I thought about that. But I'd like to reserve the major version of TC
for actually major things. Making the API control the TC version
number feels like the tail wagging the dog. Most other projects don't
do it that way, either.
It might not be so bad, except that we make breaking changes on a
fairly regular basis. It would feel weird revving TC to version 14
simply because we changed the datatype of a minor field for the 13th
time.
And likewise, sometimes we don't change the API. At the moment, we're
pretty API-focused. But focuses change and we might have whole
releases focused on UI or integrations. It would be strange to rev the
API when it didn't change. The point of Semantic Versioning is to
communicate changes to the API in a way that is consistent, easy to
apply, and grokkable by humans and computers alike.
I think I'm still -1 on locking the API version to the TC version.
On Thu, Oct 19, 2017 at 3:39 PM, Robert Butts <robert.o.bu...@gmail.com> wrote:
> @alficles What if we do both Semantic Versioning, and tying the API version
> to the TC version? So, we would have to increase the TC major version with
> any breaking API changes (which may inconveniently be minor to the rest of
> TC).
>
> But, that has the big advantage of letting us programmatically tie the TC
> version to every client. So, with a small upfront cost writing the code to
> read the `/VERSION` file into the client binaries when the RPM is
> built--for example, in Go with ```-ldflags "-X lib.Version=`cat
> ../VERSION`"``, and then concatenating that string into the endpoint
> request---we could synchronise all our versions, and essentially not have
> to think about versions, not have to manually update clients, not have to
> worry about what endpoint was added in what version.
>
> That alleviates a huge percentage of the brain and keyboard work we
> currently have to do surrounding versioning.
>
>> Our API version should have 3 numbers, though: major, minor, patch
>
> -1 on putting the patch in the URI, it's verbose and unnecessary, bug fixes
> don't make things incompatible and are unlikely to cause confusion.
> +1 on putting the patch in a header, e.g. `X-API-Version: 1.3.deadbeef`.
> Header makes it easy to debug, in the rare event it's necessary, without
> cluttering the URI or Body.
>
>
> On Thu, Oct 19, 2017 at 3:14 PM, Chris Lemmons <alfic...@gmail.com> wrote:
>
>> Heh, I agree on the arguing about API versions, but I just want to
>> hand the task to Semantic Versioning, so we can just ask some simple
>> questions like "did we break backward compatibility" and "did we add
>> something" and figure out what number to put on the route. And we
>> avoid arguments entirely. (We have to get used to the idea of revving
>> the top version, though, because we break compatibility a lot.)
>>
>> On Thu, Oct 19, 2017 at 3:01 PM, Jeremy Mitchell <mitchell...@gmail.com>
>> wrote:
>> > In reality, we really did break the API when we went from mysql (TC 1.8)
>> to
>> > postgres (TC 2.0) and strings became ints, for example, so the api should
>> > really be 2.x anyhow imo.
>> >
>> > Anyhow, the real reason i like syncing the api version to the TC version
>> is
>> > for simplicity and we don't have to argue all day about api versions. :)
>> >
>> >
>> >
>> >
>> >
>> > On Thu, Oct 19, 2017 at 2:54 PM, Chris Lemmons <alfic...@gmail.com>
>> wrote:
>> >
>> >> Interesting idea. I think, though, it's better to keep API versions
>> >> separate from TC versions. Many versions of TC won't rev the API at
>> >> all. I'd prefer to go all in on Semantic Versioning.
>> >>
>> >> I think it could work like this. For a given route, use the route
>> >> defined for the most recent version not later than the requested
>> >> version. So, if the quux endpoint is introduced at 1.2, and changed at
>> >> 1.4, these requests would be served by these routes:
>> >>
>> >> GET /api/1.1/quux → 404
>> >> GET /api/1.2/quux → Served by 1.2.
>> >> GET /api/1.3/quux → Served by 1.2.
>> >> GET /api/1.4/quux → Served by 1.4.
>> >> GET /api/1.5/quux → Served by 1.4.
>> >>
>> >> The advantage of this is that it's relatively easy to implement in the
>> >> router, though there are admittedly some challenges on the Perl side
>> >> of things. If we want to be clever, we can allow a client to elide
>> >> later values and just assume they meant the latest. But we don't need
>> >> to start out clever.
>> >>
>> >> Our API version should have 3 numbers, though: major, minor, patch. We
>> >> should expose these versions in a new /version endpoint that will
>> >> allow clients to self-configure and detect new versions.
>> >>
>> >> As an alternative to strict semantic versioning, we could consider the
>> >> first two numbers to be the "major" number for Semantic Versioning
>> >> purposes. I think this hurts discoverability in the community, but it
>> >> matches our current practice, for the most part. I think this would be
>> >> a reasonable compromise, if people aren't comfortable increasing the
>> >> first number every time we break compatibility in a revision.
>> >>
>> >> Lastly, we should recognize that we may need to retire API versions.
>> >> Eventually, we may make changes to the DB that mean the information
>> >> provided in a prior version simply does not exist. To that end, we
>> >> should provide a /minversion (or similar) endpoint that returns the
>> >> lowest API version supported by that server. Queries below that value
>> >> cannot be guaranteed to succeed. (Or would it be better to cut it off
>> >> an say that no queries for previous versions are permitted?)
>> >>
>> >> I'm +1 on Semantic Versioning. I'm a lukewarm +1 on a variant that
>> >> uses the first two numbers as "major" and the last as "minor". I'm -1
>> >> on locking it to the version of TC. I'm +1 on providing /version and
>> >> /minversion endpoints to allow clients to auto-detect incompatibility.
>> >>
>> >> On Thu, Oct 19, 2017 at 12:54 PM, Jeremy Mitchell <
>> mitchell...@gmail.com>
>> >> wrote:
>> >> > With the Golang API rewrite, we were not planning to break any APIs
>> but
>> >> > rather simply port them to Golang thus we did not see the need to rev
>> the
>> >> > API version from 1.2. However, maybe this is good opportunity to get
>> our
>> >> > API version inline with the TC version.
>> >> >
>> >> > So, my thought is that our Golang API's look like this:
>> >> >
>> >> > GET /api/v2.2/foos <-- this would return foos served by golang because
>> >> > we've ported this endpoint
>> >> > GET /api/v2.2/bars <-- this would return a 404 served by golang
>> because
>> >> > we've have NOT yet ported this endpoint
>> >> >
>> >> > and our perl apis are still acessible in 1.2
>> >> >
>> >> > GET /api/1.2/foos <-- this would return foos served by perl
>> >> > GET /api/1.2/bars <-- this would return bars served by perl
>> >> >
>> >> > This has 3 benefits:
>> >> >
>> >> > 1. by revving the version, it signals the community that something has
>> >> > actually changed in our API and in this case, the change may simply be
>> >> the
>> >> > fact that we now have nifty golang implemented APIs that you might
>> want
>> >> to
>> >> > explore.
>> >> > 2. it provides the ability to stay on the perl apis by specifying 1.2
>> if
>> >> > that is what you want to do. maybe you are not much of a risk taker...
>> >> > 3. it does actually provide license to break the new golang apis if
>> >> needed
>> >> > (to make them better) because the major version has incremented. it's
>> >> nice
>> >> > to have that option if needed.
>> >> >
>> >> > Also, going forward, I propose the TO API version follows in lockstep
>> >> with
>> >> > the TC version...which means the minor version will keep
>> >> incrementing...GET
>> >> > /api/v2.2/foos...GET /api/v2.3/foos..which means functionality can be
>> >> added
>> >> > to the API "in a backwards-compatible manner"
>> >> >
>> >> > Remember, at some point TO will only be the TO API so why wouldn't
>> this
>> >> > component follow the versioning that the other components do? Just my
>> >> > thoughts.
>> >> >
>> >> > Jeremy
>> >> >
>> >> > On Tue, Oct 17, 2017 at 12:02 PM, Robert Butts <
>> robert.o.bu...@gmail.com
>> >> >
>> >> > wrote:
>> >> >
>> >> >> I'm fully +1 on Semantic Versioning. We discussed it briefly on the
>> >> list a
>> >> >> long time ago, but we haven't really been doing it.
>> >> >>
>> >> >> That said, versioning requires a lot of code/work that simply doesn't
>> >> exist
>> >> >> today. That's the reason we haven't been doing it properly.
>> >> >>
>> >> >> The Go Traffic Ops has Semantic Versioning built-in to the Routing,
>> but
>> >> >> Perl support is close to nil. Perl currently has an easy way to say
>> >> >> "include all the routes in this version number", But there's no way
>> to
>> >> say
>> >> >> "this route is 1.2 only, and this route is 1.3 only" -- we'd have to
>> >> >> duplicate TrafficOpsRoutes.pm, with only a few lines changed, and
>> >> likewise
>> >> >> duplicate changed functions. It needs a framework. Or we could just
>> wait
>> >> >> until Perl goes away.
>> >> >>
>> >> >> That said, Go, especially the client, doesn't completely support
>> Minor
>> >> >> Versions like it should, either. Consider adding a new field to
>> Delivery
>> >> >> Services. Per Semantic Versioning, that field MUST not be returned by
>> >> the
>> >> >> old version `GET`, and MUST not be set if passed by a `POST`. The Go
>> >> server
>> >> >> supports that in the Routing, via different endpoints, but there's no
>> >> >> Struct framework or pattern. And the client completely doesn't
>> support
>> >> it.
>> >> >> In Go, we probably need a set of anonymously-nested structs, `type
>> >> >> DeliveryServices12 struct { Foo int }; type DeliveryServices13 struct
>> >> >> {DeliveryServices12; Bar string}`. But that simply doesn't exist
>> today,
>> >> and
>> >> >> will take development time to write.
>> >> >>
>> >> >> Option 2: Absolute Versioning. Instead of Semantic Versioning, we
>> could
>> >> >> have a single version, and break compatibility with each new version.
>> >> So,
>> >> >> all new features (breaking or not) would go in a new version, and all
>> >> >> clients must check the version, and refuse to operate on a different
>> >> >> version. So you'd be required to have a client version matching the
>> >> server
>> >> >> version; users are not allowed to talk to new servers with old
>> clients.
>> >> >>
>> >> >> Option 3: No Versioning. We get rid of the version number. Endpoints
>> >> are at
>> >> >> `/api/foo`. Over the last few years, we have _repeatedly_ broken the
>> API
>> >> >> for the same version. A 1.2 client from three years ago will fail
>> >> >> catastrophically if connected to a Traffic Ops serving `/api/1.2`
>> >> today. In
>> >> >> practice, as we've been developing, we have no version, the version
>> >> number
>> >> >> is meaningless and confusing. If we're going to continue breaking
>> >> >> compatibility without updating the version number, we should get rid
>> of
>> >> it.
>> >> >> Then at least the version itself won't be confusing and painful.
>> >> >>
>> >> >> What's the consensus here? Does everyone agree with Semantic
>> >> Versioning? Do
>> >> >> we want to commit to requiring it? Is there a consensus? Or should we
>> >> take
>> >> >> a vote, whether to require Semantic Versioning, Absolute Versioning,
>> or
>> >> No
>> >> >> Version?
>> >> >>
>> >> >>
>> >> >> On Thu, Oct 12, 2017 at 7:39 AM, Dave Neuman <neu...@apache.org>
>> wrote:
>> >> >>
>> >> >> > Traffic ops currently does not handle versioning very well. I
>> think
>> >> we
>> >> >> do
>> >> >> > support 1.1 and 1.2 versions of the API, but I think there are
>> only a
>> >> few
>> >> >> > (maybe asns and deliveryservices) that are actually different.
>> >> >> > Versioning is something we look to improve as we move to the golang
>> >> >> version
>> >> >> > of the API.
>> >> >> >
>> >> >> > On Thu, Oct 12, 2017 at 6:50 AM, Eric Friedrich (efriedri) <
>> >> >> > efrie...@cisco.com> wrote:
>> >> >> >
>> >> >> > > Does Traffic Ops expose a semantic version number as part of its
>> >> API?
>> >> >> > >
>> >> >> > > http://semver.org/
>> >> >> > > "Given a version number MAJOR.MINOR.PATCH, increment the:
>> >> >> > >
>> >> >> > > 1. MAJOR version when you make incompatible API changes,
>> >> >> > > 2. MINOR version when you add functionality in a
>> >> >> backwards-compatible
>> >> >> > > manner, and
>> >> >> > > 3. PATCH version when you make backwards-compatible bug fixes.
>> >> >> > >
>> >> >> > > “
>> >> >> > >
>> >> >> > > We have some TO clients and would like to improve their backwards
>> >> >> > > compatibility. Without this version number, it is not easy to
>> >> determine
>> >> >> > > which fields in the API are supported by any given version.
>> >> >> > >
>> >> >> > > Thanks,
>> >> >> > > Eric
>> >> >> > >
>> >> >> > >
>> >> >> >
>> >> >>
>> >>
>>
