107 lines
4.0 KiB
Markdown
107 lines
4.0 KiB
Markdown
# AWS SDK for Zig
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Ok, so it's not actually an SDK (yet). Right now this is SDK supports sts
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get-caller-identity action only. Why? Because it's one of the easiest to
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support, so I started there. From here, the next major step is to codegen
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the types necessary to support the various services. Currently this code is
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dynamically generating the sts types so we are somewhat codegen ready, but
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current comptime limitations might trip us up. The advantage of comptime is
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that only types actually used would be generated vs the whole surface area
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of AWS. That said, with most of the heavy lifting now coded, the addition
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of the request/response types, even if all of them are added, should not
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balloon the size beyond "reasonable". Of course this still needs to be be seen.
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This is my first serious zig effort, so please issue a PR if the code isn't
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"ziggy" or if there's a better way.
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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. Implementing
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get-caller-identity with all dependencies statically linked gives us a stripped
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executable size of 5.3M for x86_linux (which is all that's tested at the moment).
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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. Openssl in
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particular will take a while, but without any particular knowledge
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I'm also hoping/expecting AWS to factor out that library sometime in
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the future.
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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 0.7.1 installed. The build.zig currently relies on
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[this PR to allow stripping -static](https://github.com/ziglang/zig/pull/8248),
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so either:
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* Modify build.zig, then strip (or not) after the fact
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* Install make and use the included Makefile
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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 program to call sts GetCallerIdentity.
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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 `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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* Implement error handling for 4xx, 5xx and other unexpected return values
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* Implement generic response body -> Response type handling (right now, this is hard-coded)
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* Implement codegen for services with xml structures (using Smithy models)
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* Implement codegen for others (using Smithy models)
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* Switch to aws-c-cal upsream once PR for full static musl build support is merged (see Dockerfile)
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* Remove compiler 0.7.1 shims when 0.8.0 is released
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Compiler wishlist/watchlist:
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* Fix the weirdness we see with comptime type generation (see aws.zig around line 251)
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* [Allow declarations for comptime type generation](https://github.com/ziglang/zig/issues/6709)
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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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