DVLA would like to be able to identify letters sent by the Insolvency
Service, so we are changing the zipfile name. They need all zipfile
names to have the same structure, so we can't just add a marker to files
sent by that service - we have to change all filenames.
The new format is like this:
`{NOTIFY}.{DATE}.{SEQUENCE_ID}.{UNIQUE_ID}.{SERVICE_ID}.{ORG_NAME}.{EXTENSION}`
This is not required by DVLA and since [1] we no longer care about
the end of letter filenames when collating them, so removing it is
safe to do. Note that the name of the ZIP files of collated letters
is based on a hash of the filenames, which needed updating in tests.
Before merging this we need to do a test run in Staging, so DVLA can
check that a mixture of the old / new filenames won't cause issues.
[1]: https://github.com/alphagov/notifications-api/pull/3172
Previously we did some unnecessary work:
- Collate task. This had one S3 request to get a summary of the object,
which was then used in another request to get the full object. We only
need the size of the object, which is included in the summary [1].
- Archive task. This had one S3 request to get a summary of the object,
which was then used to make another request to delete it. We still need
both requests, but we can remove the S3.Object in the middle.
[1]: https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/s3.html#objectsummary
Previously, the function would just return a presumed filename. Now that
it actually checks s3, if the file doesn't exist it'll raise an
exception. By default that's a StopIteration at the end of the bucket
iterator, which isn't ideal as this will get supressed if the function
is called within a generator loop further up or anything.
There are a couple of places where we expect the file may not exist, so
we define a custom exception to rescue specifically here. I did consider
subclassing boto's ClientError, but this wasn't straightforward as the
constructor expects to know the operation that failed, which for me is a
signal that it's not an appropriate (re-)use of the class.
Previously we generated the filename we expected a letter PDF to be
stored at in S3, and used that to retrieve it. However, the generated
filename can change over the course of a notification's lifetime e.g.
if the service changes from crown ('.C.') to non-crown ('.N.').
The prefix of the filename is stable: it's based on properties of the
notification - reference and creation - that don't change. This commit
changes the way we interact with letter PDFs in S3:
- Uploading uses the original method to generate the full file name.
The method is renamed to 'generate_' to distinguish it from the new one.
- Downloading uses a new 'find_' method to get the filename using just
its prefix, which makes it agnostic to changes in the filename suffix.
Making this change helps to decouple our code from the requirements DVLA
have on the filenames. While it means more traffic to S3, we rely on S3
in any case to download the files. From experience, we know S3 is highly
reliable and performant, so don't anticipate any issues.
In the tests we favour using moto to mock S3, so that the behaviour is
realistic. There are a couple of places where we just mock the method,
since what it returns isn't important for the test.
Note that, since the new method requires a notification object, we need
to change a query in one place, the columns of which were only selected
to appease the original method to generate a filename.
All other tasks in app/celery/*_tasks.py have timers on them. Some
of these timers will be useful to check before/after performance as
a way to reassure ourselves about the impact of [1].
[1]: https://github.com/alphagov/notifications-api/pull/3172
previously we were returning the entire ORM object. Returning columns
has a couple of benefits:
* Means we can join on to services there and then, avoiding second
queries to get the crown status of the service later in the collate
flow.
* Massively reduces the amount of data we return - particularly free
text fields like personalisation that could be potentially quite big.
5 columns rather than 26 columns.
* Minor thing, but will skip some CPU cycles as sqlalchemy will no
longer construct an ORM object and try and keep track of changes. We
know this function doesn't change any of the values to persist them
back, so this is an unnecessary step from sqlalchemy.
Disadvantages are:
* The dao_get_letters_to_be_printed return interface is now much more
tightly coupled to the get_key_and_size_of_letters_to_be_sent_to_print
function that calls it.
we had issues where we had 150k 2nd class notifications, and the collate
task never ran properly, presumably because the volume of data being
returned was too big.
to try and help with this, we can switch to streaming rather than using
`.all` and building up lists of data. This should help, though the
initial query may be a problem still.
This is at request of DVLA. They would prefer to have zip files with the
same number of arguments in the name. After being offered a few
different options, such as including an org and service id for all zips,
they chose to just remove the 'INSOLVENCY' tag.
For more context see PR that added the tag
https://github.com/alphagov/notifications-api/pull/3006
When letters are sent to DVLA, we will now put them in a separate
ZIP file for each service, so that if there are printing issues
due to bad files from one service, other services will hopefully
not be affected by that.
we don't name letters based on the day we send them on, rather, the day
we create them on. If we process a letter for a second time for whatever
reason, even if it's a couple of days later, it'll still go in a folder
based on the created_at timestamp. There's still a slight confusion,
however - if the timestamp is after 5:30pm, the folder will be for the
day after. However, still the day after creation, so I think created_at
still makes the most sense.
Remove the term `sending_date` to try and make this relationship more
apparent.
`_now`? why would we ever use a different _now? instead say created_at,
because that's what it'll always be set to, even if we're replaying old
letters. We always set the folder name to when the letter was
created_at, or we might not know where to look to find it.
`dont_use_sending_date` doesn't really tell us what might happen if we
don't use it - the answer is we return an empty string. we ignore the
folder entirely. so lets call it that.
Also, remove use of freeze_gun in the tests, to prove that we don't use
the current time in any calculations. Also add an assert to a mock in
the get_pdf_for_templated_letter test, because we were mocking but not
asserting before, so the tests didn't fail when the function signature
changed.
We were determing the filename for precompiled letters before we had
checked if the letters were international. This meant that a letter
could have a filename indicating it was 2nd class, but once we had
sanitised the letter and checked the address we were setting the
notification to international.
This stopped these letters from being picked up to be sent to the DVLA,
since the filename and postage of the letter did not match.
We now regenerate the filename after the letter has been sanitised (and when
we know the postage) and use the updated filename when moving the letter
into the live PDF letters bucket.
This will help us better understand how far through the task has got if
it gets interrupted halfway (as was the case this morning and we
struggled to understand).
We will split them into three categories:
- first class
- second class
- international - this zip file will have letters for both europe
and rest-of-world postage classes
If a service has permission to send international letters then it should
tell template preview, so that template preview knows what rule to
apply when it’s validating the address of the letter.
Depends on:
- [ ] https://github.com/alphagov/notifications-template-preview/pull/445
This has been replaced by a new task, `sanitise-letter`, to this deletes
all the code in the old task and ensures that when antivirus is not
enabled locally we are calling the new task.
This task didn't have retries before, based on the assumption that if
the task failed it was likely to be due to a Boto error, so retrying
would not help because a file was probably not in the expected bucket.
During an incident with the database, we had some letters that were
stuck in the `pending-virus-check` state because this task failed.
This change adds retries to the task if there was an Exception that was
not a `BotoClientError`.
Previously, when running the `collate_letter_pdfs_for_day` task, we
would only send letters that were created between 5:30pm yesterday and
5:30 today.
Now we send letters that were created before 5:30pm today and that are
still waiting to be sent. This will help us automatically attempt to
send letters that may have fallen through the gaps and not been sent the
previous day when they should have been.
Previously we solved the problem of letters that had fallen the gap by
having to run the task with a date parameter for example
`collate_letter_pdfs_for_day('2020-02-18'). We no longer need this date
parameter as we will always look back across previous days too for
letters that still need sending.
Note, we have to change from using the pagination `list_objects_v2` to
instead getting each individual notification from s3. We reduce load by
using `HEAD` rather than `GET` but this will still greatly increase the
number of API calls. We acknowledge there will be a small cost to this,
say 50p for 5000 letters and think this is tolerable. Boto3 also handles
retries itself so if when making one of the many HEAD requests, there is
a networking blip then it should be retried automatically for us.
If the letter passed sanitisation, the recipient address will be
returned from template preview, so we want to save this as the `to`
field of the notification.
Template preview will now send an encrypted dict containing all the args
to the `process_sanitised_letter` task, so this updates the task to
handle data in the new format.
When a precompiled letter is sent via the admin app, we now pass in the address which can be set in the Notifications.to field.
Once a precompiled letters sent by the API has passed validation we can set the address in Notifications.to field.
The celery tasks to validate precompiled letters sent by the API will be done in another PR.
Added a task, `sanitise-letter`, that will be called from antivirus when
a letter has passed virus scan. This calls a new task in
template-preview which will sanitise the PDF.
A second new task, `process-sanitised-letter`, will be called from the
template preview task and deals with updating the notification and
moving it to the relevant bucket.
