DPC-3767 Add infrastructure for DPC WAF-sync lambda (#127)

## 🎫 Ticket

https://jira.cms.gov/browse/DPC-3767

## 🛠 Changes

- Added wav-sync as service
- Added plan and apply wav-sync github actions

## ℹ️ Context

DPC needs to synchronize ip addresses in a database with an AWS WAF IP
Set. We [decided](https://confluence.cms.gov/x/1ZUZQQ) to use a
cron-triggered lambda to manage this. This ticket creates the
infrastructure for automated deployment of the lambda.

The aws_waf_access inline policy seems to be the minimum necessary for
the lambda to run. It may require updating (the lambda has not been
written).

The name of the IP Set was intuited by browsing the WAF IP Sets in AWS
Console.

The terraform scripts and github actions are modified versions of the
opt-out-import service.

## 🧪 Validation

- Comparison of the plan output to opt-out-import plan output show that
the permissions necessary are present.
- Plan applied successfully

.github/workflows/api-waf-sync-apply.yml

@@ -0,0 +1,49 @@
+name: api-waf-sync apply terraform
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - .github/workflows/api-waf-sync-apply.yml
+      - terraform/modules/bucket/**
+      - terraform/modules/key/**
+      - terraform/modules/function/**
+      - terraform/modules/queue/**
+      - terraform/modules/subnets/**
+      - terraform/modules/vpc/**
+      - terraform/services/api-waf-sync/**
+  workflow_dispatch: # Allow manual trigger
+
+jobs:
+  terraform-apply:
+    permissions:
+      contents: read
+      id-token: write
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: ./terraform/services/api-waf-sync
+    strategy:
+      fail-fast: false
+      matrix:
+        env: [dev]
+    env:
+      TF_VAR_env: ${{ matrix.env }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./actions/setup-tfenv-terraform
+      - uses: aws-actions/configure-aws-credentials@v4
+        with:
+          role-to-assume: arn:aws:iam::${{ secrets.BCDA_ACCOUNT }}:role/delegatedadmin/developer/dpc-${{ matrix.env }}-github-actions
+          aws-region: ${{ vars.AWS_REGION }}
+      - run: terraform init -reconfigure -backend-config=../../backends/dpc-$TF_VAR_env.s3.tfbackend
+      - run: terraform apply -auto-approve
+      - uses: slackapi/slack-github-action@v1.26.0
+        if: ${{ failure() }}
+        with:
+          channel-id: 'C04UG13JF9B'
+          slack-message: "Terraform apply failure: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}"
+        env:
+          SLACK_BOT_TOKEN: ${{ secrets.SLACK_BOT_TOKEN }}
+

.github/workflows/api-waf-sync-plan.yml

@@ -0,0 +1,47 @@
+name: api-waf-sync plan terraform
+
+on:
+  pull_request:
+    paths:
+      - .github/workflows/api-waf-sync-plan.yml
+      - terraform/modules/bucket/**
+      - terraform/modules/key/**
+      - terraform/modules/function/**
+      - terraform/modules/queue/**
+      - terraform/modules/subnets/**
+      - terraform/modules/vpc/**
+      - terraform/services/api-waf-sync/**
+  workflow_dispatch: # Allow manual trigger
+
+jobs:
+  check-terraform-fmt:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./actions/setup-tfenv-terraform
+      - run: terraform fmt -check -diff -recursive terraform/services/api-waf-sync
+
+  terraform-plan:
+    needs: check-terraform-fmt
+    permissions:
+      contents: read
+      id-token: write
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: ./terraform/services/api-waf-sync
+    strategy:
+      fail-fast: false
+      matrix:
+        env: [dev]
+    env:
+      TF_VAR_env: ${{ matrix.env }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./actions/setup-tfenv-terraform
+      - uses: aws-actions/configure-aws-credentials@v4
+        with:
+          role-to-assume: arn:aws:iam::${{ secrets.BCDA_ACCOUNT }}:role/delegatedadmin/developer/dpc-${{ matrix.env }}-github-actions
+          aws-region: ${{ vars.AWS_REGION }}
+      - run: terraform init -reconfigure -backend-config=../../backends/dpc-$TF_VAR_env.s3.tfbackend
+      - run: terraform plan

terraform/services/api-waf-sync/README.md

@@ -0,0 +1,17 @@
+# Terraform for api-waf-sync function and associated infra
+
+This service sets up the infrastructure for the api-waf-sync lambda function in dev for dpc.
+
+## Manual deploy
+
+Pass in a backend file when running terraform init. See variables.tf for variables to include. Example:
+
+```bash
+export TF_VAR_env=dev
+terraform init -backend-config=../../backends/dpc-dev.s3.tfbackend
+terraform apply
+```
+
+## Automated deploy
+
+This terraform is automatically applied on merge to main by the waf-sync-apply.yml workflow.

terraform/services/api-waf-sync/main.tf

@@ -0,0 +1,60 @@
+locals {
+  full_name  = "dpc-${var.env}-api-waf-sync"
+  db_sg_name = "dpc-${var.env}-db"
+}
+
+module "api_waf_sync_function" {
+  source = "../../modules/function"
+
+  app = "dpc"
+  env = var.env
+
+  name        = local.full_name
+  description = "Synchronizes the IP whitelist in DPC with the WAF IP Set"
+
+  handler = "bootstrap"
+  runtime = "provided.al2"
+
+  function_role_inline_policies = {
+    waf-access = data.aws_iam_policy_document.aws_waf_access.json
+  }
+
+  schedule_expression = "cron(0/10 * * * ? *)"
+
+  environment_variables = {
+    ENV             = var.env
+    APP_NAME        = "dpc-${var.env}-api-waf-sync"
+    WAF_IP_SET_NAME = "DPC_${upper(var.env)}_Implementer_IP_Set"
+  }
+}
+
+# Add a rule to the database security group to allow access from the function
+
+data "aws_security_group" "db" {
+  name = local.db_sg_name
+}
+
+resource "aws_security_group_rule" "function_access" {
+  type        = "ingress"
+  from_port   = 5432
+  to_port     = 5432
+  protocol    = "tcp"
+  description = "api-waf-sync function access"
+
+  security_group_id        = data.aws_security_group.db.id
+  source_security_group_id = module.api_waf_sync_function.security_group_id
+}
+
+# Because we inline policies, we cannot just link to aws:policy/AWSWAFFullAccess
+data "aws_iam_policy_document" "aws_waf_access" {
+  statement {
+    effect    = "Allow"
+    resources = ["*"]
+
+    actions = [
+      "wafv2:GetIpSet",
+      "wafv2:UpdateIpSet",
+    ]
+  }
+}
+

terraform/services/api-waf-sync/outputs.tf

@@ -0,0 +1,7 @@
+output "function_role_arn" {
+  value = module.api_waf_sync_function.role_arn
+}
+
+output "zip_bucket" {
+  value = module.api_waf_sync_function.zip_bucket
+}

terraform/services/api-waf-sync/terraform.tf

@@ -0,0 +1,18 @@
+provider "aws" {
+  default_tags {
+    tags = {
+      application = "dpc"
+      business    = "oeda"
+      code        = "https://github.com/CMSgov/ab2d-bcda-dpc-platform/tree/main/terraform/services/api-waf-sync"
+      component   = "api-waf-sync"
+      environment = var.env
+      terraform   = true
+    }
+  }
+}
+
+terraform {
+  backend "s3" {
+    key = "api-waf-sync/terraform.tfstate"
+  }
+}

terraform/services/api-waf-sync/variables.tf

@@ -0,0 +1,8 @@
+variable "env" {
+  description = "The application environment (dev, test, prod)"
+  type        = string
+  validation {
+    condition     = contains(["dev", "test", "prod"], var.env)
+    error_message = "Valid value for env is dev, test, or prod."
+  }
+}