server/writer: properly handle result encoding errors #7114
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Signed-off-by: Stephan Renatus <stephan@styra.com>
…te content-type headers Signed-off-by: Stephan Renatus <stephan@styra.com>
srenatus
commented
Oct 11, 2024
| w.WriteHeader(status) | ||
| _, _ = w.Write(append(err.Bytes(), byte('\n'))) | ||
| } | ||
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| // JSON writes a response with the specified status code and object. The object | ||
| // will be JSON serialized. | ||
| // Deprecated: This method is problematic when using a non-200 status `code`: if | ||
| // encoding the payload fails, it'll print "superfluous call to WriteHeader()" | ||
| // logs. | ||
| func JSON(w http.ResponseWriter, code int, v interface{}, pretty bool) { |
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There is only a single caller to this method, and it's the health check logging an error. The payloads involved with that are so simple that this problem shouldn't really apply -- but we could refactor this nonetheless.
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If the encoding of a result of some sort -- any payload passed to
writer.JSON()orwriter.JSONOK()-- failed, we'd emit a log line likeand nobody likes these. Also, the encoding error would be the response payload, but the status code had still been 200.
Now, errors encoding the payload properly lead to 500 statuses, without extra logs.
Also headers should be set using Set(), not Add(), to avoid response headers like