High Level Explanation

This repo contains a basic example of implementing a custom terraform provider. When run, it will simply populate a postgres database depending on the provided terraform resources. This example consists of 4 parts: a server, a client, and a provider, all written in golang, and the example terraform code which uses the provider.

Server

The server is a simple api which accepts simple REST api requests and inserts, deletes or modifies rows in a database.

Client

The client is a simple client which sends requests to the server.

Provider

The provider works alongside terraform core to parse and interpret terraform code, and call the client methods appropritately. Under the hood, terraform core also manages the state file.

Example Terraform Code

The example .tf files show how we can now write new terraform resources, which will be interpreted by the provider.

Installation and Running

1. Create Database

Start by installing postgres and ensure it is running. With brew you can do this by

sudo brew services start postgres

The following command will create the foods table used by the server.

cd server
psql postgres -f foods.sql;
cd ..

2. Run the server

Open server/main.go and edit the user and password for your postgres database.

To run the server,

cd server
go mod init
go mod vendor
go run main.go
cd ..

3. Build and install the provider

If running on an OS other than MacOS, you will need to change the OS_ARCH variable in provider/Makefile.

Then, to install the provider, run

cd provider
make
cd ..

This will build and install the provider in a place terraform can find it.

4. Run the terraform code

Now that the provider is installed, we can run the terraform code in the examples directory. The provided example will create a few resources, each which will add a row to the database table created in step 1. Commenting the resource out and re-running the terraform will cause these rows to be deleted.

cd examples
terraform init
terraform apply
cd ..