WASM Postgres

An attempt to build postgres server to wasm so that it can be run in browsers or cloudflare workers.

Why?

Embedded postgres anywhere where WebAssembly is supported.
SQLite has incredible in-memory test fixtures, let's get those with postgres in NodeJS and Python!
Cloudflare Workers could run postgres server and provide ultra-cheap 50MB databases

How to Port

If you haven't compiled C to wasm before, check out this very simple example:

#include <stdio.h>

int main(void)
{
    puts("Hello");
    return 0;
}

We can build this to wasm using...

clang --target=wasm32-unknown-wasi --sysroot $(pwd)/wasi-libc/sysroot -O2 -s -o test.wasm test.c

We can now run our wasm code, it's that simple!

$ wasmer test.wasm
Hello

Porting is just configuring the postgres Makefile to have our --target and --sysroot, then fixing any compiler errors by introducing missing headers or libraries.

Getting Started

0. Installing Stuff

This might be a bit incomplete, google around as the errors come up and PR or open an issue!

TODO why not just shove all this into a Dockerfile

You'll need a bunch of things, this is what I installed on Arch Linux via yay:

wasi-sdk-bin
wasm-ld
clang
llvm
lld

1. Building sysroot

You'll need to configure your system a little bit. Let's start with wasm32-libc, wasm-32libc provides a system root with implementations of common C header files. Basically this is your /usr/include directory, but specifically made for wasm!

cd wasi-libc
make

You now have a sysroot at wasi-libc/sysroot

2. Configure postgres for WASM building

Before we make postgres, we run the configure script to configure our Makefile. We'll want to set a couple things in our environment to make sure postgres is configured with WASM as it's target...

# This is in ./configure-postgres.sh
export CC=clang
export PG_SYSROOT=$(pwd)/wasi-libc/sysroot
cd postgres
./configure

Now let's start building postgres. We can do this by jumping into the postgres/src directory and running...

export COPT="--target=wasm32-unknown-wasi --sysroot=$(pwd)/../../wasi-libc/sysroot"
make

3. Show Stopper - No netdb.h

Here's our first show-stopper. The wasi-libc lacks networking headers!

make[1]: Entering directory '/home/seve/workspace/os/wasm-postgres/postgres/src/port'
clang -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -Wno-unused-command-line-argument -O2 --target=wasm32-unknown-wasi --sysroot=/home/seve/workspace/os/wasm-postgres/postgres/src/../../wasi-libc/sysroot -I../../src/port -DFRONTEND -I../../src/include  -D_GNU_SOURCE   -c -o path.o path.c
In file included from path.c:19:
In file included from ../../src/include/postgres_fe.h:25:
In file included from ../../src/include/c.h:1355:
../../src/include/port.h:17:10: fatal error: 'netdb.h' file not found
#include <netdb.h>
         ^~~~~~~~~
1 error generated.
make[1]: *** [<builtin>: path.o] Error 1
make[1]: Leaving directory '/home/seve/workspace/os/wasm-postgres/postgres/src/port'
make: *** [Makefile:42: all-port-recurse] Error 2

unable to compile simple httpclient wasm module

seveibar/wasm-postgres