Phase 1 complete: load + execute Wasm modules from VCL

- Rust test module (get_constant, add_numbers, on_request_allow/block)
- 4 passing VTC tests: basic load, allow/block decisions, error handling
- Fixed build: vcc_if.h naming, vwasm_ prefix to avoid Wasmtime symbol clash
- Dockerfile with Varnish 7.5 + Wasmtime 25 + Rust toolchain
- LD_LIBRARY_PATH for runtime Wasmtime shared library resolution

Author: RamazanKara

.gitignore

@@ -29,8 +29,8 @@ Makefile
 Makefile.in
 
 # VMOD generated
-src/vcc_wasm_if.c
-src/vcc_wasm_if.h
+src/vcc_if.c
+src/vcc_if.h
 
 # IDE
 .vscode/

Dockerfile

@@ -15,6 +15,7 @@ RUN apt-get update && apt-get install -y \
     curl \
     ca-certificates \
     gnupg \
+    xz-utils \
     && rm -rf /var/lib/apt/lists/*
 
 # Install Varnish from official repo
@@ -33,11 +34,25 @@ RUN ARCH=$(dpkg --print-architecture) \
     && ln -s /opt/wasmtime-v${WASMTIME_VERSION}-${WASMTIME_ARCH}-linux-c-api /opt/wasmtime
 
 ENV WASMTIME_DIR=/opt/wasmtime
+ENV LD_LIBRARY_PATH=/opt/wasmtime/lib
+
+# Install Rust (for building test Wasm modules)
+RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable \
+    && . "$HOME/.cargo/env" \
+    && rustup target add wasm32-unknown-unknown
+
+ENV PATH="/root/.cargo/bin:${PATH}"
 
 WORKDIR /src
 
 COPY . .
 
+# Build the test Wasm module
+RUN cd examples/rust && cargo build --release \
+    && mkdir -p /src/tests/wasm \
+    && cp target/wasm32-unknown-unknown/release/test_module.wasm /src/tests/wasm/
+
+# Build the VMOD
 RUN chmod +x autogen.sh \
     && ./autogen.sh \
     && ./configure --with-wasmtime=${WASMTIME_DIR} \

Makefile.am

@@ -12,7 +12,10 @@ check-local:
 	@if test -n "$(VARNISHTEST)"; then \
 		for t in $(srcdir)/tests/*.vtc; do \
 			echo "Running $$t..."; \
-			$(VARNISHTEST) -Dvmod_wasm="$(abs_top_builddir)/src/.libs/libvmod_wasm.so" $$t || exit 1; \
+			$(VARNISHTEST) \
+				-Dvmod_wasm="$(abs_top_builddir)/src/.libs/libvmod_wasm.so" \
+				-Dwasm_module="$(abs_top_srcdir)/tests/wasm/test_module.wasm" \
+				$$t || exit 1; \
 		done; \
 	else \
 		echo "WARNING: varnishtest not found, skipping VTC tests"; \

autogen.sh

@@ -2,6 +2,8 @@
 # Bootstrap the autotools build system
 set -e
 
+mkdir -p m4
+libtoolize --force --copy
 aclocal -I m4
 autoheader
 automake --add-missing --foreign

examples/rust/.cargo/config.toml

@@ -0,0 +1,2 @@
+[build]
+target = "wasm32-unknown-unknown"

examples/rust/Cargo.lock

@@ -0,0 +1,11 @@
+[package]
+name = "test-module"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+crate-type = ["cdylib"]
+
+[profile.release]
+opt-level = "s"
+lto = true

examples/rust/Cargo.toml

@@ -0,0 +1,28 @@
+/// Minimal test Wasm module for vmod-wasm Phase 1 testing.
+///
+/// Exports simple functions that the VMOD can call to verify
+/// basic load + execute functionality.
+
+/// Returns a constant (42) — simplest possible test.
+#[no_mangle]
+pub extern "C" fn get_constant() -> i32 {
+    42
+}
+
+/// Adds two hardcoded numbers — verifies the runtime works.
+#[no_mangle]
+pub extern "C" fn add_numbers() -> i32 {
+    17 + 25
+}
+
+/// Simulates an "allow" decision (return 0 = allow).
+#[no_mangle]
+pub extern "C" fn on_request_allow() -> i32 {
+    0
+}
+
+/// Simulates a "block" decision (return 403 = block).
+#[no_mangle]
+pub extern "C" fn on_request_block() -> i32 {
+    403
+}

examples/rust/src/lib.rs

@@ -1,4 +1,4 @@
-AM_CFLAGS = $(VARNISHAPI_CFLAGS) $(WASMTIME_CFLAGS)
+AM_CFLAGS = $(VARNISHAPI_CFLAGS) $(WASMTIME_CFLAGS) -I$(top_builddir)/src
 
 vmoddir = $(VMOD_DIR)
 vmod_LTLIBRARIES = libvmod_wasm.la
@@ -18,12 +18,12 @@ libvmod_wasm_la_LIBADD = $(VARNISHAPI_LIBS) $(WASMTIME_LIBS)
 
 # Generate VMOD interface from .vcc
 nodist_libvmod_wasm_la_SOURCES = \
-	vcc_wasm_if.c \
-	vcc_wasm_if.h
+	vcc_if.c \
+	vcc_if.h
 
-vcc_wasm_if.c vcc_wasm_if.h: vmod_wasm.vcc
-	$(PYTHON) $(VMODTOOL) $(srcdir)/vmod_wasm.vcc
+vcc_if.c vcc_if.h: vmod_wasm.vcc
+	$(VMODTOOL) $(srcdir)/vmod_wasm.vcc
 
-BUILT_SOURCES = vcc_wasm_if.c vcc_wasm_if.h
+BUILT_SOURCES = vcc_if.c vcc_if.h
 CLEANFILES = $(BUILT_SOURCES)
 EXTRA_DIST = vmod_wasm.vcc

src/Makefile.am

@@ -29,13 +29,13 @@
 #include "cache/cache.h"
 #include "vcl.h"
 
-#include "vcc_wasm_if.h"
+#include "vcc_if.h"
 #include "wasm_engine.h"
 
 #define VMOD_WASM_VERSION "0.1.0"
 
 /* Global Wasm engine — shared across all VCL instances and threads */
-static struct wasm_engine *wasm_engine_global = NULL;
+static struct vwasm_engine *vwasm_engine_global = NULL;
 static pthread_mutex_t engine_mtx = PTHREAD_MUTEX_INITIALIZER;
 
 /*
@@ -44,25 +44,25 @@ static pthread_mutex_t engine_mtx = PTHREAD_MUTEX_INITIALIZER;
  * DISCARD: destroy the Wasm engine
  */
 int v_matchproto_(vmod_event_f)
-vmod_event(VRT_CTX, struct vmod_priv *priv, enum vcl_event_e e)
+vmod_vmod_event(VRT_CTX, struct vmod_priv *priv, enum vcl_event_e e)
 {
 	(void)priv;
 
 	switch (e) {
 	case VCL_EVENT_LOAD:
 		AZ(pthread_mutex_lock(&engine_mtx));
-		if (wasm_engine_global == NULL)
-			wasm_engine_global = wasm_engine_new();
+		if (vwasm_engine_global == NULL)
+			vwasm_engine_global = vwasm_engine_new();
 		AZ(pthread_mutex_unlock(&engine_mtx));
-		if (wasm_engine_global == NULL)
+		if (vwasm_engine_global == NULL)
 			return (-1);
 		return (0);
 
 	case VCL_EVENT_DISCARD:
 		AZ(pthread_mutex_lock(&engine_mtx));
-		if (wasm_engine_global != NULL) {
-			wasm_engine_destroy(&wasm_engine_global);
-			wasm_engine_global = NULL;
+		if (vwasm_engine_global != NULL) {
+			vwasm_engine_destroy(&vwasm_engine_global);
+			vwasm_engine_global = NULL;
 		}
 		AZ(pthread_mutex_unlock(&engine_mtx));
 		return (0);
@@ -90,9 +90,9 @@ vmod_load(VRT_CTX, VCL_STRING name, VCL_STRING path)
 		return;
 	}
 
-	AN(wasm_engine_global);
+	AN(vwasm_engine_global);
 
-	if (wasm_engine_load_module(wasm_engine_global, name, path) != 0) {
+	if (vwasm_engine_load_module(vwasm_engine_global, name, path) != 0) {
 		VRT_fail(ctx, "wasm.load(): failed to load module '%s' from '%s'",
 		    name, path);
 	}
@@ -116,10 +116,10 @@ vmod_execute(VRT_CTX, VCL_STRING name, VCL_STRING function)
 		return (-1);
 	}
 
-	AN(wasm_engine_global);
+	AN(vwasm_engine_global);
 
 	int result = 0;
-	if (wasm_engine_call(wasm_engine_global, ctx, name, function, &result) != 0) {
+	if (vwasm_engine_call(vwasm_engine_global, ctx, name, function, &result) != 0) {
 		VSLb(ctx->vsl, SLT_Error,
 		    "wasm.execute(): failed to call '%s' in module '%s'",
 		    function, name);