Changeset Fails On Ignore Pattern: How To Fix It?

by Alex Johnson 50 views

Have you ever encountered a situation where your changeset fails due to an ignore pattern, even when there are no matching files? This can be a frustrating issue, especially when you're trying to automate your release process. In this article, we'll explore a common scenario involving Prisma and changesets, and we'll discuss a proposed solution to address this problem.

Understanding the Issue

Let's dive into the details. Imagine you're using Prisma, a popular ORM, in your project. Prisma generates nested subfolders, including a package.json file, during the prisma generate command, which you might run as part of your postinstall script. These generated folders are often gitignored because they are automatically created and shouldn't be tracked in your repository.

The challenge arises when you use changesets, a tool for managing versioning and releases in monorepos. Your changeset configuration might include an ignore pattern to prevent changes in certain directories from triggering a new release. However, the changeset bot, which runs in your CI/CD environment, might not execute the postinstall script, meaning the Prisma-generated folders don't exist when the bot runs. This leads to a situation where the ignore pattern fails because it can't find any matching directories, even though you intend to ignore them.

This issue is exemplified in the following configuration snippet:

{
  "$schema": "https://unpkg.com/@changesets/config@3.1.1/schema.json",
  "changelog": "@changesets/cli/changelog",
  "commit": false,
  "privatePackages": {
    "version": true,
    "tag": true
  },
  "fixed": [],
  "linked": [],
  "access": "restricted",
  "baseBranch": "main",
  "updateInternalDependencies": "patch",
  "ignore": ["prisma-client-*"]
}

In this configuration, the ignore pattern "prisma-client-*" is intended to prevent changes within Prisma client directories from triggering a release. However, if these directories don't exist during the changeset bot's execution, the process will fail, as shown in the following error message:

[Error Image]

This error indicates that the changeset process expects the ignored paths to exist, which is not always the case, especially in CI/CD environments where dependencies might not be fully installed before the changeset bot runs.

Diving Deeper: Why This Happens

To truly grasp the issue, let's break down the sequence of events and the underlying reasons for this behavior:

  1. Prisma Generation: The prisma generate command, typically executed during postinstall, creates the Prisma client directories and their contents, including the package.json file.
  2. Gitignore: These generated directories are usually added to .gitignore to prevent them from being tracked in the repository, as they are generated artifacts.
  3. Changeset Configuration: The changeset config includes an ignore pattern that mirrors the intent of .gitignore, aiming to exclude these directories from triggering releases.
  4. CI/CD Execution: The changeset bot runs in the CI/CD environment, often before or without a full npm install or yarn install. This means the postinstall script, and therefore prisma generate, might not have been executed.
  5. Missing Directories: As a result, the directories targeted by the ignore pattern don't exist on the filesystem when the changeset bot runs.
  6. Changeset Failure: The changeset process, expecting these directories to exist based on the ignore pattern, fails because it cannot find them.

The core problem here is a mismatch between the environment in which changesets are evaluated and the environment in which the ignored directories are created. Locally, developers typically have the generated directories present, so the issue doesn't manifest. However, in CI/CD, the environment is often cleaner, and the generated directories might be missing.

This behavior highlights a fundamental assumption within the changeset process: that ignored paths should exist. While this assumption might hold true in many cases, it breaks down when dealing with generated directories or other scenarios where paths are conditionally present.

Real-World Implications

The consequences of this issue can be significant, especially in large monorepos with complex build and deployment pipelines. A failing changeset process can block releases, disrupt CI/CD workflows, and ultimately delay the delivery of new features and bug fixes.

Imagine a scenario where a team has just merged a critical bug fix into the main branch. The CI/CD pipeline kicks off, but the changeset bot fails due to this ignore pattern issue. The release is blocked, and the bug fix cannot be deployed to production. This can lead to frustrated users and potential business impact.

Furthermore, this issue can be challenging to debug and resolve, particularly for developers who are not intimately familiar with the intricacies of changesets and Prisma. The error message itself might not be immediately clear, and the root cause—the mismatch between environments—can be difficult to pinpoint.

To mitigate these risks, it's crucial to understand the underlying cause of the issue and implement a robust solution that addresses the problem without introducing new complexities.

Proposed Solution

The proposed solution is straightforward yet effective: the ignore configuration in changesets should not fail if the specified paths do not have a match. In other words, if a pattern in the ignore array doesn't find any corresponding files or directories, the process should continue without throwing an error.

This approach aligns with the intent of the ignore option, which is to exclude certain paths from consideration. If a path doesn't exist, it's already effectively excluded, so there's no need to raise an error.

Benefits of the Solution

This solution offers several key benefits:

  • Resilience: It makes the changeset process more resilient to variations in the environment. Whether the ignored directories exist or not, the process will continue smoothly.
  • Simplicity: It's a simple and intuitive fix that doesn't require complex workarounds or configuration changes.
  • Consistency: It aligns with the behavior of other tools and systems that use ignore patterns, such as Git, which don't typically fail if an ignored path doesn't exist.

Implementation Considerations

Implementing this solution would likely involve modifying the changeset CLI to handle cases where ignored paths are not found. This could be achieved by wrapping the file system operations that check for ignored paths in a try-catch block or by adding a conditional check to ensure that a path exists before attempting to access it.

The change should be implemented in a way that doesn't introduce any performance regressions or unexpected side effects. Thorough testing would be essential to ensure that the fix works as expected in various scenarios.

Alternatives Considered

While the proposed solution is the most direct and intuitive, there are alternative approaches that could be considered:

  1. Ensure Directories Exist: One alternative would be to ensure that the ignored directories always exist during the changeset process. This could involve adding a step to the CI/CD pipeline to run prisma generate before running the changeset bot.

    However, this approach has several drawbacks. It adds complexity to the CI/CD configuration, increases the build time, and might not be feasible in all environments. It also tightly couples the changeset process to the Prisma generation step, which might not be desirable.

  2. Conditional Ignore Patterns: Another option would be to allow conditional ignore patterns, where patterns are only applied if certain conditions are met (e.g., if a directory exists).

    While this approach is more flexible, it also adds complexity to the configuration and the changeset CLI. It would require a new syntax for specifying conditions and could make the configuration harder to understand and maintain.

Compared to these alternatives, the proposed solution—making the ignore pattern non-fatal—is the simplest, most robust, and least intrusive.

Practical Steps to Implement the Solution

While the ultimate solution lies in a code change within the changesets CLI, there are practical steps you can take in the meantime to mitigate this issue in your projects.

1. Modify Your CI/CD Pipeline

One immediate workaround is to ensure that the prisma generate command is executed before the changeset bot runs in your CI/CD pipeline. This will guarantee that the ignored directories exist, preventing the error.

Here's an example of how you might modify your pipeline:

steps:
  - name: Checkout code
    uses: actions/checkout@v3

  - name: Set up Node.js
    uses: actions/setup-node@v3
    with:
      node-version: 16

  - name: Install dependencies
    run: npm install

  - name: Generate Prisma client
    run: npx prisma generate

  - name: Run changesets
    run: npx changeset version

In this example, the Generate Prisma client step explicitly runs npx prisma generate before the Run changesets step. This ensures that the Prisma client directories are present when changesets are evaluated.

2. Use a Shell Script Wrapper

Another approach is to wrap the changeset command in a shell script that checks for the existence of the ignored directories and creates them if they are missing.

Here's an example of such a script:

#!/bin/bash

# Check if the prisma client directory exists
if [ ! -d "prisma-client-foo" ]; then
  # Create the directory if it doesn't exist
  mkdir -p prisma-client-foo
  # Optionally, create a dummy package.json file
  touch prisma-client-foo/package.json
fi

# Run the changeset command
npx changeset version

This script checks for the existence of the prisma-client-foo directory and creates it if it's missing. It also creates a dummy package.json file inside the directory, which might be necessary depending on your changeset configuration.

3. Contribute to Changesets

The most impactful step you can take is to contribute to the changesets project itself. If you're comfortable with JavaScript and open-source development, consider submitting a pull request that implements the proposed solution.

This will not only fix the issue for your project but also benefit the entire changesets community.

Conclusion

The issue of changesets failing due to ignore patterns when there are no matches can be a significant hurdle in monorepo management. However, by understanding the root cause and implementing the proposed solution, you can create a more resilient and efficient release process.

Whether you choose to modify your CI/CD pipeline, use a shell script wrapper, or contribute to the changesets project, taking action to address this issue will ultimately save you time and frustration in the long run.

By making the changeset ignore pattern non-fatal, we can ensure that the tool works seamlessly in various environments, regardless of whether the ignored paths exist or not. This will lead to a smoother and more reliable release process for everyone.

For more information about changesets and its configuration options, you can visit the official Changesets documentation.