Q4 maintenance

[tublitzed]

• Upgrade Rusoto
• convert various Db init functions (e.g. diesel migrations) to "fairings" (and update diesel)
• replace legacy failure error handlers with modern thiserror & anyhow

[AzureMarker]

Rocket 0.4 still requires nightly (and is the version currently in use). Rocket 0.5 (unreleased) will no longer require nightly.

Here's the GitHub milestone tracking 0.5 progress: https://github.com/SergioBenitez/Rocket/milestone/8

[jrconlin]

Thanks Mark!

We should still migrate to 0.4, since we're on a pretty old version of rocket as is.

[AzureMarker]

According to Cargo.lock it's using 0.4.5 0.4.4 while the latest version is 0.4.5, so there is an update to be made but it's just a patch update.

Edit: The lock file is always more accurate; it's actually using 0.4.5, which is the latest version.

[jrconlin]

I'm going to suggest that this issue is still accurate, but that the scope and target are going to be vastly different.

Pushbox is written with a lot of legacy. Rocket, currently, is not.

In order to get Pushbox over onto the latest Rocket the following will probably be required:

• [x] Convert futures 0.1 to modern async/await
• [ ] ~convert various Db init functions (e.g. diesel migrations) to "fairings" (and update diesel)~ Skipping this because I'm not sure that this will get any significant advantage over what we're doing now. on_request is more about modifying incoming Request and Payload data.
• [x] replace legacy failure error handlers with modern thiserror & anyhow etc.

[pjenvey]

* Convert futures 0.1 to modern async/await

I didn't think there was any async in pushbox

[jrconlin]

Not in pushbox directly, but recent versions of rusoto are all async, so we should couch those calls correctly.