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Author: DevOpsWithDheeraj

13_Logging_and_Debugging/README.md

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+# 🧩 13_Logging_and_Debugging
+
+In DevOps automation, **logging and debugging** are essential for identifying issues, tracking execution, and ensuring reliability in scripts and systems.
+Python provides a robust **logging module** and built-in debugging tools like **pdb** to help developers monitor and fix issues efficiently.
+
+---
+
+## 🔹 1. Python Logging Module
+
+### 📘 Definition:
+
+The **logging module** in Python is used to record messages that describe the flow of a program, including information, warnings, and errors.
+
+It allows:
+
+* Tracking **events and errors** in automation scripts
+* Writing logs to **console or file**
+* Setting different **log levels** for better filtering
+
+---
+
+### 🧩 Example 1: Basic Logging Example
+
+```python
+import logging
+
+# Configure basic logging
+logging.basicConfig(level=logging.INFO)
+
+logging.debug("This is a debug message")
+logging.info("Script started successfully")
+logging.warning("Low disk space warning")
+logging.error("File not found!")
+logging.critical("Server down! Immediate attention needed!")
+```
+
+🟢 Output:
+
+```
+INFO:root:Script started successfully
+WARNING:root:Low disk space warning
+ERROR:root:File not found!
+CRITICAL:root:Server down! Immediate attention needed!
+```
+
+✅ *Use Case:* Log automation progress (e.g., file backup, deployment steps).
+
+---
+
+## 🔹 2. Logging Levels and Configuration
+
+### 📘 Definition:
+
+Logging levels help define the **severity** of log messages.
+Python provides the following levels (from lowest to highest severity):
+
+| Level    | Description                                           |
+| -------- | ----------------------------------------------------- |
+| DEBUG    | Detailed information, useful for debugging            |
+| INFO     | General information about normal operations           |
+| WARNING  | Something unexpected happened, but program still runs |
+| ERROR    | Serious issue; some function failed                   |
+| CRITICAL | Very serious error; may cause system failure          |
+
+---
+
+### 🧩 Example 2: Custom Logging Configuration
+
+```python
+import logging
+
+logging.basicConfig(
+    level=logging.DEBUG,
+    format='%(asctime)s - %(levelname)s - %(message)s',
+    datefmt='%Y-%m-%d %H:%M:%S'
+)
+
+logging.debug("Debugging the script execution")
+logging.info("Deployment script initiated")
+logging.warning("Memory usage high")
+logging.error("Build failed due to missing dependency")
+logging.critical("Critical failure in pipeline execution")
+```
+
+🟢 Output (formatted):
+
+```
+2025-11-02 22:00:01 - DEBUG - Debugging the script execution
+2025-11-02 22:00:02 - INFO - Deployment script initiated
+2025-11-02 22:00:03 - WARNING - Memory usage high
+2025-11-02 22:00:04 - ERROR - Build failed due to missing dependency
+2025-11-02 22:00:05 - CRITICAL - Critical failure in pipeline execution
+```
+
+✅ *Use Case:* Helps in Jenkins or CI/CD jobs for detailed run logs.
+
+---
+
+## 🔹 3. Writing Logs to Files
+
+### 📘 Definition:
+
+You can store logs in files for **long-term tracking, analysis, or debugging**.
+This is useful for DevOps pipelines, cron jobs, and background services.
+
+---
+
+### 🧩 Example 3: Writing Logs to File
+
+```python
+import logging
+
+logging.basicConfig(
+    filename='automation.log',
+    level=logging.INFO,
+    format='%(asctime)s - %(levelname)s - %(message)s'
+)
+
+logging.info("Script started")
+logging.warning("API response delayed")
+logging.error("Failed to connect to database")
+```
+
+🟢 File: `automation.log`
+
+```
+2025-11-02 22:05:01 - INFO - Script started
+2025-11-02 22:05:02 - WARNING - API response delayed
+2025-11-02 22:05:03 - ERROR - Failed to connect to database
+```
+
+✅ *Use Case:* Maintain automation or monitoring logs in `/var/log/devops_scripts.log`.
+
+---
+
+## 🔹 4. Debugging with **pdb** (Python Debugger)
+
+### 📘 Definition:
+
+`pdb` is the **Python Debugger**, a built-in tool that helps you **pause code execution**, inspect variables, and step through lines interactively.
+
+It is invaluable when troubleshooting complex automation logic.
+
+---
+
+### 🧩 Example 4: Using pdb for Debugging
+
+```python
+import pdb
+
+def divide(a, b):
+    pdb.set_trace()  # Pauses execution here
+    return a / b
+
+result = divide(10, 0)
+print(result)
+```
+
+When you run this, Python enters **debug mode** in the terminal:
+
+```
+(Pdb) p a
+10
+(Pdb) p b
+0
+(Pdb) c
+ZeroDivisionError: division by zero
+```
+
+✅ *Common pdb Commands:*
+
+| Command   | Description          |
+| --------- | -------------------- |
+| `n`       | Next line            |
+| `s`       | Step into function   |
+| `c`       | Continue execution   |
+| `p <var>` | Print variable value |
+| `q`       | Quit debugger        |
+
+✅ *Use Case:* Debug automation errors like failed file transfers or API calls.
+
+---
+
+## 🔹 5. Debugging with IDE Debuggers
+
+### 📘 Definition:
+
+Modern IDEs (like **VS Code**, **PyCharm**, or **IDLE**) come with **graphical debuggers** that allow:
+
+* Setting **breakpoints**
+* Viewing **variable values in real-time**
+* Stepping through code visually
+
+✅ *Use Case:* Debug Jenkins scripts or AWS automation functions before deployment.
+
+---
+
+## 🧾 Summary
+
+| Concept        | Description                         | DevOps Use Case                |
+| -------------- | ----------------------------------- | ------------------------------ |
+| Logging module | Built-in library for event tracking | Monitor automation scripts     |
+| Log levels     | Define severity                     | Filter logs in CI/CD           |
+| File logging   | Write logs to files                 | Persist job logs               |
+| pdb            | Command-line debugger               | Debug runtime errors           |
+| IDE Debugger   | Visual debugging                    | Test Python automation locally |
+
+---
+
+## 💡 DevOps Real-Life Use Cases
+
+* Record execution of **infrastructure provisioning scripts**.
+* Debug failed **AWS automation (boto3)** or **API integrations**.
+* Maintain **deployment logs** for auditing and compliance.
+* Detect and resolve **cron job or CI/CD failures**.
+
+---