Use Terraform Graph in MermaidJS

Posted on 11th May 2022 in cloud | terraform

Terraform has a built-in command to generate a Graphviz digraph representing the output of terraform plan, but this output is pretty messy and can’t render in MermaidJS.

These steps should clean things up so your graphs can be used in Gitlab, your blog, anywhere that supports MermaidJS!

digraph {
	compound = "true"
	newrank = "true"
	subgraph "root" {
		"[root] google_compute_address.nextcloud (expand)" [label = "google_compute_address.nextcloud", shape = "box"]
		"[root] google_compute_firewall.iap-to-nextcloud (expand)" [label = "google_compute_firewall.iap-to-nextcloud", shape = "box"]
		"[root] google_compute_firewall.nextcloud-external (expand)" [label = "google_compute_firewall.nextcloud-external", shape = "box"]
		"[root] google_compute_firewall.nextcloud-internal (expand)" [label = "google_compute_firewall.nextcloud-internal", shape = "box"]
...

Remove all lines with label = " as they aren’t setting any useful aliases and won’t work in MermaidJS.

Remove the strings [root] , " (expand)", " (close)" & \" as they are added to every element and don’t serve a purpose. Presumably Hashicorp imagined this graph being interactive.

Convert -> to --> and remove all " & \", lastly remove the top config lines (that don’t have ->) and the closing } at the end of file.

Example command:

sed -ri '/label =/d; s|\[root\] ||g; s| \(expand\)||g; s| \(close\)||g; s|\\"||g; s|\"||g; s|\s+->\s+|-->|g; /\t+?}/d' graph.dot

MermaidJS supports many graph formats but the one I typically use, and the only one I’ve properly tested these instructions against, is Flow Chart. To use flowchart add a line to the top with either flowchart LR; for left-to-right or flowchart TD; for top-to-bottom.

flowchart TD; google_compute_address.nextcloud-->provider[registry.terraform.io/hashicorp/google] google_compute_firewall.iap-to-nextcloud-->google_compute_network.nextcloud google_compute_firewall.nextcloud-external-->google_compute_network.nextcloud google_compute_firewall.nextcloud-internal-->google_compute_network.nextcloud google_compute_global_address.nextcloud_ip_address-->google_compute_network.nextcloud google_compute_health_check.nextcloud-->provider[registry.terraform.io/hashicorp/google] google_compute_instance_group_manager.nextcloud-->google_compute_health_check.nextcloud google_compute_instance_group_manager.nextcloud-->google_compute_instance_template.nextcloud google_compute_instance_template.nextcloud-->google_compute_address.nextcloud google_compute_instance_template.nextcloud-->google_service_account.nextcloud google_compute_instance_template.nextcloud-->google_sql_database_instance.nextcloud google_compute_instance_template.nextcloud-->var.container_name google_compute_instance_template.nextcloud-->var.container_tag google_compute_instance_template.nextcloud-->var.objectstore google_compute_instance_template.nextcloud-->var.smtp google_compute_network.nextcloud-->provider[registry.terraform.io/hashicorp/google] google_monitoring_dashboard.nextcloud-overview-->provider[registry.terraform.io/hashicorp/google] google_project_service.project-->provider[registry.terraform.io/hashicorp/google] google_service_account.nextcloud-->provider[registry.terraform.io/hashicorp/google] google_service_networking_connection.nextcloud_vpc_connection-->google_compute_global_address.nextcloud_ip_address google_sql_database.nextcloud-->google_sql_database_instance.nextcloud google_sql_database_instance.nextcloud-->google_service_networking_connection.nextcloud_vpc_connection google_sql_database_instance.nextcloud-->var.prefix google_sql_database_instance.nextcloud-->var.sql google_sql_user.nextcloud-->google_sql_database_instance.nextcloud google_storage_bucket.nextcloud-data-->provider[registry.terraform.io/hashicorp/google] google_storage_bucket.nextcloud-data-->var.domain google_storage_bucket.nextcloud-data-->var.objectstore provider[registry.terraform.io/hashicorp/google]-->google_compute_firewall.iap-to-nextcloud provider[registry.terraform.io/hashicorp/google]-->google_compute_firewall.nextcloud-external provider[registry.terraform.io/hashicorp/google]-->google_compute_firewall.nextcloud-internal provider[registry.terraform.io/hashicorp/google]-->google_compute_instance_group_manager.nextcloud provider[registry.terraform.io/hashicorp/google]-->google_monitoring_dashboard.nextcloud-overview provider[registry.terraform.io/hashicorp/google]-->google_project_service.project provider[registry.terraform.io/hashicorp/google]-->google_sql_database.nextcloud provider[registry.terraform.io/hashicorp/google]-->google_sql_user.nextcloud provider[registry.terraform.io/hashicorp/google]-->google_storage_bucket.nextcloud-data provider[registry.terraform.io/hashicorp/google]-->var.gcp_project provider[registry.terraform.io/hashicorp/google]-->var.gcp_region provider[registry.terraform.io/hashicorp/google]-->var.gcp_zone root-->provider[registry.terraform.io/hashicorp/google] root-->var.label root-->var.machine_type root-->var.nextcloud_repo root-->var.redis

This can be further tidied up by getting rid of the root--> & provider[registry.terraform.io/hashicorp/google].

sed -ri '/provider\[registry\.terraform\.io\/hashicorp\/google\]/d; /root-->/d' graph.dot

flowchart TD; google_compute_firewall.iap-to-nextcloud-->google_compute_network.nextcloud google_compute_firewall.nextcloud-external-->google_compute_network.nextcloud google_compute_firewall.nextcloud-internal-->google_compute_network.nextcloud google_compute_global_address.nextcloud_ip_address-->google_compute_network.nextcloud google_compute_instance_group_manager.nextcloud-->google_compute_health_check.nextcloud google_compute_instance_group_manager.nextcloud-->google_compute_instance_template.nextcloud google_compute_instance_template.nextcloud-->google_compute_address.nextcloud google_compute_instance_template.nextcloud-->google_service_account.nextcloud google_compute_instance_template.nextcloud-->google_sql_database_instance.nextcloud google_compute_instance_template.nextcloud-->var.container_name google_compute_instance_template.nextcloud-->var.container_tag google_compute_instance_template.nextcloud-->var.objectstore google_compute_instance_template.nextcloud-->var.smtp google_service_networking_connection.nextcloud_vpc_connection-->google_compute_global_address.nextcloud_ip_address google_sql_database.nextcloud-->google_sql_database_instance.nextcloud google_sql_database_instance.nextcloud-->google_service_networking_connection.nextcloud_vpc_connection google_sql_database_instance.nextcloud-->var.prefix google_sql_database_instance.nextcloud-->var.sql google_sql_user.nextcloud-->google_sql_database_instance.nextcloud google_storage_bucket.nextcloud-data-->var.domain google_storage_bucket.nextcloud-data-->var.objectstore

I hope this can save you time with your next infrastructure diagram!