ZSI / Automatizácia

We are programmers

Our job is to automate

Don't Use Manual Procedures

A computer will execute the same instructions, in the same order, time after time.

— The Pragmatic Programmer

Shell scripts

Shebang

#!/bin/sh
echo "Hello!"

Different languages

#!/bin/bash

#!/usr/bin/env python

#!/usr/bin/env python3

Shell programming

• sequence of commands
• variables
• conditions
• loops

Use the Power of Command Shells

Use the shell when graphical user interfaces don’t cut it.

— The Pragmatic Programmer

Just make it!

make

• classical automation tool
• files based

Makefile

targets: prerequisites
	recipe
	recipe…

Running

make target

• builds dependencies
• compares timestamps
  • rebuilds if prerequisites are newer

Phony targets – not files

.PHONY: clean
clean:
        rm *.o temp

Automatic variables

• $@ - target file name
• #< - first prerequisite name
• Automatic Variables (GNU make)

Dependencies

Package management

• JavaScript:
  • npm
• Python
  • pip, virtualenv, pipenv, etc.
• Ruby
  • gem, bundler
• Java
  • maven, gradle

Dependencies

• reproducible builds
  • fixed version numbers
  • “lock” file
    • package-lock.json
    • Pipfile.lock
    • requirements.txt
    • etc.

Getting started

• git clone ...
• cd project
• some setup command
• start coding
• run the app

Dependencies

• not only libraries
• tools
• operating system

Virtualization

• virtual machine for each application
  • own OS, disk, network settings
• overhead
  • performance
  • management

Containers

Containers — standardized units for development, shipment and deployment

• isolate from the environment

Docker

• de-facto standard for containerization
• kernel-level virtualization
  • isolation and limiting of processes
  • separate environment and filesystem
  • share only Linux kernel

Concepts

• Container — virtual environment for running application
• Image — template for creating containers
• Registry — storage for images
  • https://hub.docker.com/
  • GitHub, GitLab, etc.

Example — src/index.php

<?php
echo("Hello world!");

Dependencies:

• PHP
• Apache

Dockerfile — instructions for building image

FROM php:7.2-apache-stretch
COPY src /var/www/html

• Official Images: https://hub.docker.com/search?image_filter=official

Build image and start container

$ docker build  -t hello-php  .
$ docker run  -p 8000:80  --name running-hello  hello-php

Other commands

• docker container ls
• docker container stop / start
• docker container rm
• docker image ls
• docker image rm
• docker system prune
• Documentation: https://docs.docker.com/reference/cli/docker/

Layers

• a layer for each command in Dockerfile
  • read-only
• container — temporary read-write layer
• copy-on-write
• identical layers are shared

Persistent data storage — volumes

• anonymous volumes
• named volumes -v <volume-name>:<container-path>
• bind mounts -v <host-path>:<container-path>
• https://docs.docker.com/storage/

Dockerfile

FROM php:7.2-apache-stretch
COPY src /var/www/html
VOLUME /var/www/html/uploads

In development

Bind mount

• Unix:

docker run -p 8000:80 -v "$(pwd)"/src:/var/www/html hello-php

• Windows:

docker run -p 8000:80 -v d:/hello/src:/var/www/html hello-php

Let’s connect to database

<?php
$conn = new mysqli(
    "db-server", "user", "my-password", "hello");
if ($conn->connect_error)
    die("Oh, no! Connection failed!");
echo "Hello MariaDB!";

Dockerfile

FROM php:7.2-apache-stretch
RUN docker-php-ext-install mysqli
COPY src /var/www/html

We need to run a database server

Docker Compose

• Definition of multiple containers
• Manipulation with the group of containers
• Documentation: https://docs.docker.com/compose/

compose.yaml

services:
    web:
        build: .
        image: hello-php
        ports:
            - "8000:80"
        volumes:
            - ./src:/var/www/html

    db-server:
        image: mariadb:10.3
        environment:
            MYSQL_ROOT_PASSWORD: my-root-pwd
            MYSQL_DATABASE: hello
            MYSQL_USER: user
            MYSQL_PASSWORD: my-password

Up!

$ docker-compose build web
$ docker-compose up
$ docker-compose down

Examples

Continuous integration

• practice of merging to mainline often
  • more than once per day
• no long-lasting branches
• automatic testing

Continuous Delivery

CI/CD server

CI/CD server

• servis for running checks and other actions on repository
• build, test, deploy
• pipeline
• examples:
  • Jenkins, JetBrains TeamCity, GitLab CI, GitHub Actions

Use Version Control to Drive Builds, Tests, and Releases

Use commits or pushes to trigger builds, tests, releases. Use a version control tag to deploy to production.

— The Pragmatic Programmer

Examples