App not available during provisioning

Plugins
1

I am creating a custom middleware which has a dependency on a custom app.
There are times the app is shown as not configured what starting up caddy.
How can I enforce the app is created before provisioning the middleware?
Or what work arounds can do?

Caddyfile

{
   app_name config
}

localhost {
  route {
    middleware
  }
}

During Provisioning the middleware
I have the following check.

   app := ctx.AppIfConfigured(“app_name”)
   if app == nil {
      return errors.New("The app_name is not configured")
   }
2

If you need to ensure the App exists, use App(), not AppIfConfigured(). See if that helps you out.

1 Like
3

Thank you Matt.
I will try that and let you know.

4

That worked thank you.
The issue seems to some the fact the order of loading apps seems to be random.

5

Would you want me to create an issue for this or it is fine?

6

This is by design. App provisioning order is not guaranteed, but they can be loaded on-demand if they’re depended on.

2 Likes
7

Yep. The point of AppIfConfigured() is to only provision an app if one was explicitly configured by the user, so another module can choose to “do nothing” or “choose a default” if no config exists. If you expect config to actually exist, then App() is the correct thing to use. The Godoc comment for these methods explain this.

2 Likes
8

It seems that AppIfConfigured can fail in a module’s provisioning process even if the app configured.
For now I am using the my App’s default state as an error state.

9

I see, so basically you’re looking for a way to tell apart whether an app was provisioned from no config (default), or actually user-configured. I think that is an ambiguous case with the current API. We should improve that.

1 Like
10

If you want I can do a pull request on this or you can just take it.

diff --git a/context.go b/context.go
index 4307dda8..7af75d39 100644
--- a/context.go
+++ b/context.go
@@ -469,7 +469,25 @@ func (ctx Context) AppIfConfigured(name string) any {
                // been loaded yet
                return nil
        }
-       return ctx.cfg.apps[name]
+
+       if app, ok := ctx.cfg.apps[name]; ok {
+               return app
+       }
+
+       appRaw, ok := ctx.cfg.AppsRaw[name]
+       if !ok {
+               return nil
+       }
+
+       modVal, err := ctx.LoadModuleByID(name, appRaw)
+       if err != nil {
+               return nil
+       }
+
+       ctx.cfg.AppsRaw[name] = nil // allow GC to deallocate
+       ctx.cfg.apps[name] = modVal.(App)
+
+       return modVal
 }

 // Storage returns the configured Caddy storage implementation.
1 Like
11

I don’t think we should change AppIfConfigured, it has a specific purpose. It specifically documents that it will not load a module if not already loaded.

I think we should add a new AppStrict() which works just like App() (and returns an error if any) which returns an error early if the app is not configured.

I’m working on that now.

2 Likes
12

Ok thank you for your help on this

13
3 Likes
14

Part of the confusion is about a year ago AppIfConfigured was changed. Prior to that, it actually would load the app if was configured but not loaded. See caddytls: Reuse certificate cache through reloads (#5623) · caddyserver/caddy@0e2c7e1 · GitHub

2 Likes