{"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

S\u00eb fundmi, lan\u00e7uam Kubernetes 1.9 n\u00eb AWS duke p\u00ebrdorur Kops. Dje, gjat\u00eb lan\u00e7imit t\u00eb qet\u00eb t\u00eb trafikut t\u00eb ri n\u00eb nj\u00ebrin nga klaster\u00ebt tan\u00eb m\u00eb t\u00eb m\u00ebdhenj t\u00eb Kubernetes, fillova t\u00eb v\u00ebrej nj\u00eb s\u00ebr\u00eb gabimesh t\u00eb pazakonta n\u00eb zgjidhjen e emrave DNS, t\u00eb regjistruara nga aplikacioni yn\u00eb.<\/p>\n

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

N\u00eb GitHub ka pasur shum\u00eb diskutime rreth k\u00ebsaj<\/a><\/noindex>, prandaj vendosa t\u00eb hetoj. N\u00eb fund, kuptova se n\u00eb rastin ton\u00eb, kjo \u00ebsht\u00eb shkaktuar nga nj\u00eb ngarkes\u00eb e shtuar n\u00eb kube-dns<\/code> dhe dnsmasq<\/code>. Ajo q\u00eb m\u00eb interesoi dhe ishte e re p\u00ebr mua ishte vet\u00eb shkaku i rritjes s\u00eb konsiderueshme t\u00eb trafikut t\u00eb k\u00ebrkesave DNS. Rreth k\u00ebsaj dhe \u00e7far\u00eb mund t\u00eb b\u00ebjm\u00eb me t\u00eb, \u00ebsht\u00eb ky postim.<\/p>\n

<\/p>\n

Zgjidhja e DNS brenda kontejnerit \u2014 ashtu si n\u00eb \u00e7do sistem Linux \u2014 p\u00ebrcaktohet nga skedari i konfigurimit \/etc\/resolv.conf<\/code>. Si\u00e7 \u00ebsht\u00eb e zakonshme, Kubernetes dnsPolicy<\/code> kjo ClusterFirst<\/code>, q\u00eb do t\u00eb thot\u00eb se \u00e7do k\u00ebrkes\u00eb DNS do t\u00eb drejtohet te dnsmasq<\/code>, e cila ekzekutohet n\u00eb pod kube-dns<\/code> brenda klasterit, i cili, nga ana e tij, do ta drejtoj\u00eb k\u00ebrkes\u00ebn te aplikacioni kube-dns<\/code>, n\u00ebse emri p\u00ebrfshin sufixin e klasterit, ose, ndryshe, te serveri DNS i niveleve m\u00eb t\u00eb larta.<\/p>\n

<\/p>\n

Skedari \/etc\/resolv.conf<\/code> brenda \u00e7do kontejneri n\u00eb m\u00ebnyr\u00eb t\u00eb zakonshme 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 mund t\u00eb v\u00ebrehet, k\u00ebtu ka tre direktiva:<\/p>\n
<\/p>\n
    \n
  1. Serveri i emrave \u00ebsht\u00eb IP i sh\u00ebrbimit kube-dns<\/code><\/li>\n
  2. Jan\u00eb specifikuar 4 domenet lokale t\u00eb k\u00ebrkimit k\u00ebrko<\/code><\/li>\n
  3. Ekziston nj\u00eb opsion ndots:5<\/code><\/li>\n<\/ol>\n
    <\/p>\n
    Nj\u00eb pjes\u00eb interesante e k\u00ebsaj konfigurimi \u00ebsht\u00eb se si domenet lokale t\u00eb k\u00ebrkimit dhe cil\u00ebsimet ndots:5<\/code> bashk\u00ebjetojn\u00eb. P\u00ebr ta kuptuar k\u00ebt\u00eb, \u00ebsht\u00eb e nevojshme t\u00eb kuptojm\u00eb si funksionon zgjidhja DNS p\u00ebr emrat e pap\u00ebrfunduar.<\/p>\n
    <\/p>\n
    \u00c7far\u00eb \u00ebsht\u00eb emri i plot\u00eb?<\/h3>\n
    <\/p>\n
    Nj\u00eb em\u00ebr i plot\u00eb i p\u00ebrcaktuar \u00ebsht\u00eb emri p\u00ebr t\u00eb cilin nuk do t\u00eb kryhet nj\u00eb k\u00ebrkim lokal, dhe emri do t\u00eb konsiderohet si absolut gjat\u00eb zgjidhjes s\u00eb emrave. Sipas marr\u00ebveshjes, softueri DNS e konsideron emrin si t\u00eb plot\u00eb t\u00eb p\u00ebrcaktuar, n\u00ebse p\u00ebrfundon me nj\u00eb pik\u00eb (.) dhe jo plot\u00ebsisht t\u00eb p\u00ebrcaktuar ndryshe. Pra, google.com.<\/code> \u00ebsht\u00eb plot\u00ebsisht e p\u00ebrcaktuar, nd\u00ebrsa google.com<\/code> \u2014 jo. <\/p>\n
    <\/p>\n
    Si p\u00ebrpunohuan emrat e pap\u00ebrfunduar?<\/h3>\n
    <\/p>\n
    Kur nj\u00eb aplikacion lidhet me nj\u00eb host t\u00eb larg\u00ebt, i specifikuar n\u00eb em\u00ebr, zgjidhja e emrave DNS zakonisht realizohet p\u00ebrmes thirrjes s\u00eb sistemit, p\u00ebr shembull, getaddrinfo()<\/code>. Po n\u00ebse emri nuk \u00ebsht\u00eb i plot\u00eb (nuk p\u00ebrfundon n\u00eb .), a do t\u00eb p\u00ebrpiqet thirrja sistemike fillimisht ta zgjidh\u00eb emrin si t\u00ebr\u00ebsor, apo do t\u00eb kaloj\u00eb fillimisht p\u00ebrmes domain-eve lokale t\u00eb k\u00ebrkimit? Kjo varet nga opsioni ndots<\/code>.<\/p>\n
    <\/p>\n
    Nga manuali p\u00ebr resolv.conf<\/code>:<\/p>\n
    <\/p>\n
    ndots:n\n\nvendos kufirin p\u00ebr numrin e pikave q\u00eb duhet t\u00eb shfaqen n\u00eb em\u00ebr, para se t\u00eb b\u00ebhet nj\u00eb k\u00ebrkes\u00eb fillestare absolute. Vlera e paracaktuar 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 provoni fillimisht si emri absolut, para se t'i shtohen ndonj\u00eb element i list\u00ebs s\u00eb k\u00ebrkimit.<\/code><\/pre>\n
    <\/p>\n
    Kjo do t\u00eb thot\u00eb se n\u00ebse p\u00ebr ndots<\/code> vendoset vlera 5, dhe emri p\u00ebrmban m\u00eb pak se 5 pika, thirrja sistemike do t\u00eb p\u00ebrpiqet ta zgjidh\u00eb at\u00eb rresht pas rreshti, fillimisht duke kaluar p\u00ebrmes t\u00eb gjith\u00eb domain-eve lokale t\u00eb k\u00ebrkimit, dhe, n\u00eb rast d\u00ebshtimi, 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 e kuptoni, n\u00ebse aplikacioni juaj p\u00ebrdor shum\u00eb trafik t\u00eb jasht\u00ebm, p\u00ebr \u00e7do lidhje TCP t\u00eb vendosur (ose, m\u00eb sakt\u00eb, p\u00ebr \u00e7do em\u00ebr t\u00eb lejuar) ai do t\u00eb jap\u00eb 5 k\u00ebrkesa DNS, para se emri t\u00eb zgjidhet si\u00e7 duhet, sepse fillimisht do t\u00eb kaloj\u00eb p\u00ebrmes 4 domain-eve lokale t\u00eb k\u00ebrkimit 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 tre modulet tona kube-dns para dhe pas ndryshimit t\u00eb disa emrave t\u00eb hosteve t\u00eb konfiguruar n\u00eb aplikacionin ton\u00eb n\u00eb emra t\u00eb p\u00ebrcaktuar plot\u00ebsisht.<\/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 ndryshimit t\u00eb disa emrave t\u00eb hosteve t\u00eb konfiguruar 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\u00ebrdorimi i emrave t\u00eb plot\u00eb t\u00eb p\u00ebrcaktuar<\/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), t\u00eb cilave u krijoni nj\u00eb sasi t\u00eb madhe lidhjesh, ndoshta zgjidhja m\u00eb e thjesht\u00eb \u00ebsht\u00eb t'i kaloni ato n\u00eb emra t\u00eb plot\u00eb, duke shtuar thjesht 'n\u00eb fund.'<\/p>\n
    <\/p>\n
    Kjo nuk \u00ebsht\u00eb nj\u00eb zgjidhje p\u00ebrfundimtare, por ndihmon p\u00ebr t\u00eb p\u00ebrmir\u00ebsuar shpejt, ndon\u00ebse jo n\u00eb m\u00ebnyr\u00eb t\u00eb p\u00ebrsosur, situat\u00ebn. Ky patch e aplikuam p\u00ebr t\u00eb zgjidhur problemin ton\u00eb, rezultatet e s\u00eb cil\u00ebs u treguan n\u00eb screenshot-et m\u00eb sip\u00ebr.<\/p>\n
    <\/p>\n
    Zgjidhja #2 \u2014 personalizimi ndots<\/code> n\u00eb dnsConfig<\/code><\/h3>\n
    <\/p>\n
    N\u00eb Kubernetes 1.9, u shfaq n\u00eb modin alfa nj\u00eb funksionalitet (versioni beta v1.10) q\u00eb lejon nj\u00eb kontroll m\u00eb t\u00eb mir\u00eb t\u00eb parametrave DNS p\u00ebrmes pron\u00ebs s\u00eb pods n\u00eb dnsConfig<\/code>. Mes t\u00eb tjerash, ai lejon konfigurimin e vler\u00ebs 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