this is a pretty big and convoluted refactor unfortunately.
Previously:
There was one global `cbc_proxy_client` object in apps. This class has
the information about how to invoke the bt-ee lambda, and handles all
calls to lambda. This includes calls to the canary too (which is a
separate lambda).
The future:
There's one global `cbc_proxy_client`. This knows about the different
provider functions and lambdas, and you'll need to ask this client for a
proxy for your chosen provider. call cbc_proxy_client.get_proxy('ee')`
and it'll return you a proxy that knows what ee's lambda function is,
how to transform any content in a way that is exclusive to ee, and in
future how to parse any response from ee.
The present:
I also cleaned up some duplicate tests.
I'm really not sure about the names of some of these variables - in
particular `cbc_proxy_client` isn't a client - it's more of a java style
factory, where you call a function on it to get the client of your
choice.
moved the lambda invocation to a separate function to keep DRY
asserts on exception types need to be outside of with blocks, or they
won't trip (as the exception will stop execution of the inner with
block). the asserts were also the wrong way round so fixed that.
A BroadcastEvent knows when an event was sent and should expire
We pass through these values directly to the CBC Proxy, because
BroadcastEvent knows how they should be formatted
Signed-off-by: Toby Lorne <toby.lornewelch-richards@digital.cabinet-office.gov.uk>
When we ask the CBC Proxy to send a message, we should specify that we
want to send a real message, when we want a real message
We will do this by specifying the message_type which can have 4 types, 3
of which represent a real message:
| Name | Effect |
| ------ | ------------------------ |
| alert | Create an alert |
| update | Update an existing alert |
| cancel | Cancel an existing alert |
| test | Send a link test |
We will use message_type to represent the table above
Signed-off-by: Toby Lorne <toby.lornewelch-richards@digital.cabinet-office.gov.uk>
Co-authored-by: Richard <richard.baker@digital.cabinet-office.gov.uk>
Co-authored-by: Pea <pea.tyczynska@digital.cabinet-office.gov.uk>
The CBC Proxy is essentially a lambda function which we invoke with
various arguments.
A way in which this can fail is that the notifications-api app invoking
the function may not be able, any longer, to invoke the function.
This could be caused by, for example:
* an egress restriction preventing access to eu-west-2.lambda.amazonaws.com
* a network partition preventing access to eu-west-2.lambda.amazonaws.com
* the app's credentials have been rotated or revoked
If we invoke a simple "canary" lambda function for which the app should
have access to invoke, and check it for failures, we will know quickly
if something is likely to be broken.
This is especially important for cell broadcasts compared to email/SMS
because we always have a baseline of traffic for email/SMS, and so any
failure is observed almost immediately. This is not true for CB where we
may expect to only see one CB message every week/month/quarter/year, as
opposed to every minute or second for email/SMS.
Signed-off-by: Toby Lorne <toby.lornewelch-richards@digital.cabinet-office.gov.uk>
Co-authored-by: Pea <pea.tyczynska@digital.cabinet-office.gov.uk>
