Day 08

Topics to cover

01 Gitalab Installation

02 Curl

03 Openssl

🚀 Introduction to GitLab

GitLab is a web-based DevOps lifecycle tool that provides a Git repository manager with built-in features like:

  • Issue tracking
  • Continuous Integration/Continuous Deployment (CI/CD)
  • Code review
  • Project management
  • Wiki and more

It enables teams to collaborate on code, automate testing, and deploy software efficiently.

🔧 What Is Git?

Before diving into GitLab, it’s important to understand Git:

  • Git is a version control system that lets you track code changes.
  • It allows multiple developers to work on the same project simultaneously.

GitLab builds on Git by providing a collaborative platform for managing and deploying code.

🌐 GitLab vs GitHub vs Bitbucket

FeatureGitLabGitHubBitbucket
CI/CD Built-in✅ Yes⚠️ Needs Actions✅ Yes
Self-hosted✅ Available✅ Enterprise✅ Available
Open Source✅ Core version❌❌

🔑 Key Features of GitLab

  • Repositories: Git-based version control for code.
  • CI/CD Pipelines: Automate building, testing, and deploying your code.
  • Merge Requests: Review and approve code changes.
  • Issue Tracking: Built-in project management tools.
  • Security & Compliance: SAST, DAST, container scanning, etc.
  • Wiki & Docs: Project documentation support.

🛠️ GitLab Editions

  • GitLab SaaS: Hosted on GitLab.com
  • GitLab Self-Managed: You install and run GitLab on your own server

Versions:

  • Free – Core features
  • Premium – Enhanced CI/CD and support
  • Ultimate – Security, compliance, and performance features

📦 Basic GitLab Workflow

  1. Clone the Repository

    git clone https://gitlab.com/username/project.git

  2. Create a Branch

    git checkout -b feature-branch

  3. Make Changes and Commit

    git add .
git commit -m "Added new feature"

  4. Push to GitLab

    git push origin feature-branch

  5. Create a Merge Request (MR) via the GitLab UI

  6. Code Review and Merge into the main branch

📈 CI/CD Pipeline Example

.gitlab-ci.yml file defines your pipeline:

stages:
  - build
  - test
  - deploy

build-job:
  stage: build
  script:
    - echo "Building the app..."

test-job:
  stage: test
  script:
    - echo "Running tests..."

deploy-job:
  stage: deploy
  script:
    - echo "Deploying the app..."

✅ Why Use GitLab?

  • All-in-one DevOps platform
  • Improves collaboration and code quality
  • Automates the software delivery lifecycle
  • Scalable for both small teams and large enterprises

📚 Learn More

GitLab helps you code, collaborate, and deploy — all in one place. 💻🚀

Gitlab Installation

🚀 Most Common curl Commands

curl is a command-line tool used for transferring data to or from a server using various protocols such as HTTP, HTTPS, FTP, and more.

🌐 1. Test Connectivity (Like telnet for HTTP)

To check if a service is reachable and responding on a specific port:

curl -v telnet://hostname:port

Example:

curl -v telnet://example.com:80

Works similar to telnet, but only for protocols curl supports.

📥 2. Download a File (Like wget)

curl -O https://example.com/file.tar.gz
  • -O: Saves the file with its original name.

Download and rename:

curl -o newname.tar.gz https://example.com/file.tar.gz

📤 3. Upload a File (Using POST)

curl -F "file=@/path/to/file.txt" https://example.com/upload

Used for uploading files via web forms.

🔄 4. Make a POST Request

curl -X POST -d "username=user&password=pass" https://example.com/login

Or with JSON:

curl -X POST -H "Content-Type: application/json" \
-d '{"username":"user", "password":"pass"}' \
https://example.com/api/login

🔍 5. View HTTP Headers Only

curl -I https://example.com

Shows only the response headers (HEAD request).

🧪 6. Check HTTP Status Code

curl -o /dev/null -s -w "%{http_code}\n" https://example.com

Only prints the HTTP response code like 200, 404, etc.

🪪 7. Send Custom Headers (e.g. API Tokens)

curl -H "Authorization: Bearer <token>" https://api.example.com/data

🧰 8. Debug Full Request/Response

curl -v https://example.com

Use -v (verbose) or --trace for full request/response logs.

🔁 9. Follow Redirects

curl -L https://short.url/link

Follows HTTP 3xx redirects (like a shortened URL).

📡 10. Download from FTP Server

curl -u username:password ftp://ftp.example.com/file.zip -O

💡 Tips

  • Add -k to ignore SSL certificate validation (not recommended for production):
    curl -k https://example.com
  • Add -s for silent mode (no progress bar or errors).
  • Use -u user:pass for basic auth.

📚 Learn More

curl is like a Swiss Army knife for HTTP and beyond — learn it once, use it everywhere. 🔧🌍

Openssl Commands

  • 1️⃣ Generate a Self-Signed Certificate: Create a self-signed SSL certificate with a private key
openssl req -new -newkey rsa:2048 -days 365 -nodes -x509 -keyout server.key -out server.crt
  • 2️⃣ Generate a Private Key: Generate a private RSA key
openssl genpkey -algorithm RSA -out private.key
  • 3️⃣ Generate a Public Key: Generate a public key from a private key
openssl rsa -in private.key -pubout -out public.key
  • 4️⃣ Convert PEM to DER: Convert a PEM-encoded certificate to DER format
openssl x509 -in certificate.pem -outform DER -out certificate.der
  • 5️⃣ Convert DER to PEM: Convert a DER-encoded certificate to PEM format
openssl x509 -in certificate.der -inform DER -out certificate.pem -outform PEM
  • 6️⃣ View Certificate Information: View details about an SSL certificate
openssl x509 -in certificate.crt -text -noout
  • 7️⃣ Verify Certificate: Verify if a certificate is valid for a specific domain
openssl s_client -connect example.com:443 -showcerts
  • 8️⃣ Create a CSR (Certificate Signing Request): Generate a CSR using a private key
openssl req -new -key private.key -out request.csr
  • 9️⃣ Sign a CSR with a CA (Certificate Authority): Sign a CSR with a CA certificate
openssl x509 -req -in request.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out signed.crt -days 365
  • 🔟 Check SSL Certificate Expiry: Check the expiration date of an SSL certificate
openssl x509 -in certificate.crt -noout -enddate
  • 1️⃣1️⃣ Create a PKCS12 File: Convert a private key and certificate to a PKCS12 file
openssl pkcs12 -export -in certificate.crt -inkey private.key -out certificate.p12
  • 1️⃣2️⃣ Extract Certificate from PKCS12 File: Extract a certificate from a PKCS12 file
openssl pkcs12 -in certificate.p12 -clcerts -nokeys -out certificate.crt
  • 1️⃣3️⃣ Extract Private Key from PKCS12 File: Extract the private key from a PKCS12 file
openssl pkcs12 -in certificate.p12 -nocerts -out private.key
  • 1️⃣4️⃣ Encrypt a File with AES: Encrypt a file using AES encryption
openssl enc -aes-256-cbc -salt -in plaintext.txt -out encrypted.txt
  • 1️⃣5️⃣ Decrypt a File with AES: Decrypt a file that was encrypted with AES
openssl enc -d -aes-256-cbc -in encrypted.txt -out decrypted.txt
  • 1️⃣6️⃣ Generate a Diffie-Hellman Parameters File: Generate a DH parameters file
openssl dhparam -out dhparams.pem 2048
  • 1️⃣7️⃣ Create an SSL/TLS Server Certificate: Generate a server certificate from a CSR
openssl req -new -newkey rsa:2048 -nodes -keyout server.key -out server.csr
openssl x509 -req -in server.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out server.crt -days 365
  • 1️⃣8️⃣ Test SSL Connection: Test an SSL connection to a server
openssl s_client -connect example.com:443
  • 1️⃣9️⃣ Generate an MD5 Hash of a File: Generate an MD5 hash of a file
openssl dgst -md5 file.txt
  • 2️⃣0️⃣ Generate a SHA256 Hash of a File: Generate a SHA256 hash of a file
openssl dgst -sha256 file.txt
  • 1️⃣ Generate a Self-Signed Certificate: Create a self-signed SSL certificate with a private key
openssl req -new -newkey rsa:2048 -days 365 -nodes -x509 -keyout server.key -out server.crt
  • 2️⃣ Generate a Private Key: Generate a private RSA key
openssl genpkey -algorithm RSA -out private.key
  • 3️⃣ Generate a Public Key: Generate a public key from a private key
openssl rsa -in private.key -pubout -out public.key
  • 4️⃣ Convert PEM to DER: Convert a PEM-encoded certificate to DER format
openssl x509 -in certificate.pem -outform DER -out certificate.der
  • 5️⃣ Convert DER to PEM: Convert a DER-encoded certificate to PEM format
openssl x509 -in certificate.der -inform DER -out certificate.pem -outform PEM
  • 6️⃣ View Certificate Information: View details about an SSL certificate
openssl x509 -in certificate.crt -text -noout
  • 7️⃣ Verify Certificate: Verify if a certificate is valid for a specific domain
openssl s_client -connect example.com:443 -showcerts
  • 8️⃣ Create a CSR (Certificate Signing Request): Generate a CSR using a private key
openssl req -new -key private.key -out request.csr
  • 9️⃣ Sign a CSR with a CA (Certificate Authority): Sign a CSR with a CA certificate
openssl x509 -req -in request.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out signed.crt -days 365
  • 🔟 Check SSL Certificate Expiry: Check the expiration date of an SSL certificate
openssl x509 -in certificate.crt -noout -enddate
  • 1️⃣1️⃣ Create a PKCS12 File: Convert a private key and certificate to a PKCS12 file
openssl pkcs12 -export -in certificate.crt -inkey private.key -out certificate.p12
  • 1️⃣2️⃣ Extract Certificate from PKCS12 File: Extract a certificate from a PKCS12 file
openssl pkcs12 -in certificate.p12 -clcerts -nokeys -out certificate.crt
  • 1️⃣3️⃣ Extract Private Key from PKCS12 File: Extract the private key from a PKCS12 file
openssl pkcs12 -in certificate.p12 -nocerts -out private.key
  • 1️⃣4️⃣ Encrypt a File with AES: Encrypt a file using AES encryption
openssl enc -aes-256-cbc -salt -in plaintext.txt -out encrypted.txt
  • 1️⃣5️⃣ Decrypt a File with AES: Decrypt a file that was encrypted with AES
openssl enc -d -aes-256-cbc -in encrypted.txt -out decrypted.txt
  • 1️⃣6️⃣ Generate a Diffie-Hellman Parameters File: Generate a DH parameters file
openssl dhparam -out dhparams.pem 2048
  • 1️⃣7️⃣ Create an SSL/TLS Server Certificate: Generate a server certificate from a CSR
openssl req -new -newkey rsa:2048 -nodes -keyout server.key -out server.csr
openssl x509 -req -in server.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out server.crt -days 365
  • 1️⃣8️⃣ Test SSL Connection: Test an SSL connection to a server
openssl s_client -connect example.com:443
  • 1️⃣9️⃣ Generate an MD5 Hash of a File: Generate an MD5 hash of a file
openssl dgst -md5 file.txt
  • 2️⃣0️⃣ Generate a SHA256 Hash of a File: Generate a SHA256 hash of a file
openssl dgst -sha256 file.txt