use pipenv for third-party packages

The tricky thing about this is finding the `site-packages` directory where
`pipenv` has installed our packages and mounting it where Python can find it
during Wizer initialization.

Signed-off-by: Joel Dice <[email protected]>

Author: dicej

Makefile

@@ -4,8 +4,10 @@ build: target/config.txt target/lib
 	env -i wasi-vfs/target/release/wasi-vfs pack target/wasm32-wasi/release/python_wasi.wasm \
 		--mapdir lib::$$(pwd)/target/lib \
 		-o target/wasm32-wasi/release/python-wasi-vfs.wasm
-	env -i PYTHONUNBUFFERED=1 PYTHONPATH=/py $$(which wizer) target/wasm32-wasi/release/python-wasi-vfs.wasm \
+	env -i PYTHONUNBUFFERED=1 PYTHONPATH=/py:/site-packages \
+		$$(which wizer) target/wasm32-wasi/release/python-wasi-vfs.wasm \
 		--inherit-env true --wasm-bulk-memory true --allow-wasi --dir py \
+		--mapdir site-packages::$$(cd py && find $$(pipenv --venv)/lib -name site-packages | head -1) \
 		-o target/wasm32-wasi/release/python-wasi-vfs-wizer.wasm
 
 target/config.txt:

README.md

@@ -10,6 +10,7 @@ This is an experiment to build a Spin Python SDK using CPython, wasi-vfs, and Py
 - [Wizer](https://github.com/bytecodealliance/wizer) v1.6.0 or later
 - [Spin](https://github.com/fermyon/spin)
 - [rsync](https://rsync.samba.org/) -- used at build time for copying files around; we could replace this with something more portable, if desired
+- [pipenv](https://pypi.org/project/pipenv/) for installing Python project dependencies
 
 ## Building and Running
 
@@ -40,6 +41,7 @@ Then, build the wasi-vfs CLI:
 Finally, build and run this app:
 
 ```
+(cd py && pipenv install)
 spin build
 spin up
 ```

py/Pipfile

@@ -0,0 +1,12 @@
+[[source]]
+url = "https://pypi.org/simple"
+verify_ssl = true
+name = "pypi"
+
+[packages]
+toml = "*"
+
+[dev-packages]
+
+[requires]
+python_version = "3.10"

py/Pipfile.lock

@@ -2,12 +2,23 @@
 from spin_redis import redis_get, redis_set
 from spin_config import config_get
 from os import environ
+import toml
 
 def handle_request(request):
     print(f"Got request URI: {request.uri}")
 
     print(f"Here's my environment: {environ}")
 
+    some_toml = """
+    title = "foo"
+
+    [bar]
+    baz = "wow"
+    such = "toml"
+    """
+
+    print(f"And here's some TOML: {toml.loads(some_toml)}")
+
     response = http_send(Request("GET", "https://some-random-api.ml/facts/dog", [], None))
     print(f"Got dog fact: {str(response.body, 'utf-8')}")