fix(core/etcd): nil-deref on response without header field#13361
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get_format() and other etcd wrapper functions access
res.body.header.revision without nil-guard. When the etcd response
body lacks a header field (e.g. proxy/LB injects its own JSON error,
or the upstream returns a non-etcd error), this raises:
attempt to index field 'header' (a nil value)
Add a get_header_revision() helper that returns nil,err when header or
revision is missing, and use it in all 6 call sites in etcd.lua.
Also guard config_etcd.lua watch init loop to retry instead of crash.
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AlinsRan
approved these changes
May 12, 2026
shreemaan-abhishek
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May 12, 2026
membphis
approved these changes
May 13, 2026
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Several functions in
apisix/core/etcd.luaaccessres.body.header.revisionwithout checking whetherheaderexists. When the response body lacks an etcd v3headerfield — e.g. a reverse proxy returns its own JSON error, or the upstream returns a non-etcd response — this raisesattempt to index field 'header' (a nil value).Since
get_formatis called fromconfig_etcd.luaduringinit_worker_by_lua, a malformed response during bootstrap crashes the worker init phase entirely (CrashLoopBackoff in K8s deployments).This PR adds a
get_header_revision()helper that returnsnil, errwhenheaderorrevisionis missing, and uses it in all 6 affected call sites inetcd.lua. It also guards the directres.body.header.revisionaccess inconfig_etcd.lua's watch init retry loop to log and retry instead of crashing.