An alternative implementation could be for the TrafficOps client to be able to specify the backend, on a per request basis (via HTTP header, params, or some other mechanism), instead of a whitelist in TrafficOps. In this case, TrafficOps would still ultimately decide if a route could be serviced by multiple backends or not.
One nice property is that tests, automated or otherwise, could easily compare behavior from multiple backends. For example, a test case in the traffic_ops/testing/api/v14 directory could use the same logic to test both the Perl and Go implementations. From: ocket 8888 <[email protected]> Reply-To: "[email protected]" <[email protected]> Date: Wednesday, November 20, 2019 at 15:25 To: "[email protected]" <[email protected]> Subject: Re: [EXTERNAL] TO API routing blacklist I think documenting all of those is going to be more work than using the actual paths. I'm also not a fan of numeric IDs in most cases because it means you wouldn't be able to tell which routes are "Perl'd" or disabled just by looking at the config file On Wed, Nov 20, 2019 at 3:16 PM Rawlin Peters <[email protected]<mailto:[email protected]>> wrote: No, operators wouldn't need to read the source code, they would just have to read something like this in the log (printed on startup): 1 GET /api/1.1/cdns 2 PUT /api/1.1/cdns ... and so on. Then in cdn.conf you would put: { .... "routing_blacklist": { "perl_routes": [1, 2, 3, 4], "disabled_routes": [5, 6, 7, 8] }, .... } The obvious disadvantage would be that you wouldn't be able to tell which routes are "Perl'd" or disabled just by looking at the config file (although you could add comments in ignored json fields if you wanted to), but in practice I don't think this will be much of an issue. Yes, the idea is that the IDs would be statically maintained and not auto-generated on startup (as that could invalidate existing configs as you've said). Basically, we would just have to pick the next unused integer whenever adding a new route. Maintenance cost would be basically zero, since TO would fail to start if you've added a route with an ID that is already taken. - Rawlin On Wed, Nov 20, 2019 at 3:00 PM ocket 8888 <[email protected]<mailto:[email protected]>> wrote: > > If you make the configuration ID-based you're telling operators they need > to read the source code to be able to configure TO. Plus if those IDs are > generated sequentially and we need to insert a route in the middle so that > a later rule that would match it doesn't override the route then suddenly > everyone's configuration file is broken. Well, either that or we need to > statically maintain and document a magic number for every API route. > > Idk if this helps at all, but as has been pointed out before the routes > don't actually need to be regular expressions. > > On Wed, Nov 20, 2019 at 2:55 PM Rawlin Peters > <[email protected]<mailto:[email protected]>> wrote: > > > Hey folks, > > > > I'm currently working on this TO API routing blacklist feature, and > > while I've identified which routes should be on the whitelist of > > "routes that have been rewritten to Go but that are still safe to fall > > back to Perl for", the tediousness of copying route regular > > expressions for the whitelist has given me another idea. > > > > Rather than have the configuration be based on regular expressions > > that are meant to match the actual routes in the code, I was thinking > > of giving each route an ID, including the ID as part of the Route > > struct, and making the configuration based on these IDs instead of > > trying to mirror the regex. > > > > That way, you can't accidentally disable routes or have Perl handle > > routes you didn't mean to from writing a bad regular expression. > > Essentially, every route would get a unique ID that can be referenced > > in the config for either disabling it or routing it to Perl. Whether > > or not a Go route would be routable to Perl would also become part of > > the Route struct. TO would print the route IDs on startup (so you can > > easily find them and match them to the routes you're trying to disable > > or fall back to Perl) and verify that the actual given route IDs are > > unique (to ensure that IDs stay unique as routes are moved around or > > new routes are added). > > > > What do you think? Stick to regular expressions, or go with this IDea > > instead (see what I did there)? > > > > - Rawlin > > > > On Fri, Nov 1, 2019 at 4:01 PM Gray, Jonathan < [email protected]<mailto:[email protected]>> > > wrote: > > > > > > I largely don't care about the blacklisted routes for this purpose. I > > really care about a conclusive list of whitelisted routes (for which the > > example json payload could be expanded to carry). It seems like we're > > solving the exact same issue from two directions. It permits each native > > client library to assert that the routes it expects and needs to exist, > > exist on the other side. I have no desire to actively modify the runtime > > routes (for security I don't think we every should), just to get the list > > of what it had at startup. Having the override config file on disk to > > switch on/off independent route/methods is something I'd expect to have to > > restart TO for (no different than changes in the cdn.conf). I do also > > agree with proper 503 handling, but it allows us to perform a basic sanity > > check to prevent half-completed workflows necessitating complex recovery > > paths. For applications that use the client SDK, it gives an easy handle > > to know if every single upgrade necessitates recompiling and deploying 3rd > > party applications, such as a CZF File generator. > > > > > > Jonathan G > > > > > > > > > On 11/1/19, 1:49 PM, "Rawlin Peters" > > > <[email protected]<mailto:[email protected]>> wrote: > > > > > > > Not trying to sideswipe, but could we expose that as an endpoint > > with a Golang list as well to solve: > > https://urldefense.com/v3/__https://protect2.fireeye.com/url?k=5d57b4c9-01b3ba02-5d57937d-000babff3540-17d7cedf2908de8b&u=https:**Agithub.com*apache*trafficcontrol*issues*2872__;Ly8vLy8v!rx_L75ITgOQ!VMUtDsupfJ7TCk0L1Blt_1O4ovxM1nalp21_Fpmbp1Htn9o2oWOC83kc0nWYfOWdDzCc$<https://urldefense.com/v3/__https:/protect2.fireeye.com/url?k=5d57b4c9-01b3ba02-5d57937d-000babff3540-17d7cedf2908de8b&u=https:**Agithub.com*apache*trafficcontrol*issues*2872__;Ly8vLy8v!rx_L75ITgOQ!VMUtDsupfJ7TCk0L1Blt_1O4ovxM1nalp21_Fpmbp1Htn9o2oWOC83kc0nWYfOWdDzCc$> > > > > > > While I do agree with the request for an API endpoint that tells the > > > client what API versions are supported, I wouldn't want to > > > overcomplicate *this* particular feature with an API endpoint to > > > expose the information that is in the config file. > > > > > > If we implement that kind of "API information" API endpoint, I > > > wouldn't be opposed to including the currently blacklisted routes in > > > its response as a minor goal, but I don't really think it's warranted > > > by this routing blacklist feature alone. You should have a really, > > > really good reason to blacklist a route or bypass a TO-Go route for > > > the Perl, so this should be a (hopefully) relatively rare operation > > to > > > begin with. I don't think it would be all that useful for API clients > > > to be able to see the list of currently blacklisted APIs. The API > > > client should be written to properly handle 503s whenever they occur, > > > and to the client it shouldn't matter if the 503 is from the database > > > being overloaded at the time or if the route is blacklisted. > > > > > > - Rawlin > > > > > > > >
