role should not hard-fail if the CRD isn't installed and a given TerdutServer uses BYO DSN instead).

9. RBAC

• The operator's own ServiceAccount needs, per namespace it's granted: get/list/watch/create/update/patch/delete on Deployments, Services, Secrets it owns, and get/list/watch on postgresql.acid.zalan.do (optional, degrade gracefully if absent per §8), plus cluster-wide get/list on Namespace (labels only, for allowedTeams: {from: Selector} evaluation — §4.1, §4.6).
• No cluster-scoped resources are created by this operator (namespaced CRDs only, per §1) — a Role + RoleBinding per watched namespace is sufficient; a ClusterRole is only needed for watching CRDs across all namespaces, which is the normal Kubebuilder multi-tenant-operator default and doesn't imply cluster-scoped managed resources.
• The operator's ServiceAccount is the only thing that ever holds cross-namespace Secret write. It is a single Deployment/binary already watching every namespace it's granted (the normal Kubebuilder shape), so mirroring a credentials Secret into a consenting namespace (§6) is not a new Kubernetes RBAC boundary — it's the same ServiceAccount that already reconciles objects there — but it is new scope (create/update on Secrets cluster-wide rather than only within each object's own namespace), and should be called out explicitly in the operator's ClusterRole/RBAC review, not left implicit. No human or team's own RBAC is ever granted cross-namespace Secret access by this design — TerdutServer.spec.allowedTeams only ever authorizes the operator to act on a TerdutTeam's behalf, never a person or a workload directly. This is a statement about Kubernetes RBAC only, though — it says nothing about what the mirrored terdut-server credential itself can do once it's there. Today that credential is the server-admin-equivalent bot key (§6), so a compromised or over-read namespace can reach every team on the server, not just its own; allowedTeams bounds who may attach, not what an attached namespace's copy of the credential can then do. That's a real privilege-boundary gap, and it closes once §6's team-scoped service-account keys exist and mirroring is dropped in favor of a key minted directly per TerdutTeam.
• terdut-server's own RBAC is unaffected — the operator talks to it purely over HTTP with the bot user's API key, never via the Kubernetes API for app-level state.

10. Relationship to charts/terdut-server

Recommendation (flagged explicitly as a decision to confirm before implementation starts, not settled by this document alone): the chart's Deployment/Service/bootstrap-job templates become redundant once TerdutServer exists — running both would mean two controllers (Helm and this operator) reconciling the same Deployment, which is exactly the conflict Kubernetes operators exist to avoid. Proposed path:

• The chart is repurposed into an installer chart: it installs the operator + CRDs (and optionally one TerdutServer CR from values.yaml, for users who want "helm install and get a server" without hand-writing a CR) rather than templating the Deployment directly.
• Existing installs migrate by: helm template the current release's values.yaml into an equivalent TerdutServer CR (mechanical, since §4.1 is deliberately shaped to make that mapping 1:1), install the operator, apply the CR, then let Helm's release be uninstalled or reduced to just the CRD/operator subchart.
• This is a breaking change to the chart's contract and needs its own migration guide and probably a major chart version bump — out of scope for this design doc beyond flagging it; do not start that migration work without separately confirming this recommendation.
• This decision isn't only about the migration — it also decides who owns bootstrap. §6 assumed the operator could always get its own bootstrap identity separately from the chart's; §6 point 1 shows that's false, so whichever of {chart's Job, operator controller} is expected to call /api/bootstrap first has to be settled explicitly (a one-paragraph call, not the full migration plan) before writing any operator bootstrap/credential code, not deferred alongside the rest of this section.

11. Testing strategy

• envtest (controller-runtime's fake API server) for every controller's reconcile logic against the Kubernetes side.
• terdut-server's REST API is faked with a small httptest.Server per controller test driven by fixtures matching the real handlers' request/response shapes (already well-documented in internal/api/*_test.go on the server side) — no real Postgres or real terdut-server binary needed for controller unit tests.
• A smaller number of true end-to-end tests (kind cluster + real terdut-server image + real Postgres) covering the golden path per CRD: create TerdutServer → TerdutTeam → one of each child kind → verify via terdut-server's own API that the objects exist with the right shape → delete the CR → verify the server-side object is gone.

12. Observability

• Standard controller-runtime metrics (reconcile duration/error counts) are enough for v1 — no custom metrics.
• Every externally-visible action (bootstrap, key rotation-needed, delete- and-recreate on the no-PUT resources, adopt-on-conflict) emits a Kubernetes Event on the CR, since that's what shows up in kubectl describe and gitops tooling (Argo CD/Flux) surfaces without extra wiring.

13. Deferred / explicitly out of scope for this design

• A real scoped service-account/token type in terdut-server — not merely deferred, this is v1-blocking for §6 as written (verified: without it, §6's bootstrap flow has no working credential-rotation path and no clean answer to the chart-vs-operator bootstrap race; see §6 points 1, 5, 6 and §10). Sequence this server-side change before implementing the TerdutServer controller's bootstrap logic, not after.
• A version-discovery endpoint on terdut-server (e.g. GET /api/version). Neither this operator nor terdut-tui has one today — both independently detect capability by probing specific routes (terdut-tui via GET /api/teams 404-checking; this operator would otherwise need to invent its own equivalent probe). An unattended reconciler is more exposed to a silent breaking API change than an interactive TUI a human is watching; raising this alongside the service-account request rather than inventing another route-probe here.
• CloudNativePG support — same spec.database shape as Zalando should extend to it, but the concrete field/Secret-naming conventions need their own look.
• Cross-namespace teamRef on the child CRDs (TerdutEscalationRule, TerdutDeadmanSwitch, TerdutAlertSource) — only TerdutTeam.serverRef crosses namespaces in v1 (§2, §4.2, §4.6); these stay same-namespace as their TerdutTeam until a real need for splitting them out shows up.
• Gitops-managed team membership (see §4.2).
• Automatic Deployment restart on upstream Postgres credential rotation.
• Admission webhooks / CEL-only validation limits (e.g. verifying a teamRef exists at admission time rather than surfacing it as a status condition after the fact).
• OLM packaging, Helm chart migration execution (§10 is a recommendation, not a plan to execute).