terraform-generator

terraform-generator

Use Node.js to generate Terraform plan.

You do not need to have Terraform installed to use this module.

The end result of using this module is Terraform plan in plain text, you will need to write the text into a file and execute it yourself.

Currently support generating plan for Terraform version 0.11 and 0.12.

Benefit

Make use of all Javascript programming features (some of which is not available in Terraform), e.g. functions, array, loops, if-else, map, etc. to generate a plain Terraform plan.

You can easily maintain your infra in Javascript/Typescript.

You don't need to use Terraform variables, you can use your own Javascript/JSON variables or use dot env.

You don't need to use Terraform modules for reusable resource creations, you can make use of Javascript functions.

Limitation

The generated text is unformatted, use terraform fmt to format it yourself.

Example

import TerraformGenerator, { Provider, Resource, DataSource, Output, Map } from 'terraform-generator';
import fs from 'fs';
import path from 'path';

const project = 'example';

const configs = {
  env: 'dev',
  tiers: [
    {
      name: 'web',
      cidr: '172.88.100.0/22',
      subnetCidrs: ['172.88.100.0/24', '172.88.101.0/24', '172.88.102.0/24']
    },
    {
      name: 'app',
      cidr: '172.88.104.0/22',
      subnetCidrs: ['172.88.104.0/24', '172.88.105.0/24', '172.88.106.0/24']
    },
    {
      name: 'db',
      cidr: '172.88.108.0/22',
      subnetCidrs: ['172.88.108.0/24', '172.88.109.0/24', '172.88.110.0/24']
    }
  ]
};

const getAvailabilityZone = (i: number): string => {
  if (i === 0) {
    return 'ap-southeast-1a';
  } else if (i === 1) {
    return 'ap-southeast-1b';
  } else {
    return 'ap-southeast-1c';
  }
};

const getTagName = (type: string, name?: string): string =>
  `${type}-${project}-${configs.env}${name ? `-${name}` : ''}`;

const getTags = (type: string, name?: string): Map => new Map({
  Name: getTagName(type, name),
  Project: project,
  Env: configs.env
});

const tfGenerator = new TerraformGenerator({ version: '0.12' });

new Provider(tfGenerator, 'aws', {
  region: 'ap-southeast-1',
  profile: 'example'
});

const vpc = new DataSource(tfGenerator, 'aws_vpc', 'vpc', {
  filter: [{
    name: 'tag:Name',
    values: [getTagName('vpc')]
  }]
});

const webSubnets: Resource[] = [];
const appSubnets: Resource[] = [];
const dbSubnets: Resource[] = [];

configs.tiers.forEach(tier => {
  tier.subnetCidrs.forEach((cidr, i) => {
    const name = `${tier.name}${i}`;
    const subnet = new Resource(tfGenerator, 'aws_subnet', `subnet_${name}`, {
      vpc_id: vpc.getAttribute('id'),
      cidr_block: cidr,
      availability_zone: getAvailabilityZone(i),
      tags: getTags('subnet', name)
    });
    if (tier.name === 'web') {
      webSubnets.push(subnet);
    } else if (tier.name === 'app') {
      appSubnets.push(subnet);
    } else if (tier.name === 'db') {
      dbSubnets.push(subnet);
    }
  })
});

new Output(tfGenerator, 'subnets', {
  value: new Map({
    webSubnets: webSubnets.map(subnet => subnet.getAttribute('id')),
    appSubnets: appSubnets.map(subnet => subnet.getAttribute('id')),
    dbSubnets: dbSubnets.map(subnet => subnet.getAttribute('id'))
  })
});

const outputPath = path.join('output', configs.env, 'subnets', 'terraform.tf');
fs.writeFileSync(outputPath, tfGenerator.generate());