This is so we can distinguish custom broadcasts in the Admin app
[1]. I've also extended the POST test for custom broadcasts to
check we're correctly reading data for "names", as this wasn't
being tested previously.
[1]: 411fda81c0
For the public API we actually receive a "name" instead of an ID,
which we also want to start sending from the Admin app.
Unlike IDs, which aren't really used anywhere, we want the names
to display the alerts on gov.uk/alerts.
Currently we have:
- An "areas" column in the DB that stores a JSON blob.
- An "areas" field inside the "areas" JSON that stores area IDs.
- Each field has to be manually copied into the JSON column.
We want to move to:
- An "areas" column in the DB (unchanged).
- An "ids" field inside the "areas" JSON (to replace "areas").
- The Admin app sending other data inside an "areas" JSON field.
The API design for areas is confusing and difficult to extend.
Here we duplicate the current API functionality using an "areas_2"
field. Once the Admin app is using this field, we'll be able to
rename it to just "areas", which is where we want to get to.
In the next commits we'll build on this to support the migration
from "areas"."areas" to "areas"."ids".
If a polygon is smaller than the largest polygon in our dataset of
simplified polygons then we’re only throwing away useful detail by
simplifying it.
We should still simplify larger polygons as a fallback, to avoid sending
anything to the CBC that we’re not sure it will like.
The thresholds here are low: we can raise them as we test and experiment
more.
Here’s some data about the Flood Warning Service polygons
Percentile | 80% | 90% | 95% | 98% | 99% | 99.9%
-----------|-----|-------|--------|---------|---------|---------
Point count| 226 | 401.9 | 640.45 | 1015.38 | 1389.07 | 3008.609
Percentile | 80% | 90% | 95% | 98% | 99% | 99.9%
--------------|-----|-------|--------|---------|---------|---------
Polygon count |2----|3------|5-------|8--------|10-------|40.469
This new version of utils implements the transformation of our polygons
to a Cartesian plane. In other words, it converts them from being
defined in spherical degrees to metres.
For the API this means our simplification will be slightly more
accurate.
See https://github.com/alphagov/notifications-utils/pull/878 for
details.
Changes we had to make for our app and tests to work correctly
after the dependency updates:
1. Update emergency alerts polygons test because we changed
how exact we are with locations of the points on the map.
2. Use Flask's g object to set additional request attributes
So far we have been storing them in _request_ctx_stack which is
an innard for Flask's request context.
Because of major update to Werkzeug dependency, which Flask relies
on, the way we were using it stopped working, so we had a new
way to set those values.
The way we set those values now, by using g object, seems to also
be favoured in Flask documentation:
https://flask.palletsprojects.com/en/1.1.x/reqcontext/#how-the-context-works
The maximum content count of a broadcast varies depending on its
encoding, so we can’t simply validate it against a schema. This commit
moves to using the validation from `notifications-utils`, and raising a
custom error response.
We don’t support these methods at the moment. Instead we were just
ignoring the `msgType` field, so issuing one of these commands would
cause a new alert to be broadcast 🙃
We might want to support `Cancel` in the future, but for now let’s
reject anything that isn’t `Alert` (CAP terminology for the initial
broadcast).
We’re going to let people pass in fairly complex polygons, but:
- we don’t want to store massive polygons
- we don’t want to pass the CBCs massive polygons
So this commit adds a step to simplify the polygons before storing them.
We think it’s best for us to do this because:
- writing code to do polygon simplification is non-trivial, and we don’t
want to make all potential integrators do it
- the simplification we’ve developed is domain-specific to emergency
alerting, so should throw away less information than
There’s a bit more detail about how we simplify polygons in
https://github.com/alphagov/notifications-admin/pull/3590/files
This gives us some extra confidence that there aren’t any problems with
the data we’re getting from the other service. It doesn’t address any
specific problems we’ve seen, rather it seems like a sensible precaution
to take.
This commit makes the existing endpoint also accept CAP XML, should the
appropriate `Content-Type` header be set.
It uses the translation code we added in a previous commit to convert
the CAP to a dict. We can then validate that dict against with the JSON
schema to ensure it’s something we can work with.
We know there is at least one system which wants to integrate with
Notify to send out emergency alerts, rather than creating them manually.
This commit adds an endpoint to the public API to let them do that.
To start with we’ll just let the system create them in a single call,
meaning they still have to be approved manually. This reduces the risk
of an attacker being able to broadcast an alert via the API, should the
other system be compromised.
We’ve worked with the owners of the other system to define which fields
we should care about initially.
