do we have a way to get the path avoiding the cast?

There‘s no other way except using client{} structure. The Interface way is more recommended in the Go world.

I'd try adding a SocketPath method to the Client interface and evaluate the impacts.

or, in general, carrying this information around somehow. I'd really like to explore options to avoid the cast.

I'd try adding a SocketPath method to the Client interface and evaluate the impacts.

I added it in this PR.

I wonder (and I'm not pushing for this solution, but let's give it a fair evaluation) if we can use a defer to catch the issue instead of moving PluginConnected above. Something like

func (c *client) Connect() (rerr error) {
    // ...

    c.mutex.Lock()
    c.grpc = conn
    c.client = client
    c.mutex.Unlock()
    defer func() {
        if rerr == nil {
            return
        }
        klog.ErrorS(err, "Failed to connect to device plugin", "resource", c.resource)
        if err := conn.Close(); err != nil {
            klog.V(2).ErrorS(err, "Failed to close grcp connection", "resource", c.resource)
           return
        }
        c.grpc = nil
    }()
    return c.handler.PluginConnected(c.resource, c)
}

If so, we have to lock again to reset c.grpc and c.client in defer func

right. On second look the order of operations should not be too critical here. I'll have a deeper look later on.

line 80: Failed to close grcp connection
"grcp"?

fixed.

And @ffromani I follow your suggestion.

Fantastic work. Stick with one

go-staticcheck: error strings should not be capitalized (ST1005)

got it, thx