forked from wrenn/wrenn
pptx704
7ef9a64613
After Firecracker snapshot restore, zombie TCP sockets from the previous session cause Go runtime corruption inside the guest VM, making envd unresponsive. This manifests as infinite loading in the file browser and terminal timeouts (524) in production (HTTP/2 + Cloudflare) but not locally. Four-part fix: - Add ServerConnTracker to envd that tracks connections via ConnState callback, closes idle connections and disables keep-alives before snapshot, then closes all pre-snapshot zombie connections on restore (while preserving post-restore connections like the /init request) - Split envdclient into timeout (2min) and streaming (no timeout) HTTP clients; use streaming client for file transfers and process RPCs - Close host-side idle envdclient connections before PrepareSnapshot so FIN packets propagate during the 3s quiesce window - Add StreamingHTTPClient() accessor; streaming file transfer handlers in hostagent use it instead of the timeout client
33 lines
1020 B
Go
33 lines
1020 B
Go
// SPDX-License-Identifier: Apache-2.0
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// Modifications by M/S Omukk
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package api
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import (
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"net/http"
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)
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// PostSnapshotPrepare quiesces continuous goroutines (port scanner, forwarder),
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// closes idle HTTP connections, and forces a GC cycle before Firecracker takes
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// a VM snapshot. Closing connections prevents Go runtime corruption from stale
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// TCP state after snapshot restore. Keep-alives are disabled so the current
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// request's connection also closes after the response.
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//
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// Called by the host agent as a best-effort signal before vm.Pause().
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func (a *API) PostSnapshotPrepare(w http.ResponseWriter, r *http.Request) {
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defer r.Body.Close()
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if a.portSubsystem != nil {
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a.portSubsystem.Stop()
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a.logger.Info().Msg("snapshot/prepare: port subsystem quiesced")
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}
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if a.connTracker != nil {
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a.connTracker.PrepareForSnapshot()
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a.logger.Info().Msg("snapshot/prepare: idle connections closed, keep-alives disabled")
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}
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w.Header().Set("Cache-Control", "no-store")
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w.WriteHeader(http.StatusNoContent)
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}
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