monitoring-logging

Monitoring and Logging

Set up SAP Cloud Logging for application monitoring in Cloud Foundry.

Purpose

Replace Neo's built-in monitoring and availability checks with SAP Cloud Logging service for centralized logging, custom metrics, and application observability.

Detection

This skill applies if any of these patterns are found:

• Application uses Neo monitoring dashboards
• Availability checks configured in Neo
• Custom JMX metrics exposed
• Performance monitoring requirements

Prerequisites

Working directory: This skill must run inside the -cf-migration copy of your app, created by jakarta-java25-migration or neo-to-cf-migration-orchestrator. If your current directory does not end in -cf-migration, switch to it before proceeding.

Before invoking this skill, ensure you have invoked:

1. sdk-replacement - Use the sdk-replacement skill
   • Sets up SAP Cloud SDK
   • REQUIRED before this skill

Also required:

• Cloud Logging service entitlement

Transformation Steps

Step 1: Update MTA Descriptor

Add Cloud Logging service and OpenTelemetry configuration:

_schema-version: "3.2"
ID: ${app-name}
version: 0.0.1

modules:
  - name: ${app-name}
    type: java.tomcat
    path: target/${app-name}.war
    parameters:
      buildpack: sap_java_buildpack_jakarta
      disk-quota: 512MB
      memory: 512MB
    properties:
      ENABLE_SECURITY_JAVA_API_V2: true
      SET_LOGGING_LEVEL: 'ROOT: INFO, com.example: DEBUG'
      # OpenTelemetry configuration
      OTEL_JAVAAGENT_ENABLED: true
      OTEL_SERVICE_NAME: ${app-name}
      OTEL_TRACES_EXPORTER: otlp
      OTEL_METRICS_EXPORTER: otlp
      OTEL_LOGS_EXPORTER: otlp
    requires:
      - name: ${app-name}-cls

resources:
  - name: ${app-name}-cls
    type: org.cloudfoundry.managed-service
    parameters:
      service: cloud-logging
      service-plan: standard

Step 2: Configure Logging in Application

Create or update src/main/resources/logback.xml:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>

    <!-- Console appender for Cloud Foundry log collection -->
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
        </encoder>
    </appender>

    <!-- JSON format for structured logging (recommended) -->
    <appender name="JSON" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="net.logstash.logback.encoder.LogstashEncoder">
            <includeMdcKeyName>correlationId</includeMdcKeyName>
            <includeMdcKeyName>userId</includeMdcKeyName>
        </encoder>
    </appender>

    <root level="INFO">
        <appender-ref ref="JSON" />
    </root>

    <!-- Application-specific logging -->
    <logger name="com.example" level="DEBUG" />

    <!-- SAP libraries -->
    <logger name="com.sap.cloud.sdk" level="WARN" />

</configuration>

Add logstash encoder dependency to pom.xml:

<dependency>
    <groupId>net.logstash.logback</groupId>
    <artifactId>logstash-logback-encoder</artifactId>
    <version>7.4</version>
</dependency>

Step 3: Implement Structured Logging

Create a logging utility:

package com.example.logging;

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

public class AppLogger {

    private final Logger logger;

    public AppLogger(Class<?> clazz) {
        this.logger = LoggerFactory.getLogger(clazz);
    }

    /**
     * Log with correlation ID for request tracing
     */
    public void logWithCorrelation(String correlationId, String message, Object... args) {
        try {
            MDC.put("correlationId", correlationId);
            logger.info(message, args);
        } finally {
            MDC.remove("correlationId");
        }
    }

    /**
     * Log with user context
     */
    public void logWithUser(String userId, String message, Object... args) {
        try {
            MDC.put("userId", userId);
            logger.info(message, args);
        } finally {
            MDC.remove("userId");
        }
    }

    /**
     * Log business event with structured data
     */
    public void logBusinessEvent(String eventType, String entityId, String action) {
        try {
            MDC.put("eventType", eventType);
            MDC.put("entityId", entityId);
            MDC.put("action", action);
            logger.info("Business event: {} on {} - {}", eventType, entityId, action);
        } finally {
            MDC.clear();
        }
    }

    // Standard logging methods
    public void info(String message, Object... args) {
        logger.info(message, args);
    }

    public void error(String message, Throwable t) {
        logger.error(message, t);
    }

    public void debug(String message, Object... args) {
        logger.debug(message, args);
    }
}

Step 4: Implement Health Check Endpoint

Replace Neo availability checks with a health endpoint:

package com.example.health;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import javax.sql.DataSource;
import java.io.IOException;
import java.sql.Connection;

@WebServlet("/health")
public class HealthCheckServlet extends HttpServlet {

    private static final ObjectMapper objectMapper = new ObjectMapper();

    // Inject or lookup DataSource if database is used
    private DataSource dataSource;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws IOException {

        ObjectNode health = objectMapper.createObjectNode();
        health.put("status", "UP");
        health.put("timestamp", System.currentTimeMillis());

        // Check database connectivity
        ObjectNode database = objectMapper.createObjectNode();
        try {
            if (dataSource != null) {
                try (Connection conn = dataSource.getConnection()) {
                    database.put("status", "UP");
                }
            } else {
                database.put("status", "N/A");
            }
        } catch (Exception e) {
            database.put("status", "DOWN");
            database.put("error", e.getMessage());
            health.put("status", "DOWN");
        }
        health.set("database", database);

        // Check memory
        ObjectNode memory = objectMapper.createObjectNode();
        Runtime runtime = Runtime.getRuntime();
        memory.put("total", runtime.totalMemory());
        memory.put("free", runtime.freeMemory());
        memory.put("used", runtime.totalMemory() - runtime.freeMemory());
        memory.put("max", runtime.maxMemory());
        health.set("memory", memory);

        resp.setContentType("application/json");
        resp.setStatus(health.get("status").asText().equals("UP") ? 200 : 503);
        objectMapper.writeValue(resp.getOutputStream(), health);
    }
}

Step 5: Access Logs in Cloud Logging

View Application Logs

1. Open Cloud Logging dashboard (from BTP Cockpit)
2. Navigate to Discover
3. Use index pattern: logs-cfsyslog-*
4. Filter by cf.app_name: ${app-name}

View Metrics

1. Navigate to Metrics Explorer
2. Use index pattern: metrics-otel-v1-*
3. Query custom metrics: app.requests.total

Create Dashboard

1. Navigate to Dashboards
2. Create visualizations for:
   • Request rate
   • Error rate
   • Response time percentiles
   • JVM memory usage

Cloud Logging Query Examples

Error Logs

cf.app_name: "my-app" AND level: "ERROR"

Slow Requests

cf.app_name: "my-app" AND http.response_time > 1000

User Activities

cf.app_name: "my-app" AND userId: *

Configuration Files

File	Location	Purpose
logback.xml	src/main/resources/	Logging configuration

CF Services

Service	Plan	Purpose
cloud-logging	standard	Centralized logging and monitoring

Verification

1. Check Service Binding

cf services
# Should show cloud-logging service bound

2. Generate Test Logs

curl "https://${app-url}/test"
# Should generate log entries

3. View Logs

cf logs ${app-name} --recent

4. Check Health Endpoint

curl "https://${app-url}/health"
# Should return JSON health status

Common Issues

Issue: Logs not appearing in Cloud Logging

Cause: Service not bound or wrong index pattern. Solution:

1. Verify service binding
2. Wait a few minutes for log ingestion
3. Check index pattern in Cloud Logging

Issue: Metrics not collected

Cause: OTEL agent not enabled. Solution: Set OTEL_JAVAAGENT_ENABLED: true in mtad.yaml.

Issue: High log volume

Solution: Adjust log levels:

properties:
  SET_LOGGING_LEVEL: 'ROOT: WARN, com.example: INFO'

Neo to CF Monitoring Comparison

Neo Feature	CF Equivalent
Application logs	Cloud Logging / cf logs
Availability checks	Health endpoint + external monitoring
JMX metrics	OpenTelemetry + Cloud Logging metrics
Performance tracing	Distributed tracing with OTEL
Alerting	Cloud Logging alerting rules

Next Steps

After completing this skill, your monitoring setup is complete. Consider:

• Setting up alerting rules in Cloud Logging
• Creating custom dashboards
• Implementing distributed tracing for microservices