Fetch GDC trust bundles

A trust bundle, also known as a trust list, is a group of trust anchors, such as entities, that are inherently trusted and whose trust is not transferred by another entity (trusted third parties). These trust anchors are delivered as certificate authority (CA) certificates. The certification path-building algorithm uses these CA certificates to establish a chain between a certificate obtaining validation and the trust anchors.

Google Distributed Cloud (GDC) air-gapped has dedicated trust bundles. This guide outlines the steps to fetch the trust bundle for organizational administrators.

Trust bundle types

Distributed Cloud provides two types of managed trust bundles for platform administrators:

trust-store-root-ext: contains the internal root CA and web-tls CA. The content is different depending on where it resides, such as the root or the tenant organization. Use this trust bundle to communicate across organization boundaries or to access services like object storage within the organization.
trust-store-global-root-ext: available in the global API server and zonal API server platform namespace. When the global API server is ready, the bundle populates all other zonal trust-store-root-ext data, including local data.

Fetch the trust bundle

You can fetch trust bundles from the well-known server endpoint, or from the cluster using kubectl.

Fetch from the well-known server

GDC provides a secure way to access trust bundles through a well-known server endpoint. Use this method when you need to fetch the trust-store-global-root-ext bundle without directly interacting with the cluster using kubectl.

Export the following environment variables:
```
export STORAGE=STORAGE
export ORG_NAME=ORG_NAME
```
Replace the following:
- STORAGE: the directory path where you want to store the trust bundle file.
- ORG_NAME: the name of your organization within GDC.

Set the WELL_KNOWN_URL environment variable:

export WELL_KNOWN_URL=https://console.${ORG_NAME:?}.zone1.google.gdch.test/.well-known/certificate-authority

Set the GLOBAL_TRUST_BUNDLE_FILEenvironment variable. This file stores the GDC trust bundle locally in your specified $STORAGE location.
```
export GLOBAL_TRUST_BUNDLE_FILE="$STORAGE/global/ca-bundles/global-trust-bundle"
```

Obtain the trust-store-global-root-ext trust bundle from the well-known server and store it in the file created in the previous step:

echo -n | curl ${WELL_KNOWN_URL:?} > ${GLOBAL_TRUST_BUNDLE_FILE:?}

The fetched trust bundle file contains one or more CA certificates. The output is similar to the following:

Fetch from the cluster using kubectl

You can fetch trust bundles directly from the GDC cluster using the kubectl command-line tool. Use this method if you have direct access to the cluster and its configuration, and you need to fetch either the trust-store-root-ext or the trust-store-global-root-ext trust bundles.

You must obtain the following before you can complete the steps in this section:

Required permissions: Ask your Organization IAM Admin to grant you the Trust Store Viewer (trust-store-viewer) role.
Kubeconfig file: Sign in and generate the kubeconfig file for the Management API server if you don't already have one. You need the path to the kubeconfig file to replace MANAGEMENT_API_SERVER_KUBECONFIG in the following steps.

Fetch the trust bundle from the cluster using kubectl:

Export the following environment variables:
```
export KUBECONFIG=MANAGEMENT_API_SERVER_KUBECONFIG
export STORAGE=STORAGE
export ZONE=ZONE
```
Replace the following:
- MANAGEMENT_API_SERVER_KUBECONFIG: the path to the Management API server kubeconfig.
- STORAGE: the directory path where you want to store the trust bundle file.
- ZONE: your GDC zone name.

Set the TRUST_BUNDLE_FILE environment variable. This file stores the GDC trust bundle locally in your specified $STORAGE location for your GDC $ZONE:

export TRUST_BUNDLE_FILE="$STORAGE/$ZONE/ca-bundles/trust-bundle"
export GLOBAL_TRUST_BUNDLE_FILE="$STORAGE/global/ca-bundles/global-trust-bundle"

Set the NS namespace environment variable for the namespace:
```
export NS=platform
```

Obtain the certificate authorities (CA) and store them in the file created in step 2:

For trust-store-root-ext:

kubectl --kubeconfig ${KUBECONFIG} get secret trust-store-root-ext -n ${NS} -o go-template='{{ index .data "ca.crt" }}' | base64 -d | sed '$a\' > ${TRUST_BUNDLE_FILE}

For trust-store-global-root-ext:

kubectl --kubeconfig ${KUBECONFIG} get secret trust-store-global-root-ext -n ${NS} -o go-template='{{ index .data "ca.crt" }}' | base64 -d | sed '$a\' > ${GLOBAL_TRUST_BUNDLE_FILE}