Scales and read-only frontend

[krissik]

We have a Plone setup with two frontends. One for editors which uses read-write plone instances and one for publicity with read-only plone instances, this looks like this:

      ┌─────────────────┐                 ┌──────────────────┐
      │ www.oursite.com │                 │ cms.oursite.com  │
      │ for publicity   │                 │ for editors      │
      └───────┬─────────┘                 └────────┬─────────┘
              │                                    │
              │                                    │
              ▼                                    ▼
 ┌────────────────────────────┐        ┌───────────────────────────┐
 │ read-only plone instances  │        │read-write plone instances │
 └─────────────┬──────────────┘        └───────────┬───────────────┘
               │                                   │
               │                                   │
               │                                   │
               │            ┌───────────┐          │
               └─────────►  │           │ ◄────────┘
                            │    ZEO    │
                            │           │
                            │           │
                            └───────────┘

cms.oursite.com is only accessible from our intranet - so we have some extra security here.

If an image scale is not accessed via cms.oursite.com before it is accessed via www.oursite.com we will get an "ReadOnlyError" because scaling happens on demand.

We have tried to work around this issue by creating scales on save but it is not very reliable.

Now we consider read-write access from www.oursite.com but maybe there is an other better solution for this?

[yurj]

You can ask in https://community.plone.org/
You can catch ReadOnlyError and do a subrequest to cms.oursite.com to create the image, then continue if successful. Another option is to use the proxy (apache, varnish, ngix) to react to an 500 http error on images. You can also use the event handler on image creation to force the creation of all scales. Or change the scaling methods to scale all sizes instead of the requested one.