Skip to content

Warn that cnameStrategy Follow also follows wildcard-synthesized CNAMEs #2230

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
cert-manager-prow merged 2 commits into from
Aug 20, 2026
Merged

Warn that cnameStrategy Follow also follows wildcard-synthesized CNAMEs #2230

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
3d670c9
Warn that cnameStrategy Follow also follows wildcard-synthesized CNAMEs
wallrj Aug 10, 2026
b6e6dea
Keep inline code spans on one line in the wildcard CNAME warning
wallrj Aug 20, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
13 changes: 13 additions & 0 deletions content/docs/configuration/acme/dns01/README.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -138,6 +138,19 @@ _acme-challenge.bar.example.com IN CNAME _acme-challenge.less-privileged.example
With this configuration cert-manager will follow CNAME records recursively in order to determine
which DNS zone to update during DNS01 challenges.

> ⚠️ With `cnameStrategy: Follow`, cert-manager follows *any* CNAME record
> found at `_acme-challenge.<domain>`, including one synthesized by a
> wildcard record. For example, a record like
> `*.example.com IN CNAME lb.example.org` also answers CNAME queries for
> `_acme-challenge.example.com`, so cert-manager will try to create the
> challenge TXT record at `lb.example.org` — typically failing with an error
> such as Route 53's
> `RRSet with DNS name lb.example.org. is not permitted in zone example.com.`.
> To avoid this, create an explicit record at `_acme-challenge.<domain>`
> (an exact-match name prevents wildcard synthesis), or use the default
> `cnameStrategy: None` if you are not delegating challenges to another
> zone.


## Supported DNS01 providers

Expand Down