terdut-server/SERVICE-ACCOUNTS.md

Service accounts: a scoped, non-human credential type

This is a design note for a feature, not an implementation plan — it exists to propose the shape before writing code. It's raised directly by terdut-operator (a separate repo, no shared code — see its DESIGN.md §6, §9, §13), which needs a credential for unattended, repeatable API access and currently has no good one available. Anything automating terdut-server long-term (this operator, CI, future integrations) hits the same gap, so this is written as a general primitive, not operator-specific.

The problem

terdut-server has two credential types today, and neither fits "an unattended process that manages teams/schedules/policies on someone's behalf":

• User API keys (api_keys, internal/api/users.go) are always tied to a real users row and carry that user's full rights — every team they're a member of, their admin flag if set. There's no kind/service marker distinguishing "a human's personal automation key" from "a login session," and no way to mint one scoped to less than the full user.
• Integration keys (integrations, internal/api/*teams*.go) are team-scoped, but narrowly: they authenticate exactly one inbound Alertmanager webhook call (POST /api/integrations/{key}/alertmanager) and nothing else. They're not a general management-API credential and shouldn't become one — overloading a narrow, one-way ingestion credential with broad read/write access would weaken the one property that makes it safe to embed in an Alertmanager config today.

The result: any automation that needs to create teams, set escalation policies, manage dead-man switches, or rotate integration keys has to hold a real human admin's or team owner's API key. That key is exactly as powerful as that person logging in — full team access, and full instance access if they're an admin. terdut-operator's design ran directly into this (its DESIGN.md §6): its described bootstrap/rotation flow assumed a repeatable, identity-scoped way to get a credential, and /api/bootstrap's actual behavior (single-shot per install, gated on COUNT(*) FROM users, confirmed via internal/api/users.go and charts/terdut-server/templates/bootstrap-job.yaml) doesn't provide one — it mints exactly one founding admin, once, ever.

Goals

• A credential type that isn't a human: doesn't touch OIDC group sync, login, session, or the is_admin/account-management semantics that come with a real users row.
• Two scopes matching the two shapes automation actually needs: instance-wide (create/list teams — what a server-owning controller needs) and team-scoped (manage one team's escalation policy, dead-man switches, integrations, schedule, OIDC group bindings — what a per-team controller or integration needs).
• Repeatable issuance and rotation — unlike /api/bootstrap, callable more than once, by anything that already holds admin rights, without destroying and recreating state to get a fresh credential.
• Visibly distinct from a human in every place identity shows up (audit trails, timeline entries, UI attribution) — a service account acting on a team should never be indistinguishable from a person.

Non-goals

• Not a general OAuth2/OIDC client-credentials flow — this is a bearer-token primitive matching the shape api_keys already uses (SHA-256 hash stored, raw key shown once at creation), not a new auth protocol.
• Not replacing integration keys — those stay as the narrow, one-way webhook credential they are today.
• Not modeling per-endpoint or per-verb permissions within a scope — instance and team are the only two scopes for now; finer-grained scoping is future work if a real need shows up.

Proposed shape

Schema

CREATE TABLE service_accounts (
    id          BIGSERIAL PRIMARY KEY,
    name        TEXT NOT NULL UNIQUE,       -- e.g. "terdut-operator"
    scope       TEXT NOT NULL CHECK (scope IN ('instance', 'team')),
    team_id     BIGINT REFERENCES teams(id) ON DELETE CASCADE,
    -- team_id required iff scope = 'team'; NULL iff scope = 'instance'
    created_by  BIGINT REFERENCES users(id),
    created_at  TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE TABLE service_account_keys (
    id                  BIGSERIAL PRIMARY KEY,
    service_account_id  BIGINT NOT NULL REFERENCES service_accounts(id) ON DELETE CASCADE,
    key_hash            TEXT NOT NULL UNIQUE,
    name                TEXT NOT NULL,       -- e.g. "initial", "2026-Q4-rotation"
    created_at           TIMESTAMPTZ NOT NULL DEFAULT now(),
    last_used_at         TIMESTAMPTZ
);

Deliberately not a users row: no password_hash, no is_admin, no user_identities linkage, so it's structurally impossible for a service account to be pulled into OIDC group sync or password login. Multiple keys per account (mirroring api_keys' existing one-user-many-keys shape) so rotation is "mint a new key, revoke the old one," not "recreate the account."

Endpoints

• POST /api/service-accounts — instance-scope/admin-only. Body: {"name": ..., "scope": "instance"|"team", "teamID": ... } (teamID required iff scope=team, and caller must be that team's owner or a system admin). Returns the account plus its first raw key (shown once, same pattern as POST /api/users/{id}/api-keys). Safe to call again with the same name — see "idempotent lookup" below — unlike /api/bootstrap, which is inherently one-shot by design (it's answering "does any user exist yet," a question with no analogue once one already does).
• POST /api/service-accounts/{id}/keys — mint an additional key on an existing account (self-service-equivalent: instance admin for instance scope, team owner or system admin for team scope). Enables rotation without recreating the account or losing its identity/audit history.
• DELETE /api/service-accounts/{id}/keys/{keyID} — revoke one key, mirroring DELETE /api/users/{id}/api-keys/{keyID}.
• GET /api/service-accounts?name= — look up an existing account by name. This is what turns "I tried to create my account and got a conflict" into a normal flow instead of an error: a controller that expects to have already registered itself calls this first, and only falls through to POST if nothing comes back.

Auth middleware

internal/api/middleware.go's existing dual resolution (Authorization: Bearer → apiKeyUser(), or session cookie → sessionUser(), both landing on the same models.User + team-membership context) gains a third path: a bearer token that hashes to a service_account_keys.key_hash resolves to a distinct principal type, not a synthesized models.User. requireTeamMember/requireTeamOwner treat a matching team-scoped service account as owner-equivalent for that one team (satisfies the same checks a real team owner would), and an instance-scoped one as satisfying AdminOnly for team-creation/listing purposes and for minting a team-scoped service account against any team (POST /api/service-accounts {"scope":"team","teamID":...}) — this second permission is what lets an operator-style caller create a team, then immediately mint that team its own narrower credential, without a human in the loop for every team. Neither permission extends to user-management endpoints (POST /api/users, PUT /api/users/{id}/admin, etc.), which stay human-admin-only. Anywhere identity is recorded for a human (incident timeline acknowledged_by/assigned_to, audit-relevant fields), a service-account principal is stored and displayed distinctly, e.g. service-account:terdut-operator, never coerced into a user_id FK.

What this unblocks

Directly resolves terdut-operator DESIGN.md §6's two broken assumptions:

1. Bootstrap becomes single-purpose again. /api/bootstrap mints exactly the founding human admin, once. The operator's actual first-reconcile flow: call /api/bootstrap only on a genuinely empty install; otherwise (or immediately after, if it won the bootstrap race) call GET /api/service-accounts?name=terdut-operator, and POST one if it doesn't exist yet. From then on the operator never touches /api/bootstrap again.
2. Rotation becomes real. POST /api/service-accounts/{id}/keys + revoke the old one — no destructive DB-level workaround, no re-triggering a single-shot endpoint that can't fire twice.
3. Cross-namespace credential mirroring is no longer needed at all. terdut-operator's current design holds every credential — instance- and team-scoped alike — privately in the operator's own namespace, never in the namespace of the CR each one authenticates for; reconciliation happens entirely inside the operator's controller loop, so no CR owner ever needs read access to a terdut-server credential regardless of same- or cross-namespace serverRef. Team scoping is still what bounds the blast radius of any individual credential: a leaked team-scoped key exposes exactly one team's resources, never the whole server, which is what makes holding many credentials in one place (the operator's namespace) an acceptable trade rather than reintroducing the mirrored design's server-admin-equivalent-everywhere problem.

Suggested sequencing

Land this before terdut-operator implements any bootstrap/credential-handling code — that code would otherwise be written against the current one-shot, user-only credential model as a known-temporary workaround, which is wasted effort on a repo that currently has zero implementation to begin with.