aws-sdk-for-zig/README.md

AWS SDK for Zig (zig native branch)

NOTE: All tests pass, but credentials currently must be passed through environment

This SDK currently supports all AWS services except EC2 and S3. These two services only support XML, and zig 0.8.0 and master both trigger compile errors while incorporating the XML parser. S3 also requires some plumbing tweaks in the signature calculation. Examples of usage are in src/main.zig.

Current executable size for the demo is 953k (90k of which is the AWS PEM file) after compiling with -Drelease-safe and stripping the executable after compilation. This is for x86_linux. Tested targets:

• x86_64-linux
• riscv64-linux
• aarch64-linux
• x86_64-windows
• arm-linux

Building

zig build should work. It will build the code generation project, run the code generation, then build the main project with the generated code.

First time build should use zig build -Dfetch to fetch dependent packages (zfetch and friends).

Running

This library mimics the aws c libraries for it's work, so it operates like most other 'AWS things'. main.zig gives you a handful of examples for working with services. For local testing or alternative endpoints, there's no real standard, so there is code to look for AWS_ENDPOINT_URL environment variable that will supersede all other configuration. Note that an alternative endpoint may require passing in a client option to specify an different TLS root certificate (pass null to disable certificate verification).

Given that credential handling is still very basic, you may want to look at the old branch if your needs include something more robust. Note that that branch supports x86_64 linux only.

Limitations

There are many nuances of AWS V4 signature calculation. S3 is not supported because it uses many of these test cases. STS tokens using a session token are not yet implemented, though should be trivial. I have also seen a few service errors caused by discrepancies in signatures, though I don't know yet if this was an issue in the service itself (has not repro'd) or if there is a latent bug.

Only environment variable based credentials can be used at the moment.

TODO List:

• Add STS key support
• Add option to cache signature keys
• Implement credentials provider
• Implement jitter/exponential backoff
• Implement timeouts and other TODO's in the code
• Implement AWS restXml protocol. Includes S3. Total service count 4. This may be blocked due to the same issue as EC2.
• Implement AWS EC2 query protocol. Includes EC2. Total service count 1. This may be blocked on a compiler bug, though has not been tested with zig 0.9.0. It may need to wait for zig 0.10.0 when self-hosted compiler is likely to be completed (zig 0.10.0 eta May 2022) discovered. More details and llvm ir log can be found in the XML branch.
• Implement sigv4a signing

Compiler wishlist/watchlist:

• Merge PR to allow stripping -static
• comptime allocations so we can read files, etc (or is there another way)