125 lines
5.1 KiB
Markdown
125 lines
5.1 KiB
Markdown
# AWS SDK for Zig
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[](https://drone.lerch.org/lobo/aws-sdk-for-zig)
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This SDK currently supports all AWS services except EC2 and S3. These two
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services only support XML, and zig 0.8.0 and master both trigger compile
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errors while incorporating the XML parser. S3 also requires some plumbing
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tweaks in the signature calculation, which is planned for a zig version
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(probably self-hosted 0.9.0) that no longer has an error triggered. Examples
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of usage are in src/main.zig.
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This is designed to be built statically using the `aws_c_*` libraries, so
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we inherit a lot of the goodness of the work going on there. Current
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executable size is 9.7M, about half of which is due to the SSL library.
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Running strip on the executable after compilation (it seems zig strip
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only goes so far), reduces this to 4.3M. This is for x86_linux,
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(which is all that's tested at the moment).
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# 2022-01-10 SDK Update
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To get smaller executable size and better portability with faster compilation,
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my intent is to rework the http communications using
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[requestz](https://github.com/ducdetronquito/requestz). This relies on a
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couple other projects, and will require the creation of a zig implementation
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for [Signature Version 4](https://docs.aws.amazon.com/general/latest/gr/signature-version-4.html),
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along with support for some S3 quirks, etc. It will also reduce compatibility
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with some edge cases. Long term I think this is a better approach, however and
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will remove (or replace) a ton of the C dependencies as well as avoid a bunch
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of complexity such as the event loop C implementation found in the AWS
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libraries, which eventually could be replaced by zig async. I have created a
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[new branch](https://github.com/elerch/aws-sdk-for-zig/tree/zig-native)
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for this work as master is currently working fairly well. I'd also love to have
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an official package manager in zig, but I know this is high on the priority
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list for the foundation. In the meantime I will depend on git commands executed
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by build.zig to handle packages.
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## Building
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I am assuming here that if you're playing with zig, you pretty much know
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what you're doing, so I will stay brief.
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First, the dependencies are required. Use the Dockerfile to build these.
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a `docker build` will do, but be prepared for it to run a while. The
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Dockerfile has been tested on x86_64 linux, but I do hope to get arm64
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supported as well.
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Once that's done, you'll have an alpine image with all dependencies ready
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to go and zig master installed. There are some build-related things still
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broken in 0.8.0 and hopefully 0.8.1 will address those and we can be on
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a standard release.
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* `zig build` should work. It will build the code generation project, run
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the code generation, then build the main project with the generated code.
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There is also a Makefile included, but this hasn't been used in a while
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and I'm not sure that works at the moment.
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## Running
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This library uses the aws c libraries for it's work, so it operates like most
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other 'AWS things'. Note that I tested by setting the appropriate environment
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variables, so config files haven't gotten a run through.
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main.zig gives you a handful of examples for working with services.
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For local testing or alternative endpoints, there's no real standard, so
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there is code to look for `AWS_ENDPOINT_URL` environment variable that will
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supercede all other configuration.
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## Dependencies
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Full dependency tree:
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aws-c-auth
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* s2n
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* aws-lc
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* aws-c-common
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* aws-c-compression
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* aws-c-common
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* aws-c-http
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* s2n
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* aws-c-common
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* aws-c-io
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* aws-c-common
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* s2n
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* aws-lc
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* aws-c-cal
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* aws-c-common
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* aws-lc
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* aws-c-compression
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* aws-c-common
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* aws-c-cal
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* aws-c-common
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* aws-lc
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Build order based on above:
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1. aws-c-common
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1. aws-lc
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2. s2n
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2. aws-c-cal
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2. aws-c-compression
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3. aws-c-io
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4. aws-c-http
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5. aws-c-auth
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Dockerfile in this repo will manage this
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TODO List:
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* Implement jitter/exponential backoff. This appears to be configuration of
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`aws_c_io` and should therefore be trivial
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* Implement timeouts and other TODO's in the code
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* Switch to aws-c-cal upstream once [PR for full static musl build support is merged](https://github.com/awslabs/aws-c-cal/pull/89)
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(see Dockerfile)
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* Implement [AWS restXml protocol](https://awslabs.github.io/smithy/1.0/spec/aws/aws-restxml-protocol.html).
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Includes S3. Total service count 4. This may be blocked due to the same issue as EC2.
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* Implement [AWS EC2 query protocol](https://awslabs.github.io/smithy/1.0/spec/aws/aws-ec2-query-protocol.html).
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Includes EC2. Total service count 1. This is currently blocked, probably on
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self-hosted compiler coming in zig 0.9.0 (January 2022) due to compiler bug
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discovered. More details and llvm ir log can be found in the
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[XML branch](https://git.lerch.org/lobo/aws-sdk-for-zig/src/branch/xml).
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Compiler wishlist/watchlist:
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* [Merge PR to allow stripping -static](https://github.com/ziglang/zig/pull/8248)
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* [comptime allocations](https://github.com/ziglang/zig/issues/1291) so we can read files, etc (or is there another way)
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