DNF module stream cache expiration behavior with metadata_expire

Answer to the Questions

1. Does metadata_expire control module stream metadata? Yes. DNF treats the modulemd files that describe streams and profiles as part of the repository metadata tree, so the same metadata_expire value applies to them.

2. Is there a separate expiration setting? No. There is no dedicated option; the default timer governs all metadata DNF downloads.

3. Can stale module metadata cause install failures? Absolutely. If the cached modulemd list is older than metadata_expire, dnf module list may still show an outdated stream list. A subsequent dnf module install will then return "stream not found" even though dnf repolist shows a current repo.

Underlying Behavior

When DNF resolves a command, it first checks the local metadata cache. If the cache age exceeds metadata_expire (default 6 h), DNF re‑downloads all repository metadata, including the modulemd payloads. Because module streams are stored in the same cache directory, the expiration logic is identical. There is no separate timestamp for modulemd.

Practical Verification

1. On a clean Rocky 9.2 system run dnf module list and note the available streams.
2. Have an upstream change add or remove a stream (or edit a local repo’s modulemd file).
3. Wait until the current metadata_expire interval elapses, or set metadata_expire=0 in /etc/dnf/dnf.conf to force an immediate refresh.
4. Run dnf module list again. If the list still shows the old streams, run dnf clean metadata and retry.
5. Attempt dnf module install <stream>. A “stream not found” error indicates that the modulemd cache was stale.

When Stale Metadata Causes Errors

Stale module metadata typically surfaces when an upstream repo updates its module streams shortly after you last ran dnf module list. Because dnf repolist only shows repository existence, it can be misleading: the repo may be up‑to‑date, but the cached module list is not.

Mitigating Stale Cache

• dnf clean metadata clears both base and module metadata, forcing a fresh download on the next command.
• Setting metadata_expire=0 in /etc/dnf/dnf.conf disables the timer, making DNF always fetch the latest metadata.
• For long‑running environments, consider a cron job that runs dnf clean metadata nightly to keep the module cache fresh.

Key Takeaway

In Rocky Linux 9.x, metadata_expire is a single, global expiration policy that covers both repository and module‑stream metadata. A stale module cache can cause install failures even when the repository list appears current, and the simplest remedy is to clear or refresh the metadata cache.