Building a cloud-friendly application (in Java)

These are separate questions...

The Cloud™: noun

Someone else's hard drive

Cloud computing: noun

Abstracting away physical infrastructure

Disposable application design

What makes an application
cloud-friendly?

They're not rules

They're more like guidelines

Split code from content

Your application is disposable.
Your data is not.

Data flow

You don't get an in-between option

Take-away

Cleanly separate "Dev provided" and "user provided" files

What is configuration?

Does config come from the developer or the user?

Git or Database?

Drupal Config Management

1. Configure in UI / DB
2. Export to YAML
3. Commit to Git
4. Push / Pull
5. Import back to DB

Take-away

Decide

What happens at runtime
stays at runtime

Dependency inject your environment

• DB credentials (Solr, Redis, etc.)
• API keys
• All paths on disk
• Domain names

Environment variables

          // PHP
          getenv('foo');
        

          // Node.js
          process.env["foo"];
        

          // Go
          os.Getenv("foo");
        

          // Java
          System.getEnv("foo");
        

Etc.

Need glue code

Platform.sh / Symfony 3

// platform_parameters.php
if (getenv('PLATFORM_RELATIONSHIPS')) {
    $relationships = json_decode(base64_decode(getenv('PLATFORM_RELATIONSHIPS')), true);

    foreach ($relationships['database'] as $endpoint) {
        if (!empty($endpoint['query']['is_master'])) {
            $container->setParameter('database_driver', 'pdo_'.$endpoint['scheme']);
            $container->setParameter('database_host', $endpoint['host']);
            $container->setParameter('database_port', $endpoint['port']);
            $container->setParameter('database_name', $endpoint['path']);
            $container->setParameter('database_user', $endpoint['username']);
            $container->setParameter('database_password', $endpoint['password']);
            break;
        }
    }
}
$container->setParameter('kernel.secret', getenv('PLATFORM_PROJECT_ENTROPY'));
        

Platform.sh / Go

package conf
import (
  psh "github.com/platformsh/config-reader-go/v2"
)
var PshConfig = createPshConfigObj()

func createPshConfigObj() *psh.RuntimeConfig {
  config, _ := psh.NewRuntimeConfig()
  return config
}
        

package main

func main() {
  engine := gin.Default()
  // ...
  err := ginInstance.Run(":" + conf.PshConfig.Port())
}
        

Platform.sh / Java Spring

package sh.platform.template;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import sh.platform.config.Config;
import sh.platform.config.MySQL;

import javax.sql.DataSource;

@Configuration
public class DataSourceConfig {
    @Bean(name = "dataSource")
    public DataSource getDataSource() {
        Config config = new Config();
        MySQL database = config.getCredential("database", MySQL::new);
        return database.get();
    }
}
        

Platform.sh / Kotlin

package sh.platform.template.spring.kotlin

import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import sh.platform.config.Config
import sh.platform.config.MySQL
import javax.sql.DataSource

@Configuration
class DataSourceConfig {

    @Bean(name = ["dataSource"])
    fun getDataSource(): DataSource {
        val config = Config()
        val database = config.getCredential("database") { MySQL(it) }
        return database.get()
    }
}
        

Use DotEnv (.env files)

(Many to pick from in every language)

Trusted domains

(App-specific configuration)

Constants? Static config files?

Take-away

Dependency inject your environment

User-configured connections

Installers

1. Ask for DB credentials
2. Ask user for basic site info
3. Write credentials to config file
4. Populate DB
5. Write basic site info to config file/DB
6. Profit!!!

Cloud

Better installers

• Pre-include connection glue
• Installer skips pre-populated values
• Do not download from installer

Avoid lock-in

Always be able to
take your business elsewhere.

Google has killed...

• Reader
• iGoogle
• Google Talk
• Google Health
• Knol
• Google Insights
• Picnik
• Buzz
• Aardvark
• Sidewiki
• Notebook
• Dictionary
• Labs
• Wave
• SearchWiki
• Dodgeball
• Jaiku
• Lively
• Page Creator
• Plus
• Zeitgeist
• Answers
• Google X
• Catalog
• Web Accelerator
• Video Player
• Sets
• SearchMash
• Writely
• Plus+

Source: WordStream (2015)

Use Free Software

Use replaceable services

To summarize...

Remember what they say when you assume