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plugin: Handle panics from agent requests #785

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merged 1 commit into from
Feb 12, 2024
Merged

plugin: Handle panics from agent requests #785

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15 changes: 14 additions & 1 deletion pkg/plugin/run.go
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Original file line number Diff line number Diff line change
Expand Up @@ -34,11 +34,24 @@ const (
func (e *AutoscaleEnforcer) startPermitHandler(ctx context.Context, logger *zap.Logger) error {
mux := http.NewServeMux()
mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
logger := logger // copy locally, so that we can add fields and refer to it in defers

var finalStatus int
defer func() {
e.metrics.resourceRequests.WithLabelValues(r.RemoteAddr, strconv.Itoa(finalStatus)).Inc()
}()

// Catch any potential panics and report them as 500s
defer func() {
if err := recover(); err != nil {
msg := "request handler panicked"
logger.Error(msg, zap.String("error", fmt.Sprint(err)))
finalStatus = 500
w.WriteHeader(finalStatus)
_, _ = w.Write([]byte(msg))
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how about sending not just msg here, but msg: err?

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@sharnoff sharnoff Feb 5, 2024 •
edited
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Hm, yeah. My impression was that it was better from a security perspective to not include the full error message (especially considering it's already visible in the logs), but tbh maybe it doesn't matter.
wdyt?

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Hmm, I see your concern. Although this is our internal API, so risk is not high.

But I guess, it can be left as is, it is easy to grep for logs. Maybe make the message more distinct, like "permit handler panicked" or else.

@areyou1or0 do you have an opinion on whether we should return the full error message, from catch-all exception handler?

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@Omrigan somehow I didn't get the notification for the mention, just seeing this now.
Yes, it's best practice to not reveal non-customised error message as this can disclose the details of underlying technology. Low severity but valid.

}
}()

if r.Method != "POST" {
finalStatus = 400
w.WriteHeader(400)
Expand All @@ -58,7 +71,7 @@ func (e *AutoscaleEnforcer) startPermitHandler(ctx context.Context, logger *zap.
return
}

logger := logger.With(zap.Object("pod", req.Pod))
logger = logger.With(zap.Object("pod", req.Pod))
logger.Info(
"Received autoscaler-agent request",
zap.String("client", r.RemoteAddr), zap.Any("request", req),
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