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, for example, the root or the tenant organization. Use this trust bundle to communicate across organization boundaries or to access service like object storage within the organization.
trust-store-global-root-ext: available in the global API server cert-manager namespace and all namespaces in the zonal API server. When The global API server is ready, the bundle populates all other zonal trust-store-root-ext data, including local data.

Before you begin

To get the permissions you need to fetch trust bundles, ask your Organization IAM Admin to grant you the Trust Store Viewer (trust-store-viewer) role in the platform namespace.

Get the kubeconfig file

To run commands using the kubeconfig file of the org admin cluster, ensure you have the following resources:

Sign in and generate the kubeconfig file for the org admin cluster if you don't have one.
Use the path to the kubeconfig file of the org admin cluster kubeconfig to replace ORG_ADMIN_KUBECONFIG in these instructions.

Fetch the trust bundle

Export the following environment variables:
```
export KUBECONFIG=ORG_ADMIN_KUBECONFIG
export STORAGE=STORAGE
export ZONE=ZONE
```
Replace the following:
- ORG_ADMIN_KUBECONFIG: the path to the kubeconfig file from the org admin cluster.
- 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}

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