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Drop to a shell on panic #25

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Drop to a shell on panic #25

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3399f48
Drop to a shell on panic
jspc Feb 26, 2023
323951a
Stop all services on a panic
jspc Feb 26, 2023
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43 changes: 41 additions & 2 deletions main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ import (
"os"
"os/exec"
"path/filepath"
"runtime/debug"

"github.com/grpc-ecosystem/go-grpc-middleware"
"github.com/grpc-ecosystem/go-grpc-middleware/tags"
Expand All @@ -17,13 +18,28 @@ import (
)

var (
// supervisor is the thing that handles all of the
// running of services, including tracking whether or not
// they're even running
//
// Why is this a global variable?
// Because we need to be able to stop all services and drop to
// a shell if our init process panics, so we can suss out what
// happened.
//
// Without a global, this needs all kinds of software architecture
// changes
supervisor *Supervisor

sockAddr = "/run/vinit.sock"
svcDir = envOrDefault("SVC_DIR", "/etc/vinit/services")
certDir = "certs"
kmesgF = "/dev/kmsg"
)

func main() {
defer panicHandler()

var err error
sugar, err = NewLogger(kmesgF)
if err != nil {
Expand Down Expand Up @@ -75,8 +91,6 @@ func main() {
}

func Setup() (grpcServer *grpc.Server, err error) {
var supervisor *Supervisor

supervisor, err = New(svcDir)
if err != nil {
if _, ok := err.(ConfigParseError); !ok {
Expand Down Expand Up @@ -141,6 +155,31 @@ func loadTLSCredentials() (credentials.TransportCredentials, error) {
return credentials.NewTLS(config), nil
}

func panicHandler() {
err := recover()
if err != nil {
if supervisor != nil {
_ = supervisor.StopAll()
}

stack := string(debug.Stack())
errStr := err.(error).Error()

if sugar.c != nil {
sugar.Errorw("vinit panic!",
"error", errStr,
"trace", stack,
)
} else {
// This branch occurs on any panic before our
// kmesg handler is enabled
fmt.Printf("panic:\n%s\n%s", errStr, stack)
}

recoveryShell()
}
}

func recoveryShell() {
fmt.Println("Press Ctrl+D to reboot")

Expand Down