Update ENV Variables w/Values

[metaskills]

Thoughts on changing the way this project works by updated each matching ENV variable with the returned value. So in stead of this:

echo $FOO_PARAM
ssm_parameter:/my/parameter

We would have this. And every runtime can simply use the environment vs constructing a fetch to localhost.

echo $FOO_PARAM
my-parameter

A friend shared this project as an idea on how to tap into LD_PRELOAD to update environments before the "real" lambda function/application starts. Thoughts?

https://github.com/mmanciop/opentelemetry-injector

[metaskills]

Little proof of concept work thanks to @hmadison

[dependencies]
redhook = "2.0"
libc = "0.2.126"
log = "0.4.17"

[lib]
name = "ssmhook"
crate_type = ["dylib"]

extern crate libc;

use std::ffi::CStr;
use std::ffi::CString;

redhook::hook! {
    unsafe fn getenv(name: *const libc::c_char) -> *mut libc::c_char => dangerously_mutate_getenv {
    let given_pointer = redhook::real!(getenv)(name);
    if given_pointer.is_null() {
        return given_pointer;
    }
    let given_name = CStr::from_ptr(name).to_str().unwrap();
    let given_value = CStr::from_ptr(given_pointer).to_str().unwrap();
    println!("Got: {} / {}", given_name, given_value);
    if given_name == "HELLO" {
        // https://doc.rust-lang.org/std/ffi/struct.CStr.html#method.as_ptr
        let result = CString::new("WORLD").unwrap();
        return result.into_raw();
    }
        return given_pointer;
    }
}

[metaskills]

Reference for Lambda Extension state & Runtime.

• https://docs.aws.amazon.com/lambda/latest/dg/runtimes-extensions-api.html
• https://docs.aws.amazon.com/lambda/latest/dg/lambda-runtime-environment.html

[metaskills]

Latest main has a working prototype. The sequence diagram is not needed because every extension inits before the runtime init. I tested this too by putting a sleep in the extension prior to SSM parameter fetching with a puts at the beginning of the runtime handler.