Using Docker for Development

An intro to using docker for development.

Transcript

1. USING DOCKER FOR DEVELOPMENT @all4miller vulcanlabs.com
2. WHAT IS DOCKER? • "The Docker platform leverages Docker containers to enable IT operations teams and Development teams to build, ship and run any application, anywhere." • Lightweight containers. • Better and faster than all those VM’s!
3. WHAT’S A CONTAINER?
4. TRADITIONAL VM vs. DOCKER
5. TRADITIONAL VM vs. DOCKER Containers are an abstraction at the app layer that packages code and dependencies together. Virtual machines (VMs) are an abstraction of physical hardware turning one server into many servers.
6. IMAGES vs. CONTAINERS
7. WHY SHOULD YOU CARE? • It's suport fast. • Minimal overhead/resource usage. • Easy to run your whole production stack locally. • Ensure your whole team runs the same version of everything.
8. ARCHITECTURE
9. HOW DO I USE IT?
10. WHAT WE’VE LEARNED SO FAR? • Container - Lightweight virtualization. • Image - Immutable snapshot of a container. • Hub/Index - Central hub for sharing images.
11. EXAMPLE: POSTGRESQL SERVER • General purpose PostgreSQL instance • Docker needs to be installed • We’ll use “data containers” for pg data
12. STEP 1: CREATE DATA CONTAINER docker create -v /var/lib/postgresql/data --name postgres-data busybox • Creates a container named postgres-data • Container has a volume /var/lib/postgresql/data • Container is built from busybox image
13. STEP 2: CREATE PG CONTAINER docker run --name local-postgres-latest -p 5432:5432 -e POSTGRES_PASSWORD=vlabs -d --volumes-from postgres-data postgres:latest • Creates a container named local-postgres-latest • Container uses volume from postgres-data • Container specifies env var -e POSTGRES_PASSWORD=vlabs • Container runs in background -d • Container maps port -p 5432:5432
14. STEP 3: CONNECT TO CONTAINER psql -h localhost -p 5432 -U postgres • Launch psql client and connect to container
15. DOCKER COMPOSE • Compose is a tool for defining and running multi-container Docker applications • You use a Compose file to configure your application’s services. • Using a single command, you create and start all the services from your configuration.
16. EXAMPLE: RAILS APP • Let’s create a hello world rails app • Docker and Docker Compose need to be installed
17. STEP 1: CREATE DOCKERFILE • Find a suitable local directory • Create file called Dockerfile as follows: FROM ruby:2.3.3 RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs RUN mkdir /myapp WORKDIR /myapp ADD Gemfile /myapp/Gemfile ADD Gemfile.lock /myapp/Gemfile.lock RUN bundle install ADD . /myapp
18. STEP 2: CREATE RAILS FILES • We need a Gemfile and empty Gemfile.lock • Gemfile must have source 'https://rubygems.org' gem 'rails'
19. STEP 3: CREATE DOCKER-COMPOSE FILE • Create file called docker-compose.yml: version: '2' services: db: image: postgres web: build: . command: bundle exec rails s -p 3000 -b '0.0.0.0' volumes: - .:/myapp ports: - "3000:3000" depends_on: - db
20. STEP 4: BUILD THE PROJECT • Now can provision our image/containers docker-compose run web rails new . --force --database=postgresql
21. STEP 5: UPDATE DB CONFIG • Replace the contents of config/database.yml with: development: &default adapter: postgresql encoding: unicode database: myapp_development pool: 5 username: postgres password: host: db test: <<: *default database: myapp_test
22. STEP 6: BOOT THE APP • Boot the app using: docker-compose build docker-compose up
23. RECAP • Run containers: docker run. • Use Dockerfiles for building images. • Use Docker Compose for app services.
24. BUILD ONCE AND RUN ANYWHERE!
25. THANKS! QUESTIONS?