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[Feat] Pre exechook #990

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757c143
pre hook
Mohamed-elg Jun 11, 2026
2d84026
readme + tab fix
Mohamed-elg Jun 11, 2026
47f28c6
fix def
Mohamed-elg Jun 11, 2026
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16 changes: 16 additions & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -297,6 +297,22 @@ OPTIONS
The timeout for the --exechook-command. If not specifid, this
defaults to 30 seconds ("30s").

--pre-exechook-backoff <duration>, $GITSYNC_PRE_EXECHOOK_BACKOFF
The time to wait before retrying a failed --pre-exechook-command. If
not specified, this defaults to 3 seconds ("3s").

--pre-exechook-command <string>, $GITSYNC_PRE_EXECHOOK_COMMAND
An optional command to be executed before syncing a new hash of the
remote repository. This command does not take any arguments and
executes with the synced repo as its working directory. The
$GITSYNC_HASH environment variable will be set to the previous git hash that
was synced. This hook will always be invoked as it runs before any sync attempt.

--pre-exechook-timeout <duration>, $GITSYNC_PRE_EXECHOOK_TIMEOUT
The timeout for the --pre-exechook-command. If not specifid, this
defaults to 30 seconds ("30s").


--filter <string>, $GITSYNC_FILTER
Use partial clone with the specified filter. This can reduce
the amount of data transferred when cloning large repositories.
Expand Down
72 changes: 71 additions & 1 deletion main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -230,6 +230,16 @@ func main() {
envDuration(3*time.Second, "GITSYNC_EXECHOOK_BACKOFF", "GIT_SYNC_EXECHOOK_BACKOFF"),
"the time to wait before retrying a failed exechook")

flPreExechookCommand := pflag.String("pre-exechook-command",
envString("", "GITSYNC_PRE_EXECHOOK_COMMAND", "GIT_SYNC_PRE_EXECHOOK_COMMAND"),
"an optional command to be run before syncs complete (must be idempotent)")
flPreExechookTimeout := pflag.Duration("pre-exechook-timeout",
envDuration(30*time.Second, "GITSYNC_PRE_EXECHOOK_TIMEOUT", "GIT_SYNC_PRE_EXECHOOK_TIMEOUT"),
"the timeout for the pre-exechook")
flPreExechookBackoff := pflag.Duration("pre-exechook-backoff",
envDuration(3*time.Second, "GITSYNC_PRE_EXECHOOK_BACKOFF", "GIT_SYNC_PRE_EXECHOOK_BACKOFF"),
"the time to wait before retrying a failed pre-exechook")

flWebhookURL := pflag.String("webhook-url",
envString("", "GITSYNC_WEBHOOK_URL", "GIT_SYNC_WEBHOOK_URL"),
"a URL for optional webhook notifications when syncs complete (must be idempotent)")
Expand Down Expand Up @@ -541,6 +551,15 @@ func main() {
}
}

if *flPreExechookCommand != "" {
if *flPreExechookTimeout < time.Second {
fatalConfigErrorf(log, true, "invalid flag: --pre-exechook-timeout must be at least 1s")
}
if *flPreExechookBackoff < time.Second {
fatalConfigErrorf(log, true, "invalid flag: --pre-exechook-backoff must be at least 1s")
}
}

if *flWebhookURL != "" {
if *flWebhookStatusSuccess == -1 {
// Back-compat: -1 and 0 mean the same things
Expand Down Expand Up @@ -859,8 +878,10 @@ func main() {
// Startup exechooks goroutine
var exechookRunner *hook.HookRunner
if *flExechookCommand != "" {
log := log.WithName("exechook")
logname := "exechook"
log := log.WithName(logname)
exechook := hook.NewExechook(
logname,
cmd.NewRunner(log),
*flExechookCommand,
func(hash string) string {
Expand All @@ -880,6 +901,32 @@ func main() {
go exechookRunner.Run(context.Background())
}

// Startup pre-exechooks goroutine
var preExechookRunner *hook.HookRunner
if *flPreExechookCommand != "" {
logname := "pre-exechook"
log := log.WithName(logname)
exechook := hook.NewExechook(
logname,
cmd.NewRunner(log),
*flPreExechookCommand,
func(hash string) string {
return git.worktreeFor(hash).Path().String()
},
[]string{},
*flPreExechookTimeout,
log,
)
preExechookRunner = hook.NewHookRunner(
exechook,
*flPreExechookBackoff,
hook.NewHookData(),
log,
*flOneTime,
)
go preExechookRunner.Run(context.Background())
}

// Setup signal notify channel
sigChan := make(chan os.Signal, 1)
if syncSig != 0 {
Expand Down Expand Up @@ -935,6 +982,7 @@ func main() {
syncCount := uint64(0)
initialSyncDone := false
waitTime := *flInitPeriod
prevHash := ""
// getMaxFailures returns the effective max-failure limit for the current
// phase. During the initial sync phase, --init-max-failures (if set)
// overrides --max-failures; otherwise --max-failures applies.
Expand All @@ -948,6 +996,10 @@ func main() {
start := time.Now()
ctx, cancel := context.WithTimeout(context.Background(), *flSyncTimeout)

if preExechookRunner != nil {

@thockin thockin Jun 12, 2026

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This doesn't seem right? This will send the old hash on every loop, then sync a new hash. Unless I totally misunderstood the request, you want to try to sync, and ONLY IF there is a new hash, call the hook before publishing the symlink.

Did I misunderstand?

Unfortunately, the sync and the publish are inside git.SyncRepo. You can either decompose that (which would need to share a bunch of state) or you could pass function pointers into it like we do for refreshCreds - pass a struct like:

type syncHooks struct {
    refreshCreds func(context.Context) error
    beforePublish func(context.Context, changed bool, hash string) error
    afterPublish func(context.Context, changed bool, hash string) error
}

preExechookRunner.Send(prevHash)
}

if changed, hash, err := git.SyncRepo(ctx, refreshCreds); err != nil {
failCount++
updateSyncMetrics(metricKeyError, start)
Expand Down Expand Up @@ -981,6 +1033,9 @@ func main() {
if exechookRunner != nil {
exechookRunner.Send(hash)
}
if preExechookRunner != nil {
prevHash = hash
}
updateSyncMetrics(metricKeySuccess, start)
} else {
updateSyncMetrics(metricKeyNoOp, start)
Expand Down Expand Up @@ -2528,6 +2583,21 @@ OPTIONS
The timeout for the --exechook-command. If not specifid, this
defaults to 30 seconds ("30s").

--pre-exechook-backoff <duration>, $GITSYNC_PRE_EXECHOOK_BACKOFF

@thockin thockin Jun 12, 2026

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Flags should be in alphabetic-sorted order, sorry

The time to wait before retrying a failed --pre-exechook-command. If
not specified, this defaults to 3 seconds ("3s").

--pre-exechook-command <string>, $GITSYNC_PRE_EXECHOOK_COMMAND
An optional command to be executed before syncing a new hash of the

@thockin thockin Jun 12, 2026

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This isn't quite right.

I think we should update the docs on --exechook-command to say something like:

"""
An optional command to be executed after syncing a new hash of the remote repository and publishing the symlink (see --link).
"""

Then this can be:

"""
An optional command to be executed after syncing a new hash of the remote repository but before publishing the symlink (see --link).
"""

The rest should the same. What do you think?

remote repository. This command does not take any arguments and
executes with the synced repo as its working directory. The
$GITSYNC_HASH environment variable will be set to the previous git hash that
was synced. This hook will always be invoked as it runs before any sync attempt.

--pre-exechook-timeout <duration>, $GITSYNC_PRE_EXECHOOK_TIMEOUT
The timeout for the --pre-exechook-command. If not specifid, this
defaults to 30 seconds ("30s").

--filter <string>, $GITSYNC_FILTER
Use partial clone with the specified filter. This can reduce
the amount of data transferred when cloning large repositories.
Expand Down
7 changes: 5 additions & 2 deletions pkg/hook/exechook.go
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,8 @@ import (

// Exechook implements Hook in terms of executing a command.
type Exechook struct {
// Name
name string
// Runner
cmdrunner cmd.Runner
// Command to run
Expand All @@ -42,8 +44,9 @@ type Exechook struct {
}

// NewExechook returns a new Exechook.
func NewExechook(cmdrunner cmd.Runner, command string, getWorktree func(string) string, args []string, timeout time.Duration, log logintf) *Exechook {
func NewExechook(name string, cmdrunner cmd.Runner, command string, getWorktree func(string) string, args []string, timeout time.Duration, log logintf) *Exechook {
return &Exechook{
name: name,
cmdrunner: cmdrunner,
command: command,
getWorktree: getWorktree,
Expand All @@ -55,7 +58,7 @@ func NewExechook(cmdrunner cmd.Runner, command string, getWorktree func(string)

// Name describes hook, implements Hook.Name.
func (h *Exechook) Name() string {
return "exechook"
return h.name
}

// Do runs exechook.command, implements Hook.Do.
Expand Down
3 changes: 3 additions & 0 deletions pkg/hook/exechook_test.go
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Expand Up @@ -29,6 +29,7 @@ func TestNotZeroReturnExechookDo(t *testing.T) {
t.Run("test not zero return code", func(t *testing.T) {
l := logging.New("", "", 0)
ch := NewExechook(
"exechook",
cmd.NewRunner(l),
"false",
func(string) string { return "/tmp" },
Expand All @@ -47,6 +48,7 @@ func TestZeroReturnExechookDo(t *testing.T) {
t.Run("test zero return code", func(t *testing.T) {
l := logging.New("", "", 0)
ch := NewExechook(
"exechook",
cmd.NewRunner(l),
"true",
func(string) string { return "/tmp" },
Expand All @@ -65,6 +67,7 @@ func TestTimeoutExechookDo(t *testing.T) {
t.Run("test timeout", func(t *testing.T) {
l := logging.New("", "", 0)
ch := NewExechook(
"exechook",
cmd.NewRunner(l),
"/bin/sh",
func(string) string { return "/tmp" },
Expand Down