Deploying Python Projects with CelerBuild Using the FastAPI Framework Example

This guide demonstrates how to deploy a Python FastAPI application using CelerBuild Standard Edition, including branch deployment, tag deployment, and tag version rollback operations.

Prerequisites

Important Note:

  • This project requires Python 3.8+
  • Local Python installation is recommended depending on your build strategy:
    • If building locally and uploading to remote server: both local and remote installation needed
    • If building only on remote server: only remote installation needed
  • The System Service Setup must be configured on the target deployment server

1. System Prerequisites

Complete all Prerequisites setup steps.

2. Python Environment Setup

Installing Python and pip

macOS
# Using Homebrew
brew install [email protected]  # or any version 3.8+
 
# Add to ~/.zshrc
echo 'export PATH="/usr/local/opt/python/bin:$PATH"' >> ~/.zshrc
 
# Verify installation
python3 --version  # Should show 3.8 or higher
pip3 --version
Ubuntu/Debian
# Update package list
sudo apt update
 
# Install Python and pip (3.8 or higher)
sudo apt install python3 python3-pip python3-venv
 
# Verify installation
python3 --version  # Should show 3.8 or higher
pip3 --version
CentOS/RHEL
# Enable EPEL repository (required for Python 3.8+)
sudo yum install epel-release
 
# Install Python and pip
sudo yum install python3 python3-pip python3-devel
 
# If you need a specific version, you can use:
# sudo yum install python38 python38-pip python38-devel
 
# Verify installation
python3 --version  # Should show 3.8 or higher
pip3 --version

3. System Service Setup

On the target deployment server, create a systemd service file for managing the FastAPI application. This step is required for proper application management and auto-restart capabilities.

Important: This setup must be performed on each target deployment server.

sudo vim /etc/systemd/system/celerbuild-example-python.service

Add the following content:

[Unit]
Description=CelerBuild Example Python Application
After=network.target
 
[Service]
User=ubuntu
WorkingDirectory=/home/ubuntu/celerbuild-example-python
# Set environment: use 'dev' for development, 'prod' for production
Environment=APP_ENV=dev
# Use the full path to gunicorn executable
# Find path using: which gunicorn (after adding ~/.local/bin to PATH)
ExecStart=/home/ubuntu/.local/bin/gunicorn app.main:app -c gunicorn/gunicorn.${APP_ENV}.py
# Exit code 143 indicates graceful termination
SuccessExitStatus=143
# Maximum time to wait for the service to stop
TimeoutStopSec=10
# Restart policy
Restart=on-failure
# Time to wait before restart attempts
RestartSec=5
 
[Install]
WantedBy=multi-user.target

Configuration Notes:

  • User: Change ubuntu to your actual service user
  • WorkingDirectory: Adjust /home/ubuntu/... to match your user's home directory
  • ExecStart: The path to gunicorn may vary based on your installation method
    • Find the correct path using: export PATH=$PATH:/home/ubuntu/.local/bin && which gunicorn
    • Common paths: /home/ubuntu/.local/bin/gunicorn or /usr/local/bin/gunicorn
  • Environment: Set APP_ENV=dev for development environment or APP_ENV=prod for production environment
    • Development: Environment=APP_ENV=dev
    • Production: Environment=APP_ENV=prod

Branch Deployment (Development Environment)

1. Create Server Infrastructure

Create Server Cluster

  • Navigate to Global/Server Clusters
  • Create a cluster named "example-python-server-cluster(dev)"

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Add Server

  • Navigate to the Global/Servers section
  • Select cluster "example-python-server-cluster(dev)"
  • Fill in:
    • Server Name
    • Server IP
    • SSH Port (default: 22)

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2. Import Project Template

Download Template

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Import Template

  • Navigate to Projects/Projects
  • Click "Import YAML"
  • Upload the downloaded template

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Create Project

  • Review and confirm project settings
  • Click "Create Project" to finish

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Note: This example uses Ubuntu system with ubuntu user. Please adjust the Deployment Configuration (Target Deployment Path, Target Repository Path, Deployment User, etc.) according to your actual environment.

3. Initiating Deployment

  1. Go to Operations/Applications
  2. Select project "celerbuild-example-python-dev"
  3. Fill in Title and Description
  4. Click sync icon next to "Branch" and select latest dev branch
  5. Click "Submit Application"

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4. Executing Deployment

  1. In Operations/Tasks, find your project task
  2. Click "Deploy" button
  3. On the task page, click "Start Deploy"
  4. Monitor Server Status and Operation Logs
  5. If issues occur, check error messages and retry deployment after fixing

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5. Verification

Access http://server:8084/version (replace "server" with your server address)

# Example command
➜  ~ curl http://server:8084/version
 
# Expected response
{"version":"1.0.0"}

Tag Deployment (Production Environment)

1. Create Server Infrastructure

Create Server Cluster

  • Navigate to Global/Server Clusters
  • Create a cluster named "example-python-server-cluster(prod)"

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Add Server

  • Navigate to the Global/Servers section
  • Select cluster "example-python-server-cluster(prod)"
  • Fill in:
    • Server Name
    • Server IP
    • SSH Port (default: 22)

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2. Import Project Template

Download Template

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Import Template

  • Navigate to Projects/Projects
  • Click "Import YAML"
  • Upload the downloaded template

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Create Project

  • Review and confirm project settings
  • Click "Create Project" to finish

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Note: This example uses Ubuntu system with ubuntu user. Please adjust the Deployment Configuration (Target Deployment Path, Target Repository Path, Deployment User, etc.) according to your actual environment.

3. Initiating Deployment

  1. Go to Operations/Applications
  2. Select project "celerbuild-example-python-prod"
  3. Fill in deployment information:
    • Title: "Deploy v1.0.0"
    • Description: "Initial deployment of v1.0.0"
  4. Click sync icon next to "Tag" and select "v1.0.0"
  5. Click "Submit Application"

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4. Executing Deployment

Follow the same steps as branch deployment execution.

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5. Verification

curl http://server:8084/version
{"version":"1.0.0"}

Rollback Operations

Note: Branch deployment rollback is not demonstrated here because the system only maintains the latest committed version. We'll demonstrate rollback using tag deployments instead.

Tag Deployment Rollback Example

1. Initial Deployment (v1.0.0)

For detailed deployment steps, refer to:

Verify deployment:

curl http://server:8084/version
{"version":"1.0.0"}

2. Upgrade to v1.0.1

  1. Go to Operations/Applications
  2. Create new deployment
  3. Fill in deployment information:
    • Title: "Upgrade to v1.0.1"
    • Description: "Upgrading from v1.0.0 to v1.0.1"
  4. Select tag "v1.0.1"
  5. Submit and execute deployment
  6. Verify upgrade:
curl http://server:8084/version
{"version":"1.0.1"}

3. Rollback to v1.0.0

  1. In Operations/Applications, find your project
  2. Click Actions (three dots) and select "Apply Rollback"
  3. Fill in rollback information:
    • Title: "Rollback to v1.0.0"
    • Description: "Rolling back from v1.0.1 to v1.0.0"
  4. Click sync icon next to "Select Rollback Tag"
  5. Select "v1.0.0" from the available tags
  6. Click "Submit Rollback"

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4. Execute Rollback

  1. Go to Operations/Tasks
  2. Find your rollback task
  3. Click "Rollback" in Actions
  4. Click "Start Rollback" on the task page
  5. Monitor Server Status and Operation Logs
  6. Verify rollback success:

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curl http://server:8084/version
{"version":"1.0.0"}

For detailed rollback instructions, see:

Additional Notes

Application Logs

View application logs using systemd:

# View all logs
sudo journalctl -u celerbuild-example-python
 
# View recent logs
sudo journalctl -u celerbuild-example-python -n 100
 
# Follow logs in real-time
sudo journalctl -u celerbuild-example-python -f

Service Management

Common systemd commands for managing the application:

# Check service status
sudo systemctl status celerbuild-example-python
 
# Start service
sudo systemctl start celerbuild-example-python
 
# Stop service
sudo systemctl stop celerbuild-example-python
 
# Restart service
sudo systemctl restart celerbuild-example-python

Congratulations! You have successfully learned how to deploy FastAPI Framework using CelerBuild Standard Edition, including branch deployment, tag deployment, and tag version rollback operations! 🎉

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