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fix(tailnet): disable wireguard trimming #9098

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Merged
merged 5 commits into from
Aug 15, 2023
Merged

fix(tailnet): disable wireguard trimming #9098

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09dc7d7
fix(tailnet): disable wireguard trimming
coadler Aug 15, 2023
d243dbf
Merge branch 'main' into colin/wg-trim
coadler Aug 15, 2023
ad86474
Merge branch 'main' into colin/wg-trim
matifali Aug 15, 2023
1baad76
fixup! Merge branch 'main' into colin/wg-trim
coadler Aug 15, 2023
5e1da90
Merge branch 'main' into colin/wg-trim
coadler Aug 15, 2023
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fix(tailnet): disable wireguard trimming 
Since Tailscale removed keep-alives, it seems like open but idle
connections (SSH, port-forward, etc) can get trimmed fairly easily,
causing hangs for a few seconds while the connection is setup again.

This was taken from Spike's PR #8492

Co-authored-by: Spike Curtis <spike@coder.com>
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@coadler @spikecurtis
coadler and spikecurtis committed Aug 15, 2023
commit 09dc7d7a00c8eb2070656066a51b04df9f95e8ff
17 changes: 17 additions & 0 deletions tailnet/conn.go
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Expand Up @@ -19,6 +19,7 @@ import (
"golang.org/x/xerrors"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/adapters/gonet"
"tailscale.com/envknob"
"tailscale.com/hostinfo"
"tailscale.com/ipn/ipnstate"
"tailscale.com/net/connstats"
Expand Down Expand Up @@ -64,6 +65,22 @@ func init() {
// Globally disable network namespacing. All networking happens in
// userspace.
netns.SetEnabled(false)
// Tailscale, by default, "trims" the set of peers down to ones that we are "actively" communicating with in
// an effort to save memory. But, we want to make sure the Wireguard connection is up and handshaked before sending
// TCP traffic over it to avoid anomalously long round-trip time of the initial handshake
// c.f. https://github.com/coder/coder/issues/7388#issuecomment-1625463069 for more details.
//
// If Tailscale is waiting for traffic to bring up Wireguard, and we wait for Wireguard to send traffic, that's a
// deadlock. So, disable this feature.
//
// Note that Tailscale.com's use case is very different from ours: in their use case, users create one persistent
// tailnet per device, and it allows connections to every other thing in Tailscale that belongs to them. The
// tailnet stays up as long as your laptop or phone is turned on.
//
// Our use case is different: for clients, it's a point-to-point connection to a single workspace, and lasts only as
// long as the connection. For agents, it's connections to a small number of clients (CLI or Coderd) that are being
// actively used by the end user.
envknob.Setenv("TS_DEBUG_TRIM_WIREGUARD", "false")
}

type Options struct {
Expand Down