44 lines
2.7 KiB
Markdown
44 lines
2.7 KiB
Markdown
# The why and the how of Resource Factories
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Terraform modules can be designed - where it makes sense - to implement a resource factory, which is a configuration-driven approach to resource creation meant to:
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- accelerate and rationalize the repetitive creation of common resources, such as firewall rules and subnets
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- enable teams without Terraform specific knowledge to leverage IaC via human-friendly and machine-parseable YAML files
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- make it simple to implement specific requirements and best practices (e.g. "always enable PGA for GCP subnets", or "only allow using regions `europe-west1` and `europe-west3`")
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- codify and centralise business logics and policies (e.g. labels and naming conventions)
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- allow to easily parse and understand sets of specific resources, for documentation purposes
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Generally speaking, the configurations for a resource factory consists in one or more YaML files, optionally grouped in folders, that describe resources following a well defined, validable schema, such as in the example below for the subnet factory of the [`net-vpc`](../../modules/net-vpc) module, which allows for the massive creation of subnets for a given VPC.
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```yaml
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region: europe-west3
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ip_cidr_range: 10.0.0.0/24
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description: Sample Subnet in project project-prod-a, vpc-alpha
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secondary_ip_ranges:
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secondary-range-a: 192.168.0.0/24
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secondary-range-b: 192.168.1.0/24
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```
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Terraform natively supports YaML, JSON and CSV parsing - however Fabric has decided to embrace YaML for the following reasons:
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- YaML is easier to parse for a human, and allows for comments and nested, complex structures
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- JSON and CSV can't include comments, which can be used to document configurations, but are often useful to bridge from other systems in automated pipelines
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- JSON is more verbose (reads: longer) and harder to parse visually for humans
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- CSV isn't often expressive enough (e.g. dit oesn't allow for nested structures)
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If needed, converting factories to consume JSON is a matter of switching from `yamldecode()` to `jsondecode()` in the right place on each module.
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## Resource factories in Fabric
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### Fabric Modules
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- [folder](../../modules/folder/README.md#firewall-policy-factory) and [organization](../../modules/organization/README.md#firewall-policy-factory) implement factories for [hierarchical firewall policies](https://cloud.google.com/vpc/docs/firewall-policies)
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- [net-vpc](../../modules/net-vpc/README.md#subnet-factory) for subnets creation
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- [net-vpc-firewall](../../modules/net-vpc-firewall/README.md#rules-factory) for massive rules creation
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### Dedicated Factories
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- [net-vpc-firewall-yaml](net-vpc-firewall-yaml/README.md) for VPC firewall rules across different projects/VPCs
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- [project-factory](project-factory/README.md) for projects
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