+1. I don’t think we actually use (old) steering anywhere in production.
Steering does support the regex feature (use a regex to “pin” to a DS) and
I don’t think the client_steering does, so we might want to consider moving
that feature into client_steering. Steering also supports an overwrite
header that may or may not be in client steering.
On Wed, May 1, 2019 at 13:14 Rawlin Peters <rawlin.pet...@gmail.com> wrote:
> Hey all,
>
> I think we should consider deprecating the STEERING delivery service
> type in favor of CLIENT_STEERING.
>
> tl;dr:
> Everything that a STEERING delivery service provides can be provided
> by a CLIENT_STEERING delivery service instead, and CLIENT_STEERING
> provides more advanced features like Geolocation-based steering that
> are not available to the plain STEERING type. There are some small
> differences in request payloads when passing the `?format=json` query
> parameter, but other than that the client-facing interface is the same
> between CLIENT_STEERING and STEERING.
>
> What do you think of this proposal? Can you think of a good reason why
> we should keep STEERING in addition to CLIENT_STEERING? If you're
> skeptical or unsure, feel free to read the longer explanation below.
>
>
> Longer explanation:
> The main difference in the results returned by STEERING vs
> CLIENT_STEERING is that the STEERING result only contains the "top"
> target. This "top" target can still be returned as a json payload, as
> a 200 or a 302, depending on query parameters passed in the request,
> which is the same behavior as CLIENT_STEERING. However,
> CLIENT_STEERING will include *all* of the possible targets not just
> the "top" target.
>
> For clients that just consume and follow the 302, changing the
> delivery service from STEERING to CLIENT_STEERING won't really affect
> the clients -- that behavior would stay the same. However, if clients
> of the STEERING-type are passing `?format=json` in the request, that
> JSON payload differs slightly from STEERING to CLIENT_STEERING.
>
> For STEERING, the payload looks like this:
> {"location": "http://myedge.myds.mycdn.example.net/foo?format=json"}
> For CLIENT_STEERING, it uses an array like this:
> {"locations":["http://myedge.myds.mycdn.example.net/foo?format=json"]}
>
> For either STEERING or CLIENT_STEERING, if the client passes
> `?trred=false` to get a 200 response instead of a 302, the payload
> formats are the same.
>
> So, we couldn't really automatically convert all STEERING DSes to
> CLIENT_STEERING through a DB migration because of those small
> differences in the `?format=json` payloads between the two, but we
> could at least prevent the creation of new STEERING-type DSes during
> the deprecation period and encourage existing STEERING-type DSes to be
> converted to CLIENT_STEERING. Then after a major release or two we can
> draw a line in the sand and automatically convert STEERING types to
> CLIENT_STEERING, and/or make it a requirement that all STEERING-types
> must be converted to CLIENT_STEERING before a certain major release.
>
> Eliminating the STEERING type would allow us to simplify Traffic
> Router a little bit and make it less confusing for users by not having
> two different STEERING types to choose from. Going forward a lot of
> new features are only being added to the CLIENT_STEERING type because
> they don't really apply to STEERING, so the feature disparity between
> the two is only going to grow.
>
> - Rawlin
>
