ロードバランサーって何？ / What is the load balancer?

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ϩʔυόϥϯαʔ͕  Θ͔Βͳ͍ ϋτωίΤ @nekonenene 2017೥07݄31೔

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• ϩʔυόϥϯαʔ͸ɺௐ΂Ε͹ௐ΂Δ΄Ͳ  NAT΍SSL௨৴ͳͲલఏͱͳΔωοτϫʔΫ ஌͕ࣝ੝Γ୔ࢁͳ͜ͱ͕Θ͔ͬͯɺ  શ෦͸৮ΕΒΕͳ͍ͷͰɺؾʹͳͬͯͨ  ࣍ϖʔδͷ͜ͱͷΈѻ͍·͢ • L4ʢτϥϯεϙʔτ૚ɿTCP/UDPʣ • L7ʢΞϓϦέʔγϣϯ૚ʣ ϩʔυόϥϯαʔΘ͔Βͳ͍

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• ϩʔυͬͯͳʹʁ ಓʁ • ͲΜͳ࢓૊Έͳͷʁ • σʔλΛͲ͏΍ͬͯΫϥΠΞϯτʹ౉͢ͷʁ • ઐ༻ͷػցΛങΘͳͯ͘΋࣮ݱͰ͖Δʁ • ෳ਺ͷϩʔυόϥϯαΛཱͯͨͱ͖ɺ  ͦΕ΁ͷ઀ଓ؅ཧ͸Ͳ͕͓͜͜ͳ͏ͷʁ ͕͜͜Θ͔Βͳ͍

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• load ͱ͍͏ͱʮσʔλΛಡΈࠐΉʢಈࢺʣʯ ͷΠϝʔδ͕ڧ͍͚Ͳɺʮॏՙʢ໊ࢺʣʯͷ ҙຯ͕ݩʑɻͭ·Γʮෛՙʯ • ʮՙ෺ΛੵΉɾ٧ΊࠐΉʯˠʮ૷ర͢Δʯ ˠʮσʔλΛॻ͖ࠐΉɾಡΈࠐΉʯ  ͱ͍͏ྲྀΕͰίϯϐϡʔλ༻ޠͱͯ͠΋࢖Θ ΕΔΑ͏ʹͳͬͨͬΆ͍ 1. ϩʔυͬͯͳʹʁ

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• load balancing ͸ʮෛՙ෼ࢄʯͱ͍͏ҙຯͰ  ϩʔυόϥϯα͸ͦΕΛ΍ͬͯ͘ΕΔ΋ͷ • ͳͷͰɺҙຯ߹͍ͱͯ͠͸޿͍͚Ͳɺ  جຊతʹϩʔυόϥϯγϯά༻ʹ࡞ΒΕͨ΋ ͷΛϩʔυόϥϯαͱͯ͠ޠ͍͖ͬͯ·͢ ϩʔυόϥϯα

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• ϩʔυόϥϯα͕ͲͷαʔόʔΛબ୒͢Δ͔ ͷख๏͸͍͘Β͔͋Δɻ͓΋ͳྫˣ • ϥ΢ϯυϩϏϯํࣜɿ୯७ʹॱ൪ʹબ୒ • ॏΈ͚ͮɿൺ཰Λఆٛ • ࠷খ઀ଓɿݱࡏͷίωΫγϣϯ਺͕࠷΋খ͞ ͍αʔόʹసૹ 2. ͲΜͳ࢓૊Έͳͷʁ ࢀߟ : http://www.infraexpert.com/study/loadbalancer4.html

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• DNSͷAϨίʔυͰɺಉυϝΠϯʹ  ෳ਺ͷIPΞυϨεΛׂΓ౰ͯΔ͜ͱͰ  ϥ΢ϯυϩϏϯํࣜΛ࣮ݱ͢Δ΋ͷ  ʢϩʔυόϥϯα͍Βͣʂ खܰʂʣ • RFC3484ʹͯʮෳ਺ׂΓ౰͕ͯ͋Δ৔߹͸ ΋ͬͱ΋͍ۙαʔόΛબ୒ʯͱͳͬͨͷͰݱ ࡏ͸ϥ΢ϯυϩϏϯʹ͸ͳΒͳ͍͜ͱ΋ DNSϥ΢ϯυϩϏϯ

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• ϥ΢ϯυϩϏϯͰ͸ͳ͍Ͱ͕͢ɺ  AWS Route53Ͱ͸Weightͷࢦఆ͕͓͜ͳ ͑ɺDNSʹΑΔʮॏΈ͚ͮʯͷෛՙ෼ࢄ͕Մ ೳͰ͢ DNSʹΑΔෛՙ෼ࢄ ࢀߟ : http://qiita.com/nagizero/items/385ed12c60f229a4df9c

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• AWSͷυΩϡϝϯτతʹ͸ɺELB͸  CLBʢClassic Load Balancerʣ  ALBʢApplication Load Balancerʣ  ʹ෼͔Ε·͕͢ɺELBʹCLBͱ͠·͢ • ͳ͓ɺALB͸EC2Πϯελϯε಺ͷ  Ͳͷίϯςφʹͭͳ͙͔·ͰΛ੍ޚ͢Δ෺ɻ  ϥ΢ϯυϩϏϯϧʔςΟϯάΞϧΰϦζϜisԿ ELB͸Ͳͷํࣜʁ

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• ʰσϑΥϧτͰ͸ɺϩʔυόϥϯαʔ͸ɺ ϩʔυόϥϯαʔʹରͯ͠༗ޮʹ͢ΔΞϕΠ ϥϏϦςΟʔκʔϯؒͰۉ౳ʹτϥϑΟοΫ Λ෼ࢄ͠·͢ʱ  ( http://docs.aws.amazon.com/ja_jp/elasticloadbalancing/latest/classic/ introduction.html ) • ॏΈ͚ͮ 1:1:1:1:1:1:ʢུ  ͷ෼ࢄํࣜΛऔ͍ͬͯΔΑ͏Ͱ͢Ͷ CLB͸Ͳͷํࣜʁ

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• αʔόʔ͔ΒͷϨεϙϯε͕ϩʔυόϥϯ αʔΛܦ༝͍ͯͯ͠͸ɺϩʔυόϥϯαʔͷ ෛՙେ͖͍ΑͶʁ  ͱࢥ͍ͬͯͨͷͰɺ௚઀ΫϥΠΞϯτ΁ૹΔ ͷͩͱࢲ͸ࢥ͍ͬͯͨɻ • ্هํࣜΛDSRʢDirect Server Returnʣߏ ੒ͱݴ͏ 3. ΫϥΠΞϯτ΁͸Ͳ͏΍ͬͯʁ

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• αʔόʔ಺͔Βฦ͢৘ใ͕ϩʔυόϥϯαʔ Λ௨Βͳ͍ͷͰɺΞϓϦέʔγϣϯ૚ͷ৘ใ ͸ಘΒΕͳ͍ • ΞϓϦέʔγϣϯతͳ৘ใʹΑΔෛՙ෼ࢄ͕ ͓͜ͳ͑ͳ͍ʢ͖ͬ͞ͷ࠷খ઀ଓͳͲʣ • CookieΛ༻͍ͨεςΟοΩʔηογϣϯ ʢύʔγεςϯεʣ͸͓͜ͳ͑ͳ͍ DSRͷσϝϦοτ ࢀߟ : http://knowledge.sakura.ad.jp/tech/527

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• HTTPS௨৴Λ͓͜ͳ͏৔߹ɺ҉߸Խɾ෮߸ʹ ͸ͦΕͳΓͷෛՙ • ϩʔυόϥϯαʔʹ͍ͬͨΜฦ͢͜ͱͰ  SSLΞΫηϥϨʔλʢ҉߸Խɾ෮߸͢Δ΋ ͷʣ෇͖ϩʔυόϥϯαʔͰ͋Ε͹ɺ  ͦ͜ʹෛՙΛҰ೚Ͱ͖Δ͠ɺSSLূ໌ॻ͸ͦ ͜ʹ͚ͩஔ͍ͯɺαʔόͱ͸HTTP௨৴Մೳ DSRΛ࢖Θͳ͍ϝϦοτ

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• ಈըετϦʔϛϯά࠶ੜͷΑ͏ʹɺ  େྔͷϨεϙϯεΛαʔόʔ͕ฦ͢γεςϜ ͷ৔߹ɺϩʔυόϥϯαʔͷεϧʔϓοτ ʢσʔλసૹʣੑೳ͕௥͍͔ͭͳ͍͔Β  DSRΛ࢖͏΄͏͕͍͍ɺͱ͍͏৔߹΋͋Δ • ͨͩɺௐ΂ͯΈͨײ͡͸DSRΛקΊͳ͍࿦ௐ ͕ଟ͘ײͨ͡ DSRΛ࢖͏΄͏͕͍͍৔߹ ࢀߟ : http://www.infraexpert.com/study/loadbalancer12.html

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• ϩʔυόϥϯαʔΛௐ΂Δͱ  F5 Networks.Inc ͷʰBIG-IPʱͷ࿩͕ଟ͍… • Ͱ͸ɺࣗ୐αʔόͰ͸ݐͯΒΕͳ͍͔ʁ • ʰLinux Virtual Server (LVS)ʱͱ ʰKeepalivedʱΛ༻͍Δ͜ͱͰɺ  αʔόʔΛϩʔυόϥϯαʔԽͰ͖Δ 4. ઐ༻ͷػց͕ඞཁʁ

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• LVS͸ॏΈ͚ͮʹΑΔ෼ࢄΛ͓͜ͳ͑·͢  ʢઃఆํ๏ : http://dsas.blog.klab.org/archives/50664843.html ʣ • Keepalived͸֤αʔόʔͷࢮ׆ঢ়گΛɺ  TCPίωΫγϣϯ͕ுΕΔ͔(TCP_CHECK)  HTTPΞΫηεͰ͖Δ͔(HTTP_GET)  ͱ͍ͬͨํ๏Ͱ؂ࢹ͠·͢  ʢઃఆํ๏ : http://blog.idcf.jp/entry/cloud/keepalived ʣ LVS + Keepalived

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• AWSͷElastic Load Balancingʹ͓͚Δ  ϩʔυόϥϯαʔ͸উखʹ૿ݮ͢ΔΒ͍͠ɻ • ͡Ό͋ͲͷϩʔυόϥϯαʔʹৼΔ͔͸  Ͳ͏͍͏࢓૊Έʁ • ͜ͷࢿྉ7ϖʔδʹ͋ͬͨDNSϥ΢ϯυϩϏϯ ͱಉ༷ͷํ๏Ͱղܾ͍ͯ͠Δ 5. ϩʔυόϥϯαʔͷόϥϯαʔʁ

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ΫϥΠΞϯτ͕ϦΫΤετΛϩʔυόϥϯαʔʹૹ৴͢ΔલʹɺυϝΠϯωʔϜγεςϜ (DNS) αʔόʔΛ࢖༻ͯ͠ϩʔυόϥϯαʔͷυϝΠϯ໊Λղܾ͠·͢ɻ Πϯελϯε͸ amazonaws.com υϝΠϯʹ͋ΔͨΊɺDNS ΤϯτϦ͸ Amazon ʹ Α੍ͬͯޚ͞Ε·͢ɻAmazon DNS αʔόʔ͸ɺ1 ͭҎ্ͷ IP ΞυϨε (ϩʔυόϥϯ αʔ༻ͷϩʔυόϥϯαʔϊʔυͷ IP ΞυϨε) ΛΫϥΠΞϯτʹฦ͠·͢ɻ ΞϓϦέʔγϣϯ΁ͷτϥϑΟοΫ͕࣌ؒͷܦաͱͱ΋ʹมԽ͢ΔͱɺElastic Load Balancing ͸ϩʔυόϥϯαʔΛεέʔϦϯάͯ͠ DNS ΤϯτϦΛߋ৽͠·͢ɻDNS Τ ϯτϦͰ͸ɺ༗ޮظݶ (TTL) ΋ 60 ඵʹࢦఆ͞Ε͍ͯΔͨΊɺτϥϑΟοΫͷมԽʹԠ͡ ͯ IP ΞυϨε͕ਝ଎ʹ࠶Ϛοϓ͞ΕΔ఺ʹ஫ҙ͍ͯͩ͘͠͞ɻ AWSυΩϡϝϯτΑΓ Ҿ༻ݩ : http://docs.aws.amazon.com/ja_jp/elasticloadbalancing/latest/ userguide/how-elastic-load-balancing-works.html#request-routing

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εοΩϦʂ

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ΑΓਂ͘஌Γͨ͘ͳͬͨํ͸  ͜ͷεϥΠυ͕ྑ͛͞Ͱ͢ ʰϩʔυόϥϯα࠶ೖ໳ʱ  https://www.slideshare.net/ ryuichitakashima3/ ss-72343772