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Merged
skevetter merged 5 commits into from
Sep 12, 2026
Merged

fix(ssh): harden tunnel forwarding reliability #1217

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13471bd
fix(ssh): harden tunnel forwarding reliability
skevetter Sep 11, 2026
b7cabe1
fix(lint): resolve CI lint findings
skevetter Sep 11, 2026
7a91f05
fix(ssh): address review feedback
skevetter Sep 11, 2026
4b99be3
fix(ssh): guard timeout dispatch and bound diagnostics
skevetter Sep 11, 2026
83be057
fix(ssh): stop timeout timer rearming during dispatch
skevetter Sep 11, 2026
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71 changes: 66 additions & 5 deletions cmd/workspace/ssh.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,9 @@ import (
)

const (
DisableSSHKeepAlive time.Duration = 0 * time.Second
DisableSSHKeepAlive time.Duration = 0 * time.Second
sshKeepAliveProbeTimeout = 10 * time.Second
sshKeepAliveMaxFailures = 3
)

// SSHCmd holds the ssh cmd flags.
Expand Down Expand Up @@ -685,27 +687,86 @@ func (cmd *SSHCmd) startServices(
}
}

type sshKeepAliveClient interface {
SendRequest(string, bool, []byte) (bool, []byte, error)
Close() error
}

type sshKeepAliveOptions struct {
interval time.Duration
probeTimeout time.Duration
maxFailures int
}

func startSSHKeepAlive(
ctx context.Context,
client *ssh.Client,
client sshKeepAliveClient,
interval time.Duration,
) {
ticker := time.NewTicker(interval)
startSSHKeepAliveWithOptions(ctx, client, sshKeepAliveOptions{
interval: interval,
probeTimeout: sshKeepAliveProbeTimeout,
maxFailures: sshKeepAliveMaxFailures,
})
}

func startSSHKeepAliveWithOptions(
ctx context.Context,
client sshKeepAliveClient,
opts sshKeepAliveOptions,
) {
ticker := time.NewTicker(opts.interval)
defer ticker.Stop()
failures := 0

for {
select {
case <-ctx.Done():
return
case <-ticker.C:
ok, _, err := client.SendRequest("keepalive@openssh.com", true, nil)
if err := checkKeepAliveResponse(ok, err); err != nil {
if err := sendBoundedKeepAlive(ctx, client, opts.probeTimeout); err != nil {
if ctx.Err() != nil {
return
}
log.Errorf("failed to send keepalive: %v", err)
failures++
if failures >= opts.maxFailures {
log.Errorf(
"SSH keepalive failed %d consecutive times; closing client",
failures,
)
_ = client.Close()
return
}
continue
}
failures = 0
}
}
}

func sendBoundedKeepAlive(
ctx context.Context,
client sshKeepAliveClient,
timeout time.Duration,
) error {
result := make(chan error, 1)
go func() {
ok, _, err := client.SendRequest("keepalive@openssh.com", true, nil)
result <- checkKeepAliveResponse(ok, err)
}()
timer := time.NewTimer(timeout)
defer timer.Stop()
select {
case err := <-result:
return err
case <-ctx.Done():
return ctx.Err()
case <-timer.C:
return fmt.Errorf("keepalive probe timed out after %s", timeout)
}
}

// A positive or negative SSH reply proves that the peer is alive. Only a
// transport error means that the keepalive request failed.
func checkKeepAliveResponse(_ bool, err error) error {
Expand Down
20 changes: 10 additions & 10 deletions go.mod
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@ require (
github.com/devsy-org/agentapi v1.0.1
github.com/devsy-org/api v1.1.0
github.com/devsy-org/apiserver v1.5.3
github.com/devsy-org/ssh v1.2.5
github.com/devsy-org/ssh v1.2.9
github.com/distribution/reference v0.6.0
github.com/docker/cli v29.7.2+incompatible
github.com/docker/docker v28.5.2+incompatible
Expand Down Expand Up @@ -64,11 +64,11 @@ require (
go.uber.org/atomic v1.11.0
go.uber.org/goleak v1.3.0
go.uber.org/zap v1.28.0
golang.org/x/crypto v0.55.0
golang.org/x/mod v0.38.0
golang.org/x/sync v0.22.0
golang.org/x/sys v0.47.0
golang.org/x/term v0.45.0
golang.org/x/crypto v0.57.0
golang.org/x/mod v0.41.0
golang.org/x/sync v0.23.0
golang.org/x/sys v0.48.0
golang.org/x/term v0.46.0
google.golang.org/grpc v1.83.0
google.golang.org/protobuf v1.36.12-0.20260120151049-f2248ac996af
gopkg.in/yaml.v3 v3.0.1
Expand Down Expand Up @@ -506,12 +506,12 @@ require (
go4.org/netipx v0.0.0-20231129151722-fdeea329fbba // indirect
gocloud.dev v0.46.0 // indirect
golang.org/x/exp v0.0.0-20260603202125-055de637280b // indirect
golang.org/x/net v0.57.1-0.20260729233039-99c3b0a8f463 // indirect
golang.org/x/net v0.58.0 // indirect
golang.org/x/oauth2 v0.36.0 // indirect
golang.org/x/telemetry v0.0.0-20260708182218-49f421fb7959 // indirect
golang.org/x/text v0.41.0 // indirect
golang.org/x/telemetry v0.0.0-20260811182544-a038080d80e5 // indirect
golang.org/x/text v0.42.0 // indirect
golang.org/x/time v0.15.0 // indirect
golang.org/x/tools v0.48.0 // indirect
golang.org/x/tools v0.49.0 // indirect
golang.org/x/xerrors v0.0.0-20240903120638-7835f813f4da // indirect
golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2 // indirect
golang.zx2c4.com/wireguard/windows v0.5.3 // indirect
Expand Down
40 changes: 20 additions & 20 deletions go.sum
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -414,8 +414,8 @@ github.com/devsy-org/api v1.1.0 h1:l7T9k7RVwatwN4lxeDTF3iN6EYmfGZgR3ZTJMDGha1M=
github.com/devsy-org/api v1.1.0/go.mod h1:mAZklKdnywJYiXDReBLte/H+3m69z6G7RHB3n1lI53Q=
github.com/devsy-org/apiserver v1.5.3 h1:tFKMgPxxfvojJ+C+wo0oqSmbE9PTJ2ur1E2yFj0eISI=
github.com/devsy-org/apiserver v1.5.3/go.mod h1:m7gpbrh++Hp8iEM5jaP7vjjODPbs9Bmh3l4+iPFg1jE=
github.com/devsy-org/ssh v1.2.5 h1:Z7gTanYs2ZslT1swTw4leoVVuDEmuNNhQi48W2kNqMU=
github.com/devsy-org/ssh v1.2.5/go.mod h1:6r5tZ+H9JFoMl6NrxXRgltg9HhEryTd69avY831Lio8=
github.com/devsy-org/ssh v1.2.9 h1:KHqX1xAplGFanm0FMSAojtiC9nV/UFxUeP/5jU5quak=
github.com/devsy-org/ssh v1.2.9/go.mod h1:Uff10+cSSDZk3bG07u5D9+eQ8GMGqsgE70WCUJWcHv4=
github.com/devsy-org/tailscale v1.102.2 h1:9SB6htvO+HmG8alal8WGCshHapfHR7dUFRSMYiFIzIM=
github.com/devsy-org/tailscale v1.102.2/go.mod h1:kQUA0lYb/bqCJJZzShx+gqLSxggEFgXB4VDVZDzxWc8=
github.com/dghubble/go-twitter v0.0.0-20211115160449-93a8679adecb h1:7ENzkH+O3juL+yj2undESLTaAeRllHwCs/b8z6aWSfc=
Expand Down Expand Up @@ -1459,8 +1459,8 @@ golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5y
golang.org/x/crypto v0.0.0-20220622213112-05595931fe9d/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
golang.org/x/crypto v0.0.0-20220722155217-630584e8d5aa/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
golang.org/x/crypto v0.17.0/go.mod h1:gCAAfMLgwOJRpTjQ2zCCt2OcSfYMTeZVSRtQlPC7Nq4=
golang.org/x/crypto v0.55.0 h1:+KWHjbgOaAQ66dh/YlkZKHlz9ZUlq61AFirAR9ntP8M=
golang.org/x/crypto v0.55.0/go.mod h1:uq0V9dE/fzQuJtbnL+2EhWOE63vo164FY8xqEnV9xis=
golang.org/x/crypto v0.57.0 h1:3ZVCjf8Ggz7zneR/EHRVx68Ctf+2pmIMP2UFhh9cC6M=
golang.org/x/crypto v0.57.0/go.mod h1:Fdz0i5U6CoizGwLda9DttjSk6qlZo25zYNtR+ycvuZA=
golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
golang.org/x/exp v0.0.0-20260603202125-055de637280b h1:v1uXiEBHo8QA0LiGCo7UgHMzHT4Kdfpl2zmtH5vaP1Q=
golang.org/x/exp v0.0.0-20260603202125-055de637280b/go.mod h1:d2fgXJLVs4dYDHUk5lwMIfzRzSrWCfGZb0ZqeLa/Vcw=
Expand All @@ -1478,8 +1478,8 @@ golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
golang.org/x/mod v0.38.0 h1:MECBjubtXD7yj4HrhIUcywNaGeNVUdfVnxmPajOk4yk=
golang.org/x/mod v0.38.0/go.mod h1:V6Xz0pq8TQ3dGqVQ1FVHuelZpAL0uNhSkk9ogYP3c40=
golang.org/x/mod v0.41.0 h1:qJmnOUb4YB+FsEuM3HcWucdZASCPGhsX6uljO6pog0c=
golang.org/x/mod v0.41.0/go.mod h1:Ek9pY8RKWXwsWvd3rQiHYtMqkjSUV+s1Rj7j4H5Ur6o=
golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
golang.org/x/net v0.0.0-20180826012351-8a410e7b638d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
golang.org/x/net v0.0.0-20190213061140-3a22650c66bd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
Expand All @@ -1495,8 +1495,8 @@ golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2/go.mod h1:9nx3DQGgdP8bBQD5qx
golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
golang.org/x/net v0.6.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
golang.org/x/net v0.57.1-0.20260729233039-99c3b0a8f463 h1:56+vNxUDjzdwAJjglL/DMnp31nd8UeytlPRLbZfz55Q=
golang.org/x/net v0.57.1-0.20260729233039-99c3b0a8f463/go.mod h1:KpXc8iv+r3XplLAG/f7Jsf9RPszJzdR0f58q9vGOuEU=
golang.org/x/net v0.58.0 h1:ynWG7rqYi4ccpTEuPZ2QGWHktVEM9DMCj9yzDE0Q7To=
golang.org/x/net v0.58.0/go.mod h1:YwCddHnFlT7eLQqVprV19OnhLGtc5xOKgE0RyqgfWAU=
golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
golang.org/x/oauth2 v0.36.0 h1:peZ/1z27fi9hUOFCAZaHyrpWG5lwe0RJEEEeH0ThlIs=
golang.org/x/oauth2 v0.36.0/go.mod h1:YDBUJMTkDnJS+A4BP4eZBjCqtokkg1hODuPjwiGPO7Q=
Expand All @@ -1508,8 +1508,8 @@ golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJ
golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.22.0 h1:SZjpbeLmrCk4xhRSZFNZW5gFUeCeFgjekvI/+gfScek=
golang.org/x/sync v0.22.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
golang.org/x/sync v0.23.0 h1:KameEIfc1IkluZyXWLn39Wd4tURc6GbCiISGiZm2bQk=
golang.org/x/sync v0.23.0/go.mod h1:sUUOizhqBxiL6pEWpqNLUiaJn1ShEbZ6BBqskPbjZm0=
golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
Expand Down Expand Up @@ -1537,17 +1537,17 @@ golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/sys v0.15.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
golang.org/x/sys v0.47.0 h1:o7XGOvZQCADBQQ4Y7VNq2dRWQR7JmOUW8Kxx4ZsNgWs=
golang.org/x/sys v0.47.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
golang.org/x/telemetry v0.0.0-20260708182218-49f421fb7959 h1:RJhm5l6Fo4rmEIcndxDllNhhf/fAx8qIm4t6A7vpm2A=
golang.org/x/telemetry v0.0.0-20260708182218-49f421fb7959/go.mod h1:LV7u5Oco+Z/g6XI7PqN+EUUUGGkEcmB1uj2ceI0fOVg=
golang.org/x/sys v0.48.0 h1:bbX/i/6MgT9BVLM9RT1thmxL04yeTAhbEz4SyadbXoo=
golang.org/x/sys v0.48.0/go.mod h1:hNLxWAXmnKAxqDtdwIYC4bM9oQPEecfsnNMuSxOs3og=
golang.org/x/telemetry v0.0.0-20260811182544-a038080d80e5 h1:ZUSxONxc981v7AW7QUg+I9WwZzSTTJ019ENBYr5pV/Q=
golang.org/x/telemetry v0.0.0-20260811182544-a038080d80e5/go.mod h1:LVehoXe41cL5SCVQilsV7Gg6BNG+Js6P9PhSbYTIUkQ=
golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
golang.org/x/term v0.8.0/go.mod h1:xPskH00ivmX89bAKVGSKKtLOWNx2+17Eiy94tnKShWo=
golang.org/x/term v0.15.0/go.mod h1:BDl952bC7+uMoWR75FIrCDx79TPU9oHkTZ9yRbYOrX0=
golang.org/x/term v0.45.0 h1:NwWyBmoJCbfTHpxrWoZ9C6/VxOf7ic219I8xZZFdrf0=
golang.org/x/term v0.45.0/go.mod h1:9aqxs0blBcrm/n0L9QW0aRVD+ktan8ssZromtqJC43w=
golang.org/x/term v0.46.0 h1:3+OXuTbaKDgwk8jTi3aSLHRlmWqHEUDUtxnbFigO4YE=
golang.org/x/term v0.46.0/go.mod h1:+K02xbkittuwc0Am4abfA3Fc+XRGXkvBXNO88NCXPoc=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
Expand All @@ -1558,8 +1558,8 @@ golang.org/x/text v0.4.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
golang.org/x/text v0.9.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
golang.org/x/text v0.41.0 h1:vz/seA0lnX87Othu2f/0L24RcgrXD9/YFTSuGjj3rH8=
golang.org/x/text v0.41.0/go.mod h1:jvf1O8ajNzZqhSrQBPbutR/EB83Cc0CFrezNQIwbb5M=
golang.org/x/text v0.42.0 h1:JbOZXgfeCPU9gacVtYliJqOhD+zhrEqK4LfdpmlUZqI=
golang.org/x/text v0.42.0/go.mod h1:ojzP1Z+2QtioaF8DTtO8K5q7JWVVYwZKenzujK0Zd0E=
golang.org/x/time v0.15.0 h1:bbrp8t3bGUeFOx08pvsMYRTCVSMk89u4tKbNOZbp88U=
golang.org/x/time v0.15.0/go.mod h1:Y4YMaQmXwGQZoFaVFk4YpCt4FLQMYKZe9oeV/f4MSno=
golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
Expand All @@ -1577,8 +1577,8 @@ golang.org/x/tools v0.0.0-20210106214847-113979e3529a/go.mod h1:emZCQorbCU4vsT4f
golang.org/x/tools v0.1.5/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
golang.org/x/tools v0.48.0 h1:3+hClM1aLL5mjMKm5ovokw9epgRXPuu2tILgismM6RE=
golang.org/x/tools v0.48.0/go.mod h1:08xX0orndb/F7jJxGDicx061tyd5pcMto75YMAXr6lk=
golang.org/x/tools v0.49.0 h1:3NI7VXzL9+1WZD52Dx2ttoPwD5DWrFGpl9mFZDlmisI=
golang.org/x/tools v0.49.0/go.mod h1:SJNXV9DBKT0UbdttsQjbfJlAE/q+y36++zo3uL3N0Oo=
golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
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17 changes: 10 additions & 7 deletions pkg/devcontainer/sshtunnel/sshtunnel.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -153,8 +153,8 @@ func runSSHTunnel(ctx context.Context, p sshTunnelParams) (*config2.Result, erro
err = p.grpcBridge.RunPair(ctx,
func(ctx context.Context, stdin, stdout *os.File) error {
return runCommandInSSHTunnel(ctx, sshCommandParams{
sshClient: sshClient,
command: p.opts.Command,
session: sess,
command: p.opts.Command,
}, stdin, stdout)
},
func(ctx context.Context, stdout, stdin *os.File) error {
Expand Down Expand Up @@ -231,17 +231,16 @@ func setupSSHAgentForwarding(sshClient *ssh.Client, sess *ssh.Session) {
}

type sshCommandParams struct {
sshClient *ssh.Client
command string
session *ssh.Session
command string
}

func runCommandInSSHTunnel(ctx context.Context, p sshCommandParams, stdin, stdout *os.File) error {
streamer := newSSHTunnelJSONLogStreamer()
defer func() { _ = streamer.Close() }()

log.Debugf("running agent command in SSH tunnel: %q", p.command)
err := devssh.Run(ctx, devssh.RunOptions{
Client: p.sshClient,
err := devssh.RunSession(ctx, p.session, devssh.RunSessionOptions{
Command: p.command,
Stdin: stdin,
Stdout: stdout,
Expand All @@ -257,12 +256,16 @@ func runCommandInSSHTunnel(ctx context.Context, p sshCommandParams, stdin, stdou
return nil
}

const maxLogLines = 1
const (
maxLogLines = 25
maxLogBytes = 256 * 1024
)

func newSSHTunnelJSONLogStreamer() *log.JSONLogStreamer {
return log.NewJSONLogStreamer(log.StreamerOptions{
FallbackLevel: log.LevelDebug,
CaptureLines: maxLogLines,
CaptureBytes: maxLogBytes,
DetectLevelPrefixes: true,
TreatUnknownJSONAsDebug: true,
})
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44 changes: 37 additions & 7 deletions pkg/log/streamer.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,9 @@ type StreamerOptions struct {
FallbackLevel int
// CaptureLines retains this many raw lines for ErrorOutput.
CaptureLines int
// CaptureBytes bounds the total raw bytes retained for ErrorOutput,
// including newline separators. A zero value means no byte limit.
CaptureBytes int
// DetectLevelPrefixes preserves a level from timestamp-prefixed plain text.
DetectLevelPrefixes bool
// TreatUnknownJSONAsDebug preserves the historical tunnel behavior for
Expand All @@ -34,11 +37,13 @@ type JSONLogStreamer struct {
detectLevelPrefixes bool
treatUnknownJSONAsDebug bool
captureLines int
captureBytes int

mu sync.Mutex
lastLines []string
closeOnce sync.Once
closeErr error
mu sync.Mutex
lastLines []string
capturedBytes int
closeOnce sync.Once
closeErr error
}

// NewJSONLogStreamer returns a writer that decodes Devsy JSON log lines while
Expand All @@ -52,6 +57,7 @@ func NewJSONLogStreamer(options StreamerOptions) *JSONLogStreamer {
detectLevelPrefixes: options.DetectLevelPrefixes,
treatUnknownJSONAsDebug: options.TreatUnknownJSONAsDebug,
captureLines: options.CaptureLines,
captureBytes: options.CaptureBytes,
}
if options.CaptureLines > 0 {
streamer.lastLines = make([]string, 0, options.CaptureLines)
Expand Down Expand Up @@ -126,15 +132,39 @@ func (s *JSONLogStreamer) process(reader io.Reader) {
}

func (s *JSONLogStreamer) capture(line string) {
if s.captureLines <= 0 {
if s.captureLines <= 0 && s.captureBytes <= 0 {
return
}
if s.captureBytes > 0 && len(line) > s.captureBytes {
line = line[len(line)-s.captureBytes:]

@greptile-apps greptile-apps Bot Sep 11, 2026

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P2 UTF-8 diagnostics can corrupt

When retained remote output exceeds the byte limit, this raw byte slice can split a multi-byte UTF-8 character. ErrorOutput then carries invalid UTF-8 into the user-facing tunnel error, corrupting non-ASCII diagnostics precisely when truncation is needed. Truncation should preserve valid UTF-8 boundaries.

}
s.mu.Lock()
defer s.mu.Unlock()
if len(s.lastLines) >= s.captureLines {
s.lastLines = s.lastLines[1:]
for (s.captureLines > 0 && len(s.lastLines) >= s.captureLines) ||
(s.captureBytes > 0 && len(s.lastLines) > 0 &&
s.capturedBytes+1+len(line) > s.captureBytes) {
s.dropOldestLine()
}
if s.captureBytes > 0 && len(s.lastLines) > 0 &&
s.capturedBytes+1+len(line) > s.captureBytes {
line = line[len(line)-(s.captureBytes-s.capturedBytes-1):]
}
if len(s.lastLines) > 0 {
s.capturedBytes++
}
s.lastLines = append(s.lastLines, line)
s.capturedBytes += len(line)
}

func (s *JSONLogStreamer) dropOldestLine() {
if len(s.lastLines) == 0 {
return
}
s.capturedBytes -= len(s.lastLines[0])
if len(s.lastLines) > 1 {
s.capturedBytes--
}
s.lastLines = s.lastLines[1:]
}

type jsonLine struct {
Expand Down
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