config: don't require CA to be configured when rotating client cert#902
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zakcutner wants to merge 1 commit intoprometheus:mainfrom
Open
config: don't require CA to be configured when rotating client cert#902zakcutner wants to merge 1 commit intoprometheus:mainfrom
zakcutner wants to merge 1 commit intoprometheus:mainfrom
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When `cert_file` and `key_file` are configured but `ca_file` is not, `tlsRoundTripper.RoundTrip` rebuilds the transport on every rotation of the cert or key. The rebuild path unconditionally calls `updateRootCA` with empty CA data, which always fails (`x509.CertPool.AppendCertsFromPEM` returns false on empty input), surfacing a spurious "unable to use specified CA cert: none configured" error on every subsequent request. This error is sticky: once a rotation triggers it, the `RoundTripper` never recovers without a process restart. It is easy to hit in practice with short-lived client certificates managed by tools such as cert-manager. Skip the `updateRootCA` call when no CA is configured, so rotation of `cert_file`/`key_file` works without requiring a CA. Signed-off-by: Zak Cutner <zak@cloudflare.com>
MichaHoffmann
approved these changes
Apr 30, 2026
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Summary
When
cert_fileandkey_fileare configured butca_fileis not,tlsRoundTripper.RoundTriprebuilds the transport on every rotation of the cert or key. The rebuild path unconditionally callsupdateRootCAwith empty CA data, which always fails (x509.CertPool.AppendCertsFromPEMreturns false on empty input), surfacing a spuriousunable to use specified CA cert: none configurederror on every subsequent request.This error is sticky: once a rotation triggers it, the
RoundTrippernever recovers without a process restart. It is easy to hit in practice with short-lived client certificates managed by tools such as cert-manager.Background
#792 landed a guard in this same code path to prevent a nil-pointer panic when
t.settings.CA == nil. It correctly stopped the crash, but it preserved the underlying logic error: the rebuild path is entered whenever the cert or key hash changes, not only when the CA changes, and it then tries to parse a CA that was never configured.This PR fixes the root cause: when no CA is configured, skip the
updateRootCAcall entirely and keep using the originally configured TLS roots (typically the system trust store). Rotation ofcert_file/key_filenow works whether or not a CA is configured.