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feat: Add standalone env-utils module (#345)
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Lines changed: 403 additions & 175 deletions

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‎env-utils/pom.xml‎

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<?xml version="1.0" encoding="UTF-8"?>
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<!--
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Copyright © 2026 DataSQRL (contact@datasqrl.com)
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<parent>
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<groupId>com.datasqrl.flinkrunner</groupId>
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<artifactId>flink-sql-runner-parent</artifactId>
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<version>1.0-SNAPSHOT</version>
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</parent>
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<artifactId>env-utils</artifactId>
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<name>Environment Utilities</name>
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<dependencies>
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<!-- Add logging framework, to produce console output when running in the IDE. -->
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<!-- These dependencies are excluded from the application JAR by default. -->
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<dependency>
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<groupId>org.slf4j</groupId>
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<artifactId>slf4j-api</artifactId>
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<scope>provided</scope>
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</dependency>
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<dependency>
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<groupId>com.fasterxml.jackson.core</groupId>
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<artifactId>jackson-databind</artifactId>
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</dependency>
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</dependencies>
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</project>

flink-sql-runner/src/main/java/com/datasqrl/flinkrunner/EnvUtils.java renamed to env-utils/src/main/java/com/datasqrl/flinkrunner/utils/EnvUtils.java

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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.datasqrl.flinkrunner;
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package com.datasqrl.flinkrunner.utils;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.UUID;
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import lombok.AccessLevel;
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import lombok.NoArgsConstructor;
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/** Utility class for environment variable operations. */
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final class EnvUtils {
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@NoArgsConstructor(access = AccessLevel.PRIVATE)
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public final class EnvUtils {
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/**
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* Returns a map of environment variables with deployment-specific defaults.
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*
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*
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* @return an immutable map containing all environment variables with defaults applied
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*/
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static Map<String, String> getEnvWithDefaults() {
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public static Map<String, String> getEnvWithDeploymentDefaults() {
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var env = new HashMap<>(System.getenv());
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env.putIfAbsent("DEPLOYMENT_ID", UUID.randomUUID().toString());
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env.putIfAbsent("DEPLOYMENT_TIMESTAMP", String.valueOf(System.currentTimeMillis()));
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getDeploymentDefaults().forEach(env::putIfAbsent);
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return Map.copyOf(env);
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}
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private EnvUtils() {
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throw new UnsupportedOperationException();
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public static Map<String, String> getDeploymentDefaults() {
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return Map.of(
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"DEPLOYMENT_ID",
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UUID.randomUUID().toString(),
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"DEPLOYMENT_TIMESTAMP",
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String.valueOf(System.currentTimeMillis()));
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}
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}

‎env-utils/src/main/java/com/datasqrl/flinkrunner/utils/EnvVarResolver.java‎

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/*
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* Copyright © 2026 DataSQRL (contact@datasqrl.com)
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.datasqrl.flinkrunner.utils;
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import com.fasterxml.jackson.core.JsonParser;
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import com.fasterxml.jackson.databind.DeserializationContext;
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import com.fasterxml.jackson.databind.JsonDeserializer;
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import com.fasterxml.jackson.databind.ObjectMapper;
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import com.fasterxml.jackson.databind.module.SimpleModule;
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import java.io.IOException;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.Map;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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import lombok.extern.slf4j.Slf4j;
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/**
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* Environment variable resolving functionality.
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*
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* <p>Resolver instances replace {@code ${VAR}} placeholders with values from a configured
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* environment map. Missing variables either fail resolution in strict mode or remain unresolved in
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* non-strict mode.
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*/
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@Slf4j
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public class EnvVarResolver {
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private static final Pattern ENVIRONMENT_VARIABLE_PATTERN = Pattern.compile("\\$\\{(.*?)\\}");
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private final Map<String, String> envVars;
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private final ObjectMapper objectMapper;
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private final boolean strict;
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private EnvVarResolver(Map<String, String> envVars, boolean strict) {
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this.envVars = envVars;
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this.strict = strict;
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objectMapper = initObjectMapper();
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}
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/**
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* Creates a strict resolver backed by the current process environment.
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*
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* @return a resolver backed by {@link System#getenv()}
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*/
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public static EnvVarResolver of() {
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return of(true);
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}
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/**
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* Creates a resolver backed by the current process environment.
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*
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* @param strict whether missing variables should fail resolution
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* @return a resolver backed by {@link System#getenv()}
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*/
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public static EnvVarResolver of(boolean strict) {
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return of(System.getenv(), strict);
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}
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/**
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* Creates a strict resolver backed by the supplied environment variables.
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*
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* @param envVars environment variables used for placeholder resolution
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* @return a resolver backed by the supplied environment variables
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*/
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public static EnvVarResolver of(Map<String, String> envVars) {
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return of(envVars, true);
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}
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/**
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* Creates a resolver backed by the supplied environment variables.
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*
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* @param envVars environment variables used for placeholder resolution
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* @param strict whether missing variables should fail resolution
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* @return a resolver backed by the supplied environment variables
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*/
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public static EnvVarResolver of(Map<String, String> envVars, boolean strict) {
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return new EnvVarResolver(envVars, strict);
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}
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/**
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* Creates a strict resolver backed by the current process environment plus deployment defaults.
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*
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* @return a resolver with deployment defaults applied
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*/
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public static EnvVarResolver withDeploymentDefaults() {
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return withDeploymentDefaults(true);
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}
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/**
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* Creates a resolver backed by the current process environment plus deployment defaults.
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*
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* @param strict whether missing variables should fail resolution
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* @return a resolver with deployment defaults applied
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*/
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public static EnvVarResolver withDeploymentDefaults(boolean strict) {
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return new EnvVarResolver(EnvUtils.getEnvWithDeploymentDefaults(), strict);
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}
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/**
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* Creates a strict resolver backed by the supplied environment variables plus deployment
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* defaults.
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*
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* @param envVars environment variables used for placeholder resolution
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* @return a resolver with deployment defaults applied
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*/
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public static EnvVarResolver withDeploymentDefaults(Map<String, String> envVars) {
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return withDeploymentDefaults(envVars, true);
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}
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/**
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* Creates a resolver backed by the supplied environment variables plus deployment defaults.
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*
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* <p>Deployment defaults are only added when the supplied map does not already contain those
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* keys.
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*
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* @param envVars environment variables used for placeholder resolution
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* @param strict whether missing variables should fail resolution
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* @return a resolver with deployment defaults applied
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*/
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public static EnvVarResolver withDeploymentDefaults(Map<String, String> envVars, boolean strict) {
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var modifiedEnvVars = new HashMap<>(envVars);
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EnvUtils.getDeploymentDefaults().forEach(modifiedEnvVars::putIfAbsent);
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return new EnvVarResolver(Map.copyOf(modifiedEnvVars), strict);
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}
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/**
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* Resolves environment variables referenced in a given source string. Searches for environment
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* variable references based on {@link EnvVarResolver#ENVIRONMENT_VARIABLE_PATTERN}. If a blank
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* source string is passed, it will be returned as is.
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*
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* @param src given source string that may contain environment variable references
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* @return a new string with the resolved environment variables
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* @throws IllegalStateException if strict mode is enabled and any referenced environment variable
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* is not available
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*/
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public String resolve(String src) {
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if (src == null || src.isBlank()) {
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return src;
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}
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var res = new StringBuilder();
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// First pass to replace environment variables
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var matcher = ENVIRONMENT_VARIABLE_PATTERN.matcher(src);
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var missingEnvVars = new HashSet<String>();
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while (matcher.find()) {
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var rawKey = matcher.group(1);
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String key;
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String defaultValue = null;
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// Support bash-style default values: ${VAR:-default} or ${VAR:=default}
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int splitIdx = rawKey.indexOf(":-");
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if (splitIdx == -1) {
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splitIdx = rawKey.indexOf(":=");
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}
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if (splitIdx >= 0) {
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key = rawKey.substring(0, splitIdx);
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defaultValue = rawKey.substring(splitIdx + 2);
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} else {
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key = rawKey;
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}
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if (envVars.containsKey(key)) {
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var envValue = envVars.get(key);
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matcher.appendReplacement(res, Matcher.quoteReplacement(envValue));
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} else if (defaultValue != null) {
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matcher.appendReplacement(res, Matcher.quoteReplacement(defaultValue));
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} else {
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missingEnvVars.add(key);
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}
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}
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matcher.appendTail(res);
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if (strict && !missingEnvVars.isEmpty()) {
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throw new IllegalStateException(
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String.format(
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"The following environment variables were referenced, but not found: %s",
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missingEnvVars));
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}
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return res.toString();
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}
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/**
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* Resolves environment variables referenced in a given JSON source string. Searches for
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* environment variable references in any string leaf nodes based on {@link
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* EnvVarResolver#ENVIRONMENT_VARIABLE_PATTERN}.
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*
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* @param jsonSrc given JSON source string that may contain environment variable references
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* @return JSON string with the resolved environment variables
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* @throws IOException if the JSON processing fails in any way
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*/
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public String resolveInJson(String jsonSrc) throws IOException {
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var res = objectMapper.readValue(jsonSrc, Map.class);
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return objectMapper.writeValueAsString(res);
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}
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/**
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* Creates an {@link ObjectMapper} configured to resolve environment variables in string values.
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*
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* @return an object mapper with environment-variable resolution enabled for string
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* deserialization
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*/
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public ObjectMapper initObjectMapper() {
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return initObjectMapper(new ObjectMapper());
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}
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/**
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* Configures an {@link ObjectMapper} to resolve environment variables in string values.
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*
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* @param mapper mapper to configure
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* @return the supplied mapper with environment-variable resolution enabled for string
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* deserialization
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*/
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public ObjectMapper initObjectMapper(ObjectMapper mapper) {
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var module = new SimpleModule();
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module.addDeserializer(String.class, new JsonEnvVarDeserializer());
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mapper.registerModule(module);
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return mapper;
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}
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private class JsonEnvVarDeserializer extends JsonDeserializer<String> {
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@Override
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public String deserialize(JsonParser parser, DeserializationContext ctx) throws IOException {
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var value = parser.getText();
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return resolve(value);
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}
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}
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}

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