Terraform-nomad-postgres

This module is IaC - infrastructure as code which contains a nomad job of postgres.

Content

Requirements
1. Required modules
2. Required software
Usage
Example usage
Inputs
Outputs
Secrets & credentials
1. Set credentials manually
2. Set credentials using Vault secrets
Volumes
Contributors
License

Requirements

Required modules

No required modules.

Required software

Usage

The following command will run a standalone instance of postgres found in the example folder.

make test

Verifying setup

You can verify that Postgres is running by checking the connection. The following command uses Consul (required software) to set up a proxy.

make proxy

Further, you can verify the connection by connecting with the psql CLI (required software) using the command bellow. You can find the username and password in the Vault UI (localhost:8200).

psql "dbname=metastore host=127.0.0.1 user=<username> password=<password> port=5432 sslmode=disable"

Intentions

The intentions in the table below will need to be put in place if you are going to use this module in a hashistack ecosystem, we have done so in our vagrantbox example (00_create_intetion.yml).

Intention between	type
postgres-local => postgres	allow

:warning: Note that these intentions needs to be created if you are using the module in another module.

Providers

Nomad

Example usage

The example-code shows some of the variables you need to provide to use this module. See the postgres_standalone example for more details.

module "postgres" {
  source = "github.com/fredrikhgrelland/terraform-nomad-postgres.git?ref=0.2.0"

  # nomad
  nomad_datacenters = ["dc1"]
  nomad_namespace   = "default"
  nomad_host_volume = "persistence"

  # postgres
  service_name                    = "postgres"
  container_image                 = "postgres:12-alpine"
  container_port                  = 5432
  vault_secret                    = {
                                      use_vault_provider      = false,
                                      vault_kv_path           = "",
                                      vault_kv_field_username = "",
                                      vault_kv_field_password = ""
                                    }
  admin_user                      = "postgres"
  admin_password                  = "postgres"
  database                        = "metastore"
  volume_destination              = "/var/lib/postgresql/data"
  use_host_volume                 = true
  use_canary                      = false
  container_environment_variables = ["PGDATA=/var/lib/postgresql/data/"]
}

Inputs

Name	Description	Type	Default	Required
nomad_datacenters	Nomad data centers	list(string)	["dc1"]	no
nomad_namespace	[Enterprise] Nomad namespace	string	"default"	no
nomad_host_volume	Nomad host volume name	string	"persistence"	no
consul_tags	List of one or more tags to announce in Consul, for service discovery purposes	list(string)	[""]	no
service_name	Postgres service name	string	"postgres"	no
container_port	Postgres port	number	5432	no
container_image	Postgres docker image	string	"postgres:12-alpine"	no
admin_user	Postgres admin username	string	"postgres"	no
admin_password	Postgres admin password	string	"postgres"	no
database	Postgres database name	string	"metastore"	no
container_environment_variables	Postgres container environement variables	list(string)	["PGDATA=/var/lib/postgresql/data"]	no
volume_destination	Postgres volume destination	string	"/var/lib/postgresql/data"	no
use_host_volume	Use nomad host volume	bool	false	no
use_canary	Switch to use canary deployment for Postgres	bool	no
vault_secret.use_vault_provider	Set if want to access secrets from Vault	bool	true	no
vault_secret.vault_kv_policy_name	Vault policy name to read secrets	string	"kv-secret"	no
vault_secret.vault_kv_path	Path to the secret key in Vault	string	"secret/data/postgres"	no
vault_secret.vault_kv_field_username	Secret key name in Vault kv path	string	"username"	no
vault_secret.vault_kv_field_password	Secret key name in Vault kv path	string	"password"	no
memory	Memory allocation for Postgres in MB	number	428	no
cpu	CPU allocation for Postgres in MHz	number	350	no
resource_proxy	Resource allocations for proxy	obj(number, number)	{ cpu = 200, memory = 128 }	no

Outputs

Name	Description	Type
service_name	Postgres service name	string
username	Postgres username	string
password	Postgres password	string
database_name	Postgres database name	string
port	Postgres port	number

Secrets & credentials

This module presents two ways of setting credentials (username and password). You can set them manually or upload secrets to Vault.

Set credentials manually

To set the credentials manually you first need to tell the module to not fetch credentials from vault. To do that, set vault_secret.use_vault_provider to false (see below for example). If this is done the module will use the variables admin_user and admin_password to set the postgres credentials. These will default to postgres if not set by the user.
Below is an example on how to disable the use of vault credentials, and setting your own credentials.

module "postgres" {
...

  vault_secret  = {
                    use_vault_provider      = false,
                    vault_kv_path           = "",
                    vault_kv_field_username = "",
                    vault_kv_field_password = ""
                  }
  admin_user     = "myadminuser"     # default 'postgres'
  admin_password = "myadminpassword" # default 'postgres'
}

Set credentials using Vault secrets

By default use_vault_provider is set to false. However, when testing using the box (e.g. make dev) the postgres username and password is randomly generated and put in secret/postgres inside Vault, from the 01_generate_secrets_vault.yml playbook. This is an independet process and will run regardless of the vault_secret.use_vault_provider is false/true.

If you want to use the automatically generated credentials in the box, you can do so by changing the vault_secret object as seen below:

module "postgres" {
...

  vault_secret  = {
                    use_vault_provider      = true,
                    vault_kv_policy_name    = "kv-secret"
                    vault_kv_path           = "secret/postgres",
                    vault_kv_field_username = "username",
                    vault_kv_field_password = "password"
                  }
}

If you want to change the secrets path and keys/values in Vault with your own configuration you would need to change the variables in the vault_secret-object. Say that you have put your secrets in secret/services/postgres/users and change the keys to guestuser and guestpassword. Then you need to do the following configuration:

module "postgres" {
...

  vault_secret  = {
                    use_vault_provider      = true,
                    vault_kv_policy_name    = "kv-users-secret"
                    vault_kv_path           = "secret/services/postgres/users",
                    vault_kv_field_username = "guestuser",
                    vault_kv_field_password = "guestpassword"
                  }
}

Volumes

Module (optionally) supports host volume to store postgres data. If the use_host_volume is set to true (default: false), Postgres data will be available in root /persistence/postgres folder inside the Vagrant box.