Guided Setup Tool for Cluster Installations

Problem

Setting up OpenShift clusters on diverse cloud providers such as cloudscale and Exoscale is a complex, error-prone process requiring technical expertise, manual coordination, loads of state in environment variables (30+), ~100 steps, configuration files, Git repos, and the VSHN portal.

The existing installation workflows are somewhat fragmented and hard to extend due to an array of assorted templates loosely tied together. A change in one template can have unforeseen consequences on other parts of the installation process. Every new cloud provider requires more branching paths and adds to the overall complexity.

We eventually want to support a fully automated setup, without any manual steps involved. As we’re not there quite yet and might never be, we need a solution where we can gradually automate more and more steps.

installation branching
Figure 1. An example of the branching complexity in the installation process

Goals

  • Guide users through the necessary steps, ensuring all prerequisites are met before proceeding.

  • Allow user input where necessary.

  • Abstract away cloud provider specifics to ensure a consistent and repeatable deployment process.

  • Allow error recovery and resumption of interrupted installations.

  • Enable gradual automation of the setup process, reducing the need for manual intervention over time.

  • Allow easier iteration of interconnected steps/templates without breaking the overall installation process.

Non-Goals

  • Fully automated setup without any manual steps involved (at least not initially).

  • Replacement of existing tools like openshift-install or terraform, but rather complementing them.

Proposals

Proposal 1: Use config management tool (for example Ansible) to create a guided setup tool

We use a configuration management tool like Ansible to create a guided setup tool that orchestrates the installation process.

There is a myriad of existing config management tools (Ansible, SaltStack, Puppet, Chef, etc.). Some of them allow for interactive prompts and guided workflows. Most of them also have good support for modularization, allowing us to break down the installation process into smaller, manageable tasks or roles. We can create a series of playbooks or roles that represent each step of the installation process.

State management and interruption handling isn’t trivial with most of these tools, but can be achieved with some custom logic and careful planning. Most tools don’t have a single state file that can be modified easily by the user, which makes it harder to resume from a specific point after fixing an issue in the state.

Advantages

  • Big ecosystem

  • Mature tooling

  • Active community

Disadvantages

  • Complexity in setup, configuration and maintenance

  • Not every framkework has good support for interactive prompts

  • State management can be tricky, especially when dealing with interrupted installations and resuming from a specific point.

  • Learning curve for team members unfamiliar with the chosen tool.

Proposal 2: Write a custom guided setup tool

We develop a custom tool tailored specifically for our installation process, focusing on the unique requirements and challenges we face.

A big focus can be put on state management and interruption handling, allowing users to easily resume from where they left off. We can design a user-friendly interface that guides users through the installation steps, providing clear instructions and feedback. The state management can be implemented in a way that allows users to easily modify the state file to fix issues and resume the installation process.

Advantages

  • Full control over the implementation and user experience

  • Ability to design the tool specifically for our use case

  • Easier integration with existing workflows and tools

  • Potential for simpler state management and interruption handling

Disadvantages

  • Limited community support and resources compared to popular config management tools

Decision

We will proceed with Proposal 2: Write a custom guided setup tool.

Rationale

We believe that a custom tool will provide us with the flexibility and control we need to address the specific challenges of our installation process. By tailoring the tool to our requirements, we can create a more seamless and efficient user experience.

References