2021-01-28 16:36:32 +08:00
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# Overview
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This module performs the following tasks:
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- Create VPC, vpcflow log
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- Create subnets in every AZ
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- Create IGW, NGW
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2021-01-28 16:52:18 +08:00
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## Subnet addressing
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This module takes in the VPC cidr. Then add 4 bits to the netmask and divide the cidr into 2 ranges.
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First range will be used for private subnet and second for public subnets.
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Another 4 bits are added to these ranges for each subnet.
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For example, if the VPC cidr is 10.2.0.0/16, the following subnets will be created:
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| Subnet Type | Subnet AZ1 | Subnet AZ2 | Subnet AZ3 |
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|-------------|------------|------------|------------|
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| Private | 10.2.0.0/24 | 10.2.1.0/24 | 10.2.2.0/24 |
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| Public | 10.2.16.0/24 | 10.2.17.0/24 | 10.2.18.0/24 |
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The VPC cidr netmask should be /20 or above, to produce subnets with /28 netmasks or above.
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Subnet smaller than /28 is unlikely useful.
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2021-01-28 16:36:32 +08:00
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## Inputs:
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| Name | Description | Type | Default | Required |
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|------|-------------|------|---------|:-----:|
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| application | name of application | string | none | yes |
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| environment | capacity of environment (prd/dev/lab) | string | none | yes |
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| customer-name | owner of aws resources | string | none | yes |
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| project | name of project | string | none | yes |
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| default-tags | tags to be added to resources | list | none | yes |
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| number-of-private-subnets-per-az | number of private subnets per az | number | 0 | yes |
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| number-of-public-subnets-per-az | number of public subnets per az | number | 0 | yes |
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| create-nat-gateway | whether to deploy NAT gateway for private subnets | bool | true | yes |
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| vpc-cidr | VPC cidr | string | none | yes |
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| enable-flowlog | whether to enable vpc flowlog | bool | true | yes |
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| vpcflowlog-retain-days | number of days to retain vpc cloudwatch log | number | 90 | yes |
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| aws-region-short | short name of aws region (e.g. apne1) | string | none | yes |
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| aws-region | aws region (e.g. ap-northeast-1) | string | none | yes |
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| vpcflowlog-cwl-loggroup-key-arn | kms key alias arn for log group encryption | string | none | yes |
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## Outputs:
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| Name | Description | Type |
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|------|-------------|------|
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| vpc_id | vpc id | string |
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| public_subnets | list of cidr blocks | list |
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| private_subnets | list of cidr blocks | list |
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