Add example using the transfer service

Pulls an image to the containerd content store

Signed-off-by: Phil Estes <estesp@amazon.com>

crates/client/examples/container_pull.rs

@@ -0,0 +1,91 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+use std::env::consts;
+
+use client::{
+    services::v1::{transfer_client::TransferClient, TransferOptions, TransferRequest},
+    to_any,
+    types::{
+        transfer::{ImageStore, OciRegistry, UnpackConfiguration},
+        Platform,
+    },
+    with_namespace,
+};
+use containerd_client as client;
+use tonic::Request;
+
+const IMAGE: &str = "docker.io/library/alpine:latest";
+const NAMESPACE: &str = "default";
+
+/// Make sure you run containerd before running this example.
+/// NOTE: to run this example, you must prepare a rootfs.
+#[tokio::main(flavor = "current_thread")]
+async fn main() {
+    let arch = match consts::ARCH {
+        "x86_64" => "amd64",
+        "aarch64" => "arm64",
+        _ => consts::ARCH,
+    };
+
+    let channel = client::connect("/run/containerd/containerd.sock")
+        .await
+        .expect("Connect Failed");
+    let mut client = TransferClient::new(channel.clone());
+
+    // Create the source (OCIRegistry)
+    let source = OciRegistry {
+        reference: IMAGE.to_string(),
+        resolver: Default::default(),
+    };
+
+    let platform = Platform {
+        os: "linux".to_string(),
+        architecture: arch.to_string(),
+        variant: "".to_string(),
+        os_version: "".to_string(),
+    };
+
+    // Create the destination (ImageStore)
+    let destination = ImageStore {
+        name: IMAGE.to_string(),
+        platforms: vec![platform.clone()],
+        unpacks: vec![UnpackConfiguration {
+            platform: Some(platform),
+            ..Default::default()
+        }],
+        ..Default::default()
+    };
+
+    let anys = to_any(&source);
+    let anyd = to_any(&destination);
+
+    println!("Pulling image for linux/{} from source: {:?}", arch, source);
+
+    // Create the transfer request
+    let request = TransferRequest {
+        source: Some(anys),
+        destination: Some(anyd),
+        options: Some(TransferOptions {
+            ..Default::default()
+        }),
+    };
+    // Execute the transfer (pull)
+    client
+        .transfer(with_namespace!(request, NAMESPACE))
+        .await
+        .expect("unable to transfer image");
+}