api: add world accessible ping dummy endpoint

This is indented to be used for the PVE storage library, replacing
the missuse of the much more expensive status API call.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

src/api2/ping.rs

@@ -0,0 +1,29 @@
+use anyhow::{Error};
+use serde_json::{json, Value};
+
+use proxmox::api::{api, Router, Permission};
+
+#[api(
+    returns: {
+        description: "Dummy ping",
+        type: Object,
+        properties: {
+            pong: {
+                description: "Always true",
+                type: bool,
+            }
+        }
+    },
+    access: {
+        description: "Anyone can access this, because it's used for a cheap check if the API daemon is online.",
+        permission: &Permission::World,
+    }
+)]
+/// Dummy method which replies with `{ "pong": True }`
+fn ping() -> Result<Value, Error> {
+    Ok(json!({
+        "pong": true,
+    }))
+}
+pub const ROUTER: Router = Router::new()
+    .get(&API_METHOD_PING);