Command Line Options

This section contains the following information:

• Terrascan commands
• Scanning with examples
• Configuring the output format for a scan

The following is a description of all the commands available. Terrascan’s interface is divided into subcommands as follows:

• init = Initializes Terrascan by downloading the latest Rego policies into ~/.terrascan. The scan command will implicitly run this before a scan if it detects that there are no policies found.
• scan = scans Infrastructure as code files based on the policies contained within the “.terrascan” directory
• server = Starts the Terrascan’s API server
• help = You can view the usage menu by typing help or using the -h flag on any subcommand (e.g. terrascan init -h). You can also view this by typing terrascan without flags or other arguments.

Terrascan Commands

$ terrascan
Terrascan

Detect compliance and security violations across Infrastructure as Code to mitigate risk before provisioning cloud native infrastructure.
For more information, please visit https://runterrascan.io/

Usage:
  terrascan [command]

Available Commands:
  help        Provides usage info about any command
  init        Initialize Terrascan
  scan        Start scan to detect compliance and security violations across Infrastructure as Code.
  server      Run Terrascan as an API server
  version     Shows the Terrascan version you are currently using.

Flags:
  -c, --config-path string      config file path
  -h, --help                    help for terrascan
  -l, --log-level string        log level (debug, info, warn, error, panic, fatal) (default "info")
      --log-output-dir string   directory path to write the log and output files
  -x, --log-type string         log output type (console, json) (default "console")
  -o, --output string           output type (human, json, yaml, xml, junit-xml, sarif, github-sarif) (default "human")
      --temp-dir string         temporary directory path to download remote repository,module and templates

Use "terrascan [command] --help" for more information about a command.

Initializing (optional)

The initialization process downloads the latest policies from the repository into ~/.terrascan. By default the policies are installed here: ~/.terrascan/pkg/policies/opa/rego and are fetched while scanning an IaC. Use the following command to start the initialization process if you are updating the policies:

$ terrascan init

Note: The init command is implicitly executed if the scan command does not find policies while executing.

Scanning

If the scan command is used with no arguments (as shown below), the scan will include all supported cloud providers on Terraform HCL files:

$ terrascan scan

The scan command supports flags to configure the following:

• Specify a directory to be scanned
• Specify a particular IaC file to be scanned
• Configure IaC provider type
• Directory path to policies
• Specify policy type
• Retrieve vulnerability scanning results from docker images referenced in IaC

The full list of flags for the scan command can be found by typing terrascan scan -h

Scanning current directory containing terraform files for AWS Resources

The following will scan the current directory containing Terraform HCL2 files for AWS resources:

$ terrascan scan -t aws

Scanning for a specific IaC provider

By default, Terrascan defaults to scanning Terraform HCL files. Use the -i flag to change the IaC provider. Here’s an example of scanning kubernetes yaml files:

$ terrascan scan -i k8s

Scanning code remotely

Terrascan can be installed remotely to scan remote repositories or code resources using the -r and -u flags. Here’s an example:

$ terrascan scan -t aws -r git -u git@github.com:tenable/KaiMonkey.git//terraform/aws

Important: The URLs for the remote repositories should follow similar naming conventions as the source argument for modules in Terraform. For more details, see this article.

Scanning private Terraform module repositories

When scanning Terraform code, Terrascan checks for the environment variable TF_CLI_CONFIG_FILE. If found uses the credential file provided in that environment variable to authenticate a private terraform module registry. If the env variable is not found then checks for the availability of the file ~/.terraformrc. This file contains credential information to authenticate a private terraform module registry. If this file is present, Terrascan will attempt to use the credentials when authenticating the private repository. For more details on the format of this file, please see Terraform’s config file documentation.

Configuring the output format for a scan

By default, Terrascan output is displayed in a human friendly format. Use the -o flag to change this to YAML, JSON, XML, JUNIT-XML and SARIF formats.

Note: Terrascan will exit with an error code if any errors or violations are found during a scan.

List of possible Exit Codes

Scenario	Exit Code
scan summary has errors and violations	5
scan summary has errors but no violations	4
scan summary has violations but no errors	3
scan summary has no violations or errors	0
scan command errors out due to invalid inputs	1

Terrascan’s output is a list of security violations present in the scanned IaC files. The example below is terrascan’s output in YAML.

$ terrascan scan -t aws
results:
  violations:
  - rule_name: scanOnPushDisabled
    description: Unscanned images may contain vulnerabilities
    rule_id: AWS.ECR.DataSecurity.High.0578
    severity: MEDIUM
    category: Data Security
    resource_name: scanOnPushDisabled
    resource_type: aws_ecr_repository
    file: ecr.tf
    line: 1
  count:
    low: 0
    medium: 1
    high: 0
    total: 1

Scanning a Helm Chart

Helm chart can be scanned by specifying “helm” on the -i flag as follows:

$ terrascan scan -i helm

This command will recursively look for Chart.yaml files in the current directory and scan rendered .yaml, .yml, .tpl template files found under the corresponding /templates directory.

A specific directory to scan can be specified using the -d flag. The Helm IaC provider does not support scanning of individual files using the -f flag.

Scanning a Kustomize Chart

A Kustomize chart can be scanned by specifying “kustomize” on the -i flag as follows:

$ terrascan scan -i kustomize

This command looks for a kustomization.yaml file in the current directory and scans rendered .yaml or .yml template files.

Terrascan considers Kustomize v4 as the default version. Other supported versions (v2 and v3) of Kustomize could be scanned by specifying –iac-version flag as follows:

$ terrascan scan -i kustomize --iac-version v2

Scanning v2 and v3 requires the corresponding Kustomize binary and the path to the binary must be specified in the KUSTOMIZE_<VERSION> ENV variable.

e.g: For –iac-version v2, we need to have:

KUSTOMIZE_V2=path/to/kustomize/v2/binary

To install Kustomize one can use this script

A specific directory to scan can be specified using the -d flag. The Kustomize IaC provider does not support scanning of individual files using the -f flag.

Scanning a Dockerfile

A Dockerfile can be scanned by specifying “docker” on the -i flag as follows:

$ terrascan scan -i docker

This command looks for a Dockerfile in the current directory and scans that file.

A specific directory to scan can be specified using the -d flag. With the -d flag, it will check for all the docker files (named as Dockerfile) in the provided directory recursively. A specific dockerfile can be scanned using -f flag by providing a path to the file.

Retrieve Container Image Vulnerabilities

Terrascan can display vulnerabilities for container images present in the IaC files being scanned by specifying the --find-vuln flag along with the scan command as follows:

$ terrascan scan -i <IaC Provider> --find-vuln

This command looks for container images referenced in the IaC files and retrieves any vulnerabilities as reported by its container registry.

Supported container registries: AWS Elastic Container Registry (ECR), Azure Container Registry, Google Container Registry, Google Artifact Registry, and Harbor Container Registry.

The following environment variables are required when connecting to the container registries:

AWS Elastic Container Registry (ECR)

ECR requires your environment to be configured similar to the requirements of AWS’s SDK. For example, the AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_REGION environment variables can be set when connecting to AWS using API keys for an AWS user. More information here.

Google Container Registry and Artifact Registry

Terrascan requires a service account with access to the Container Analysis and Container Registry permissions. The GOOGLE_APPLICATION_CREDENTIALS environment variable can be set to the path of the service account’s key when scanning. More information about GCP authentication available here.

Azure Container Registry

When integrating vulnerability results from Azure, Terrascan requires the AZURE_AUTH_LOCATION, and AZURE_ACR_PASSWORD environment variables.

The AZURE_AUTH_LOCATION should contain the path to your azure authentication json. You can generate this as follows:

az ad sp create-for-rbac --sdk-auth > azure.auth

After generating the file, set the azure.auth file path as the AZURE_AUTH_LOCATION environment variable. More information about using file based authentication for the Azure SDK available here.

Terrascan also requires the password to the registry set into the AZURE_ACR_PASSWORD environment variable. This can be fetched using the az cli as follows:

az acr credential show --name RegistryName

Harbor Container Registry

When integrating vulnerability results from Harbor, Terrascan requires the HARBOR_REGISTRY_USERNAME, HARBOR_REGISTRY_PASSWORD,HARBOR_REGISTRY_CACERT, HARBOR_SKIP_TLS, and HARBOR_REGISTRY_DOMAIN environment variables.

The HARBOR_REGISTRY_DOMAIN environment variable helps Terrascan identify the registry’s domain.

The HARBOR_SKIP_TLS environment variable can be set to true to avoid TLS errors when Harbor is using a non-trusted TLS certificate. This is not recommended for production use.

Resource Config

While scanning a IaC, Terrascan loads all the IaC files, creates a list of resource configs and then processes this list to report violations. For debugging purposes, you can print this resource configs list as an output by using the --config-only flag to the terrascan scan command.

$  terrascan scan -i terraform -t aws -f elb.tf --config-only -o json
{
  "aws_elb": [
    {
      "id": "aws_elb.public_elb",
      "name": "public_elb",
      "module_name": "root",
      "source": "elb.tf",
      "line": 1,
      "type": "aws_elb",
      "config": {
        "connection_draining": true,
        "health_check": [
          {
            "healthy_threshold": 2,
            "interval": 15,
            "target": "HTTP:80/index.html",
            "timeout": 3,
            "unhealthy_threshold": 2
          }
        ],
        "instances": "${aws_instance.web.*.id}",
        "listener": [
          {
            "instance_port": 80,
            "instance_protocol": "http",
            "lb_port": 80,
            "lb_protocol": "http"
          }
        ],
        "name": "${local.prefix.value}-public-elb",
        "security_groups": [
          "${aws_security_group.public_internet.id}"
        ],
        "subnets": "${aws_subnet.public.*.id}",
        "tags": {
          "Name": "${local.prefix.value}-public-elb"
        }
      },
      "line_config": {
        "connection_draining": 16,
        "health_check": [
          {
            "healthy_threshold": 9,
            "interval": 13,
            "target": 12,
            "timeout": 11,
            "unhealthy_threshold": 10
          }
        ],
        "instances": 6,
        "listener": [
          {
            "instance_port": 18,
            "instance_protocol": 19,
            "lb_port": 20,
            "lb_protocol": 21
          }
        ],
        "name": 2,
        "security_groups": 5,
        "subnets": 4,
        "tags": {
          "Name": 25
        }
      },
      "skip_rules": null,
      "max_severity": "",
      "min_severity": ""
    }
  ]
}

More details on scan command

List of options for scan command:

Full help for scan command:

$ terrascan scan -h
Terrascan

Detect compliance and security violations across Infrastructure as Code to mitigate risk before provisioning cloud native infrastructure.

Usage:
  terrascan scan [flags]

Flags:
      --categories strings                  list of categories of violations to be reported by terrascan (example: --categories="category1,category2")
      --config-only                         will output resource config (should only be used for debugging purposes)
      --find-vuln                           fetches vulnerabilities identified in Docker images
  -h, --help                                help for scan
  -d, --iac-dir string                      path to a directory containing one or more IaC files (default ".")
  -f, --iac-file string                     path to a single IaC file
  -i, --iac-type string                     iac type (arm, cft, docker, helm, k8s, kustomize, terraform, tfplan)
      --iac-version string                  iac version (arm: v1, cft: v1, docker: v1, helm: v3, k8s: v1, kustomize: v2, v3, v4, terraform: v12, v13, v14, v15, tfplan: v1)
      --non-recursive                       do not scan directories and modules recursively
      --webhook-token string   the auth token to call the notification webhook URL
      --webhook-url string     the URL where terrascan will send the scan report and normalized config json
  -p, --policy-path stringArray             policy path directory
  -t, --policy-type strings                 policy type (all, aws, azure, docker, gcp, github, k8s) (default [all])
  -r, --remote-type string                  type of remote backend (git, s3, gcs, http, terraform-registry)
  -u, --remote-url string         url pointing to remote IaC repository
      --repo-ref string           branch of the repo being scanned
      --repo-url string           URL of the repo being scanned, will be reflected in scan summary
      --scan-rules strings                  one or more rules to scan (example: --scan-rules="ruleID1,ruleID2")
      --severity string                     minimum severity level of the policy violations to be reported by terrascan
      --show-passed                         display passed rules, along with violations
      --skip-rules strings                  one or more rules to skip while scanning (example: --skip-rules="ruleID1,ruleID2")
      --use-colors string                   color output (auto, t, f) (default "auto")
      --use-terraform-cache                 use terraform init cache for remote modules (when used directory scan will be non recursive, flag applicable only with terraform IaC provider)
  -v, --verbose                             will show violations with details (applicable for default output)

Global Flags:
  -c, --config-path string      config file path
  -l, --log-level string        log level (debug, info, warn, error, panic, fatal) (default "info")
      --log-output-dir string   directory path to write the log and output files
  -x, --log-type string         log output type (console, json) (default "console")
  -o, --output string           output type (human, json, yaml, xml, junit-xml, sarif, github-sarif) (default "human")
      --temp-dir string         temporary directory path to download remote repository,module and templates