Fixing Redocly CLI Installation Errors: The Missing Ajv Dependency

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Fixing Redocly CLI Installation Errors: The Missing ajv Dependency

Hey folks! Have you ever run into a brick wall trying to install @redocly/cli? Specifically, have you seen your builds fail because of missing peer dependencies? It's a real head-scratcher, I know. But don't worry, we're going to dive deep into this issue, figure out what's going on with the missing ajv dependency in better-ajv-errors, and get your Redocly CLI installation back on track. This problem mostly hits when you're using strict peer dependency environments, which is a good practice for keeping your projects clean and tidy.

The Core Problem: Unmet Peer Dependencies

So, what's the deal? Well, the heart of the matter lies in how better-ajv-errors, a dependency of @redocly/respect-core (which in turn is a dependency of @redocly/cli), handles its dependencies. It declares ajv as a peer dependency. In simple terms, this means that better-ajv-errors is saying, "Hey, I need ajv to work, but I'm not going to install it myself. Someone else (the parent package) needs to make sure it's available." This system works fine most of the time, but when you throw strictPeerDependencies: true into the mix, things get tricky.

When strictPeerDependencies: true is enabled (usually in your pnpm-workspace.yaml), your package manager (like pnpm, in this case) becomes super strict about ensuring that all peer dependencies are actually met. If a peer dependency is missing, the installation flat-out fails. This is exactly what happens with @redocly/cli. Because better-ajv-errors needs ajv, and @redocly/respect-core doesn't explicitly make it available, the build crashes. This can be a major pain, especially in automated builds and containerized deployments where you need everything to work flawlessly.

Let's break down the error message. It's usually something along the lines of:

ERR_PNPM_PEER_DEP_ISSUES Unmet peer dependencies

└─┬ @redocly/cli 1.34.2
└─┬ @redocly/respect-core 1.34.2
└─┬ better-ajv-errors 1.2.0
└── ✕ missing peer ajv@"4.11.8 - 8"

See that ✕ missing peer ajv? That's the smoking gun. It clearly indicates that ajv is not being provided where it's needed, causing the installation to halt. The error message is very clear, but understanding why it's happening is key to fixing it. And the 'why' is that the peer dependency isn't being satisfied by the parent package.

Why Strict Peer Dependencies Matter

You might be wondering why we even care about strictPeerDependencies. Well, using this setting is a best practice for a few key reasons:

  • Dependency Hygiene: It helps you avoid situations where you might have multiple versions of the same dependency floating around, which can lead to unexpected behavior and hard-to-debug issues.
  • Predictability: It makes your builds more predictable because you know exactly which versions of dependencies are being used.
  • Security: By controlling your dependencies tightly, you reduce the risk of vulnerabilities sneaking into your project.

So, while it can be a bit of a hassle when things don't line up perfectly, using strictPeerDependencies is worth it in the long run for a more stable and secure development process. The key is to address these peer dependency issues head-on, so your builds don't get blocked.

Reproducing the Issue: Steps to Failure

Let's walk through how you can recreate this issue yourself. This will help you understand the problem better and verify that any solutions you try actually work.

  1. Set up your workspace: First, you'll need a pnpm-workspace.yaml file. If you don't have one, create it in the root of your project. This file is what tells pnpm that you're working with a monorepo (a project with multiple packages).
packages:
  - 'packages/*'
  - 'apps/*'
strictPeerDependencies: true

  1. Create a package: Next, create a package within your workspace. For example, you might create a folder called packages/my-package and initialize a package.json inside it. This is where you'll add @redocly/cli as a dependency.

  2. Add @redocly/cli: Add @redocly/cli as a dependency to your workspace package. You can do this using pnpm add @redocly/cli in your package's directory or the root of your project. The exact location depends on your setup.

  3. Run pnpm install: Now, run pnpm install from the root of your project. This will install all the dependencies. Because you have strictPeerDependencies: true configured, pnpm will meticulously check that all peer dependencies are met.

  4. Observe the error: If everything goes as described, you should see the ERR_PNPM_PEER_DEP_ISSUES error, indicating that the ajv peer dependency is missing. This confirms that the issue is present in your environment.

This is a consistent way to reproduce the problem. It highlights the importance of making sure that peer dependencies are correctly handled in your project setup. It also allows you to test fixes and ensure that they effectively resolve the issue.

Expected Behavior vs. Reality

What we want to happen is simple: the installation should succeed. With strictPeerDependencies: true enabled, we expect the package manager to ensure that all peer dependencies of all packages are available. In this case, that means ajv should be installed and accessible because better-ajv-errors needs it.

However, the reality is different. Because @redocly/respect-core (which includes better-ajv-errors) doesn't explicitly declare ajv as a dependency, the package manager flags the missing peer dependency and the build fails. This is where the discrepancy between the expected behavior and the actual outcome becomes clear.

The expected scenario looks like this:

  1. You run pnpm install.
  2. pnpm analyzes the dependencies.
  3. pnpm sees that @redocly/cli depends on @redocly/respect-core.
  4. pnpm sees that @redocly/respect-core depends on better-ajv-errors.
  5. pnpm sees that better-ajv-errors requires ajv as a peer dependency.
  6. pnpm somehow ensures that ajv is available, and the install completes without errors.

In the real world with the current setup, step 6 doesn't happen automatically, and the install fails.

Troubleshooting and Potential Solutions

Alright, let's get down to the nitty-gritty and discuss some potential fixes and workarounds for this ajv dependency issue. There are a few approaches you can try, and the best one for you might depend on your specific project setup and constraints.

1. Adding ajv as a Direct Dependency

The simplest solution (and often the best) is to add ajv as a direct dependency to the package where you're using @redocly/cli. This ensures that ajv is explicitly installed and available. You can do this by running pnpm add ajv (or npm install ajv, or yarn add ajv, depending on your package manager) in the same directory where you've installed @redocly/cli.

This is a straightforward fix because it directly satisfies the unmet peer dependency. However, it might not be the cleanest solution, because ajv is technically a dependency of better-ajv-errors, not the main package. But, it gets the job done and makes sure your build can proceed.

2. Using a pnpm Overrides

pnpm (and other package managers) allows you to override dependencies. You can configure pnpm to force the use of a specific version of a dependency, or to make a dependency available to another package. This approach might involve modifying your pnpm-workspace.yaml file.

packages:
  - 'packages/*'
  - 'apps/*'
strictPeerDependencies: true
overrides:
  ajv: ^8.0.0 # Or the version required by better-ajv-errors

Using overrides can solve the immediate problem by forcing the correct version of ajv to be available. However, be cautious with overrides. They can make your dependency graph more complex and harder to understand.

3. Contacting the Package Maintainers

This is often a good idea, particularly if you can't resolve the issue yourself or if you suspect there's a problem with the way a package handles its dependencies. Reach out to the maintainers of @redocly/respect-core or better-ajv-errors. Explain the issue and suggest that they consider adding ajv as a regular dependency (instead of a peer dependency) or making sure that the peer dependency is correctly handled.

By reporting the problem, you help improve the package for everyone. It's a key part of the open-source community, and it helps ensure the project remains compatible with various setups and workflows.

4. Temporary Workarounds

If you need a quick fix to unblock your builds, there are a couple of temporary workarounds you could consider, although these are not ideal long-term solutions.

  • Disable strictPeerDependencies: This is the easiest, but also the least desirable, solution. Disabling strictPeerDependencies will likely allow the installation to succeed. However, this weakens your dependency management and opens the door to potential problems.
  • Try a different package manager: While not a real solution, trying a different package manager (like npm or yarn) might work, as they handle peer dependencies differently. But, this isn't a guarantee and it could introduce its own issues.

Key Takeaways and Best Practices

Let's wrap things up with a few key takeaways and best practices to help you manage peer dependencies and avoid similar issues in the future.

  • Understand Peer Dependencies: Always know what peer dependencies are and how they affect your project. Make sure you understand the difference between regular dependencies, peer dependencies, and dev dependencies.
  • Use strictPeerDependencies: As mentioned before, embrace the strictPeerDependencies: true setting. It will help maintain a clean dependency graph.
  • Keep Dependencies Updated: Keep your dependencies up-to-date. This includes regularly updating both direct and indirect dependencies to get the latest bug fixes, security patches, and features. Make sure you test the update properly to ensure it doesn't break your existing functionality.
  • Review Dependency Trees: Use tools to visualize your dependency tree (like pnpm why or npm list) to understand how packages are connected. This can help you identify potential problems early on.
  • Communicate with Maintainers: If you find issues, report them. Open issues, contribute fixes, and engage with the open-source community to improve the packages you rely on.

By following these best practices, you can build more robust, maintainable, and secure projects. Remember, handling peer dependencies correctly is crucial for smooth installations, especially in automated build environments. These tips will help you stay on top of your dependencies and make your builds far less frustrating!

I hope this guide helps you resolve the ajv dependency issue and keeps your @redocly/cli installations running smoothly. Happy coding, and may your builds always succeed!