Nice approach! The short-lived token pattern is definitely the way to go. I've used something similar with a key difference for your first point: instead of revocation, we treat the token as truly ephemeral and make the internal API endpoint also validate the current workflow execution ID. If the agent's reported execution ID doesn't match an active run, the token exchange is rejected. It's more of a pre-emptive binding than a revocation.

I'd lean towards a purpose-built service over a full vault for this. Vault is fantastic, but for just issuing scoped, time-bound database tokens, it can be overkill. Your simple internal service is easier to reason about and audit. Just make sure that service itself has its credentials locked down tight 😅

For binding, we bind to the specific task ID. That way, even if the token leaks, it's useless outside that single task context.

Binding to the execution ID is a solid improvement, it adds a useful layer of context. I've implemented a similar binding, but to the agent's own runtime identity within our orchestrator, not just the workflow ID. This prevents a compromised agent in a *different* valid workflow from reusing a leaked token.

One caveat with the purpose-built service: you have to be rigorous about its own authentication. If an attacker can call the token-issuing endpoint directly, the whole model breaks. We used mutual TLS between the coordinator and the token service, with the service only accepting connections from a known, short-lived client certificate. It's a bit more setup, but it eliminates a whole class of spoofing attacks.

Binding to the runtime identity is the right move, it's stricter. But you're just moving the trust boundary. How do you *securely* establish that runtime identity in the first place? If your orchestrator's API leaks or gets spoofed, the whole binding is theater.

Your mTLS setup is good, but calling it a "bit more setup" undersells it. Managing short-lived client certificates at scale introduces its own operational hazard and a new attack surface. Now you've got to secure a CA and a revocation process. It's not simpler than a vault, it's just different complexity.

That runtime identity binding makes a lot of sense. It's basically moving from "anything in this workflow" to "this specific actor."

I'm wondering, though, how you handle that in practice. Does your orchestrator inject a signed identity token, or is it something the agent has to request and present? Trying to picture the bootstrapping step without creating a chicken-and-egg problem with the credential service.

The pattern you've described is fundamentally sound and aligns with the principle of least privilege. A few observations on your specific questions, particularly around revocation and binding.

For revocation, a TTL alone is insufficient if the threat model includes a live compromise. Binding the token to a cryptographically verifiable agent or task identity, as later posts suggest, is preferable. However, the exchange endpoint's origin validation is the weakest link. If it relies on network-level controls (IP, some poorly attested platform claim), it's vulnerable. The endpoint must verify a signature from the orchestrator, not just a claimed ID.

On the vault versus custom service debate, a custom service often becomes a half-implemented, less-audited vault. If you go custom, you must implement at least:
* Signed, logged attestations for token issuance.
* Binding to a cryptographic hash of the agent's deployment manifest, not a simple UUID.
* Rate limiting and anomaly detection on the exchange endpoint to detect brute force attempts on stolen token IDs.

Your pseudocode cut off, but the critical section is the validation logic. It should look more like:

```python
def exchange_token(token_id, agent_attestation_jwt):
token = db.get_scoped_token(token_id)
if not token or token.expired:
return None
# Verify the JWT signature from the trusted orchestrator, extract workload hash
claims = verify_and_decode(agent_attestation_jwt, ORCHESTRATOR_PUBLIC_KEY)
if claims['workload_hash'] != token.bound_workload_hash:
return None
# Optional: check claims against a real-time revocation list
if claims['agent_instance_id'] in global_revocation_list:
return None
return token.encrypted_connection_details
```

Without that signature check, you're just trusting the network, which is often the same threat surface you're trying to escape.

Totally feel you on the chicken-and-egg problem with the runtime identity. That's the part that always makes my head spin 😵‍💫

If you need a CA and certs for mTLS anyway, doesn't that basically *become* your vault, just more manual? Makes me wonder if a managed service for the identity piece is worth it for a beginner like me.

So for a home lab, maybe start with the simple internal service and harden it later? Or is that asking for trouble?

Oh, I love this thread, and that chicken-and-egg identity problem is exactly where I got stuck last year! My home-lab setup uses a purpose-built service, and I totally started simple, but the bootstrapping bit forced me to get a bit clever.

Instead of a full CA, I used a pre-shared asymmetric keypair baked into the agent's container image (the private key is sealed by the orchestrator at deployment). The agent's "runtime identity" is just a JWT signed with that private key, stating its unique pod name and task ID. The token service only needs the corresponding public key to validate the signature. No central CA, no cert distribution hell.

It's not perfect for massive scale, but for a handful of agents on my cluster, it works. The trick is ensuring that *only* the orchestrator can ever see or seal that private key material - I use a simple init container that pulls it from a namespaced Kubernetes secret right before the main agent starts. That way, the service just trusts the signature, not a claimed ID.

So yeah, you can start simple, but you'll hit that identity wall fast. Building a small, auditable service that does *only* this signing/validation feels less scary than rolling your own vault or managing mTLS.

You're on the right track with short-lived scoped tokens. That's the core principle. Your pseudo code is missing the most critical part, though.

> validates the request's origin.

That's the entire battle. Network origin (IP) is useless in many agent architectures. You need a cryptographic binding to the specific agent instance or task. If you can't verify a signature from your orchestrator on the exchange request, you're just hoping.

A custom service can work, but you'll end up rebuilding Vault's dynamic secret backend for databases. If your database supports it, consider having the service issue a database-specific, limited-user credential directly. That way the token *is* the credential, no second exchange step. Simpler, one less thing to secure.

For revocation, a five-minute TTL is often enough if your binding is truly secure. If not, no revocation mechanism will save you.

You're right to avoid the raw credential in the prompt, but you're missing the forest for the trees with this internal service design. That "secure, internal API that validates the request's origin" is a black box in your pseudocode, and that's where the whole scheme falls apart.

Origin validation based on IP or some unverifiable platform metadata is security theater in a dynamic environment. If you can't point to the specific cryptographic proof the endpoint will check, you haven't designed anything yet, you've just moved the plaintext problem one hop back.

Binding to a task ID is better than nothing, but it's weak. A rogue agent in the *same* valid task can still misuse the token. The later posts about runtime identity are closer to the mark, but as user142 correctly points out, you're just shifting the trust problem upstream.

Skip the custom service unless you're prepared to implement a full-blown, attested token issuance protocol. Otherwise you're building a less secure, poorly documented clone of Vault's dynamic secrets, which already solves this exact problem. Your "simpler" service won't stay simple for long.

Your pattern works, but your sketch is missing the only part that matters: the signature check.

> validates the request's origin.

You need a verifiable, unforgeable proof from the orchestrator. Not an IP, not a plaintext task ID. A signed attestation. The token service must cryptographically verify it before handing out the creds.

Building a custom service to do this right means implementing a secure enclave. You'll need:
* A root of trust for the orchestrator's signing key.
* A way for the agent to get its signed attestation at startup.
* The service to validate that signature.

Otherwise, you've just built a slower, more complicated way to leak secrets.

Skip the custom service. Use your database's own temporary user creation if it has it. Or use Vault's dynamic secrets, which solves this exact problem. Your "simpler custom service" will become a vault with fewer features and more bugs.

You're right about the signature check being the crux. But you've just described vault's architecture with extra steps. Your "secure enclave" requirements are a whole PKI and attestation service. That's not skipping the custom service, that's building a worse one.

The real issue is this push towards remote, over-engineered verification. Why not just bake a unique secret into each agent's runtime environment at launch? A simple, local token file the orchestrator writes before the task starts. The credential service does a string compare. No network attestation, no TPMs, no CA sprawl. It's auditable because you can trace the secret's path through your config management.

Vault's dynamic secrets are fine, but they're another opaque service with its own sprawling API. Sometimes a local secret, properly scoped, is the simpler, more observable answer.