Agreed, the silent failure on OIDC mismatch is a real operational headache. It's the first thing my team logs for when debugging a new setup.

> The architecture trap is thinking you can add a CT log later.

This is the crucial bit. The decision to skip the CT log gets baked into every signature you issue. Later on, you can't retrofit that timestamp proof. It's a permanent characteristic of your artifact's chain.

The thread's already covered the big policy questions, so I'll give you the concrete steps you're missing for that `fulcio-create-ca` part. It's a binary you get from building Fulcio. The steps you gloss over are:

1. Clone the repo, `make fulcio-create-ca`. This spits out the binary.
2. Run it: `fulcio-create-ca -org "Your Org" -output-dir ./my-ca`. It creates a `private` and `public` folder.
3. The root key in `private/` is the crown jewels. The config you need for the server is `public/fulcio-cert.pem` and `public/fulcio-root.pem`.

The trap is where you put that root key. A local disk is fine for a team of five? Maybe. But if you're using a secret manager for anything else, put it there from day one. The server config references the public certs, and you pass the root key's *location* via an environment variable.

Your actual blocker will be the OIDC issuer string, not the CA generation. Copy it exactly from your provider's `.well-known` endpoint, don't type it.

Oh wow, I was literally just trying to understand this myself last week! This whole thread went way over my head, honestly, but I think I can help with that last part about the fuzzy `fulcio-create-ca` commands.

I got stuck there too, because the docs sort of assume you already have the binary. I had to dig through a GitHub issue to find out you need Go installed first! So the step right before `fulcio-create-ca` is actually `go install github.com/sigstore/fulcio/cmd/fulcio-create-ca@latest`. That puts the command in your Go bin path. I spent an hour thinking the make command was broken before I realized that.

And about the simplest architecture for 5 people, I'm just a beginner too, but I've been running *just* the Fulcio server in a docker container for my personal projects, and it works to sign my test images. I think you can totally start there to get the feel of it. The certificates it issues work with `cosign verify`, you just have to pass your own root cert. It's like a test drive before you decide if you need the whole CT log garage, you know? 🙂

But, reading all the smart posts above, I'm now scared I'm missing the whole "when" part. If my container logs get messed up, is my signature useless?

Your test drive analogy is spot on for getting the mechanics down. The `go install` path you found is the right one, the `make` target can be brittle.

Where that test drive falls short is it teaches you how to turn the key, but not what happens in a crash. You've identified the exact gap: container logs are mutable. Without the CT log's separate, append-only ledger, your certificate's timestamp is just a claim written on the artifact itself. It proves "who," but the "when" is only as trustworthy as the log system you're already worried about hardening.

For a real deployment, even internal, that mismatch becomes the attack path.

The difference you're asking about is policy and identity. With your own instance, you sign for *your* company's GitLab or SSO users, not for GitHub actions in the public cloud. That's the main win.

For five people, start with Fulcio alone, but treat it as a temporary learning phase. You can issue certificates right away. The practical trap is that `fulcio-create-ca` expects a Go environment. The easiest path is:

```
go install github.com/sigstore/fulcio/cmd/fulcio-create-ca@latest
fulcio-create-ca -org "Your Team" -output-dir ./ca
```

Then mount the `public/` certs into the container and point the server to your root key via a volume or secret. This works.

But after your test run, you'll hit the timestamp problem everyone's debating. Your signatures will have a `when`, but that proof lives in your container logs or CI output. That's fine for learning, but you should plan the CT log discussion for before you sign anything real. You can't add that proof later.

That silent rejection is a logging failure, not just a config problem. If you're running this for a team, your operational logging standard (likely driven by SOX or your internal controls) must capture Fulcio's OIDC validation failures explicitly. If it doesn't, you have a gap in your detective controls.

You're right about the CT log key, but the nuance is in the threat model. If you're using this for internal software chain of custody only, and your artifact storage's immutability logging already meets a compliance requirement (like an immutable SIEM trail for PCI DSS), you can document that as your timestamp integrity control. The CT log is stronger, but its absence isn't automatically a fail. It's a risk acceptance decision that needs a paper trail.

The real sandbox escape is assuming your team will remember all these nuances a year from now when you onboard someone new. Document the OIDC issuer string exactly, and make it a monitored metric.

You're spot on about the operational logging, but that's often where teams fall into a false sense of security. They'll route Fulcio's stdout to their SIEM and assume they've captured the failures. The OIDC validation often happens deeper in the stack, before the request hits the structured application logs. Without explicit instrumentation added to the Fulcio server code to surface "OIDC issuer mismatch" as a distinct, high-priority event, it just looks like a generic 400 error.

The paper trail for skipping the CT log is the critical part, and it gets overlooked because it's paperwork, not code. You need to write down the exact threat you're accepting: that an attacker with write access to your artifact storage *and* your internal logging pipeline could backdate an entry, making a malicious signature appear to have been issued before a CVE was published. If your audit framework already requires immutable, append-only logs for your primary artifacts, you can point to that control. If not, you've just documented a gap in your own compliance.

Oh man, this thread is a lifesaver. I'm in almost the same boat - just me and one other guy trying to get our internal containers signed.

The `go install` tip from user443 is the missing step that tripped me up too. I'd add that you need a decently recent Go version (I think 1.19+). After you run the create-ca command, the config file it makes for the server needs one tweak that I didn't see anywhere: you have to set the OIDC issuer URL to match your internal identity provider. If you don't, it just silently fails like user214 said, and you'll be scratching your head for hours.

For your five person team, I got just Fulcio running in Docker Compose and it issues certificates. But after reading this, I'm realizing my "when" proof is basically just a text file in the container log. Not great.

So you can start with just Fulcio to learn the mechanics, but you're basically building on sand if you don't plan for the CT log from the start, right? That's my takeaway from this.