Using Grype in air-gapped (offline) environments for Supply Chain Security Tools - Scan

This topic tells you how to use Grype in air-gapped (offline) environments for Supply Chain Security Tools (SCST) - Scan.

The grype CLI attempts to perform two over the Internet calls:

One to verify for later versions of the CLI
One to update the vulnerability database before scanning

For the Grype CLI to function in an offline or air-gapped environment, the vulnerability database must be hosted in the environment. You must configure the Grype CLI with the internal URL.

The grype CLI accepts environment variables to satisfy these needs.

Host the Grype vulnerability database

To host Grype’s vulnerability database in an air-gapped environment:

Retrieve the Grype listing file from its public endpoint, https://toolbox-data.anchore.io/grype/databases/listing.json.

Create your own listing.json file. Different Grype versions require specific database schema versions. To avoid compatibility issues between different versions, include a database schema for each version. For example:

    {
      "available": {
        "1": [
          {
            "built": "2023-06-16T01:33:30Z",
            "version": 1,
            "url": "https://toolbox-data.anchore.io/grype/databases/vulnerability-db_v1_2023-06-16T01:33:30Z_1621f4169ffd15bea9e5.tar.gz",
            "checksum": "sha256:3f2c1b432945cca9a69b2e604f6fb231fec450fdd27f4946fc5608692b63a9d1"
          }
        ],
        "2": [
          {
            "built": "2023-06-16T01:33:30Z",
            "version": 2,
            "url": "https://toolbox-data.anchore.io/grype/databases/vulnerability-db_v2_2023-06-16T01:33:30Z_d6eee5e78d9b78285e1a.tar.gz",
            "checksum": "sha256:7b7e3a2a7712c72b8c5cc777733c4d8d140d8cfee65e4f04540abbdfe3ef1f65"
          }
        ],
        "3": [
          {
            "built": "2023-06-16T01:33:30Z",
            "version": 3,
            "url": "https://toolbox-data.anchore.io/grype/databases/vulnerability-db_v3_2023-06-16T01:33:30Z_f96ae38a7b05987c3ece.tar.gz",
            "checksum": "sha256:8ea9fae3fda3bf3bf35bd5e5eb656fc127b59cd3c42db4c36795556aab8a9cf0"
          }
        ],
        "4": [
          {
            "built": "2023-06-16T01:33:30Z",
            "version": 4,
            "url": "https://toolbox-data.anchore.io/grype/databases/vulnerability-db_v4_2023-06-16T01:33:30Z_13bba2fa8ff62b7f8b26.tar.gz",
            "checksum": "sha256:3b53d20241b88e5aa45feb817b325c53d6efbe9fa1fc5a67eeddaecafa7687e0"
          }
        ],
        "5": [
          {
            "built": "2023-06-16T01:33:30Z",
            "version": 5,
            "url": "https://toolbox-data.anchore.io/grype/databases/vulnerability-db_v5_2023-06-16T01:33:30Z_e07da3853f6db6eb1104.tar.gz",
            "checksum": "sha256:93d4d9d2f9e39f86570f832cf85b7149a949ca6f1613581b10c12393509d884f"
          }
        ]
      }
    }

Where url points to a tarball containing Grype’s vulnerability.db and metadata.json files.

Download and host the tarballs on your internal file server.

Some storage solutions for internal file servers change the name of TAR files automatically because of their limits. Record these modified names and reflect the changes in url. Ensure that the timestamp in the name is correctly formatted because Grype parses the name of TAR artifact to get the timestamp.
Update the download url to point at your internal endpoint.

For information about setting up an offline vulnerability database, see the Anchore Grype README file in GitHub.

Enable Grype in offline air-gapped environments

To enable Grype in offline air-gapped environments:

Add the following to your tap-values.yaml file:
```
grype:
  db:
    dbUpdateUrl: INTERNAL-VULN-DB-URL
```
Where INTERNAL-VULN-DB-URL is the URL that points to the internal file server.

Update Tanzu Application Platform by running:

tanzu package installed update tap -f tap-values.yaml -n tap-install

Configure Grype environmental variables

Create a secret that contains the ytt overlay to add the Grype environment variable to the ScanTemplates:

apiVersion: v1
kind: Secret
metadata:
  name: grype-airgap-environmental-variables
  namespace: tap-install
stringData:
  patch.yaml: |
    #@ load("@ytt:overlay", "overlay")

    #@overlay/match by=overlay.subset({"kind":"ScanTemplate"}),expects="1+"
    ---
    spec:
      template:
        initContainers:
          #@overlay/match by=overlay.subset({"name": "scan-plugin"}), expects="1+"
          - name: scan-plugin
            #@overlay/match missing_ok=True
            env:
              #@overlay/append
              - name: GRYPE_CHECK_FOR_APP_UPDATE
                value: "false"

Where spec.template.initContainers[] specifies setting one or more environment variables in the scan-plugin initContainer.

If you are using the Namespace Provisioner to provision a new developer namespace and want to apply a package overlay for Grype, you must import the overlay Secret. For more information, see Import overlay secrets.

Troubleshooting

The following sections have troubleshooting steps for specific issues.

ERROR failed to fetch latest cli version

The Grype CLI checks for later versions of the CLI by contacting the anchore endpoint over the Internet.

ERROR failed to fetch latest version: Get "https://toolbox-data.anchore.io/grype/releases/latest/VERSION": \
dial tcp: lookup toolbox-data.anchore.io on [::1]:53: read udp [::1]:65010->[::1]:53: read: connection refused

The Grype CLI checks for later versions of the CLI by contacting the Anchore endpoint over the Internet.

Solution

This message is a warning and the Grype scan still runs.

To deactivate this check, set the environment variable GRYPE_CHECK_FOR_APP_UPDATE to false by using a package overlay:

Create a secret that contains the ytt overlay to add the Grype environment variable to the ScanTemplates:

apiVersion: v1
kind: Secret
metadata:
  name: grype-airgap-deactivate-cli-check-overlay
  namespace: tap-install #! namespace where tap is installed
stringData:
  patch.yaml: |
    #@ load("@ytt:overlay", "overlay")

    #@overlay/match by=overlay.subset({"kind":"ScanTemplate"}),expects="1+"
    ---
    spec:
      template:
        initContainers:
          #@overlay/match by=overlay.subset({"name": "scan-plugin"}), expects="1+"
          - name: scan-plugin
            #@overlay/match missing_ok=True
            env:
              #@overlay/append
              - name: GRYPE_CHECK_FOR_APP_UPDATE
                value: "false"

Configure tap-values.yaml to use package_overlays by adding the following to your tap-values.yaml file:

package_overlays:
  - name: "grype"
    secrets:
        - name: "grype-airgap-deactivate-cli-check-overlay"

Update Tanzu Application Platform by running:

tanzu package installed update tap -f tap-values.yaml -n tap-install

Database is too old

1 error occurred:
  * db could not be loaded: the vulnerability database was built N days/weeks ago \
  (max allowed age is 5 days)

Cause

Grype needs up-to-date vulnerability information to provide accurate matches. By default, it fails to run if the local database was not built in the last 5 days.

Solution

Two options to resolve this:

(Recommended) Update the database daily. Stale databases weaken your security posture.

If you cannot update the database daily, configure the data staleness check by using the environment variable GRYPE_DB_MAX_ALLOWED_BUILT_AGE and applying a package overlay:

Create a secret that contains the ytt overlay to add the Grype environment variable to the ScanTemplates:

apiVersion: v1
kind: Secret
metadata:
name: grype-airgap-override-stale-db-overlay
namespace: tap-install #! namespace where tap is installed
stringData:
patch.yaml: |
 #@ load("@ytt:overlay", "overlay")

 #@overlay/match by=overlay.subset({"kind":"ScanTemplate"}),expects="1+"
 ---
 spec:
   template:
     initContainers:
       #@overlay/match by=overlay.subset({"name": "scan-plugin"}), expects="1+"
       - name: scan-plugin
         #@overlay/match missing_ok=True
         env:
           #@overlay/append
           - name: GRYPE_DB_MAX_ALLOWED_BUILT_AGE #! see note on best practices
             value: "120h"

Note
The default maximum allowed built age of Grype’s vulnerability database is 5 days. This means that scanning with a 6-day-old database causes the scan to fail. You can use the GRYPE_DB_MAX_ALLOWED_BUILT_AGE parameter to override the default in accordance with your security posture.

Configure tap-values.yaml to use package_overlays by adding the following to your tap-values.yaml file:

package_overlays:
- name: "grype"
 secrets:
     - name: "grype-airgap-override-stale-db-overlay"

Update Tanzu Application Platform by running:

tanzu package installed update tap -f tap-values.yaml -n tap-install

Vulnerability database is invalid

scan-pod[scan-plugin]  1 error occurred:
scan-pod[scan-plugin]  * failed to load vulnerability db: vulnerability database is invalid \
(run db update to correct): database metadata not found: /.cache/grype/db/5

Solution

To solve:

Examine the listing.json file you created. This matches the format of the listing file. The listing file is at Anchore Grype’s public endpoint. For more information, see the Grype README file in GitHub.

An example listing.json:
```
{
 "available": {
   "5": [
     {
       "built": "2023-03-28T01:29:38Z",
       "version": 5,
       "url": "https://toolbox-data.anchore.io/grype/databases/vulnerability-db_v5_2023-03-28T01:29:38Z_e49d318c32a6113eed07.tar.gz",
       "checksum": "sha256:408ce2932f04dee929a5df524e92494f2d635c6b19e30ff9f0a50425b1fc29a1"
     },
     .....
   ]
 }
}
```
Where:
- 5 refers to the Grype vulnerability database schema.
- built is the build timestamp in the format yyyy-MM-ddTHH:mm:ssZ.
- url is the download URL for the tarball containing the database. This points at your internal endpoint. The tarball contains the following files:
  - vulnerability.db, which is an SQLite file that is Grype’s vulnerability database. Each time the data shape of the vulnerability database changes, a new schema is created. Different Grype versions require specific database schema versions. For example, Grype v0.54.0 requires database schema version v5.
  - metadata.json
- checksum is the SHA used to verify the database’s integrity.
Go through the next steps to discover why the vulnerability database is not valid:
The database schema might be invalid. Confirm that the required database schema for the installed Grype version is used and confirm that the top-level version key matches the nested version. For example, the top-level version 1 in the following snippet does not match the nested version: 5.
```
{
  "available": {
    "1": [{
           "built": "2023-02-08T08_17_20Z",
           "version": 5,
           "url": "https://INTERNAL-ENDPOINT/PATH-TO-TARBALL/vulnerability-db_v5_2023-02-08T08_17_20Z_6ef73016d160043c630f.tar.gz",
           "checksum": "sha256:aab8d369933c845878ef1b53bb5c26ee49b91ddc5cd87c9eb57ffb203a88a72f"
    }]
  }
}
```
Where PATH-TO-TARBALL is the path to the tarball containing the vulnerability database.

Because stale databases weaken your security posture, VMware recommends using the newest entry of the relevant schema version in listing.json. For more information, see Anchore’s grype-db in GitHub.
Verify that the built parameters in listing.json are correctly formatted. The proper format is yyyy-MM-ddTHH:mm:ssZ.
Verify that the url that you modified to point at an internal endpoint is reachable from the cluster. For information about verifying connectivity, see Debug the Grype database in a cluster.
Search for syntax errors in listing.json by running:
```
grype db check
```
Validate the configured listing.json file by running:
```
grype db list -o raw
```

Debug the Grype database in a cluster

To debug the Grype database in a cluster:

Describe the failed sourcescan or imagescan to verify the name of the ScanTemplate being used:
- For sourcescan, run:
```
kubectl describe sourcescan SCAN-NAME -n DEV-NAMESPACE
```
  Where SCAN-NAME is the name of the sourcescan that failed.
- For imagescan, run:
```
kubectl describe imagescan SCAN-NAME -n DEV-NAMESPACE
```
  Where SCAN-NAME is the name of the imagescan that failed.
Pause reconciliation of the grype.scanning.apps.tanzu.vmware.com package by running:
```
kctrl package installed pause -i <PACKAGE-INSTALL-NAME> -n tap-install
```
Where PACKAGE-INSTALL-NAME is the name of the grype.scanning.apps.tanzu.vmware.com package. For example, grype.

Edit the ScanTemplate scan-plugin container to include a sleep entrypoint that allows you to troubleshoot inside the container:

- name: scan-plugin
  volumeMounts:
    ...
  image: #@ data.values.scanner.image
  imagePullPolicy: IfNotPresent
  env:
    ...
  command: ["/bin/bash"]
  args:
  - "sleep 1800" # insert 30 min sleep here

Run the scan again.
Get the name of the scan-plugin pod by running:
```
kubectl get pods -n DEV-NAMESPACE
```
Get a shell to the container by running:
```
kubectl exec --stdin --tty SCAN-PLUGIN-POD -c step-scan-plugin -- /bin/bash
```
Where SCAN-PLUGIN-POD is the name of the scan-plugin pod. For more information, see the Kubernetes documentation.
Inside the container, run Grype CLI commands to report the database status and verify connectivity from the cluster to the mirror. For more information, see the Grype documentation in GitHub.
Report the current status of Grype’s database, such as location, build date, and checksum by running:
```
grype db status
```
Ensure that the built parameters in listing.json have timestamps in the format yyyy-MM-ddTHH:mm:ssZ.
After you finish troubleshooting, trigger reconciliation by running:
```
kctrl package installed kick -i <PACKAGE-INSTALL-NAME> -n tap-install
```
Where PACKAGE-INSTALL-NAME is the name of the grype.scanning.apps.tanzu.vmware.com package, such as Grype.

Grype package overlays are not applied to ScanTemplates created by Namespace Provisioner

If you used the Namespace Provisioner to provision a new developer namespace and want to apply a package overlay for Grype, see Import overlay secrets.