How to fix this FirebaseApp name [DEFAULT] already exists! spring-boot and firebase - spring

Question

I am trying make firebase auth and spring boot work for my app
here is my Application.java
import com.google.auth.oauth2.GoogleCredentials;
import com.google.firebase.FirebaseApp;
import com.google.firebase.FirebaseOptions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.core.io.ClassPathResource;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.web.reactive.function.client.WebClient;
import java.io.IOException;
#SpringBootApplication
#EnableScheduling
public class Application {
public static final Logger logger = LoggerFactory.getLogger("com.qmexpress");
static String FB_BASE_URL="https://qm-tracker-backend.firebaseio.com";
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
try {
FirebaseOptions options = new FirebaseOptions.Builder()
.setCredentials(GoogleCredentials.fromStream(new ClassPathResource("/qm-tracker-backend-firebase-adminsdk-wowh8-d8b0c278a7.json").getInputStream()))
.setDatabaseUrl(FB_BASE_URL)
.build();
FirebaseApp.initializeApp(options);
} catch (IOException e) {
e.printStackTrace();
}
}
#Bean
public WebClient webClient() {
return WebClient.create();
}
}
After I run app I get this message
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.boot.maven.AbstractRunMojo$LaunchRunner.run(AbstractRunMojo.java:496)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.IllegalStateException: FirebaseApp name [DEFAULT] already exists!
at com.google.common.base.Preconditions.checkState(Preconditions.java:444)
at com.google.firebase.FirebaseApp.initializeApp(FirebaseApp.java:227)
at com.google.firebase.FirebaseApp.initializeApp(FirebaseApp.java:218)
at com.google.firebase.FirebaseApp.initializeApp(FirebaseApp.java:205)
at com.qmexpress.Application.main(Application.java:37)
... 6 more

Answer 1

Hope this can help for someone who has the same problem:
import com.google.auth.oauth2.GoogleCredentials;
import com.google.firebase.FirebaseApp;
import com.google.firebase.FirebaseOptions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.core.io.ClassPathResource;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.web.reactive.function.client.WebClient;
import java.io.IOException;
#SpringBootApplication
#EnableScheduling
public class Application {
public static final Logger logger = LoggerFactory.getLogger("com.example");
static String FB_BASE_URL="https://example.firebaseio.com";
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
try {
FirebaseOptions options = new FirebaseOptions.Builder()
.setCredentials(GoogleCredentials.fromStream(new ClassPathResource("/serviceAccountKey.json").getInputStream()))
.setDatabaseUrl(FB_BASE_URL)
.build();
if(FirebaseApp.getApps().isEmpty()) { //<--- check with this line
FirebaseApp.initializeApp(options);
}
} catch (IOException e) {
e.printStackTrace();
}
}
#Bean
public WebClient webClient() {
return WebClient.create();
}
}
pom.xml , if you want to validate.
<?xml version="1.0" encoding="UTF-8"?>
<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">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>logistic</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>Backend-API</name>
<description>example</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.2.RELEASE</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
<groupId>nz.net.ultraq.thymeleaf</groupId>
<artifactId>thymeleaf-layout-dialect</artifactId>
</dependency>
<dependency>
<groupId>joda-time</groupId>
<artifactId>joda-time</artifactId>
<version>2.10</version>
</dependency>
<dependency>
<groupId>org.json</groupId>
<artifactId>json</artifactId>
<version>20160810</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.google.firebase</groupId>
<artifactId>firebase-admin</artifactId>
<version>6.2.0</version>
<exclusions>
<exclusion>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-core-asl</artifactId>
</exclusion>
<exclusion>
<groupId>com.google.http-client</groupId>
<artifactId>google-http-client-jackson</artifactId>
</exclusion>
<exclusion>
<groupId>com.google.http-client</groupId>
<artifactId>google-http-client-gson</artifactId>
</exclusion>
<exclusion>
<groupId>com.google.api-client</groupId>
<artifactId>google-api-client-gson</artifactId>
</exclusion>
<exclusion>
<groupId>joda-time</groupId>
<artifactId>joda-time</artifactId>
</exclusion>
<exclusion>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
</exclusion>
<exclusion>
<groupId>com.google.auto.value</groupId>
<artifactId>auto-value</artifactId>
</exclusion>
<exclusion>
<groupId>org.threeten</groupId>
<artifactId>threetenbp</artifactId>
</exclusion>
<exclusion>
<groupId>org.json</groupId>
<artifactId>json</artifactId>
</exclusion>
<exclusion>
<groupId>com.google.cloud</groupId>
<artifactId>google-cloud-firestore</artifactId>
</exclusion>
<exclusion>
<groupId>com.google.apis</groupId>
<artifactId>google-api-services-storage</artifactId>
</exclusion>
<exclusion>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
</exclusion>
<exclusion>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpcore</artifactId>
</exclusion>
<exclusion>
<groupId>com.google.api</groupId>
<artifactId>gax</artifactId>
</exclusion>
<exclusion>
<groupId>com.google.cloud</groupId>
<artifactId>google-cloud-storage</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>com.google.code.findbugs</groupId>
<artifactId>jsr305</artifactId>
<version>3.0.2</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>com.google.api-client</groupId>
<artifactId>google-api-client-gson</artifactId>
<version>1.23.0</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
</project>

Answer 2

This config work for me
#Bean
FirebaseMessaging firebaseMessaging() throws IOException {
GoogleCredentials googleCredentials = GoogleCredentials
.fromStream(new ClassPathResource("fcm/appName-fa2db-firebase-adminsdk-zn2y1-98b7de2ad9.json").getInputStream());
FirebaseOptions firebaseOptions = FirebaseOptions
.builder()
.setCredentials(googleCredentials)
.build();
FirebaseApp app = null;
if(FirebaseApp.getApps().isEmpty()) {
app = FirebaseApp.initializeApp(firebaseOptions, "appName");
}else {
app = FirebaseApp.initializeApp(firebaseOptions);
}
return FirebaseMessaging.getInstance(app);
}

Answer 3

Yes the solution above is correct, this is due to the static context, for example in a spring project, this bean never throws that exception
#Configuration
public class FirestoreConfiguration {
#Value("${spring.gcp.firestore.projectid}")
private String projectId;
#Bean
public Firestore FirestoreDb() throws IOException {
// Use the application default credentials
GoogleCredentials credentials = GoogleCredentials.getApplicationDefault();
FirebaseOptions options = new FirebaseOptions.Builder()
.setCredentials(credentials)
.setProjectId(projectId)
.build();
FirebaseApp.initializeApp(options); //<-------- Here
return FirestoreClient.getFirestore();
}
}
But in another java project, I use this code and a need to validate if not exists.
public class FirestoreConfiguration {
// static method
public static Firestore FirestoreDb() throws IOException {
// Use the application default credentials
GoogleCredentials credentials = GoogleCredentials.getApplicationDefault();
FirebaseOptions options = new FirebaseOptions.Builder()
.setCredentials(credentials)
.setProjectId(Envars.getEnvar("GOOGLE_CLOUD_PROJECT"))
.build();
if(FirebaseApp.getApps().isEmpty()) { //<------- Here
FirebaseApp.initializeApp(options);
}
return FirestoreClient.getFirestore();
}
}

Answer 4

This exception appear because you are trying to create the [DEFAULT] FirebaseApp again, simply you can add a validation to check if it exist or not before the initialization, like this:
if(FirebaseApp.getInstance(FirebaseApp.DEFAULT_APP_NAME) != null) {
try {.... rest of your code
}
Also, it is better to add a configuration class instead of adding the code at main method.

Answer 5

This worked for me:
FirebaseApp app;
if (FirebaseApp.getApps().isEmpty()) {
app = FirebaseApp.initializeApp(firebaseOptions, "my-app");
} else {
app = FirebaseApp.getApps().get(0);
}