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Blaxel allows you to customize your deployments (agents, MCP servers, and batch jobs) using a Dockerfile at the root level of your project.

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Overview

By default, Blaxel builds and deploys your application using predefined container images optimized for agent workloads. However, you may need to:
  • Install additional system dependencies
  • Configure custom environment settings
  • Use specific versions of runtime environments
  • Include proprietary libraries or tools
A Dockerfile at the root of your project gives you full control over the container image that will run your workload on Blaxel’s infrastructure.
  1. Navigate to the root directory of your Blaxel project (agent, MCP server, or batch job)
  2. Create a file named Dockerfile (case-sensitive)

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Dockerfile Structure

Your Dockerfile should follow these guidelines for compatibility with Blaxel’s infrastructure:
Python

# Start from a base Python image
FROM python:3.12-slim

# Set working directory
WORKDIR /blaxel

# Install system dependencies (if needed)
RUN apt-get update && apt-get install -y \\
    build-essential \\
    # Add any other system dependencies here \\
    && rm -rf /var/lib/apt/lists/*

# Copy requirements first for better caching
COPY pyproject.toml uv.lock /blaxel/

RUN pip install uv && uv sync --refresh

# Copy application code
COPY . .

# Set env variable to use the virtual environment
ENV PATH="/blaxel/python/.venv/bin:$PATH"

# Command to run when container starts, it need to provide a server running on port 80 for agent and MCP server
ENTRYPOINT [".venv/bin/python3", "-m", "src"]
TypeScript/JavaScript

# Start from a Node.js base image
FROM node:22-alpine

# Set working directory
WORKDIR /blaxel

# Copy package files for better caching
COPY package.json pnpm-lock.yaml /blaxel/
RUN npx pnpm install

# Copy application code
COPY . .

# Command to run when container starts, it need to provide a server running on port 80 for agent and MCP server
ENTRYPOINT ["npx", "pnpm", "start"]

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Entrypoint

For Agents Hosting and MCP Servers Hosting:
  • The only requirement to deploy an app on Agents Hosting is that it exposes an HTTP API server which is bound on BL_SERVER_HOST (for the host) and BL_SERVER_PORT (for the port).
For Batch Jobs:
  • The entrypoint must run a function that terminates—if it runs infinitely, your job will continue until it hits the execution timeout.

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Environment variables

Environment variables configured in the Blaxel platform will be automatically injected into your container at runtime. You do not need to specify them in your Dockerfile.

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Test locally

Before deploying to Blaxel, you can test your Dockerfile locally. 
# Build the Docker image
docker build -t my-blaxel-app .

# Run the container locally
docker run -p 1338:1338 my-blaxel-app

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Deploy

When a Dockerfile is present at the root of your project, Blaxel will use it to build a custom container image for your deployment. Deploy your application with the Blaxel CLI as usual. 
bl deploy

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Deploy multiple resources with shared files

Using a custom Dockerfile allows for deploying multiple jobs from the same repository with shared dependencies.

Deploy multiple resources with shared files

Deploy multiple jobs with shared context from a single repository.