java操作 docker 镜像获取manifest

可以使用 Java 代码来获取 Docker 镜像的 manifest。以下是一个示例代码：

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;

import org.apache.commons.codec.binary.Hex;
import org.apache.commons.io.IOUtils;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

public class DockerManifest {

    public static void main(String[] args) throws NoSuchAlgorithmException, IOException {
        String imageName = "nginx"; // 镜像名称
        String imageTag = "latest"; // 镜像标签

        String manifest = getManifest(imageName, imageTag);
        System.out.println("Manifest: " + manifest);
    }

    public static String getManifest(String imageName, String imageTag)
            throws NoSuchAlgorithmException, IOException {
        String imageReference = imageName + ":" + imageTag;
        String encodedReference = Base64.getUrlEncoder().encodeToString(imageReference.getBytes());

        String endpoint = "https://registry-1.docker.io/v2";
        String path = "/" + imageName + "/manifests/" + imageTag;
        String url = endpoint + path;

        MessageDigest md = MessageDigest.getInstance("SHA-256");
        md.update(("GET\n\n\napplication/vnd.docker.distribution.manifest.v2+json\n" + "Accept: application/vnd.docker.distribution.manifest.v2+json\n" +
                "Docker-Content-Digest:" + encodedReference + "\n" +
                path).getBytes(StandardCharsets.UTF_8));
        String digest = Hex.encodeHexString(md.digest());

        // 发送请求
        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder()
                .url(url)
                .header("Accept", "application/vnd.docker.distribution.manifest.v2+json")
                .header("Authorization", "Bearer " + getAuthToken())
                .header("Docker-Content-Digest", encodedReference)
                .header("Content-Type", "application/vnd.docker.distribution.manifest.v2+json")
                .header("Digest", "sha256:" + digest)
                .build();

        Response response = client.newCall(request).execute();
        String responseBody = response.body().string();

        Gson gson = new GsonBuilder().setPrettyPrinting().create();
        Object json = gson.fromJson(responseBody, Object.class);

        return gson.toJson(json);
    }

    private static String getAuthToken() throws IOException {
        String endpoint = "https://auth.docker.io/token";
        String scope = "repository:library/*:pull";
        String service = "registry.docker.io";

        String url = endpoint + "?scope=" + scope + "&service=" + service;

        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder()
                .url(url)
                .build();

        Response response = client.newCall(request).execute();
        String responseBody = response.body().string();

        Gson gson = new Gson();
        AuthTokenResponse authTokenResponse = gson.fromJson(responseBody, AuthTokenResponse.class);

        return authTokenResponse.getToken();
    }

    static class AuthTokenResponse {
        private String token;

        public String getToken() {
            return token;
        }

        public void setToken(String token) {
            this.token = token;
        }
    }
}

该代码使用了 okhttp 和 Gson 库来发送 HTTP 请求并解析 JSON 响应。您需要将 `imageName` 和 `imageTag` 替换为您自己的值。执行该代码后，将输出 Docker 镜像的 manifest。