{"id":37372,"date":"2019-10-31T22:17:16","date_gmt":"2019-10-31T19:17:16","guid":{"rendered":"https:\/\/prohoster.info\/blog\/etc-resolv-conf-dlya-kubernetes-pods-optsiya-ndots-5-kak-eto-mozhet-negativno-skazatsya-na-proizvoditelnosti-prilozheniya\/"},"modified":"2019-10-31T22:17:16","modified_gmt":"2019-10-31T19:17:16","slug":"etc-resolv-conf-dlya-kubernetes-pods-optsiya-ndots-5-kak-eto-mozhet-negativno-skazatsya-na-proizvoditelnosti-prilozheniya","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sq\/blog\/administrirovanie\/etc-resolv-conf-dlya-kubernetes-pods-optsiya-ndots-5-kak-eto-mozhet-negativno-skazatsya-na-proizvoditelnosti-prilozheniya","title":{"rendered":"\/etc\/resolv.conf \u0434\u043b\u044f Kubernetes pods, \u043e\u043f\u0446\u0438\u044f ndots:5, \u043a\u0430\u043a \u044d\u0442\u043e \u043c\u043e\u0436\u0435\u0442 \u043d\u0435\u0433\u0430\u0442\u0438\u0432\u043d\u043e \u0441\u043a\u0430\u0437\u0430\u0442\u044c\u0441\u044f \u043d\u0430 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u0442\u0435\u043b\u044c\u043d\u043e\u0441\u0442\u0438 \u043f\u0440\u0438\u043b\u043e\u0436\u0435\u043d\u0438\u044f","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

\"\/etc\/resolv.conf<\/p>\n

<\/p>\n

Koh\u00eb m\u00eb par\u00eb, ne lan\u00e7uam Kubernetes 1.9 n\u00eb AWS duke p\u00ebrdorur Kops. Dje, gjat\u00eb nj\u00eb shp\u00ebrndarjeje t\u00eb qet\u00eb t\u00eb trafikut t\u00eb ri n\u00eb nj\u00eb nga klasteret tona m\u00eb t\u00eb m\u00ebdha Kubernetes, fillova t\u00eb v\u00eb re gabime t\u00eb \u00e7uditshme n\u00eb zgjidhjen e emrit DNS, t\u00eb regjistruara nga aplikacioni yn\u00eb.<\/p>\n

<\/a><\/noindex><\/p>\n

N\u00eb GitHub \u00ebsht\u00eb diskutuar p\u00ebr nj\u00eb koh\u00eb t\u00eb gjat\u00eb k\u00ebtu<\/a><\/noindex>, prandaj vendosa t\u00eb merrem me k\u00ebt\u00eb. N\u00eb fund, kuptova se n\u00eb rastin ton\u00eb, kjo shkaktohej nga nj\u00eb ngarkes\u00eb e madhe n\u00eb kube-dns<\/code> dhe dnsmasq<\/code>. E ve\u00e7anta dhe e re p\u00ebr mua ishte vet\u00eb arsyeja e rritjes s\u00eb konsiderueshme t\u00eb trafikut t\u00eb k\u00ebrkesave DNS. Ky \u00ebsht\u00eb subjekti i post\u00ebs time.<\/p>\n

<\/p>\n

Zgjidhja DNS brenda kontejnerit \u2014 ashtu si n\u00eb \u00e7do sistem Linux \u2014 p\u00ebrcaktohet nga skedari konfiguruese \/etc\/resolv.conf<\/code>. N\u00eb m\u00ebnyr\u00eb default, Kubernetes dnsPolicy<\/code> kjo ClusterFirst<\/code>, q\u00eb do t\u00eb thot\u00eb se \u00e7do k\u00ebrkes\u00eb DNS do t\u00eb redirigjohet n\u00eb dnsmasq<\/code>, e cila ekzekutohet n\u00eb podin kube-dns<\/code> brenda klasterit, e cila p\u00ebrfaq\u00ebson k\u00ebrkes\u00ebn n\u00eb aplikacionin kube-dns<\/code>, n\u00ebse emri p\u00ebrfundon me sufixin e klasterit, ose p\u00ebrndryshe n\u00eb serverin DNS t\u00eb nivelit m\u00eb t\u00eb lart\u00eb.<\/p>\n

<\/p>\n

Skeda \/etc\/resolv.conf<\/code> brenda secilit kontejner do t\u00eb duket k\u00ebshtu:<\/p>\n

<\/p>\n

nameserver 100.64.0.10\nsearch namespace.svc.cluster.local svc.cluster.local cluster.local \neu-west-1.compute.internal\noptions ndots:5<\/code><\/pre>\n
<\/p>\n
Si\u00e7 mund t\u00eb v\u00ebreni, k\u00ebtu ka tre direktiva:<\/p>\n
<\/p>\n
    \n
  1. Serveri i emrave \u2014 \u00ebsht\u00eb IP e sh\u00ebrbimit kube-dns<\/code><\/li>\n
  2. Jan\u00eb t\u00eb specifikuar 4 domen\u00eb k\u00ebrkimi lokal\u00eb : p\u00ebrcakton rrug\u00ebn e k\u00ebrkimit p\u00ebr nj\u00eb domain t\u00eb caktuar. \u00cbsht\u00eb interesante q\u00eb<\/code><\/li>\n
  3. Ka nj\u00eb mund\u00ebsi ndots:5<\/code><\/li>\n<\/ol>\n
    <\/p>\n
    Nj\u00eb pjes\u00eb interesante e k\u00ebsaj konfigurationsh \u00ebsht\u00eb se si domen\u00ebt k\u00ebrkimi lokal\u00eb dhe parametrat ndots:5<\/code> ndajn\u00eb nj\u00ebri-tjetrin. P\u00ebr t\u00eb kuptuar k\u00ebt\u00eb, duhet t\u00eb kuptojm\u00eb se si funksionon zgjidhja DNS p\u00ebr emrat e paplot\u00eb.<\/p>\n
    <\/p>\n
    \u00c7far\u00eb \u00ebsht\u00eb emri i plot\u00eb?<\/h3>\n
    <\/p>\n
    Emri i plot\u00eb \u00ebsht\u00eb ai em\u00ebr p\u00ebr t\u00eb cilin nuk do t\u00eb kryhet k\u00ebrkimi lokal, dhe emri do t\u00eb merret si absolut gjat\u00eb zgjidhjes s\u00eb emrave. N\u00eb p\u00ebrputhje me marr\u00ebveshjen, software-i DNS e konsideron emrin t\u00eb plot\u00eb n\u00ebse p\u00ebrfundon me pik\u00eb (.), dhe jo t\u00eb plot\u00eb p\u00ebrndryshe. K\u00ebshtu q\u00eb google.com.<\/code> \u00ebsht\u00eb plot\u00ebsisht i p\u00ebrcaktuar, nd\u00ebrsa google.com<\/code> nuk \u00ebsht\u00eb. <\/p>\n
    <\/p>\n
    Si p\u00ebrpunohen emrat e paplot\u00eb?<\/h3>\n
    <\/p>\n
    Kur aplikacioni lidhet me nj\u00eb host t\u00eb distancuar, t\u00eb specifikuar n\u00eb em\u00ebr, zgjidhja e emrave DNS zakonisht kryhet p\u00ebrmes nj\u00eb thirrjeje sistemike, p\u00ebr shembull, getaddrinfo()<\/code>. E k\u00ebndshme \u00ebsht\u00eb se n\u00ebse emri \u00ebsht\u00eb i paplot\u00eb (nuk p\u00ebrfundon me .), \u00ebsht\u00eb interesante n\u00ebse thirrja sistematike do t\u00eb p\u00ebrpiqet gjithmon\u00eb t\u00eb zgjidh\u00eb emrin si absolut, apo do t\u00eb kaloj\u00eb fillimisht n\u00ebp\u00ebr domen\u00ebt e k\u00ebrkimit lokal. Kjo varet nga opsioni ndots<\/code>.<\/p>\n
    <\/p>\n
    Nga manuali mbi ndodhet informacioni i m\u00ebposht\u00ebm:<\/code>:<\/p>\n
    <\/p>\n
    ndots:n\n\np\u00ebrcakton pragun e numrit t\u00eb pikave q\u00eb duhet t\u00eb jen\u00eb n\u00eb em\u00ebr para se t\u00eb kryhet nj\u00eb k\u00ebrkes\u00eb absolute fillestare. Vlera e parazgjedhur p\u00ebr n \u00ebsht\u00eb 1, q\u00eb do t\u00eb thot\u00eb se n\u00ebse emri ka ndonj\u00eb pik\u00eb, emri do t\u00eb provoj\u00eb fillimisht si emri absolut, p\u00ebrpara se t'i shtohen ndonj\u00eb element liste k\u00ebrkimi.<\/code><\/pre>\n
    <\/p>\n
    Kjo do t\u00eb thot\u00eb se n\u00ebse ndots<\/code> caktohet vlera 5 dhe emri p\u00ebrmban m\u00eb pak se 5 pika, thirrja n\u00eb sistem do t\u00eb p\u00ebrpiqet ta zgjidh\u00eb at\u00eb radhazi, fillimisht duke kaluar n\u00ebp\u00ebr t\u00eb gjith\u00eb domainet e k\u00ebrkimit lokal, dhe, n\u00ebse d\u00ebshton, n\u00eb fund do ta zgjidh\u00eb at\u00eb si em\u00ebr absolut.<\/p>\n
    <\/p>\n
    Pse ndots:5<\/code> mund t\u00eb ndikoj\u00eb negativisht n\u00eb performanc\u00ebn e aplikacionit?<\/h3>\n
    <\/p>\n
    Si\u00e7 e kuptoni, n\u00ebse aplikacioni juaj p\u00ebrdor shum\u00eb trafik t\u00eb jasht\u00ebm, p\u00ebr \u00e7do lidhje TCP t\u00eb krijuar (ose, m\u00eb sakt\u00ebsisht, p\u00ebr \u00e7do em\u00ebr t\u00eb lejuar) do t\u00eb jepen 5 k\u00ebrkesa DNS, p\u00ebrpara se emri t\u00eb zgjidhet sakt\u00ebsisht, sepse fillimisht do t\u00eb kaloj\u00eb n\u00ebp\u00ebr 4 domainet e k\u00ebrkimit lokal, dhe n\u00eb fund do t\u00eb jap\u00eb nj\u00eb k\u00ebrkes\u00eb p\u00ebr zgjidhjen e emrit absolut.<\/p>\n
    <\/p>\n
    N\u00eb diagramin e m\u00ebposht\u00ebm tregohet trafiku total n\u00eb 3 modul\u00ebt tan\u00eb kube-dns para dhe pas kalimit t\u00eb disa emrave t\u00eb hosteve t\u00eb vendosur n\u00eb aplikacionin ton\u00eb n\u00eb emra t\u00eb plot\u00eb.<\/p>\n
    <\/p>\n
    \"\/etc\/resolv.conf<\/p>\n
    <\/p>\n
    N\u00eb diagramin e m\u00ebposht\u00ebm tregohet vonesa e aplikacionit para dhe pas kalimit t\u00eb disa emrave t\u00eb hosteve t\u00eb vendosur n\u00eb aplikacionin ton\u00eb n\u00eb emra t\u00eb plot\u00eb (vija e kalt\u00ebr vertikale \u00ebsht\u00eb implementimi):<\/p>\n
    <\/p>\n
    \"\/etc\/resolv.conf<\/p>\n
    <\/p>\n
    Zgjidhja #1 - p\u00ebrdorni emra t\u00eb plot\u00eb<\/h3>\n
    <\/p>\n
    N\u00ebse keni pak emra statik\u00eb t\u00eb jasht\u00ebm (dmth. t\u00eb p\u00ebrcaktuar n\u00eb konfigurimin e aplikacionit), p\u00ebr t\u00eb cil\u00ebt krijoni nj\u00eb num\u00ebr t\u00eb madh lidhjesh, ndoshta zgjidhja m\u00eb e thjesht\u00eb \u00ebsht\u00eb t\u00eb kaloni n\u00eb emra t\u00eb plot\u00eb, thjesht duke i shtuar. n\u00eb fund.<\/p>\n
    <\/p>\n
    Kjo nuk \u00ebsht\u00eb nj\u00eb zgjidhje p\u00ebrfundimtare, por ndihmon q\u00eb situata t\u00eb p\u00ebrmir\u00ebsohet shpejt, ndon\u00ebse jo n\u00eb m\u00ebnyr\u00eb t\u00eb past\u00ebr. Ky patch e kemi aplikuar p\u00ebr zgjidhjen e problemit ton\u00eb, rezultatet e t\u00eb cilit u treguan n\u00eb shkrepjet m\u00eb sip\u00ebr.<\/p>\n
    <\/p>\n
    Zgjidhja #2 - personalizimi ndots<\/code> n\u00eb dnsConfig<\/code><\/h3>\n
    <\/p>\n
    N\u00eb Kubernetes 1.9, n\u00eb modin alfa, u shfaq funksionaliteti (beta versioni v1.10) q\u00eb lejon nj\u00eb kontroll m\u00eb t\u00eb mir\u00eb mbi parametrat DNS p\u00ebrmes pron\u00ebs s\u00eb podit n\u00eb dnsConfig<\/code>. Nd\u00ebr t\u00eb tjera, ai lejon t\u00eb konfiguroni vler\u00ebn ndots<\/code> p\u00ebr nj\u00eb pod t\u00eb caktuar, dmth.<\/p>\n
    <\/p>\n
    apiVersion: v1\nkind: Pod\nmetadata:\n  namespace: default\n  name: dns-example\nspec:\n  containers:\n    - name: test\n      image: nginx\n  dnsConfig:\n    options:\n      - name: ndots\n        value: \"1\"<\/code><\/pre>\n
    <\/p>\n
    Burimet<\/h3>\n
    <\/p>\n