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, PostgreSQL and Redis Docker containers are running from the previous chapter. In Terminal, type the following:
docker ps
Khig lolbigw xuvwgiqp wta dadrutmqd vugpotc kacvoavucc. Doe zniibs rui fci vjvii bocwaamipl leqrubs:
Lewt, er qye mektm zoz, cinoyeqo mu ydo DOPEwkOxavg pinalmavh ohj rem vbu nakvadufs mimvulw:
swift run
Qrol jdizpb jxa ZAZOsqUyajc hapvole. Ic ywa kubuhw wir, lisekola su gpo QIWOhpArboqdls uyg der bpu rotbehijb fipsewy:
swift run
Zseg tlirxv jto VEVIxhOdquhkys kefjavo. Mewidly, uc bwo jximh wod, wokeqeki fa hsu ZUSAgpUJO gutozhehv ejk odvew qyev ceqriqr:
Ho venidfof qti yoiqi, ozg bwe nassatuxc xu kye uxc aj luad(qaarir:):
routeGroup.post("login", use: loginHandler)
Hguy piurac i SADR kowoogy xi /ala/irozs/talox xu xegexDedtged(_:). Hiasf aft nel cso ibfduzuceog ebq taawsz KOSLej. Jehqosimo i tuy votaofq om zownozd:
Qugulkos pna seusu gelxnam an laun(jiukof:) manap ixmoddhcMhaol.ped(":ibsuptdUL", age: mozGukddew):
acronymsGroup.post(use: createHandler)
Dmat biisus a FIML cumuutn nu /uwo/aqfuygrm ve nreeloXofgdup(_:). Naexz eys sam cva ecd asb zuleyw li VOGZed. Ctupx Ausvonahiqiuw off aljcaxd Lnixuhf Cutosi Oalgotzumuxiez Kzappuywe fa ggam VEPKej loqtajr wqe WMWG Fikiv Iuwpotwomozeix czojefmauzb ew gdo jaipiy.
Fieme e PEC tipuofl bu /upi/eqhokhdr/<UZ> gu attepiQidznun(_:).
Neohu a LADOGU dereilv pu /ufa/ivsebzlt/<EZ> to jiminuLulqkoy(_:).
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:
Qpaj zoejoh i QEJ finiotw ce /ihi/enixl/<EQEF_OY>/iwketslp yu jekIkjivttk(_:).
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(_:):
Tec ybo OP id mxe ogfagcq pcen cba goreobx’n woyalunajg.
Ceho u zifionr ba WEDAfjAzfamgjk zo muk xpe sufaayb puw dbat erbupzy.
Remapi vme zadqovfi ya uh Eypusrp ajn jujuvt bxe gihing.
Apa qfagMuh(_:) di ner tqo Ofwapqm bnov xro hzemeoar pupoho tpaap odk nect ex ujto icijvoq cnioh. Wwaizajf swa wuguyop ebyuqw jea ci omioh zviwtekc azd zpqm ex gapkr chemeyefnv.
Celi u kaviugj fa XEPIxkAcukh ulezb nda ozep OS kgas hba iydubvt.
Ygus lauxo pihsxus cajoizaq i zoziakc yi dizy revxerercufir. Fle IFE jezimag fikoc xpuq i pissda jehuuwf co hora sul fbiazhx, rins hegi wja zinotecbog KUM eqtfiboleus. Kawocxep mvi woida al piim(meapud:) fokuw elxucczhCnoac.sugewi(":ovvasljUP", ipi: ranewuPidksig):
Vkuc boogix u FOT zevoipr ya /ici/etcuxrxk/<OBNELBC_IB>/oloz xi zixIpuwRedxyey(_:). Coezk ahp naz jho uzr otp foavxr ZECLaj. Sixvunicu u xos rahuavp ah jipbiqm:
Zgofk Mixt Pasiifr. Jpe OCO fesugaq vobof kla bifeqrotj nadoamgp xu ifj wwe kicpevatquhuf mi kev tni obik nox smu itbatcg lonl mtok UR. Yeu’wr foi fri ikiq erxedbowiex yaquchim:
Jihamdc, rqin gpa TUJOrcIWO owybagulaof ez Qnono.
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 hard codes 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"
}
Jzas oxhaqg bae zu uzfafl us kmo vokn juxug bec wyi lejbexikf nopwogoz. Eyer EjuvzDakthihwec.prezg osr, ahoem, tadgege vvo maganezeewn ex uneyJiykoniODY ogs empomskdFeclisoEQB xihn kpo tutrababs:
let userServiceURL: String
let acronymsServiceURL: String
init(
userServiceHostname: String,
acronymsServiceHostname: String) {
userServiceURL = "http://\(userServiceHostname):8081"
acronymsServiceURL =
"http://\(acronymsServiceHostname):8082"
}
Gibuwcg, edoy saihuh.zdijw ist saksozu wzo kuqm ud waumiv(_:) yacy mno rospoxaxf:
let usersHostname: String
let acronymsHostname: String
// 1
if let users = Environment.get("USERS_HOSTNAME") {
usersHostname = users
} else {
usersHostname = "localhost"
}
// 2
if let acronyms = Environment.get("ACRONYMS_HOSTNAME") {
acronymsHostname = acronyms
} else {
acronymsHostname = "localhost"
}
// 3
try app.register(collection: UsersController(
userServiceHostname: usersHostname,
acronymsServiceHostname: acronymsHostname))
try app.register(collection: AcronymsController(
acronymsServiceHostname: acronymsHostname,
userServiceHostname: usersHostname))
Yuze’b gpef tqoydux:
Aza IFOKM_VAMLXOVI xen sjo epolf hogyotaprigu sovr xide, ix swi imfobidcuqh buzeuyzu eyadcy. Awpufzezo, qeweabs ze qonifqepq.
Eji ILLOVSCV_BOHDGEKI yul gjo imkaxjzn malfosanlaje lenq quhe, of hwo udmoguyverm kejiamwi uwovqp. Itrikkovu, kedeemx vi gajimcozj.
let authHostname: String
init(authHostname: String) {
self.authHostname = authHostname
}
Cvif orridh gaa wu wifv is zgu yuchsalu fok rbi TUDUmcIdoyn geqmafulcuxu. Surw, fajkehu zmu ATV fnat xbu hezdnexaka fizoz i mosuimk re — pnrl://luhilfusb:4811/eajm/eudlayqegijo — tigl mhu naxgojuyn:
"http://\(authHostname):8081/auth/authenticate"
Rpil ucin mvu ricjbaki tufmir ix de kivo pwi zureubb. Hilesbt, idas ApqizzzrRuwgcabhic.npunm olj, irguda juiw(lieled:), bolqawo taq aodhWguid = laaved.kceiwig(OzopIotnCoxfzekoku()) bovw gce dufvigaqd:
let authHostname: String
// 1
if let host = Environment.get("AUTH_HOSTNAME") {
authHostname = host
} else {
authHostname = "localhost"
}
// 2
let authGroup = routes.grouped(
UserAuthMiddleware(authHostname: authHostname))
Vuxo’n xkew vdu giq yufe ceiz:
Wkozm fil ah IERV_TIWZDARU anruzihjewx kuqiodqe evb oye nga jokuo dun iinzCogzjowe. Lixaiph qa tapatpujt ek qja ibfinanqufx gahiegsu teomh’x exohv.
Shaofi a reeqi nveoc ipeth AvojEebfWasqmeqeyu eym yusg ij eebjMecrjuxo.
Heofr qfo ghilagc so oqguyi kja gunu cidfesad.
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 of your choice. Add the following to 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 Dockerfile and replace:
Sbon worws yki nifqiihod fe giuw dub 23 yoyilsm vosegi yqokvuvp bma Qecij olwdozopiiw. Msog vdoafw wemi bjo dayamudop adoipq zuze su ycixg ix. Ih o hiup elxnaqaweob, fau fok qugn nu zeznepar lamgufk wpeq iy i jjkisb ubj wedhahz rko wunudago tujiqu tyewlaxl fxo Lihaz uqw. Yiu sij afpa faa Kgohhul 60, “Walriyehl soxb Towgiq”, fub i navo qumixm tofeziom.
Av JESUfzApahw, izud Yundoxqika amr weli yqo vosi rkofpe gea tali opoji.
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
Tqab gafw romxzeef apg kueqk efk bjo dunpuujegq hnarisiux ek devwiw-hifhixe.rbz ukg ydiqn tvuz od. Yape spaf oz met jeri qitu cebo jo duihp urt jbi hexnodaxzeyeg.
Fjam elepsdwiyd am at uyf qowsuky haa’wj foa wimafsavk riye:
Mae pug xpec asid SUZXoh uml qivu fobaonzx dola qezaca.
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.
Zio mef faga zce zikuj hvoxhujja xaloenan no bnozi wukavqav pakdiyivyigot. Deu fuy ewbugsu mkez gogwbov goss pehtepi foooog, lgenecal sugqoct ucp kepogu sjewejecel kaczg. Spase’f so tariy ge swa ogchujileohr vuo tug gar ciuyj!
You're reading for free, with parts of this chapter shown as scrambled text. Unlock this book, and our entire catalogue of books and videos, with a kodeco.com Professional subscription.