diff --git a/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/AWSLambda.java b/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/AWSLambda.java
index cc8abe28..45301c5d 100644
--- a/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/AWSLambda.java
+++ b/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/AWSLambda.java
@@ -203,7 +203,7 @@ private static void startRuntime(String handler, LambdaLogger lambdaLogger) thro
         System.setErr(new PrintStream(new LambdaOutputStream(System.err), false, "UTF-8"));
         setupRuntimeLogger(lambdaLogger);
 
-        String runtimeApi = getEnvOrExit("AWS_LAMBDA_RUNTIME_API");
+        String runtimeApi = getEnvOrExit(ReservedRuntimeEnvironmentVariables.AWS_LAMBDA_RUNTIME_API);
         LambdaRuntimeClient runtimeClient = new LambdaRuntimeClient(runtimeApi);
 
         EnvReader envReader = new EnvReader();
diff --git a/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/LambdaEnvironment.java b/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/LambdaEnvironment.java
index 8821a113..b2d55204 100644
--- a/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/LambdaEnvironment.java
+++ b/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/LambdaEnvironment.java
@@ -8,9 +8,9 @@
 
 public class LambdaEnvironment {
     public static final EnvReader ENV_READER = new EnvReader();
-    public static final int MEMORY_LIMIT = parseInt(ENV_READER.getEnvOrDefault("AWS_LAMBDA_FUNCTION_MEMORY_SIZE", "128"));
-    public static final String LOG_GROUP_NAME = ENV_READER.getEnv("AWS_LAMBDA_LOG_GROUP_NAME");
-    public static final String LOG_STREAM_NAME = ENV_READER.getEnv("AWS_LAMBDA_LOG_STREAM_NAME");
-    public static final String FUNCTION_NAME = ENV_READER.getEnv("AWS_LAMBDA_FUNCTION_NAME");
-    public static final String FUNCTION_VERSION = ENV_READER.getEnv("AWS_LAMBDA_FUNCTION_VERSION");
+    public static final int MEMORY_LIMIT = parseInt(ENV_READER.getEnvOrDefault(ReservedRuntimeEnvironmentVariables.AWS_LAMBDA_FUNCTION_MEMORY_SIZE, "128"));
+    public static final String LOG_GROUP_NAME = ENV_READER.getEnv(ReservedRuntimeEnvironmentVariables.AWS_LAMBDA_LOG_GROUP_NAME);
+    public static final String LOG_STREAM_NAME = ENV_READER.getEnv(ReservedRuntimeEnvironmentVariables.AWS_LAMBDA_LOG_STREAM_NAME);
+    public static final String FUNCTION_NAME = ENV_READER.getEnv(ReservedRuntimeEnvironmentVariables.AWS_LAMBDA_FUNCTION_NAME);
+    public static final String FUNCTION_VERSION = ENV_READER.getEnv(ReservedRuntimeEnvironmentVariables.AWS_LAMBDA_FUNCTION_VERSION);
 }
diff --git a/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/ReservedRuntimeEnvironmentVariables.java b/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/ReservedRuntimeEnvironmentVariables.java
new file mode 100644
index 00000000..fc5006c5
--- /dev/null
+++ b/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/ReservedRuntimeEnvironmentVariables.java
@@ -0,0 +1,104 @@
+/*
+ * Copyright 2017-2020 original 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
+ *
+ * https://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.
+ */
+package com.amazonaws.services.lambda.runtime.api.client;
+
+/**
+ * Lambda runtimes set several environment variables during initialization.
+ * Most of the environment variables provide information about the function or runtime.
+ * The keys for these environment variables are reserved and cannot be set in your function configuration.
+ * @see <a href="https://docs.aws.amazon.com/lambda/latest/dg/configuration-envvars.html#configuration-envvars-runtime">Using AWS Lambda Environment Variables</a>
+ *
+ * NOTICE: This class is forked from io.micronaut.function.aws.runtime.ReservedRuntimeEnvironments found at https://github.com/micronaut-projects/micronaut-aws
+ *
+ */
+public interface ReservedRuntimeEnvironmentVariables {
+
+    /**
+     * The handler location configured on the function.
+     */
+    String HANDLER = "_HANDLER";
+
+    /**
+     * The AWS Region where the Lambda function is executed.
+     */
+    String AWS_REGION = "AWS_REGION";
+
+    /**
+     * The runtime identifier, prefixed by AWS_Lambda_—for example, AWS_Lambda_java8.
+     */
+    String AWS_EXECUTION_ENV = "AWS_EXECUTION_ENV";
+
+    /**
+     * The name of the function.
+     */
+    String AWS_LAMBDA_FUNCTION_NAME = "AWS_LAMBDA_FUNCTION_NAME";
+
+    /**
+     * The amount of memory available to the function in MB.
+     */
+    String AWS_LAMBDA_FUNCTION_MEMORY_SIZE = "AWS_LAMBDA_FUNCTION_MEMORY_SIZE";
+
+    /**
+     * The version of the function being executed.
+     */
+    String AWS_LAMBDA_FUNCTION_VERSION = "AWS_LAMBDA_FUNCTION_VERSION";
+
+    /**
+     * The name of the Amazon CloudWatch Logs group for the function.
+     */
+    String AWS_LAMBDA_LOG_GROUP_NAME = "AWS_LAMBDA_LOG_GROUP_NAME";
+
+    /**
+     * The name of the Amazon CloudWatch stream for the function.
+     */
+    String AWS_LAMBDA_LOG_STREAM_NAME = "AWS_LAMBDA_LOG_STREAM_NAME";
+
+    /**
+     * Access key id obtained from the function's execution role.
+     */
+    String AWS_ACCESS_KEY_ID = "AWS_ACCESS_KEY_ID";
+
+    /**
+     * secret access key obtained from the function's execution role.
+     */
+    String AWS_SECRET_ACCESS_KEY = "AWS_SECRET_ACCESS_KEY";
+
+    /**
+     *
+     * The access keys obtained from the function's execution role.
+     */
+    String AWS_SESSION_TOKEN = "AWS_SESSION_TOKEN";
+
+    /**
+     * (Custom runtime) The host and port of the runtime API.
+     */
+    String AWS_LAMBDA_RUNTIME_API = "AWS_LAMBDA_RUNTIME_API";
+
+    /**
+     * The path to your Lambda function code.
+     */
+    String LAMBDA_TASK_ROOT = "LAMBDA_TASK_ROOT";
+
+    /**
+     * The path to runtime libraries.
+     */
+    String LAMBDA_RUNTIME_DIR = "LAMBDA_RUNTIME_DIR";
+
+    /**
+     * The environment's time zone (UTC). The execution environment uses NTP to synchronize the system clock.
+     */
+    String TZ = "TZ";
+}
diff --git a/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/util/EnvWriter.java b/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/util/EnvWriter.java
index 839dddc9..ba090078 100644
--- a/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/util/EnvWriter.java
+++ b/aws-lambda-java-runtime-interface-client/src/main/java/com/amazonaws/services/lambda/runtime/api/client/util/EnvWriter.java
@@ -2,8 +2,11 @@
 
 package com.amazonaws.services.lambda.runtime.api.client.util;
 
+import com.amazonaws.services.lambda.runtime.api.client.ReservedRuntimeEnvironmentVariables;
+
 import java.lang.reflect.Field;
 import java.util.Map;
+import java.util.Optional;
 import java.util.function.Consumer;
 
 public class EnvWriter implements AutoCloseable {
@@ -43,24 +46,30 @@ public void setupEnvironmentCredentials() {
         modifyEnv((env) -> {
             // AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_SESSION_TOKEN are set by the runtime API daemon when
             // executing the runtime's bootstrap. Ensure these are not empty values.
-            removeIfEmpty(env, "AWS_ACCESS_KEY_ID");
-            removeIfEmpty(env, "AWS_SECRET_ACCESS_KEY");
-            removeIfEmpty(env, "AWS_SESSION_TOKEN");
+            removeIfEmpty(env, ReservedRuntimeEnvironmentVariables.AWS_ACCESS_KEY_ID);
+            removeIfEmpty(env, ReservedRuntimeEnvironmentVariables.AWS_SECRET_ACCESS_KEY);
+            removeIfEmpty(env, ReservedRuntimeEnvironmentVariables.AWS_SESSION_TOKEN);
 
             // The AWS Java SDK supports two alternate keys for the aws access and secret keys for compatibility.
             // These are not set by the runtime API daemon when executing a runtime's bootstrap so set them here.
-            addIfNotNull(env, "AWS_ACCESS_KEY", env.get("AWS_ACCESS_KEY_ID"));
-            addIfNotNull(env, "AWS_SECRET_KEY", env.get("AWS_SECRET_ACCESS_KEY"));
+            addIfNotNull(env, "AWS_ACCESS_KEY", env.get(ReservedRuntimeEnvironmentVariables.AWS_ACCESS_KEY_ID));
+            addIfNotNull(env, "AWS_SECRET_KEY", env.get(ReservedRuntimeEnvironmentVariables.AWS_SECRET_ACCESS_KEY));
         });
     }
 
     public void setupAwsExecutionEnv() {
+        executionEnvironmentForJavaVersion()
+                .ifPresent(val -> modifyEnv(env -> env.put(ReservedRuntimeEnvironmentVariables.AWS_EXECUTION_ENV, val)));
+    }
+
+    private Optional<String> executionEnvironmentForJavaVersion() {
         String version = System.getProperty("java.version");
         if (version.startsWith("1.8")) {
-            modifyEnv(env -> env.put("AWS_EXECUTION_ENV", "AWS_Lambda_java8"));
+            return Optional.of("AWS_Lambda_java8");
         } else if (version.startsWith("11")) {
-            modifyEnv(env -> env.put("AWS_EXECUTION_ENV", "AWS_Lambda_java11"));
+            return Optional.of("AWS_Lambda_java11");
         }
+        return Optional.empty();
     }
 
     private void addIfNotNull(Map<String, String> env, String key, String value) {