Core Dockerfile Instructions

Base Image Specification

Purpose

Defines the foundation image for the container.

Syntax

FROM <image-name>
FROM <image-name>:<tag>
FROM <image-name>@<digest>

Example using a Python environment with ODBC support:

FROM tadeorubio/pyodbc-msodbcsql17:latest

Key Points

• Must be the first non-comment instruction
• Omittting tag/digest defaults to 'latest' version

Maintainer Information

Purpose

Identifies the image creator

Syntax

LABEL maintainer="Your Name"

Execution Commands

Purpose

Runs commands during image build process

Working Directory

Purpose

Sets the container's default directory

Syntax

WORKDIR /app/project

Port Exposure

Purpose

Declares container network ports

Syntax

EXPOSE 8080

Container Startup Command

Purpose

Defines default execution when container starts

Complete Implementatoin Example

# Base image with Python and SQL connectivity
FROM tadeorubio/pyodbc-msodbcsql17:latest

# Metadata
LABEL maintainer="developer@example.com"

# Environment configuration
ENV PYTHONUNBUFFERED=1 \
    LANG=C.UTF-8 \
    DEBIAN_FRONTEND=noninteractive \
    APP_PORT=8080

# Project setup
RUN mkdir -p /app/project
COPY . /app/project
WORKDIR /app/project

# Dependency installation
RUN pip install --upgrade pip \
    && pip install uwsgi \
    && pip install -r requirements.txt

# Service port declaration
EXPOSE 8080