alexander-kastil/azure-appconfiguration-java

Azure App Configuration SDK for Java

Client library for Azure App Configuration, a managed service for centralizing application configurations.

Installation

<dependency>
    <groupId>com.azure</groupId>
    <artifactId>azure-data-appconfiguration</artifactId>
    <version>1.8.0</version>
</dependency>

Or use Azure SDK BOM:

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.azure</groupId>
            <artifactId>azure-sdk-bom</artifactId>
            <version>{bom_version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<dependencies>
    <dependency>
        <groupId>com.azure</groupId>
        <artifactId>azure-data-appconfiguration</artifactId>
    </dependency>
</dependencies>

Prerequisites

• Azure App Configuration store
• Connection string or Entra ID credentials

Environment Variables

AZURE_APPCONFIG_CONNECTION_STRING=Endpoint=https://<store>.azconfig.io;Id=<id>;Secret=<secret>
AZURE_APPCONFIG_ENDPOINT=https://<store>.azconfig.io

Client Creation

With Connection String

import com.azure.data.appconfiguration.ConfigurationClient;
import com.azure.data.appconfiguration.ConfigurationClientBuilder;

ConfigurationClient configClient = new ConfigurationClientBuilder()
    .connectionString(System.getenv("AZURE_APPCONFIG_CONNECTION_STRING"))
    .buildClient();

Async Client

import com.azure.data.appconfiguration.ConfigurationAsyncClient;

ConfigurationAsyncClient asyncClient = new ConfigurationClientBuilder()
    .connectionString(connectionString)
    .buildAsyncClient();

With Entra ID (Recommended)

import com.azure.identity.DefaultAzureCredentialBuilder;

ConfigurationClient configClient = new ConfigurationClientBuilder()
    .credential(new DefaultAzureCredentialBuilder().build())
    .endpoint(System.getenv("AZURE_APPCONFIG_ENDPOINT"))
    .buildClient();

Key Concepts

| Concept | Description | |---------|-------------| | Configuration Setting | Key-value pair with optional label | | Label | Dimension for separating settings (e.g., environments) | | Feature Flag | Special setting for feature management | | Secret Reference | Setting pointing to Key Vault secret | | Snapshot | Point-in-time immutable view of settings |

Configuration Setting Operations

Create Setting (Add)

Creates only if setting doesn't exist:

import com.azure.data.appconfiguration.models.ConfigurationSetting;

ConfigurationSetting setting = configClient.addConfigurationSetting(
    "app/database/connection", 
    "Production", 
    "Server=prod.db.com;Database=myapp"
);

Create or Update Setting (Set)

Creates or overwrites:

ConfigurationSetting setting = configClient.setConfigurationSetting(
    "app/cache/enabled", 
    "Production", 
    "true"
);

Get Setting

ConfigurationSetting setting = configClient.getConfigurationSetting(
    "app/database/connection", 
    "Production"
);
System.out.println("Value: " + setting.getValue());
System.out.println("Content-Type: " + setting.getContentType());
System.out.println("Last Modified: " + setting.getLastModified());

Conditional Get (If Changed)

import com.azure.core.http.rest.Response;
import com.azure.core.util.Context;

Response<ConfigurationSetting> response = configClient.getConfigurationSettingWithResponse(
    setting,      // Setting with ETag
    null,         // Accept datetime
    true,         // ifChanged - only fetch if modified
    Context.NONE
);

if (response.getStatusCode() == 304) {
    System.out.println("Setting not modified");
} else {
    ConfigurationSetting updated = response.getValue();
}

Update Setting

ConfigurationSetting updated = configClient.setConfigurationSetting(
    "app/cache/enabled", 
    "Production", 
    "false"
);

Conditional Update (If Unchanged)

// Only update if ETag matches (no concurrent modifications)
Response<ConfigurationSetting> response = configClient.setConfigurationSettingWithResponse(
    setting,     // Setting with current ETag
    true,        // ifUnchanged
    Context.NONE
);

Delete Setting

ConfigurationSetting deleted = configClient.deleteConfigurationSetting(
    "app/cache/enabled", 
    "Production"
);

Conditional Delete

Response<ConfigurationSetting> response = configClient.deleteConfigurationSettingWithResponse(
    setting,     // Setting with ETag
    true,        // ifUnchanged
    Context.NONE
);

List and Filter Settings

List by Key Pattern

import com.azure.data.appconfiguration.models.SettingSelector;
import com.azure.core.http.rest.PagedIterable;

SettingSelector selector = new SettingSelector()
    .setKeyFilter("app/*");

PagedIterable<ConfigurationSetting> settings = configClient.listConfigurationSettings(selector);
for (ConfigurationSetting s : settings) {
    System.out.println(s.getKey() + " = " + s.getValue());
}

List by Label

SettingSelector selector = new SettingSelector()
    .setKeyFilter("*")
    .setLabelFilter("Production");

PagedIterable<ConfigurationSetting> settings = configClient.listConfigurationSettings(selector);

List by Multiple Keys

SettingSelector selector = new SettingSelector()
    .setKeyFilter("app/database/*,app/cache/*");

PagedIterable<ConfigurationSetting> settings = configClient.listConfigurationSettings(selector);

List Revisions

SettingSelector selector = new SettingSelector()
    .setKeyFilter("app/database/connection");

PagedIterable<ConfigurationSetting> revisions = configClient.listRevisions(selector);
for (ConfigurationSetting revision : revisions) {
    System.out.println("Value: " + revision.getValue() + ", Modified: " + revision.getLastModified());
}

Feature Flags

Create Feature Flag

import com.azure.data.appconfiguration.models.FeatureFlagConfigurationSetting;
import com.azure.data.appconfiguration.models.FeatureFlagFilter;
import java.util.Arrays;

FeatureFlagFilter percentageFilter = new FeatureFlagFilter("Microsoft.Percentage")
    .addParameter("Value", 50);

FeatureFlagConfigurationSetting featureFlag = new FeatureFlagConfigurationSetting("beta-feature", true)
    .setDescription("Beta feature rollout")
    .setClientFilters(Arrays.asList(percentageFilter));

FeatureFlagConfigurationSetting created = (FeatureFlagConfigurationSetting)
    configClient.addConfigurationSetting(featureFlag);

Get Feature Flag

FeatureFlagConfigurationSetting flag = (FeatureFlagConfigurationSetting)
    configClient.getConfigurationSetting(featureFlag);

System.out.println("Feature: " + flag.getFeatureId());
System.out.println("Enabled: " + flag.isEnabled());
System.out.println("Filters: " + flag.getClientFilters());

Update Feature Flag

featureFlag.setEnabled(false);
FeatureFlagConfigurationSetting updated = (FeatureFlagConfigurationSetting)
    configClient.setConfigurationSetting(featureFlag);

Secret References

Create Secret Reference

import com.azure.data.appconfiguration.models.SecretReferenceConfigurationSetting;

SecretReferenceConfigurationSetting secretRef = new SecretReferenceConfigurationSetting(
    "app/secrets/api-key",
    "https://myvault.vault.azure.net/secrets/api-key"
);

SecretReferenceConfigurationSetting created = (SecretReferenceConfigurationSetting)
    configClient.addConfigurationSetting(secretRef);

Get Secret Reference

SecretReferenceConfigurationSetting ref = (SecretReferenceConfigurationSetting)
    configClient.getConfigurationSetting(secretRef);

System.out.println("Secret URI: " + ref.getSecretId());

Read-Only Settings

Set Read-Only

ConfigurationSetting readOnly = configClient.setReadOnly(
    "app/critical/setting", 
    "Production", 
    true
);

Clear Read-Only

ConfigurationSetting writable = configClient.setReadOnly(
    "app/critical/setting", 
    "Production", 
    false
);

Snapshots

Create Snapshot

import com.azure.data.appconfiguration.models.ConfigurationSnapshot;
import com.azure.data.appconfiguration.models.ConfigurationSettingsFilter;
import com.azure.core.util.polling.SyncPoller;
import com.azure.core.util.polling.PollOperationDetails;

List<ConfigurationSettingsFilter> filters = new ArrayList<>();
filters.add(new ConfigurationSettingsFilter("app/*"));

SyncPoller<PollOperationDetails, ConfigurationSnapshot> poller = configClient.beginCreateSnapshot(
    "release-v1.0",
    new ConfigurationSnapshot(filters),
    Context.NONE
);
poller.setPollInterval(Duration.ofSeconds(10));
poller.waitForCompletion();

ConfigurationSnapshot snapshot = poller.getFinalResult();
System.out.println("Snapshot: " + snapshot.getName() + ", Status: " + snapshot.getStatus());

Get Snapshot

ConfigurationSnapshot snapshot = configClient.getSnapshot("release-v1.0");
System.out.println("Created: " + snapshot.getCreatedAt());
System.out.println("Items: " + snapshot.getItemCount());

List Settings in Snapshot

PagedIterable<ConfigurationSetting> settings = 
    configClient.listConfigurationSettingsForSnapshot("release-v1.0");

for (ConfigurationSetting setting : settings) {
    System.out.println(setting.getKey() + " = " + setting.getValue());
}

Archive Snapshot

ConfigurationSnapshot archived = configClient.archiveSnapshot("release-v1.0");
System.out.println("Status: " + archived.getStatus()); // archived

Recover Snapshot

ConfigurationSnapshot recovered = configClient.recoverSnapshot("release-v1.0");
System.out.println("Status: " + recovered.getStatus()); // ready

List All Snapshots

import com.azure.data.appconfiguration.models.SnapshotSelector;

SnapshotSelector selector = new SnapshotSelector().setNameFilter("release-*");
PagedIterable<ConfigurationSnapshot> snapshots = configClient.listSnapshots(selector);

for (ConfigurationSnapshot snap : snapshots) {
    System.out.println(snap.getName() + " - " + snap.getStatus());
}

Labels

List Labels

import com.azure.data.appconfiguration.models.SettingLabelSelector;

configClient.listLabels(new SettingLabelSelector().setNameFilter("*"))
    .forEach(label -> System.out.println("Label: " + label.getName()));

Async Operations

ConfigurationAsyncClient asyncClient = new ConfigurationClientBuilder()
    .connectionString(connectionString)
    .buildAsyncClient();

// Async list with reactive streams
asyncClient.listConfigurationSettings(new SettingSelector().setLabelFilter("Production"))
    .subscribe(
        setting -> System.out.println(setting.getKey() + " = " + setting.getValue()),
        error -> System.err.println("Error: " + error.getMessage()),
        () -> System.out.println("Completed")
    );

Error Handling

import com.azure.core.exception.HttpResponseException;

try {
    configClient.getConfigurationSetting("nonexistent", null);
} catch (HttpResponseException e) {
    if (e.getResponse().getStatusCode() == 404) {
        System.err.println("Setting not found");
    } else {
        System.err.println("Error: " + e.getMessage());
    }
}

Best Practices

1. Use labels — Separate configurations by environment (Dev, Staging, Production)
2. Use snapshots — Create immutable snapshots for releases
3. Feature flags — Use for gradual rollouts and A/B testing
4. Secret references — Store sensitive values in Key Vault
5. Conditional requests — Use ETags for optimistic concurrency
6. Read-only protection — Lock critical production settings
7. Use Entra ID — Preferred over connection strings
8. Async client — Use for high-throughput scenarios

Reference Links

| Resource | URL | |----------|-----| | Maven Package | https://central.sonatype.com/artifact/com.azure/azure-data-appconfiguration | | GitHub | https://github.com/Azure/azure-sdk-for-java/tree/main/sdk/appconfiguration/azure-data-appconfiguration | | API Documentation | https://aka.ms/java-docs | | Product Docs | https://learn.microsoft.com/azure/azure-app-configuration | | Samples | https://github.com/Azure/azure-sdk-for-java/tree/main/sdk/appconfiguration/azure-data-appconfiguration/src/samples | | Troubleshooting | https://github.com/Azure/azure-sdk-for-java/blob/main/sdk/appconfiguration/azure-data-appconfiguration/TROUBLESHOOTING.md |