Custom Templates

Metlo supports writing custom templates using Typescript. You can write and test your templates locally and push them to Metlo using the CLI (Setup Instructions).

Setting Up Your Environment

The first step is to setup a node project to build your templates in. Be sure to have both Node and NPM installed before following these steps! We highly recommend using nvm.

Bash

mkdir metlo-test-templates
cd metlo-test-templates
npm init

After setting up your project install @metlo/testing for the testing utility functions.

Bash

npm install @metlo/testing

Creating a New Template

Although you can structure your templates however you want, since templates can have different versions we recommend structuring your template repository like this (with folders for templates and typescript files for each version):

metlo-test-templates/
├── node_modules
├── templates/
│   ├── <TEMPLATE_NAME>/
│   │   ├── v1.ts
│   │   └── v2.ts
└── package.json

First create a folder called templates in your project:

mkdir templates

After that create a folder inside it for your template, lets make a template that verifies if an endpoint always responds with CSP Headers called VERIFY_CSP_HEADERS.

cd templates
mkdir VERIFY_CSP_HEADERS
cd VERIFY_CSP_HEADERS
touch v1.ts

Now you can open v1.ts in the editor of your choice and paste the following:

TypeScript

import {
  AssertionType,
  GenTestEndpoint,
  TestBuilder,
  TestStepBuilder,
} from "@metlo/testing";

export default {
  name: "VERIFY_CSP_HEADERS",
  version: 1,
  builder: (endpoint: GenTestEndpoint) => {
    return new TestBuilder()
      .setMeta({
        name: `${endpoint.path} Has CSP Headers`,
        severity: "MEDIUM",
        tags: ["CSP_HEADERS"],
      })
      .addTestStep(
        TestStepBuilder.sampleRequest(endpoint).assert({
          type: AssertionType.JS,
          value: "resp.headers['content-security-policy']",
        })
      );
  },
};

You can see a deeper overview of templates here.

Generating a Test

You can generate a test with this new template using the Metlo CLI.

Bash

metlo test generate \
 -t templates/VERIFY_CSP_HEADERS/v1.ts \
 -h <ENDPOINT_HOST> \
 -e <ENDPOINT_PATH> \
 -p output.yaml

# By Endpoint UUID

metlo test generate \
 -t templates/VERIFY_CSP_HEADERS/v1.ts \
 -e <ENDPOINT_UUID> \
 -p output.yaml

Running Your Generated Test

First fill in any values you need in output.yaml. After that, you can run the generated test by running the following:

Bash

metlo test run output.yaml

Pushing Your Templates to Metlo

After you’ve verified that the template works, you can push your template to Metlo by running:

Bash

metlo template push templates

This template should now be available in the Metlo UI.

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Custom Templates

Setting Up Your Environment

Creating a New Template

Generating a Test

Running Your Generated Test

Pushing Your Templates to Metlo

​Setting Up Your Environment

​Creating a New Template

​Generating a Test

​Running Your Generated Test

​Pushing Your Templates to Metlo

Setting Up Your Environment

Creating a New Template

Generating a Test

Running Your Generated Test

Pushing Your Templates to Metlo