Zigでコンテナランタイム作ってみた

第55回情報科学若手の会での登壇資料です。
登壇者：井上紘太朗

Transcript

1. ZigͰίϯςφϥϯλΠϜ
   ࡞ͬͯΈͨ
   2022/09/24 @ ୈ55ճ৘ใՊֶएखͷձ
   LINEגࣜձࣾɹҪ্ ߛଠ࿕ (@musaprg)
   

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2. Ҫ্ ߛଠ࿕ (@musaprg)
   • ॴଐ
   

   LINEגࣜձࣾ ITαʔϏεηϯλʔ
   

   VerdaϓϥοτϑΥʔϜ։ൃKνʔϜ
   
   
   • Α͘࢖͏ݴޠ
   

   Go, Python
   
   
   • ࠷ۙͷΠνΦγ࡞඼
   

   ʮCyberpunk: Edgerunnersʯ
   

   ʮϦίϦεɾϦίΠϧʯ
   

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3. Verda
   • LINEגࣜձࣾͰ಺੡ɾӡ༻͍ͯ͠ΔϓϥΠϕʔτΫϥ΢υ
   
   
   • ΤεϖϥϯτޠͰʮ྘ʯ
   
   
   • ͞·͟·ͳαʔϏεΛఏڙ͍ͯ͠Δ
   
   
   • Server (VM/PM),
   
   
   • Load Balancer
   
   
   • MySQL
   
   
   • VOS (Object Storage)
   
   
   • Managed Kubernetes (VKS: Verda Kubernetes Service)
   
   
   • etc.
   

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4. Verdaͷن໛
   • 2022೥09݄ݱࡏͷ౷ܭ஋
   7,4
   

   ϊʔυ਺
   
   

   Ҏ্
   7,4
   

   Ϋϥελ਺
   
   

   Ҏ্
   7FSEB
   

   Ծ૝αʔό୆਺
   
   

   Ҏ্
   

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5. Ҏ߱ͷൃද಺༰͸
   

   ॴଐاۀͷۀ຿ͱ͸ؔ܎͋Γ·ͤΜ
   

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6. ຊ೔ͷ͓͠ͳ͕͖
   

   

   1. ·͓͖͑
   
   
   2. ଎शίϯςφϥϯλΠϜ
   
   
   3. runzigcͷ঺հ
   
   
   4. ZigͷΑ͔ͬͨ఺ɾࠔͬͨ఺
   
   
   5. ·ͱΊ
   

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7. ຊ೔ͷ͓͠ͳ͕͖
   

   

   1. ·͓͖͑
   
   
   2. ଎शίϯςφϥϯλΠϜ
   
   
   3. runzigcͷ঺հ
   
   
   4. ZigͷΑ͔ͬͨ఺ɾࠔͬͨ఺
   
   
   5. ·ͱΊ
   

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8. ຊηογϣϯͷΰʔϧ
   • ίϯςφϥϯλΠϜͷ࢓૊ΈΛͬ͘͟Γ஌Δ
   
   
   • ZigͷഽײΛ஌ΔʢGopherࢹ఺ʣ
   
   
   • ͋ΘΑ͘͹ίϯςφϥϯλΠϜΛࣗ࡞ͯ͠ΈΑ͏ͱ͍͏ؾʹͳΔ
   

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9. ͜Μͳਓʹͱͬͯ͸໘ന͍͔΋
   • ίϯςφϥϯλΠϜͷ࣮૷ʹڵຯ͕͋Δ
   
   
   • Zigͱ͍͏ϓϩάϥϛϯάݴޠʹڵຯ͕͋Δ
   

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10. ͜Μͳਓʹ͸෺଍Γͳ͍͔΋…
    • ʢDocker౳Λ༻͍ͯʣͦ΋ͦ΋ίϯςφΛར༻ͨ͜͠ͱ͕ͳ͍
    
    
    • ίϯςφϥϯλΠϜΛ࡞ͬͨ͜ͱ͕͋Δ or ཁૉٕज़Λཧղ͍ͯ͠Δ
    
    
    • ओཁͳίϯςφϥϯλΠϜ࣮૷ʢrunc౳ʣΛಡΜͩ͜ͱ͕͋Δ
    
    
    • ZigͰͦΕͳΓͷن໛ʹϓϩάϥϜΛॻ͍ͨ͜ͱ͕͋Δ
    

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11. ຊ೔ͷ͓͠ͳ͕͖
    

    

    1. ·͓͖͑
    
    
    2. ଎शίϯςφϥϯλΠϜ
    
    
    3. runzigcͷ঺հ
    
    
    4. ZigͷΑ͔ͬͨ఺ɾࠔͬͨ఺
    
    
    5. ·ͱΊ
    

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12. • ιϑτ΢ΣΞͱ࣮ߦ؀ڥΛͻͱ·ͱΊʹ
    

    → ίϯςφΠϝʔδ
    
    
    • ΠϝʔδΛల։ɾ࣮ߦ͢ΔͨΊͷԾ૝తͳִ཭؀ڥ
    

    → ίϯςφ
    
    
    • ίϯςφΛ࡞੒ɾ؅ཧ͢ΔͨΊͷπʔϧ܈
    

    → Docker
    Dockerίϯςφ͓͞Β͍
    ίϯςφΠϝʔδ
    ιϑτ΢ΣΞ
    ࣮ߦ؀ڥ
    -JOVYΧʔωϧ
    ίϯςφ ίϯςφ ίϯςφ
    

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13. • ΠϝʔδͷϏϧυ
    

    docker build -t musaprg/hello .
    Dockerίϯςφ͓͞Β͍
    ίϯςφΠϝʔδ
    ιϑτ΢ΣΞ
    ࣮ߦ؀ڥ
    -JOVYΧʔωϧ
    ίϯςφ ίϯςφ ίϯςφ
    

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14. • ΠϝʔδͷϏϧυ
    

    docker build -t musaprg/hello .
    
    
    • ίϯςφͷىಈ
    

    docker run musaprg/hello
    Dockerίϯςφ͓͞Β͍
    ίϯςφΠϝʔδ
    ιϑτ΢ΣΞ
    ࣮ߦ؀ڥ
    -JOVYΧʔωϧ
    ίϯςφ ίϯςφ ίϯςφ
    )FMMP
    

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15. ίϯςφΛىಈ͢Δͱى͖Δ͜ͱ
    • ߴϨϕϧϥϯλΠϜ
    
    
    • Πϝʔδͷ؅ཧ
    
    
    • ωοτϫʔΫͷઃఆ ͳͲ
    
    
    • ௿ϨϕϧϥϯλΠϜ
    
    
    • ࣮ߦ؀ڥͷִ཭
    
    
    • ίϯςφͷ؅ཧʢىಈ΍ఀࢭʣ ͳͲ
    https://medium.com/nttlabs/container-runtime-student-internship-2022-q1-89a7113e0cde
    

    ʹܝࡌ͞Ε͍ͯΔਤΛ΋ͱʹվม
    

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16. ίϯςφΛىಈ͢Δͱى͖Δ͜ͱ
    • ߴϨϕϧϥϯλΠϜ
    
    
    • Πϝʔδͷ؅ཧ
    
    
    • ωοτϫʔΫઃఆ
    
    
    • ௿ϨϕϧϥϯλΠϜ
    
    
    • ࣮ߦ؀ڥͷִ཭
    
    
    • ίϯςφͷ؅ཧʢىಈ΍ఀࢭʣ
    https://medium.com/nttlabs/container-runtime-student-internship-2022-q1-89a7113e0cde
    

    ʹܝࡌ͞Ε͍ͯΔਤΛ΋ͱʹվม
    ࠓճ࡞͍ͬͯΔͷ͸ͬͪ͜
    

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17. ௿ϨϕϧϥϯλΠϜ͕΍ͬͯΔ͜ͱ
    • OCI Runtime Specͱ͍͏ن͕֨ଘࡏ
    

    https://github.com/opencontainers/runtime-spec
    
    
    • ΠϯλʔϑΣʔε
    

    create, start, delete, kill, state
    
    
    • ֤छϑΥʔϚοτ
    
    
    • ίϯςφͷϑΝΠϧߏ଄ʢFilesystem Bundleʣ
    
    
    • ίϯςφͷ࢓༷ϑΝΠϧʢcon
    fi
    gʣ
    

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18. ௿ϨϕϧϥϯλΠϜ͕΍ͬͯΔ͜ͱ
    • ࣮ߦ؀ڥͷִ཭ํ๏͸ԿͰ΋͍͍ʢنఆ͸ͳ͍ʣ
    

    ྫɿLinuxͷػೳΛ࢖࣮ͬͯߦ؀ڥΛִ཭͢Δ
    
    
    • Namespaces
    

    → ίϯςφ༻ʹϦιʔεΛִ཭
    

    PID, UTS(hostname), mount point, network, cgroups, IPC, etc.
    
    
    • Control Group (cgroups)
    

    → Ϧιʔεͷ੍ޚʢྫ: cpu΍memoryͷ࢖༻ྔΛ੍ݶʣ
    

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19. ίϯςφٕज़Λߏ੒͢Δsyscallͨͪ
    • fork(2), clone(2) → ࢠϓϩηεͷ࡞੒
    
    
    • exec(2) → ϓϩηεͷஔ͖׵͑ʢ࣮ߦʣ
    
    
    • unshare(2) → NamespaceΛ࡞੒ɺ࣮ߦ؀ڥͷִ཭
    
    
    • pivot_root(2) → rootσΟϨΫτϦʢ”/“ʣͷมߋ
    
    
    • etc.
    

    

    ※cgroupsͷઃఆ͸ಛघϑΝΠϧγεςϜܦ༝Ͱॻ͖ࠐΉɻ
    

    mount point: /sys/fs/cgroup/${subsystem_name}
    

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20. ௿ϨϕϧϥϯλΠϜࢹ఺ͷىಈϓϩηε
    • ӈਤ͸runcͷ಺෦ॲཧ
    

    ਤ͸ോখ԰༷ͷهࣄΑΓҾ༻ʢͱͯ΋Θ͔Γ΍͍͢ͷͰΦεεϝʣ
    

    https://kurobato.hateblo.jp/entry/2021/05/02/164218
    
    
    • ίϯςφ࡞੒ʢrunc createʣ
    

    → ಺෦తͳॳظԽॲཧʢrunc initʣ
    
    
    • 2ճforkΛ͢Δͷ͕ಛ௃తʢdouble-forkʣ
    
    
    • namespace෼཭ॱংͷؔ܎
    

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21. ຊ೔ͷ͓͠ͳ͕͖
    

    

    1. ·͓͖͑
    
    
    2. ଎शίϯςφϥϯλΠϜ
    
    
    3. runzigcͷ঺հ
    
    
    4. ZigͷΑ͔ͬͨ఺ɾࠔͬͨ఺
    
    
    5. ·ͱΊ
    

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22. Zig
    • libcඇґଘͷγϯάϧόΠφϦɾΫϩείϯύΠϧɾWebAssemblyରԠ
    
    
    • ݴޠ࢓༷Λγϯϓϧʹอͭ͜ͱΛڧ͘ҙࣝͨ͠ઃܭ
    
    
    • Ӆṭ͞Ε੍ͨޚϑϩʔ͕ଘࡏ͠ͳ͍ʢe.g., ྫ֎, ԋࢉࢠΦʔόʔϩʔυʣ
    
    
    • ҉໧తͳώʔϓͷ֬อ͸ߦΘΕͳ͍ɻશͯ໌ࣔతʹϝϞϦ؅ཧΛߦ͏ɻ
    
    
    • C / C++ͱͷ૬ޓӡ༻͕ՄೳʢZig Toolchainͦͷ΋ͷ͕C/C++ίϯύΠϥʣ
    
    
    • ݴޠ࢓༷͸ະͩunstableʢݱࡏͷόʔδϣϯ: v0.9.1ʣ
    Zig Project - Logomark / CC BY-SA 4.0.
    

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23. runzigc
    • ZigͰॻ͔Εͨ௿ϨϕϧίϯςφϥϯλΠϜ
    

    https://github.com/musaprg/runzigc
    
    
    • runcͷίʔυΛ”େ͍ʹ”ࢀߟʹ͍ͯ͠·͢
    
    
    • Namespace: User, UTS, PIDͷΈ
    
    
    • cgroups v1ʢcpu, memͷΈʣ
    
    
    • OCI Runtime Specʹ͸ະ४ڌ
    

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24. Demo
    

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25. ຊ೔ͷ͓͠ͳ͕͖
    

    

    1. ·͓͖͑
    
    
    2. ଎शίϯςφϥϯλΠϜ
    
    
    3. runzigcͷ঺հ
    
    
    4. ZigͷΑͦ͞͏ͳ఺ɾࠔͬͨ఺
    
    
    5. ·ͱΊ
    

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26. ॻ͍ͯͯײͨ͡ZigͷΑ͞ 1/2
    • ޡղΛڪΕͣʹݴ͏ͱʮࡶʹॻ͚ΔCݴޠʯ
    
    
    • ײ֮తʹ͸ɺ͍͍ͩͨGoͱRustͷؒ͘Β͍
    
    
    • ߏจ͸γϯϓϧͳͷͰɺൺֱతαΫαΫॻ͚Δ
    
    
    • ܕදهʹ͍ͭͯ͸গ͠Ϋη͕͋ΔͷͰ׳Ε͸ඞཁ
    

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27. ॻ͍ͯͯײͨ͡ZigͷΑ͞ 2/2
    • ܰྔͳSingle static binaryΛు͚Δ
    
    
    • libc΁ͷґଘ͕ͳ͍ͷͰऔΓճ͕͠ྑ͍
    
    
    • ࡶͰ؆қతͳྫˠ
    

    Zig 0.9.1
    

    Target: x86_64-linux
    

    Optimize: -O ReleaseSmall
    

    debug symbol stripped
    

    single threaded
    

    →ɹ໿ 4.5 KiB
    const std = @import("std");
    pub fn main() void {
    std.debug.print("Hello, world!\n", .{});
    }
    

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28. ࠔͬͨ͜ͱ 1/4
    • Errorͦͷ΋ͷʹ࣋ͨͤΔ͜ͱ͕Մೳͳ৘ใ͕গͳ͍
    
    
    • error.PermissionDenied͸ɺ
    

    ”PermissionDenied”Ҏ্ͷ৘ใΛ΋ͨͳ͍
    

    → ελοΫτϨʔεɾσόοάϩάͳͲΛิॿతʹ༻͍Δ͜ͱͰ
    

    ݪҼՕॴͱঢ়گͷಛఆ͸Ͱ͖ΔͷͰे෼Ͱ͸͋Δʁ
    

    

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29. ࠔͬͨ͜ͱ 2/4
    • nճϧʔϓ࣮૷ʹศརͳfor(int i = 0;i
    
    • Zigͷfor͸ɺ͍ΘΏΔfor-eachɻ
    

    →ɹwhile-loopͰهड़͢Δ
    

    ɹɹɹɹor
    

    ɹɹpythonͰ͍͏range()ʹ͋ͨΔ΋ͷΛࣗલ࣮૷
    
    
    • ҰԠproposal͸ग़͍ͯΔ
    

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30. ࠔͬͨ͜ͱ 3/4
    • Ұ෦ͷLinuxγεςϜίʔϧ͸Zigඪ४ϥΠϒϥϦͷ࣮૷͕ଘࡏ͠ͳ͍
    
    
    • sethostname(2)ͳͲ
    

    → ฦΓ஋ͷerrnoΛ
    

    ZigͷerrorʹϚοϓ͢Δ
    

    ࣮૷Λఆٛͯ͠ରԠ
    pub fn valOrErr(val: anytype, errno: usize) LinuxKernelError!@TypeOf(val) {
    return switch (os.errno(errno)) {
    .SUCCESS => val,
    .PERM => error.OperationNotPermitted,
    // …
    else => |e| return os.unexpectedErrno(e),
    };
    }
    pub fn sethostname(hostname: []const u8) SetHostNameError!void {
    const result = switch (native_arch) {
    else => linux.syscall2(.sethostname, @ptrToInt(hostname.ptr),
    hostname.len),
    };
    return valOrErr({}, result);
    }
    

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31. ࠔͬͨ͜ͱ 4/4
    • ώʔϓͷ؅ཧ͕ඞཁͳͷ͸एׯ໘౗
    
    
    • defer/errdeferͱ͍ͬͨείʔϓϕʔεͷ੍ޚߏจ͸͋Δ
    
    
    • RustͷΑ͏ʹউखʹղ์͸
    

    ͯ͘͠Εͳ͍
    

    {
    var values = std.ArrayList(
    []const u8).init(allocator);
    defer values.deinit();
    }
    // είʔϓΛൈ͚ͨ࣌఺Ͱ

    // ArrayList༻ʹ֬อ͞ΕͨϝϞϦ͸dealloc͞ΕΔ
    

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32. ຊ೔ͷ͓͠ͳ͕͖
    

    

    1. ·͓͖͑
    
    
    2. ଎शίϯςφϥϯλΠϜ
    
    
    3. runzigcͷ঺հ
    
    
    4. ZigͷΑ͔ͬͨ఺ɾࠔͬͨ఺
    
    
    5. ·ͱΊ
    

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33. ·ͱΊ
    • Linuxʹ͓͚Δίϯςφ͸ɺ cgroups + namespace Λ༻͍ͯ
    

    ϓϩηεͷϦιʔεΛ෼཭࣮ͯ͠ݱ͍ͯ͠Δ
    
    
    • ίϯςφϥϯλΠϜͷ͏ͪɺ௿ϨϕϧϥϯλΠϜ͕Ϧιʔεͷ෼཭Λ
    ୲͍ͬͯΔ
    
    
    • ZigͰ௿ϨϕϧίϯςφϥϯλΠϜ runzigc Λ࡞͍ͬͯ·͢
    
    
    • Zigͷݴޠ࢓༷͸unstableɺ·ͩ·ͩൃల్্Ͱࠓޙʹ஫໨
    

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34. runzigcͷকདྷ
    • OCI Runtime Spec׬શ४ڌ
    
    
    • Cgroup v1࣮૷ɾCgroup v2ରԠ
    
    
    • SeccompରԠ
    
    
    • ߴϨϕϧϥϯλΠϜ࣮૷௥Ճ ʴ CRIରԠ
    
    
    • ྑ͍ײ͡ͷ໊લΛߟ͑Δʢืूதʣ
    

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35. ײ૝
    • ͪΌΜͱ࣮૷ͨ͠ΒऔΓճ͠ͷ͍͍ܰྔίϯςφϥϯλΠϜ͕
    

    ര஀͢ΔͷͰ͸…ʁͱ͍͏୶͍ظ଴Λ๊͍͍ͯΔɻ
    
    
    • ݱஈ֊Ͱ͸͓΋ͪΌͷҬɺΏ͘Ώ͘͸࢖͑Δ΋ͷʹ͍͖͍ͯͨ͠
    
    
    • ࢓૊ΈΛཧղ͢Δʹ͸ɺࣗ෼Ͱ࡞ͬͯΈΔͷ͕Ұ൪
    
    
    • Έͳ͞Μ΋ίϯςφϥϯλΠϜ࡞ͬͯΈ·ͤΜ͔ʁ
    

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36. Reference
    • ίϯςφϢʔβͳΒ୭΋͕࢖͍ͬͯΔϥϯλΠϜʮruncʯΛ၆ᛌ͢Δ
    [Container Runtime Meetup #1ൃදϨϙʔτ] https://medium.com/
    nttlabs/runc-overview-263b83164c98
    
    
    • Low-level Container Runtime:Runc Internals https://
    kurobato.hateblo.jp/entry/2021/05/02/164218
    
    
    • opencontainers/runc https://github.com/opencontainers/runc
    
    
    • containers/youki https://github.com/containers/youki
    

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37. ͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠
    

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38. Q&A
    

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