Skip to main content

old-chaos-studio

Last updated on

ChaosHub​

A ChaosHub is a collection of experiment templates (defined as workflow custom resources) and faults (defined as ChaosExperiment CR and ChaosEngine CR) that you can use to create and launch chaos experiments. Both experiments and faults are stored as manifests in an appropriate directory structure. This way, you can add new experiment templates and faults directly to the repository as files. In addition, you can derive the experiment templates from the existing experiments and save them to the ChaosHub from the UI.

You can add ChaosHub using a Git service provider such as GitHub, where ChaosHub exists as a repository. This allows native version control and management of the faults and experiment artefact.

HCE provides a default Enterprise ChaosHub that includes a wide array of experiments and faults out of the box. You can also add your own custom ChaosHubs to maintain and share private scenarios and faults within your organization.

This video provides a step-by-step walkthrough of using a ChaosHub.

Permissions required​

ChaosHubs are associated with chaos experiments, hence you need permissions to create new experiments and modify exisiting experiments. Chaos experiments, in turn, are executed in a chaos infrastructure, hence you need to have access to create/edit and view the chaos infrastructure. Go to Project Settings -> Access Control -> Roles and create a new role or ask your project admin to create an appropriate role.

Enterprise ChaosHub​

It is a ChaosHub with additional security and teaming features for better collaboration around chaos scenarios. It is a private GitHub repository that you can access using a special key.

Also known as Enterprise hub, it comes out-of-the-box with HCE and consists of pre-built manifests (YAML files) and chaos experiment templates. It is a prebuilt ChaosHub that represents the existing experiments and chaos faults. You can use faults from multiple categories to create chaos experiments in the Enterprise ChaosHub.

Use cases of ChaosHubs​
  • You can get secure storage of your git keys. except admins, no one else can access your git keys.
  • You can export a given chaos scenario to an Enterprise ChaosHub. Once you export a chaos scenario, it is hosted in the hub and is ready to be used as a base for cloning.
  • You get access to many chaos scenarios in the Enterprise hub where you can browse through a scenarios and directly execute it.
Reason for adding custom ChaosHub​
  • Add custom experiments suited to specific needs in your organization.
  • Share your experiments with others in your Harness project or in other Harness projects—you can add the same custom hub(s) to many projects.
  • Maintain and upgrade experiments in one place so those you share your hubs with always have the latest version.
  • Provide secure access to your custom experiments.
note

Resilience probes are currently not supported with Chaos Hubs.

Connect to a ChaosHub​

This topic describes how to add and connect a custom ChaosHub.

Prerequisites for Adding a Custom ChaosHub​

  1. Make sure you have a Git repository for your custom ChaosHub, where you will store experiments and faults. The repository must include two folders: experiments and faults. Here's an example repo:

    Private Hub

  2. Generate a personal access token from GitHub to access and sync your repository with Harness. The token must have at least the repo scope.

    GitHub New personal access token (classic) screen

Add a Custom ChaosHub​

  1. In your Harness project, navigate to the Chaos > ChaosHubs, and then select + New ChaosHub.

  2. Enter a Name for the hub and optionally add a Description and Tags.

  3. Select Continue.

  4. On the Git Connection screen, add a new Git connector to access and sync your repository with Harness.

    Git Connection screen

    1. In the ChaosHub Connector field. you'll see existing Git connectors listed under separate tabs for Project, Organization, and Account scopes.

      Existing Connectors

    2. Select New Connector, and then choose GitHub Connector.

    3. In the Overview screen, enter a Name and optional description and tags, and then select Continue.

      The Details screen is displayed.

      Add Connector Details

    4. In the Details screen, for URL Type, select Repository.

      You can select Account if you want to create an account-scoped GitHub connector. This can be used for connecting multiple ChaosHubs from a single GitHub account.

    5. For Connection Type, select HTTP.

    6. In GitHub Repository URL, enter the URL of your custom ChaosHub repository.

      If you selected Account for URL Type, fill out these fields instead:

      • In GitHub Account URL, enter the account URL for your custom ChaosHub repository.

      • In Test Repository, enter any repository name from your GitHub account to validate the connection.

    7. Select Continue.

      The Credentials screen appears.

      Credentials screen

  5. On the Credentials screen, enter the Username (in plain text) for authenticating with your GitHub repository.

  6. In Personal Access Token, select Create or Select a Secret.

    This displays all the secrets in separate tabs for Project, Organization, and Account scopes.

    Add Secret

  7. Select New Secret Text.

    New Secret

  8. In the Add new Encrypted Text screen, fill out the fields as follows:

    1. In Secret Name, enter a name for this secret.

    2. In Secret Value, enter a personal access token (PAT) generated from GitHub.

      Ensure that the token has at least a repo scope.

  9. Select Save, and then on the Credentials screen, select Continue.

    Add Credentials

    This adds your GitHub repository connector and initializes the PAT for authentication.

  10. In the Connect to provider screen, select Connect through Harness Platform, and then select Save and Continue.

    This starts a connection test to validate that Harness can access the Git repository with the given configuration.

    GitHub Connection Test

  11. When the test is successful, select Finish.

    The Git Connection screen appears.

    Git Connection

  12. In Hub Repository Branch, enter the repository branch in which the ChaosHub files are located.

  13. Select Connect Hub, and then select Finish.

    Your new custom ChaosHub appears on the ChaosHubs page.

note

To share your custom ChaosHub with another Harness project, add the hub to the other project by following the same procedure.

Manage ChaosHub​

This section explains how to save and manage experiments in your custom ChaosHub(s) and how to sync your ChaosHub GitHub repository with Harness.

View ChaosHubs​

The experiments in various ChaosHubs are templates that you can launch after specifying some details.

To view the default and custom ChaosHubs:

  1. In Harness, navigate to Chaos > ChaosHubs.

    This page lists the default Enterprise ChaosHub and any custom ChaosHubs.

    ChaosHubs page with default and custom hubs highlighted

  2. Select the ChaosHub you want to view.

    The experiments below are in a custom hub. By default, all experiments are displayed. You can select a tag (circled below) to filter the experiments.

    Viewing experiments in a ChaosHub, with an experiment tag/filter circled

    The experiments below are in the default Enterprise ChaosHub, organized by platform/technology.

    Enterprise ChaosHub

Add Experiments to a Custom ChaosHub​

When you add an experiment to a custom ChaosHub, it's saved as a template from which you can launch the experiment after specifying some details.

To add an experiment to a custom ChaosHub:

  1. Create an experiment.

  2. In the Chaos Experiments page, find the experiment you want to add to a custom ChaosHub, select the More options icon (⋮), and then select Add to ChaosHub.

    More options menu, showing Add to ChaosHub for an experiment

  3. On the Save to ChaosHub screen, verify the Name, Description and Experiment Category Tag.

    To add a new tag, type its name and then press the Enter/Return key.

    Save to ChaosHub screen

    tip

    Including Experiment Category Tag(s) helps organize your experiments. When you view the custom ChaosHub, you can see all experiments or filter them by tag.

  4. In the Hub field, choose the custom ChaosHub you want to save the experiment, and then select Apply.

  5. Select Save.

    This saves your experiment as a template in a custom ChaosHub.

note

You can also save an experiment as a template to a custom ChaosHub while creating the experiment in Chaos Studio. The Save button saves the experiment itself so that it appears on the Chaos Experiments page. Selecting the down-arrow next to Save lets you add the experiment as a template to a custom ChaosHub.

Experiment details screen with Save and Add to ChaosHub options circled

Sync Harness with a ChaosHub Git repository​

When you connect a custom ChaosHub, you can add and edit experiments in that hub in either Harness or the custom hub's GitHub repository. Changes made in Harness sync automatically with your repository. However, when you make changes in your repository, you need to sync them with Harness using the UI.

To sync your custom ChaosHub's Git repository with Harness:

  1. In Harness, navigate to Chaos > ChaosHubs.

  2. Select the More options icon (⋮) for the hub you want to sync, and then select Sync Hub.

    The More options icon (⋮) for a custom hub

Launch an Experiment from a ChaosHub​

You can launch experiments from either the default Enterprise ChaosHub or from custom hubs.

note

Launching an experiment from a hub is different from running one directly from the Chaos Experiments page. The experiments in ChaosHubs are templates, so when you launch them, you'll need to provide additional details. On the other hand, experiments on the Chaos Experiments page execute immediately, as configured.

To launch an experiment from a ChaosHub:

  1. In Harness, go to Chaos > ChaosHubs. Select the hub from which you want to launch an experiment.

    navigate

  2. Find the experiment you want to launch, and then select Launch Experiment.

    Launch

  3. Choose a chaos infrastructure, and then select Next. You can change the infrastructure type if needed.

    Select a Chaos Infrastructure

  4. This takes you to the Experiment Builder where you can configure the faults in the experiment. You can add,remove or rearrange faults as needed.

  5. Select Run to execute the experiment.

tip

You can also save your customized experiment as a template in a ChaosHub by selecting the Save button.