chore(k9-iac): Add IaC CI setup doc (#39321)

* Add IaC CI setup doc

* Fix heading capitalization and variable name mismatch in IaC CI setup doc

* Apply word-list and sentence-length fixes to IaC CI setup doc

* Update from feedback on iac-setup

* Update hugo/content/en/security/code_security/iac_security/setup.md

Co-authored-by: May Lee <may.lee@datadoghq.com>

---------

Co-authored-by: May Lee <may.lee@datadoghq.com>

Author: valeryjuli

hugo/content/en/security/code_security/iac_security/setup.md

@@ -94,6 +94,57 @@ After setting up the Azure DevOps integration, enable IaC Security for your repo
 {{% /tab %}}
 {{< /tabs >}}
 
+## Set up IaC with a generic CI provider
+
+### Overview
+
+If you don't use GitHub Actions, GitLab CI/CD, or Azure DevOps, you can run the [Datadog IaC Scanner][8] directly in your CI pipeline. Upload IaC scan results to Datadog using the [`datadog-ci` CLI][9].
+
+**If you are running IaC Security on a non-GitHub repository**, run the first scan on your default branch. If your default branch uses a name other than `master`, `main`, `default`, `stable`, `source`, `prod`, or `develop`, upload a first scan for your repository. Then, manually override the default branch in [{{< ui >}}Repository Settings{{< /ui >}}][10] so that future scans from non-default branches are uploaded and correctly processed.
+
+### Prerequisites
+
+- Node.js 20 or later and npm
+- `curl`
+- `tar`
+- Permission to install the scanner in `/usr/local/bin`
+
+Configure the following environment variables:
+
+| Name         | Description                                                                                                                                                 | Required | Default         |
+| ------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------- | -------- | --------------- |
+| `DD_API_KEY` | Your Datadog API key. Create this key in your [Datadog organization][4] and store the key as a secret.                                                     | Yes      |                 |
+| `DD_APP_KEY` | Your application key. Create this key in your [Datadog organization][4] and include the `code_analysis_read` scope. Store the key as a secret.              | Yes      |                 |
+| `DD_SITE`    | The [Datadog site][5] to send information to. Your Datadog site is `datadoghq.com`.                                                                         | No       | `datadoghq.com` |
+
+Add the following to your CI pipeline:
+
+```bash
+# Set the Datadog site to send information to
+export DD_SITE="datadoghq.com"
+
+# Install dependencies
+npm install -g @datadog/datadog-ci
+
+# Download the latest Datadog IaC Scanner (x86_64/amd64 Linux; see GitHub Releases for arm64 and other platforms)
+export IAC_SCANNER_URL="https://github.com/DataDog/datadog-iac-scanner/releases/latest/download/datadog-iac-scanner_linux_amd64.tar.gz"
+curl -L "${IAC_SCANNER_URL}" -o /tmp/datadog-iac-scanner.tar.gz
+tar xfz /tmp/datadog-iac-scanner.tar.gz -C /tmp
+mv /tmp/datadog-iac-scanner /usr/local/bin/datadog-iac-scanner
+
+# Run the Datadog IaC scanner
+exit_code=0
+/usr/local/bin/datadog-iac-scanner scan -p . -o /tmp || exit_code=$?
+if [ $exit_code -lt 20 -o $exit_code -gt 60 ]; then echo "IaC scan failed" ; exit $exit_code ; fi
+
+# Upload results
+datadog-ci sarif upload /tmp/datadog-iac-scanner-result.sarif
+```
+
+<div class="alert alert-info">
+  This example uses the x86_64 (amd64) Linux version of the Datadog IaC Scanner. The scanner also supports arm64 Linux, as well as macOS and Windows. If you're using a different OS or architecture, select the appropriate release from the <a href="https://github.com/DataDog/datadog-iac-scanner/releases">GitHub Releases</a> page and update the <code>IAC_SCANNER_URL</code> value.
+</div>
+
 ## Upload third-party static analysis results to IaC Security
 
 <div class="alert alert-info">
@@ -149,3 +200,6 @@ To ensure proper ingestion and display in Datadog IaC Scanning for third-party s
 [5]: /getting_started/site/
 [6]: https://docs.datadoghq.com/security/code_security/static_analysis/setup/?tab=github#upload-third-party-static-analysis-results-to-datadog
 [7]: https://www.oasis-open.org/committees/tc_home.php?wg_abbrev=sarif
+[8]: https://github.com/DataDog/datadog-iac-scanner
+[9]: https://github.com/DataDog/datadog-ci?tab=readme-ov-file#sarif
+[10]: https://app.datadoghq.com/source-code/repositories