Add -S inherit-env for inheriting the entire environment

crates/cli-flags/src/lib.rs

@@ -293,6 +293,10 @@ wasmtime_option_group! {
         pub udp: Option<bool>,
         /// Allows imports from the `wasi_unstable` core wasm module.
         pub preview0: Option<bool>,
+        /// Inherit all environment variables from the parent process.
+        ///
+        /// This option can be further overwritten with `--env` flags.
+        pub inherit_env: Option<bool>,
     }
 
     enum Wasi {

src/commands/run.rs

@@ -740,6 +740,11 @@ impl RunCommand {
         let mut builder = WasiCtxBuilder::new();
         builder.inherit_stdio().args(&self.compute_argv()?)?;
 
+        if self.run.common.wasi.inherit_env == Some(true) {
+            for (k, v) in std::env::vars() {
+                builder.env(&k, &v)?;
+            }
+        }
         for (key, value) in self.vars.iter() {
             let value = match value {
                 Some(value) => value.clone(),
@@ -779,6 +784,11 @@ impl RunCommand {
         let mut builder = wasmtime_wasi::WasiCtxBuilder::new();
         builder.inherit_stdio().args(&self.compute_argv()?);
 
+        if self.run.common.wasi.inherit_env == Some(true) {
+            for (k, v) in std::env::vars() {
+                builder.env(&k, &v);
+            }
+        }
         for (key, value) in self.vars.iter() {
             let value = match value {
                 Some(value) => value.clone(),

tests/all/cli_tests.rs

@@ -521,6 +521,15 @@ fn specify_env() -> Result<()> {
         .output()?;
     assert!(output.status.success());
 
+    // Inherit all env vars
+    let output = get_wasmtime_command()?
+        .args(&["run", "-Sinherit-env", "tests/all/cli_tests/print_env.wat"])
+        .env("FOO", "bar")
+        .output()?;
+    assert!(output.status.success());
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    assert!(stdout.contains("FOO=bar"), "bad output: {stdout}");
+
     Ok(())
 }