Exception with Slf4j with log4j2 implementation

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I'm getting the following while setting slf4j on top log4j 2 implementation. Even though I configured log4J2 to be my implementation for slf4j interface..I'm still seeing No SLF4J providers were found. Not sure what I'm missing

Errors in logs

01-10-2022 19:22:46,115 ERROR [stderr] (MSC service thread 1-5) SLF4J: No SLF4J providers were found.
01-10-2022 19:22:46,115 ERROR [stderr] (MSC service thread 1-5) SLF4J: Defaulting to no-operation (NOP) logger implementation
01-10-2022 19:22:46,115 ERROR [stderr] (MSC service thread 1-5) SLF4J: See http://www.slf4j.org/codes.html#noProviders for further details.
01-10-2022 19:22:46,115 ERROR [stderr] (MSC service thread 1-5) SLF4J: Class path contains SLF4J bindings targeting slf4j-api versions prior to 1.8.
01-10-2022 19:22:46,116 ERROR [stderr] (MSC service thread 1-5) SLF4J: Ignoring binding found at [vfs:/content/abc.war/WEB-INF/lib/log4j-slf4j-impl-2.17.0.jar/org/slf4j/impl/StaticLoggerBinder.class]
01-10-2022 19:22:46,116 ERROR [stderr] (MSC service thread 1-5) SLF4J: See http://www.slf4j.org/codes.html#ignoredBindings for an explanation.

Properties file

log4j.appender.file=org.apache.log4j.DailyRollingFileAppender
log4j.appender.file.File=/sasa.log
log4j.appender.file.Append=true
log4j.appender.file.MaxFileSize=100MB
log4j.appender.file.MaxBackupIndex=5
log4j.appender.file.DatePattern='.'yyyy-MM-dd'.log'
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d %-5p [%t] %-17c{2} (%13F:%L) %3x - %m%n

Java file

import org.slf4j.Logger; import org.slf4j.LoggerFactory;

@Component
public class ABC{
    
    private static final Logger log = LoggerFactory.getLogger(abc.class);
    
    public String getCall(String url) throws Exception {
        try {
            log.info("getCall url - " + url );
            response = new String(get.getResponseBody(), UTFSTR);
            log.info(": Response code:"+response);
        } catch (Exception e) {
            log.error(" getCall - EXCEPTION - " + e.getLocalizedMessage());
            throw e;
        } 
        return response;
    } 
}

pom file configured.

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.5.2</version>
    <properties>
        <java.version>1.8</java.version>
        <slf4j.version>2.0.0-alpha5</slf4j.version>
        <log4j2.version>2.17.0</log4j2.version>
    </properties>
    
    <dependencies>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-api</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-slf4j-impl</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-batch</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-logging</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>logback-classic</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-logging</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>logback-classic</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>
log4j2 spring-boot slf4j
1 Answers

Edit: Since there is a non-backward compatible change between SLF4J 1.8 and SLF4J 2.0 (see this question), at this moment there are no bindings between SLF4J 2.0 and Log4j 2.x Core. You need to downgrade SLF4J to 1.8.0-beta4 and use the solution below.

There are two different SLF4J bindings for Log4j 2.x. Since you want to use SLF4J 1.8+, you imported the wrong one. Use:

<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-slf4j18-impl</artifactId>
</dependency>

instead of:

<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-slf4j-impl</artifactId>
</dependency>

Remark: The Log4j configuration in your question is for Log4j 1.2. It will not work with Log4j 2.x and Spring Boot.

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