swumar/twitter: src/go.etcd.io/etcd/embed/etcd.go; 77 LoC

Found a possible issue in [swumar/twitter](https://www.github.com/swumar/twitter) at [src/go.etcd.io/etcd/embed/etcd.go](https://github.com/swumar/twitter/blob/663b48855d6d8309e7897688926ee0689225099c/src/go.etcd.io/etcd/embed/etcd.go#L532-L608)

Below is the message reported by the analyzer for this snippet of code. Beware that the analyzer only reports the first
issue it finds, so please do not limit your consideration to the contents of the below message.

> range-loop variable u used in defer or goroutine at line 593

[Click here to see the code in its original context.](https://github.com/swumar/twitter/blob/663b48855d6d8309e7897688926ee0689225099c/src/go.etcd.io/etcd/embed/etcd.go#L532-L608)

Click here to show the 77 line(s) of Go which triggered the analyzer.

```go
for _, u := range cfg.LCUrls {
sctx := newServeCtx(cfg.logger)
if u.Scheme == "http" || u.Scheme == "unix" {
if !cfg.ClientTLSInfo.Empty() {
cfg.logger.Warn("scheme is HTTP while key and cert files are present; ignoring key and cert files", zap.String("client-url", u.String()))
}
if cfg.ClientTLSInfo.ClientCertAuth {
cfg.logger.Warn("scheme is HTTP while --client-cert-auth is enabled; ignoring client cert auth for this URL", zap.String("client-url", u.String()))
}
}
if (u.Scheme == "https" || u.Scheme == "unixs") && cfg.ClientTLSInfo.Empty() {
return nil, fmt.Errorf("TLS key/cert (--cert-file, --key-file) must be provided for client url %s with HTTPS scheme", u.String())
}

network := "tcp"
addr := u.Host
if u.Scheme == "unix" || u.Scheme == "unixs" {
network = "unix"
addr = u.Host + u.Path
}
sctx.network = network

sctx.secure = u.Scheme == "https" || u.Scheme == "unixs"
sctx.insecure = !sctx.secure
if oldctx := sctxs[addr]; oldctx != nil {
oldctx.secure = oldctx.secure || sctx.secure
oldctx.insecure = oldctx.insecure || sctx.insecure
continue
}

if sctx.l, err = net.Listen(network, addr); err != nil {
return nil, err
}
// net.Listener will rewrite ipv4 0.0.0.0 to ipv6 [::], breaking
// hosts that disable ipv6. So, use the address given by the user.
sctx.addr = addr

if fdLimit, fderr := runtimeutil.FDLimit(); fderr == nil {
if fdLimit <= reservedInternalFDNum {
cfg.logger.Fatal(
"file descriptor limit of etcd process is too low; please set higher",
zap.Uint64("limit", fdLimit),
zap.Int("recommended-limit", reservedInternalFDNum),
)
}
sctx.l = transport.LimitListener(sctx.l, int(fdLimit-reservedInternalFDNum))
}

if network == "tcp" {
if sctx.l, err = transport.NewKeepAliveListener(sctx.l, network, nil); err != nil {
return nil, err
}
}

defer func() {
if err == nil {
return
}
sctx.l.Close()
cfg.logger.Warn(
"closing peer listener",
zap.String("address", u.Host),
zap.Error(err),
)
}()
for k := range cfg.UserHandlers {
sctx.userHandlers[k] = cfg.UserHandlers[k]
}
sctx.serviceRegister = cfg.ServiceRegister
if cfg.EnablePprof || cfg.LogLevel == "debug" {
sctx.registerPprof()
}
if cfg.LogLevel == "debug" {
sctx.registerTrace()
}
sctxs[addr] = sctx
}

```

Leave a reaction on this issue to contribute to the project by classifying this instance as a **Bug** :-1:, **Mitigated** :+1:, or **Desirable Behavior** :rocket:
See the descriptions of the classifications [here](https://github.com/github-vet/rangeclosure-findings#how-can-i-help) for more information.

commit ID: 663b48855d6d8309e7897688926ee0689225099c