diff --git a/microdroid/payload/config/Android.bp b/microdroid/payload/config/Android.bp
new file mode 100644
index 0000000..da58bdf
--- /dev/null
+++ b/microdroid/payload/config/Android.bp
@@ -0,0 +1,16 @@
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+rust_library {
+    name: "libmicrodroid_payload_config",
+    host_supported: true,
+    crate_name: "microdroid_payload_config",
+    srcs: ["src/lib.rs"],
+    prefer_rlib: true,
+    edition: "2018",
+    rustlibs: [
+        "libserde_json",
+        "libserde",
+    ],
+}
diff --git a/microdroid/payload/config/config.proto b/microdroid/payload/config/config.proto
new file mode 100644
index 0000000..b3d8d3a
--- /dev/null
+++ b/microdroid/payload/config/config.proto
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * 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.
+ */
+
+syntax = "proto3";
+
+package android.microdroid;
+
+// This .proto is for the schema of a VM payload config (JSON)
+
+message PayloadConfig {
+  uint32 version = 1;
+
+  OsConfig os = 2;
+
+  Task task = 3;
+
+  repeated ApexConfig apexes = 4;
+}
+
+message OsConfig {
+  // for now "microdroid" is the only type we support
+  string name = 1;
+}
+
+message Task {
+  enum TaskType {
+    EXECUTABLE = 0,          // "executable" in JSON
+    MICRODROID_LAUNCHER = 1, // "microdroid_launcher" in JSON
+  }
+  // when the type is "microdroid_launcher", command is searched in /mnt/apk/lib/{arch}"
+  TaskType type = 1;
+
+  string command = 2;
+  repeated string args = 3;
+}
+
+message ApexConfig {
+  string name = 1;
+
+  // TODO(b/186396080) An APEX can be identified either by
+  // (1) its name
+  // (2) name and public key (or cert)
+  // or (3) name and exact hash.
+  // Rollback index should be supported for the case (2).
+}
diff --git a/microdroid/payload/config/src/lib.rs b/microdroid/payload/config/src/lib.rs
new file mode 100644
index 0000000..6dc127b
--- /dev/null
+++ b/microdroid/payload/config/src/lib.rs
@@ -0,0 +1,89 @@
+// Copyright 2021, The Android Open Source Project
+//
+// 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.
+
+//! VM Payload Config
+
+use serde::{Deserialize, Serialize};
+
+/// VM payload config
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub struct VmPayloadConfig {
+    /// OS config. Default: "microdroid"
+    #[serde(default)]
+    pub os: OsConfig,
+
+    /// Task to run in a VM
+    #[serde(default)]
+    pub task: Option<Task>,
+
+    /// APEXes to activate in a VM
+    #[serde(default)]
+    pub apexes: Vec<ApexConfig>,
+}
+
+/// OS config
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub struct OsConfig {
+    /// The name of OS to use
+    pub name: String,
+}
+
+impl Default for OsConfig {
+    fn default() -> Self {
+        Self { name: "microdroid".to_owned() }
+    }
+}
+
+/// Payload's task can be one of plain executable
+/// or an .so library which can be started via /system/bin/microdroid_launcher
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub enum TaskType {
+    /// Task's command indicates the path to the executable binary.
+    #[serde(rename = "executable")]
+    Executable,
+    /// Task's command indicates the .so library in /mnt/apk/lib/{arch}
+    #[serde(rename = "microdroid_launcher")]
+    MicrodroidLauncher,
+}
+
+/// Task to run in a VM
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub struct Task {
+    /// Decides how to execute the command: executable(default) | microdroid_launcher
+    #[serde(default, rename = "type")]
+    pub type_: TaskType,
+
+    /// Command to run
+    /// - For executable task, this is the path to the executable.
+    /// - For microdroid_launcher task, this is the name of .so
+    pub command: String,
+
+    /// Args to the command
+    #[serde(default)]
+    pub args: Vec<String>,
+}
+
+impl Default for TaskType {
+    fn default() -> TaskType {
+        TaskType::Executable
+    }
+}
+
+/// APEX config
+/// For now, we only pass the name of APEX.
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub struct ApexConfig {
+    /// The name of APEX
+    pub name: String,
+}