1 files changed, 148 insertions, 0 deletions
diff --git a/configserver-client/src/main/java/ai/vespa/hosted/client/ConfigServerClient.java b/configserver-client/src/main/java/ai/vespa/hosted/client/ConfigServerClient.java
new file mode 100644
index 00000000000..234dbe9ee06
--- /dev/null
+++ b/configserver-client/src/main/java/ai/vespa/hosted/client/ConfigServerClient.java
@@ -0,0 +1,148 @@
+// Copyright Verizon Media. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package ai.vespa.hosted.client;
+
+import org.apache.hc.client5.http.config.RequestConfig;
+import org.apache.hc.core5.http.ClassicHttpResponse;
+import org.apache.hc.core5.http.HttpEntity;
+import org.apache.hc.core5.http.Method;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.UncheckedIOException;
+import java.net.URI;
+import java.time.Duration;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.function.BiFunction;
+import java.util.function.Function;
+import java.util.stream.IntStream;
+
+import static java.util.Objects.requireNonNull;
+import static java.util.stream.Collectors.toUnmodifiableList;
+
+/**
+ * @author jonmv
+ */
+public interface ConfigServerClient extends AutoCloseable {
+
+    /** Creates a builder for sending the given method, using the specified host strategy. */
+    RequestBuilder send(HostStrategy hosts, Method method);
+
+    /** Builder for a request against a given set of hosts, using this config server client. */
+    interface RequestBuilder {
+
+        /** Sets the request path. */
+        RequestBuilder at(String... pathSegments);
+
+        /** Sets the request body as UTF-8 application/json. */
+        RequestBuilder body(byte[] json);
+
+        /** Sets the request body. */
+        RequestBuilder body(HttpEntity entity);
+
+        /** Sets the parameter key/values for the request. Number of arguments must be even. */
+        RequestBuilder parameters(String... pairs);
+
+        /** Overrides the default socket read timeout of the request. {@code Duration.ZERO} gives infinite timeout. */
+        RequestBuilder timeout(Duration timeout);
+
+        /** Overrides the default socket read timeout of the request. {@code null} allows infinite timeout. */
+        RequestBuilder config(RequestConfig config);
+
+        /**
+         * Sets custom retry/failure logic for this.
+         * <p>
+         * Exactly one of the arguments (response, exception) are non-null.
+         * Return a value to have that returned to the caller;
+         * throw a {@link RetryException} to have the request retried; or
+         * throw any other unchecked exception to have this propagate out to the caller.
+         * The caller must close the provided response, if any.
+         */
+        <T> T handle(BiFunction<ClassicHttpResponse, IOException, T> handler) throws UncheckedIOException;
+
+        /** Sets the response body mapper for this, for successful requests. */
+        <T> T read(Function<byte[], T> mapper) throws UncheckedIOException, ConfigServerException;
+
+        /** Discards the response, but throws if the response is unsuccessful. */
+        void discard() throws UncheckedIOException, ConfigServerException;
+
+        /** Returns the raw input stream of the response, if successful. The caller must close the returned stream. */
+        InputStream stream() throws UncheckedIOException, ConfigServerException;
+
+    }
+
+    /** Exception wrapper that signals retries should be attempted. */
+    final class RetryException extends RuntimeException {
+
+        public RetryException(IOException cause) {
+            super(requireNonNull(cause));
+        }
+
+        public RetryException(RuntimeException cause) {
+            super(requireNonNull(cause));
+        }
+
+    }
+
+    /** What host(s) to try for a request, in what order. A host may be specified multiple times, for retries.  */
+    @FunctionalInterface
+    interface HostStrategy extends Iterable<URI> {
+
+        /** Attempts each request once against each listed host. */
+        static HostStrategy ordered(List<URI> hosts) {
+            return List.copyOf(hosts)::iterator;
+        }
+
+        /** Attempts each request once against each listed host, in random order. */
+        static HostStrategy shuffling(List<URI> hosts) {
+            return () -> {
+                List<URI> copy = new ArrayList<>(hosts);
+                Collections.shuffle(copy);
+                return copy.iterator();
+            };
+        }
+
+        /** Attempts each request against the host the specified number of times. */
+        static HostStrategy repeating(URI host, int count) {
+            return ordered(IntStream.range(0, count).mapToObj(__ -> host).collect(toUnmodifiableList()));
+        }
+
+    }
+
+    /** An exception due to server error, a bad request, or similar. */
+    class ConfigServerException extends RuntimeException {
+
+        private final ErrorCode errorId;
+        private final String message;
+
+        public ConfigServerException(ErrorCode errorId, String message, String context) {
+            super(context + ": " + message);
+            this.errorId = errorId;
+            this.message = message;
+        }
+
+        public ErrorCode errorId() { return errorId; }
+
+        public String message() { return message; }
+
+        public enum ErrorCode {
+            APPLICATION_LOCK_FAILURE,
+            BAD_REQUEST,
+            ACTIVATION_CONFLICT,
+            INTERNAL_SERVER_ERROR,
+            INVALID_APPLICATION_PACKAGE,
+            METHOD_NOT_ALLOWED,
+            NOT_FOUND,
+            OUT_OF_CAPACITY,
+            REQUEST_TIMEOUT,
+            UNKNOWN_VESPA_VERSION,
+            PARENT_HOST_NOT_READY,
+            CERTIFICATE_NOT_READY,
+            LOAD_BALANCER_NOT_READY,
+            INCOMPLETE_RESPONSE
+        }
+
+    }
+
+}
+\ No newline at end of file