Dockerfile & Portainer: Build ARGs & ENV Guide

Overview

This document provides step-by-step instructions for creating a Docker environment using a Dockerfile, managing environment variables, and installing Portainer for Docker container management.

Dockerfile for Terraform & Packer Setup

Purpose

This Dockerfile sets up an Ubuntu-based environment with:

Terraform & Packer installation
Required tools: jq, net-tools, curl, wget, unzip, nginx, iputils-ping
Nginx running in the foreground

Dockerfile Contents

FROM ubuntu:latest

LABEL name="kiran"

ENV AWS_ACCESS_KEY_ID=SDFSDFSDFSDFSDFSDFSDFSDF \
    AWS_SECRET_KEY_ID=SDSDSDSDSDSDSDSDSDSDSDSD \
    AWS_DEFAULT_REGION=AP-SOUTH-1A

ARG TERRAFORM_VERSION='1.6.6' \
    PACKER_VERSION='1.8.0'

RUN apt update && apt install -y jq net-tools curl wget unzip \
    && apt install -y nginx iputils-ping

RUN wget https://releases.hashicorp.com/terraform/${TERRAFORM_VERSION}/terraform_${TERRAFORM_VERSION}_linux_amd64.zip \
    && wget https://releases.hashicorp.com/packer/${PACKER_VERSION}/packer_${PACKER_VERSION}_linux_amd64.zip \
    && unzip terraform_${TERRAFORM_VERSION}_linux_amd64.zip  && unzip packer_${PACKER_VERSION}_linux_amd64.zip \
    && chmod 777 terraform && chmod 777 packer \
    && ./terraform version && ./packer version

CMD ["nginx", "-g", "daemon off;"]

Building and Running the Docker Image

Building the Docker Image

Build a Docker image with a specific tag:

docker build -f dockerfile.dev .
docker build -t imkiran13/custom:v1 -f dockerfile.dev .

Build the image without using cache:

docker build -t imkiran13/custom:v1 -f dockerfile.dev . --no-cache

verify terraform and packer version

Passing build arguments:

docker build -t imkiran13/custom:v1 --build-arg TERRAFORM_VERSION=1.4.0 --build-arg PACKER_VERSION=1.5.0 --no-cache -f dockerfile.dev .

Running the Container

Run the container go inside and check Terraform & Packer versions:

docker run --rm -d --name app1 -p 8000:80 imkiran13/custom:v1
docker exec -it app1 bash 
./terraform version
./packer version

Building with plain progress output:

docker build --progress=plain -t imkiran13/custom:v1 -f dockerfile.dev .

Setting Environment Variables

Pass environment variables when running the container:

docker run --rm -d --name app2 -p 8001:80 -e AWS_ACCESS_KEY_ID=hidden \
    -e AWS_SECRET_KEY_ID=hidden \
    -e AWS_DEFAULT_REGION=hidden \
    imkiran13/custom:v1

Useful Docker Commands

Adding a Tag

Tag an existing image:

 docker tag imkiran13/custom:v1 imkiran13/custom:latest

Check Docker Image History

docker history imkiran13/custom:v1

Cleanup Unused Docker Objects

Remove unused containers, networks, images, and optionally volumes:

docker system prune

Understanding Dockerfile Instructions

ADD: Adds files from the host to the container. Useful for archives that need extraction.
COPY: Copies files from the host system without extraction.
ENTRYPOINT: Configures a container to run as an executable.
WORKDIR: Sets the working directory for subsequent commands.

Conclusion

By following this guide, you can:

Build a Docker image for Terraform & Packer
Manage environment variables and build arguments in a Dockerfile

Day 04:Docker Guide: Dockerfile, Build ARGs, ENV Variables & Portainer Installation

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