Implement wasi-config

crates/expressions/Cargo.toml

@@ -7,6 +7,7 @@ edition = { workspace = true }
 [dependencies]
 anyhow = { workspace = true }
 async-trait = { workspace = true }
+futures = { workspace = true }
 spin-locked-app = { path = "../locked-app" }
 thiserror = { workspace = true }
 

crates/expressions/src/lib.rs

@@ -52,6 +52,22 @@ impl ProviderResolver {
         self.resolve_template(template).await
     }
 
+    /// Resolves all variables for the given component.
+    pub async fn resolve_all(&self, component_id: &str) -> Result<Vec<(String, String)>> {
+        use futures::FutureExt;
+
+        let Some(keys2templates) = self.internal.component_configs.get(component_id) else {
+            return Ok(vec![]);
+        };
+
+        let resolve_futs = keys2templates.iter().map(|(key, template)| {
+            self.resolve_template(template)
+                .map(|r| r.map(|value| (key.to_string(), value)))
+        });
+
+        futures::future::try_join_all(resolve_futs).await
+    }
+
     /// Resolves the given template.
     pub async fn resolve_template(&self, template: &Template) -> Result<String> {
         let mut resolved_parts: Vec<Cow<str>> = Vec::with_capacity(template.parts().len());

crates/factor-variables/src/host.rs

@@ -1,5 +1,5 @@
 use spin_factors::anyhow;
-use spin_world::{async_trait, v1, v2::variables};
+use spin_world::{async_trait, v1, v2::variables, wasi::config as wasi_config};
 use tracing::{instrument, Level};
 
 use crate::InstanceState;
@@ -37,6 +37,41 @@ impl v1::config::Host for InstanceState {
     }
 }
 
+#[async_trait]
+impl wasi_config::store::Host for InstanceState {
+    async fn get(&mut self, key: String) -> Result<Option<String>, wasi_config::store::Error> {
+        match <Self as variables::Host>::get(self, key).await {
+            Ok(value) => Ok(Some(value)),
+            Err(variables::Error::Undefined(_)) => Ok(None),
+            Err(variables::Error::InvalidName(_)) => Ok(None), // this is the guidance from https://github.com/WebAssembly/wasi-runtime-config/pull/19)
+            Err(variables::Error::Provider(msg)) => Err(wasi_config::store::Error::Upstream(msg)),
+            Err(variables::Error::Other(msg)) => Err(wasi_config::store::Error::Io(msg)),
+        }
+    }
+
+    async fn get_all(&mut self) -> Result<Vec<(String, String)>, wasi_config::store::Error> {
+        let all = self
+            .expression_resolver
+            .resolve_all(&self.component_id)
+            .await;
+        all.map_err(|e| {
+            match expressions_to_variables_err(e) {
+                variables::Error::Undefined(msg) => wasi_config::store::Error::Io(msg), // this shouldn't happen but just in case
+                variables::Error::InvalidName(msg) => wasi_config::store::Error::Io(msg), // this shouldn't happen but just in case
+                variables::Error::Provider(msg) => wasi_config::store::Error::Upstream(msg),
+                variables::Error::Other(msg) => wasi_config::store::Error::Io(msg),
+            }
+        })
+    }
+
+    fn convert_error(
+        &mut self,
+        err: wasi_config::store::Error,
+    ) -> anyhow::Result<wasi_config::store::Error> {
+        Ok(err)
+    }
+}
+
 fn expressions_to_variables_err(err: spin_expressions::Error) -> variables::Error {
     use spin_expressions::Error;
     match err {

crates/factor-variables/src/lib.rs

@@ -31,6 +31,7 @@ impl Factor for VariablesFactor {
     fn init<T: Send + 'static>(&mut self, mut ctx: InitContext<T, Self>) -> anyhow::Result<()> {
         ctx.link_bindings(spin_world::v1::config::add_to_linker)?;
         ctx.link_bindings(spin_world::v2::variables::add_to_linker)?;
+        ctx.link_bindings(spin_world::wasi::config::store::add_to_linker)?;
         Ok(())
     }
 

crates/world/src/lib.rs

@@ -28,6 +28,7 @@ wasmtime::component::bindgen!({
         "fermyon:spin/[email protected]/error" => v2::sqlite::Error,
         "fermyon:spin/sqlite/error" => v1::sqlite::Error,
         "fermyon:spin/[email protected]/error" => v2::variables::Error,
+        "wasi:config/store/error" => wasi::config::store::Error,
     },
     trappable_imports: true,
 });

tests/runtime-tests/tests/variables/spin.toml

@@ -0,0 +1,17 @@
+spin_manifest_version = "1"
+authors = [""]
+description = ""
+name = "variables"
+trigger = { type = "http" }
+version = "0.1.0"
+
+[variables]
+variable = { default = "value" }
+
+[[component]]
+id = "variables"
+source = "%{source=variables}"
+[component.trigger]
+route = "/..."
+[component.config]
+variable = "{{ variable }}"

tests/runtime-tests/tests/wasi-config/spin.toml

@@ -0,0 +1,17 @@
+spin_manifest_version = "1"
+authors = [""]
+description = ""
+name = "wasi-config"
+trigger = { type = "http" }
+version = "0.1.0"
+
+[variables]
+variable = { default = "value" }
+
+[[component]]
+id = "wasi-config"
+source = "%{source=wasi-config}"
+[component.trigger]
+route = "/..."
+[component.config]
+variable = "{{ variable }}"

tests/test-components/components/wasi-config/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "wasi-config"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+helper = { path = "../../helper" }
+wit-bindgen = "0.16.0"

tests/test-components/components/wasi-config/README.md

@@ -0,0 +1,8 @@
+# Variables
+
+Tests the wasi:config interface.
+
+## Expectations
+
+This test component expects the following to be true:
+* Only the variable named "variable" is defined with value "value"

tests/test-components/components/wasi-config/src/lib.rs

@@ -0,0 +1,23 @@
+use helper::ensure_matches;
+
+use bindings::wasi::config::store::{get, get_all};
+
+helper::define_component!(Component);
+
+impl Component {
+    fn main() -> Result<(), String> {
+        ensure_matches!(get("variable"), Ok(Some(val)) if val == "value");
+        ensure_matches!(get("non_existent"), Ok(None));
+
+        let expected_all = vec![
+            ("variable".to_owned(), "value".to_owned()),
+        ];
+        ensure_matches!(get_all(), Ok(val) if val == expected_all);
+
+        ensure_matches!(get("invalid-name"), Ok(None));
+        ensure_matches!(get("invalid!name"), Ok(None));
+        ensure_matches!(get("4invalidname"), Ok(None));
+
+        Ok(())
+    }
+}

wit/deps/spin@3.0.0/world.wit

@@ -9,4 +9,5 @@ world http-trigger {
 /// The imports needed for a guest to run on a Spin host
 world platform {
   include fermyon:spin/[email protected];
+  import wasi:config/[email protected];
 }

wit/deps/wasi-runtime-config-2024-09-27/store.wit

@@ -0,0 +1,30 @@
+interface store {
+    /// An error type that encapsulates the different errors that can occur fetching configuration values.
+    variant error {
+        /// This indicates an error from an "upstream" config source. 
+        /// As this could be almost _anything_ (such as Vault, Kubernetes ConfigMaps, KeyValue buckets, etc), 
+        /// the error message is a string.
+        upstream(string),
+        /// This indicates an error from an I/O operation. 
+        /// As this could be almost _anything_ (such as a file read, network connection, etc), 
+        /// the error message is a string. 
+        /// Depending on how this ends up being consumed, 
+        /// we may consider moving this to use the `wasi:io/error` type instead. 
+        /// For simplicity right now in supporting multiple implementations, it is being left as a string.
+        io(string),
+    }
+
+    /// Gets a configuration value of type `string` associated with the `key`. 
+    /// 
+    /// The value is returned as an `option<string>`. If the key is not found,
+    /// `Ok(none)` is returned. If an error occurs, an `Err(error)` is returned.
+    get: func(
+        /// A string key to fetch
+        key: string
+    ) -> result<option<string>, error>;
+
+    /// Gets a list of configuration key-value pairs of type `string`.
+    /// 
+    /// If an error occurs, an `Err(error)` is returned.
+    get-all: func() -> result<list<tuple<string, string>>, error>;
+}

wit/deps/wasi-runtime-config-2024-09-27/world.wit

@@ -0,0 +1,6 @@
+package wasi:[email protected];
+
+world imports {
+    /// The interface for wasi:config/store
+    import store;
+}