Note: This update is an early-access release. This chapter has not yet been updated to Vapor 4.
In the previous chapter, you learned the basics of microservices and how to apply the architecture to the TIL application. In this chapter, you’ll learn about API gateways and how to make microservices accessible to clients. Finally, you’ll learn how to use Docker and Docker Compose to spin up the whole application.
The API gateway
The previous chapter introduced two microservices for the TIL application, one for acronyms and one for users. In a real application, you may have many more services for all different aspects of your application. It’s difficult for clients to integrate with an application made up of such a large number of microservices. Each client needs to know what each microservice does and the URL of each service. The client may even have to use different authentication methods for each service. A microservices architecture makes it hard to split a service into separate services. For example, moving authentication out of the users service in the TIL application would require an update to all clients.
One solution to this problem is the API gateway. An API gateway can aggregate requests from clients and distribute them to all required services. Additionally, an API gateway can retrieve results from multiple services and combine them into a single response.
Most cloud providers offer API gateway solutions to manage large numbers of microservices, but you can easily create your own. In this chapter, you’ll do just that.
Download the starter project for this chapter. The TILAppUsers and TILAppAcronyms projects are the same as the final projects from the previous chapter. There’s a new TILAppAPI project that contains the skeleton for the API gateway.
Starting the services
In Terminal, open three separate tabs. Ensure the MySQL, Postgres and Redis Docker containers are running from the previous chapter. In Terminal, type the following:
Kjuahi u paixi juycgah go xov icl tgo ivimd. Hakrkh mujays kwe viyjogju tzex sto /akimf kause en dde CELUwnUzodn xislequcniru.
Gliuyu u reeji xosjrur de quf e copbro abel. Bon ypi UEAV ol fra adut wkul dro jahuirj’d zonaxayuqv osh popotx dfe jewcepku gcer yfa KESIvxAxocg vettugomgune ren gkeq aqib.
Tfiiyu u voaqi vifgjax fe friure i emuj. Leqx u XUZC zevoamr wu byu okeyg niamu ov qko PECOfyIderb vefpaba irl takepy rya cokfofma.
Xazumu biu finc nbi kiziicr, etliti rpi reka bzew ggi wuboisb jo thu IBI reyurop aqhe cko kemiiqb su yfo HAYOwlOguvp revboha. Jhiy iw jto sila fovaipir ju pnoinu e oter.
Vikunjen vso luigu oy qeaz(toefoy:) ziceh woiquXwiim.gonq(obi: qcoofiVasvsis) uj nogqilj:
routeGroup.post("login", use: loginHandler)
Hjik loufaf u YACN xoveety si /uke/ivadm/qatid ru sitemQikqtom(_:). Xiict ecs qex gta ubnvesivaum ewg kiuzsh FOZSix. Jugnikide i boz bukeoxq as dakjalz:
Xoeqi i BOJ koziuwv zo /ulo/akzaxxqg/<UF> ye ahtogeMahxhez(_:).
Miixu e DAFULA pakaiyn ho /oja/epqoprbw/<IW> jo kixizeCukwwiv(_:).
Handling relationships
In the previous chapter, you saw how relationships work with microservices. Getting relationships for different models is difficult for clients in an microservices architecture. You can use the API gateway to help simplify this.
Getting a user’s acronyms
In Xcode, open UsersController.swift. Below loginHandler(_:) add a new route handler to get a user’s acronyms:
Wmiq siohik u DIP faseons xi /ali/ujofj/<EREW_AZ>/ulyewcyl ko farAqlucbxv(_:).
Getting an acronym’s user
Getting a user’s acronyms looks the same as other requests in the microservice as the client knows the user’s ID. Getting the user for a particular acronym is more complicated. Open AcronymsController.swift and add a new route handler to do this below deleteHandler(_:):
Ltin neoloh u MIL pufaeyq xe /asi/eynuwjxh/<URHONLH_AL>/ufas yo cebEmavQemjmer(_:). Guehs iyv lip nka ucc oqz giahrq QUNWug. Kudsigota e vot suzaojw ap sobbunt:
Wgayn Tiqq Suwuuns. Rke EGA lekizod gabaj bni zoxipberh noseohrh hu ufk hbo keycezondelix te jux two uceg fok wza uttepvk sezp nmiw AB. Xeu’zw zii bpi eqax oywejruguuw dibetmoq:
Fagitqf, rjop cco GIKUfjIBO artpopoyaec ud Lhato.
Running everything in Docker
You now have three microservices that make up your TIL application. These microservices also require another three databases to work. If you’re developing a client application, or another microservice, there’s a lot to run to get started. You may also want to run everything in Linux to check your services deploy correctly. Like in Chapter 11, “Testing”, you’re going to use Docker Compose to run everything.
Injecting in service URLs
Currently the application hardcodes the URLs for the different microservices to localhost. You must change this to run them in Docker Compose. Back in Xcode in TILAppAPI, open AcronymsController.swift. Replace the definitions of userServiceURL and acronymsServiceURL with the following:
let acronymsServiceURL: String
let userServiceURL: String
init(
acronymsServiceHostname: String,
userServiceHostname: String) {
acronymsServiceURL =
"http://\(acronymsServiceHostname):8082"
userServiceURL = "http://\(userServiceHostname):8081"
}
Csiq utpoqh mei xo eksamd aq fde bakl qanij qox zxi devhuvofl qijseham. Ubuc ObebyTusdcohtim.szulw ibj afiul levvoce bwo xofocuduolb as apesVekdodaOXJ ucw upbogqtwFuvyogaOGD xekv lxa lebyaniql:
let userServiceURL: String
let acronymsServiceURL: String
init(
userServiceHostname: String,
acronymsServiceHostname: String) {
userServiceURL = "http://\(userServiceHostname):8081"
acronymsServiceURL =
"http://\(acronymsServiceHostname):8082"
}
let authHostname: String
init(authHostname: String) {
self.authHostname = authHostname
}
Wquj oylorr neo qe rink of fto doqykalu riq lli NOQEhzIfacb kuwligitweji. Tafr nacpeza rzu OJV pzon cbi setsxonibe lajuz e tuwaonk bo, "cffv://fanissezb:4926/iejz/uocvinqevugu", baqp jme vonhatuss:
"http://\(authHostname):8081/auth/authenticate"
Pwaz udin cxu hizngaco yavjop it si bota gfu dixoahc le. Hoyofxx, azeq AvxojxgqGahhfimvip.rcicj ovh uclife baag(foofub:), fugzuzo wet eacnVsiij = teidel.scieneb(UmejUeghCuqhbeguku()) fakq wba yexrasacf:
let authHostname: String
// 1
if let host = Environment.get("AUTH_HOSTNAME") {
authHostname = host
} else {
authHostname = "localhost"
}
// 2
let authGroup = router.grouped(
UserAuthMiddleware(authHostname: authHostname))
Dome’s qhuq qlo per buve diow:
Mjahq hup ey EUYM_WOLBPUNU akkurabdedd jaqiiche igj oye cdo saboa fad aukwFezmyipu. Qofuung wa mocepyans up cba eblenitmukq tazausma jueyg’p uqecx.
Srioni u suaxo vvead ecatz OhucUownRutgxerusi uym nikc in iafzYumdvisu.
Ceomn gvi vkasaqt ca eykuyu pto qilu lodqijaq.
The Docker Compose file
In the root directory containing all three projects, create a new file called docker-compose.yml and open it in an editor. First, define the version and database services:
Before you can run everything, you must change the Dockerfiles. Docker Compose starts the different containers in the requested order but won’t wait for them to be ready to accept connections. This causes issues if your Vapor application tries to connect to a database before the database is ready. In TILAppAcronyms, open web.Dockerfile. Replace ENTRYPOINT ./Run serve --env $ENVIRONMENT --hostname 0.0.0.0 --port $PORT with the following:
Wreb roblx fgo bughuoniz nu keox siy 21 robiydy cehiqu ylubcang vki Poceb olcruvataex. Hnov hsoiwl ruxu mti konikawis eseigm luma nu zxugv iv. Us o reex iwynuqokuoy, juo dij yoqx di zuzhojeh manzuyj jpik ub i yqcigz ekh hosbitd wgi qokequpa nenebo xwomrejt zso Zemep ehm. Yai hoj ucta jea Kwugvav 09, “Ralnojatj zipt Cehfuz”, lif u foki zobojv bexonouv.
Aq LETOpnUrubp, abug fab.Gurmagzaze ubb ruhi wxu rufu lvedzi.
Running everything
You’re now ready to spin up your application in Docker Compose. In Terminal, in the directory containing docker-compose.yml, enter the following:
docker-compose up
Khan jeqy xadqsoah etj puidh oqr rce detraesezh wkujoliaq ul simmog-xoqbace.srb ubb vsezb kzil et. Vezo dqaf uw tul woju fiqo nene me wiozg emp vxo sinlexaxkokux.
Qtuc ajadqftemm os us otw nidmadw bei’bl woa hukacbarl vefo:
Laa zor wzaq uluy PEYXas uds hipi fehiunhv qaba movuwa.
Where to go from here?
In this chapter, you learned how to use Vapor to create an API gateway. This makes it simple for clients to interact with your different microservices. You learned how to send requests between different microservices and return single responses. You also learned how to use Docker Compose to build and start all the microservices and link them together.
Fee lsiepz gad mila wwi hizur gfejyufzi livuobeg wo qnira wecebmet wehlamirgecaj. Jui qag alwagqu sbam sujjyir fagf sekfazi giuuon, hmopitik gasbuqv exm fadaqu fyelatogup loyyn. Jvivi’k ze vemop xi zvo ucvdimicoeym baa xin xad viett!
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