diff --git a/.env.example b/.env.example
new file mode 100644
index 0000000..20dac54
--- /dev/null
+++ b/.env.example
@@ -0,0 +1,7 @@
+DATABASE_URL=jdbc:postgresql://postgres:5432/db
+DATABASE_PASSWORD=password
+DATABASE_USERNAME=user
+
+S3_ENDPOINT=http://s3:9000
+S3_ACCESS_KEY=minioadmin
+S3_SECRET_KEY=minioadmin
diff --git a/.gitignore b/.gitignore
index 667aaef..b9fcd77 100644
--- a/.gitignore
+++ b/.gitignore
@@ -31,3 +31,5 @@ build/
 
 ### VS Code ###
 .vscode/
+
+.env
diff --git a/pom.xml b/pom.xml
index 23ab33b..4655418 100644
--- a/pom.xml
+++ b/pom.xml
@@ -31,6 +31,7 @@
         <java.version>21</java.version>
 
         <modelmapper.version>3.2.4</modelmapper.version>
+        <spring-dotenv.version>4.0.0</spring-dotenv.version>
     </properties>
     <dependencyManagement>
         <dependencies>
@@ -81,6 +82,12 @@
             <artifactId>s3</artifactId>
         </dependency>
 
+        <dependency>
+            <groupId>me.paulschwarz</groupId>
+            <artifactId>spring-dotenv</artifactId>
+            <version>${spring-dotenv.version}</version>
+        </dependency>
+
         <dependency>
             <groupId>org.postgresql</groupId>
             <artifactId>postgresql</artifactId>
diff --git a/src/main/java/com/bivashy/backend/composer/config/StorageS3Config.java b/src/main/java/com/bivashy/backend/composer/config/StorageS3Config.java
new file mode 100644
index 0000000..8307caa
--- /dev/null
+++ b/src/main/java/com/bivashy/backend/composer/config/StorageS3Config.java
@@ -0,0 +1,31 @@
+package com.bivashy.backend.composer.config;
+
+import java.net.URI;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import software.amazon.awssdk.auth.credentials.AwsBasicCredentials;
+import software.amazon.awssdk.regions.Region;
+import software.amazon.awssdk.services.s3.S3Client;
+
+@Configuration
+public class StorageS3Config {
+    @Value("${spring.s3.endpoint}")
+    private String endpoint;
+    @Value("${spring.s3.access-key}")
+    private String accessKey;
+    @Value("${spring.s3.secret-key}")
+    private String secretKey;
+
+    @Bean
+    public S3Client s3Client() {
+        return S3Client.builder()
+                .endpointOverride(URI.create(endpoint))
+                .region(Region.US_WEST_1)
+                .credentialsProvider(() -> AwsBasicCredentials.create(accessKey, secretKey))
+                .build();
+    }
+
+}
diff --git a/src/main/java/com/bivashy/backend/composer/dto/ErrorResponse.java b/src/main/java/com/bivashy/backend/composer/dto/ErrorResponse.java
new file mode 100644
index 0000000..2135efc
--- /dev/null
+++ b/src/main/java/com/bivashy/backend/composer/dto/ErrorResponse.java
@@ -0,0 +1,20 @@
+package com.bivashy.backend.composer.dto;
+
+public class ErrorResponse {
+    private final int status;
+    private final String message;
+
+    public ErrorResponse(int status, String message) {
+        this.status = status;
+        this.message = message;
+    }
+
+    public int getStatus() {
+        return status;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+}
diff --git a/src/main/java/com/bivashy/backend/composer/exception/GlobalExceptionHandler.java b/src/main/java/com/bivashy/backend/composer/exception/GlobalExceptionHandler.java
new file mode 100644
index 0000000..5d6a674
--- /dev/null
+++ b/src/main/java/com/bivashy/backend/composer/exception/GlobalExceptionHandler.java
@@ -0,0 +1,25 @@
+package com.bivashy.backend.composer.exception;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.dao.DataIntegrityViolationException;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+
+import com.bivashy.backend.composer.dto.ErrorResponse;
+
+@ControllerAdvice
+public class GlobalExceptionHandler {
+    private static final Logger logger = LoggerFactory.getLogger(GlobalExceptionHandler.class);
+
+    @ExceptionHandler(DataIntegrityViolationException.class)
+    public ResponseEntity<ErrorResponse> handleDataIntegrityViolation(DataIntegrityViolationException ex) {
+        ErrorResponse error = new ErrorResponse(
+                HttpStatus.CONFLICT.value(),
+                "Conflict: " + ex.getMostSpecificCause().getMessage());
+        logger.error("SQL create conflict", ex);
+        return ResponseEntity.status(HttpStatus.CONFLICT).body(error);
+    }
+}
diff --git a/src/main/resources/application.yaml b/src/main/resources/application.yaml
index 345078e..b4b4fcf 100644
--- a/src/main/resources/application.yaml
+++ b/src/main/resources/application.yaml
@@ -3,9 +3,14 @@ spring:
     name: composer
   datasource:
     driver-class-name: org.postgresql.Driver
-    password: password
-    url: jdbc:postgresql://postgres:5432/db
-    username: user
+    username: ${DATABASE_USERNAME}
+    password: ${DATABASE_PASSWORD}
+    url: ${DATABASE_URL}
+  s3:
+    endpoint: ${S3_ENDPOINT}
+    access-key: ${S3_ACCESS_KEY}
+    secret-key: ${S3_SECRET_KEY}
+    bucket: ${S3_BUCKET}
 
 logging:
   level: