feat: add discovery

Signed-off-by: kjuulh <contact@kjuulh.io>

crates/churn/src/agent/grpc_client.rs

@@ -0,0 +1,100 @@
+use tonic::transport::{Channel, ClientTlsConfig};
+
+use crate::grpc::{churn_client::ChurnClient, *};
+
+#[derive(Clone)]
+pub struct GrpcClient {
+    host: String,
+}
+
+impl GrpcClient {
+    pub fn new(host: impl Into<String>) -> Self {
+        Self { host: host.into() }
+    }
+
+    pub async fn get_key(
+        &self,
+        namespace: &str,
+        id: Option<impl Into<String>>,
+        key: &str,
+    ) -> anyhow::Result<Option<String>> {
+        let mut client = self.client().await?;
+
+        let resp = client
+            .get_key(GetKeyRequest {
+                key: key.into(),
+                namespace: namespace.into(),
+                id: id.map(|i| i.into()),
+            })
+            .await?;
+        let resp = resp.into_inner();
+
+        Ok(resp.value)
+    }
+
+    pub async fn set_key(
+        &self,
+        namespace: &str,
+        id: Option<impl Into<String>>,
+        key: &str,
+        value: &str,
+    ) -> anyhow::Result<()> {
+        let mut client = self.client().await?;
+
+        client
+            .set_key(SetKeyRequest {
+                key: key.into(),
+                value: value.into(),
+                namespace: namespace.into(),
+                id: id.map(|i| i.into()),
+            })
+            .await?;
+
+        Ok(())
+    }
+
+    pub async fn listen_events(
+        &self,
+        namespace: &str,
+        id: Option<impl Into<String>>,
+        exec: impl ListenEventsExecutor,
+    ) -> anyhow::Result<()> {
+        let mut client = self.client().await?;
+
+        let resp = client
+            .listen_events(ListenEventsRequest {
+                namespace: namespace.into(),
+                id: id.map(|i| i.into()),
+            })
+            .await?;
+
+        let mut inner = resp.into_inner();
+        while let Ok(Some(message)) = inner.message().await {
+            exec.execute(message).await?;
+        }
+
+        Ok(())
+    }
+
+    async fn client(&self) -> anyhow::Result<ChurnClient<tonic::transport::Channel>> {
+        let channel = if self.host.starts_with("https") {
+            Channel::from_shared(self.host.to_owned())?
+                .tls_config(ClientTlsConfig::new().with_native_roots())?
+                .connect()
+                .await?
+        } else {
+            Channel::from_shared(self.host.to_owned())?
+                .connect()
+                .await?
+        };
+
+        let client = ChurnClient::new(channel);
+
+        Ok(client)
+    }
+}
+
+#[async_trait::async_trait]
+pub trait ListenEventsExecutor {
+    async fn execute(&self, event: ListenEventsResponse) -> anyhow::Result<()>;
+}