Migrate to moon v2.0

To ease the migration process from moon v1 to v2, we've compiled a list of all breaking changes and important changes that you should be aware of. Please read through these carefully before upgrading your workspace.

To automate some of the migration process, we've created the moon migrate v2 command that will migrate all applicable settings in configuration files.

$ moon migrate v2

CLI

• Removed x86_64-apple-darwin (Apple Intel) as a supported operating system. Only aarch64-apple-darwin (Apple Silicon) is now supported.

Commands

• We've done a large polish pass for all commands, based on the CLI guidelines.
• Updated the moonx binary to use moon exec instead of moon run under the hood.
• Renamed all options and flags to kebab-case instead of camelCase.
  • Example: --logLevel -> --log-level
• Renamed options for all commands:
  • --platform -> --toolchain
• Removed commands:
  • moon node
  • moon migrate from-package-json (use the migrate-turborepo extension instead)
  • moon query hash (use moon hash instead)
  • moon query hash-diff (use moon hash instead)

moon action-graph

• Changed the output of --json to a new JSON structure (now matches the project and task graphs).

moon check

• Now runs moon exec under the hood, with some arguments/options pre-filled.
• If the project ID is not specifed, it will no longer find the closest project. Instead you must pass --closest.
• Renamed options:
  • --update-cache, -u -> --force, -f

moon ci

• Now runs moon exec under the hood, with some arguments/options pre-filled.
• Renamed options:
  • --update-cache, -u -> --force, -f

moon generate

• Changed the destination from a positional argument, to the --to option.
  • Example: moon generate <id> ./dist -> moon generate <id> --to ./dist

moon init

• Removed "scaffolding a toolchain" functionality from the command. Use the moon toolchain add command instead.
• Removed options:
  • --to (use a positional argument instead)

moon mcp

• Updated the get_projects tool to no longer have an includeTasks option.
• Updated the get_projects tool to return a list of project fragments, instead of the whole project object. This was required as the response was too large for MCP.
• Updated the get_tasks tool to return a list of task fragments, instead of the whole task object. This was required as the response was too large for MCP.

moon query projects

• Removed options:
  • --dependents

moon run

• Now runs moon exec under the hood, with some arguments/options pre-filled.
• Updated options:
  • --dependents now requires a value, either deep or direct
• Renamed options:
  • --update-cache, -u -> --force, -f
• Removed options:
  • --no-bail (use moon exec instead)
  • --profile
  • --remote (use --affected remote instead)

moon templates

• Changed the output to render a table instead of a list.

moon run

• Running a target without a scope no longer locates the closest project and instead uses the new default project feature. To run a target in the closets project, use ~: scope instead.
  • Example: moon run build -> moon run ~:build

Workspace

Configuration: .moon/workspace.*

• Renamed setting values:
  • codeowners.orderBy value project-name -> project-id
• Renamed settings:
  • codeowners.syncOnRun -> codeowners.sync
  • constraints.enforceProjectTypeRelationships -> constraints.enforceLayerRelationships
  • docker.prune.installToolchainDeps -> docker.prune.installToolchainDependencies
  • docker.scaffold.include -> docker.scaffold.configsPhaseGlobs
  • runner -> pipeline
  • unstable_remote -> remote
  • vcs.manager -> vcs.client
  • vcs.syncHooks -> vcs.sync
• Removed settings:
  • docker.scaffold.copyToolchainFiles
  • experiments.*
  • hasher.batchSize
  • pipeline.archivableTargets

Toolchains

Configuration: .moon/toolchain.*

• This file was renamed to .moon/toolchains.* (plural) to reflect that multiple toolchains are configured. This also aligns with the new .moon/extensions.* file.
• All toolchains have been stabilized, so the unstable_ prefix must be removed from identifiers.

JavaScript

The bun, deno, and node toolchains now require the javascript toolchain to be defined as well. All shared settings have been moved to the javascript toolchain.

In addition, all node package managers are no longer nested under the node toolchain, but are now top-level settings. These are only required when the javascript.packageManager setting is defined.

• Moved settings:
  • bun.dependencyVersionFormat -> javascript.dependencyVersionFormat
  • bun.inferTasksFromScripts -> javascript.inferTasksFromScripts
  • bun.rootPackageOnly -> javascript.rootPackageDependenciesOnly
  • bun.syncProjectWorkspaceDependencies -> javascript.syncProjectWorkspaceDependencies
  • node.dependencyVersionFormat -> javascript.dependencyVersionFormat
  • node.dedupeOnLockfileChange -> javascript.dedupeOnLockfileChange
  • node.inferTasksFromScripts -> javascript.inferTasksFromScripts
  • node.packageManager -> javascript.packageManager
  • node.rootPackageOnly -> javascript.rootPackageDependenciesOnly
  • node.syncPackageManagerField -> javascript.syncPackageManagerField
  • node.syncProjectWorkspaceDependencies -> javascript.syncProjectWorkspaceDependencies
  • node.bun -> bun
  • node.npm -> npm
  • node.pnpm -> pnpm
  • node.yarn -> yarn
• Renamed settings:
  • node.binExecArgs -> node.executeArgs
• Removed settings:
  • bun.packagesRoot
  • deno.depsFile
  • deno.lockfile
  • node.addEnginesConstraint
  • node.packagesRoot

.moon/toolchains.yml

# Before
node:
  version: '22.14.0'
  packageManager: 'yarn'
  inferTasksFromScripts: false
  syncPackageManagerField: true
  syncProjectWorkspaceDependencies: true
  yarn:
    version: '4.8.0'

# After
javascript:
  packageManager: 'yarn'
  inferTasksFromScripts: false
  syncPackageManagerField: true
  syncProjectWorkspaceDependencies: true

node:
  version: '22.14.0'

yarn:
  version: '4.8.0'

Extensions

Configuration: .moon/extensions.*

• The extensions setting from .moon/workspace.* has been moved (and flattened) to its own file, .moon/extensions.*.
• The built-in extensions download, migrate-nx, and migrate-turborepo must now be enabled in the configuration file before they can be used. Simply set an empty object.
  • This change was made to reduce the number of extensions that are loaded by default, improving performance.

.moon/extensions.yml

download: {}

migrate-nx: {}

Project

Configuration: moon.*

• Renamed settings:
  • docker.scaffold.include -> docker.scaffold.sourcesPhaseGlobs
  • project.name -> project.title
  • type -> layer
  • toolchain -> toolchains
  • platform -> toolchains.default
• Removed settings:
  • project.metadata
  • toolchain.*.disabled

Language detection

The primary language is now detected from toolchains, instead of being a hardcoded implementation. The result may now differ, as the first toolchain in the list will be used. Additionally, languages that don't have a toolchain yet, like PHP or Ruby, will not be detected and must be explicitly configured.

moon.yml

# After
language: 'ruby'

Custom metadata

The project.metadata setting has been removed, but all custom metadata fields can now be defined at the root of the project setting.

moon.yml

# Before
project:
  metadata:
    customField: 'value'

# After
project:
  customField: 'value'

Toolchain disabling

The toolchain.*.disabled setting was removed. Instead set the toolchain itself to null/false.

moon.yml

# Before
toolchain:
  typescript:
    disabled: true

# After
toolchains:
  typescript: null

Tasks

Configuration: moon.*, .moon/tasks

• The file .moon/tasks.yml has been removed. If you want to support tasks that are inherited by all projects, then move this to .moon/tasks/all.yml and do not configure the new inheritedBy setting.
• Renamed tokens:
  • $projectName -> $projectTitle
  • $projectType -> $projectLayer
  • $taskPlatform -> $taskToolchain
• Renamed settings:
  • tasks.*.local -> tasks.*.preset using server value
  • tasks.*.platform -> tasks.*.toolchains
• Removed setting values:
  • tasks.*.preset value watcher
• Changed option defaults:
  • tasks.*.options.envFile now defaults to a list of files, instead of a single file, when true. Refer to the blog post for more information.
  • tasks.*.options.inferInputs now defaults to false instead of true.
  • tasks.*.options.shell now defaults to true instead of false.
  • tasks.*.options.unixShell now defaults to bash instead of nothing.
  • tasks.*.options.windowsShell now defaults to pwsh instead of nothing.

Local mode

The local task setting has been removed as the name was confusing. Users assumed it meant "only run locally", but it actually meant "this is a persistent server that should only run locally". Instead, use the preset setting with a value of server.

moon.yml

# Before
tasks:
  dev:
    command: 'start-dev'
    local: true

# Before
tasks:
  dev:
    command: 'start-dev'
    preset: 'server'

If you want a task that is simply "local only" without other options changes, use options.runInCI directly.

moon.yml

tasks:
  dev:
    command: 'start-dev'
    options:
      runInCI: false

Shells by default

Tasks now run in a shell by default, and will use Bash on Unix (options.unixShell), and pwsh on Windows (options.windowsShell). You can disable this behavior by setting options.shell to false.

moon.yml

tasks:
  dev:
    command: 'start-dev'
    options:
      shell: false

Env var substitution behavior

The syntax and behavior for substituting (expanding/interpolation) environment variables has changed, to better align with the standard of .env files. The biggest change is that flagless tokens ($VAR) and ? flag tokens ($VAR?) swapped functionality. Refer to the following table:

Syntax	v1	v2
$VAR	Substitute with variable syntax ($VAR) if variable empty	💥 Substitute with empty string if variable empty
$VAR!	Don't substitute and keep variable syntax ($VAR)	💥 Removed syntax
$VAR?	Substitute with empty string if variable empty	💥 Removed syntax
${VAR}	Substitute with variable syntax ($VAR) if variable empty	💥 Substitute with empty string if variable empty
${VAR!}	Don't substitute and keep variable syntax ($VAR)	~
${VAR?}	Substitute with empty string if variable empty	💥 Substitute with variable syntax ($VAR) if variable empty
${VAR:default}	Use default value if variable empty	~
${VAR:-default}, ${VAR-default}	⛔️ Not supported	Use default value if variable empty
${VAR:+alternate}, ${VAR+alternate}	⛔️ Not supported	Use alternate value if variable non-empty

Legend:

• ~ indicates the syntax/functionality is the same as v1
• 💥 indicates breaking change
• ⛔️ indicates not supported

Env var precedence

The order of precedence for environment variables has slightly changed when running tasks, as it was confusing to users. The new order of precedence is as follows, from lowest to highest tier, with the latter overwriting the former:

• Task .env files
  • via options.envFile
• Task env variables
  • via env or deps.*.env
• System variables
  • via profile scripts (.bashrc, .zshrc, etc)
  • via command line: KEY=value moon ...

In regards to variable substitution, each tier can reference variables within the same tier, or the higher tier(s), but not from lower tier(s). This is because variables are processed in reverse order. Refer to the following table:

Tier	Can reference	Evaluated during
Dotenv	Dotenv, Task, System	Before task execution
Task	Task, System	After task creation
System	System	CLI startup

If you don't want to inherit a system variable, you can override it in the task with a null value.

tasks:
  dev:
    env:
      EXAMPLE: null

Deferred .env files

In v1, when options.envFile was enabled, the .env file(s) were loaded at the time of task creation, during the building of project/task graphs. This meant that if the .env file changed between the time of graph creation and task execution, the changes would not be reflected.

In v2 and later, .env files are loaded just before task execution, ensuring that any changes to the file are picked up.

caution

Because of this change, task env variables will continue to override .env file variables, BUT can no longer reference them for substitution. This is because the .env files are loaded later in the process.

Other changes

• When options.affectedFiles is enabled, the list of files will be joined with the OS path separator (: on Unix, ; on Windows) instead of a comma (,) when passed as the MOON_AFFECTED_FILES environment variable.

Task inheritance

Deep merged instead of shallow merged

In v1, when inheriting tasks, all global configs (those in .moon) were shallow merged into a single config ignoring merge task options, and then merged with the local config (moon.*) using merge task options. This was not intuitive, as users expected all configs to be merged in sequence. To demonstrate this, take the following example configs, in order of inherited:

# .moon/tasks.yml
tasks:
  build:
    command: 'build --cache'
    options:
      mutex: 'build'

# .moon/tasks/tag-a.yml
tasks:
  build:
    args: '--force'

# .moon/tasks/tag-b.yml
tasks:
  build:
    args: '--clean'

Users would expect the final build task to be build --cache --force --clean with the mutex option set. However, since the tasks setting was shallow merged, only the last config (tag-b) would be used, resulting in the task being noop --clean without the mutex. The noop pops up because the command setting was not configured in the last config.

To remedy this, and to improve task composition overall, global configs are no longer shallow merged into a single config before merging with the local config. Instead, all configs are merged in sequence, while respecting the task merge options. This is the order of operations for the new system:

• Load all global configs (.moon) into a list, in order, based on the inheritedBy setting.
• Load the local config (moon.*).
• Create an inheritance chain by resolving global configs first, then the local config last, while respecting extend and other composition settings.
• Merge all task options in order, to create the final task options.
• Merge all tasks in order, using the final task options to guide the merging behavior.

File groups are merged

Because of the new deep merging behavior, file groups defined in inherited configs are now merged together, instead of being replaced by the following config in the sequence. For example, given the configs:

# .moon/tasks/tag-a.yml
fileGroups:
  sources:
    - 'src/**'

# .moon/tasks/tag-b.yml
fileGroups:
  sources:
    - 'docs/**'

In v1, the final sources file group would only include docs/**, as the second config would replace the first. In v2, the final sources file group includes both src/** and docs/**.

VCS

New hooks system

We've rewritten our Git hooks from the ground up to be based around the core.hooksPath setting. The following changes have been made:

• We no longer write hooks to the .git/hooks directory.
• Instead, all hooks are written to .moon/hooks and Git is configured to use this directory.
• Bash scripts no longer end in .sh.

caution

We currently don't have an easy way to clean the previous implementation of hooks. You may need to manually remove the old scripts from .git/hooks and .moon/hooks if they are causing issues.

Other changes

Changed (touched) files

We renamed the terminology "touched files" to "changed files" throughout the codebase and documentation. This better aligns with common VCS terminology and reduces confusion. Because of this, the following changes were made:

• Renamed the moon query touched-files CLI command to moon query changed-files.
• Renamed the get_touched_files MCP tool to get_changed_files.
• Renamed the touchedFiles run report field to changedFiles.

# Before
$ moon query touched-files

# After
$ moon query changed-files

Docker

• The scaffolded .moon/docker/workspace directory was renamed to .moon/docker/configs.
• The moon docker file command will now loop through all toolchains and use the first image found, otherwise it defaults to "scratch". If you want to be explicit, set the docker.file.image setting.

Query language (MQL)

• Renamed fields:
  • projectName -> projectId
  • projectType -> projectLayer
  • taskPlatform -> taskToolchain

# Before
projectType=application && taskPlatform=node

# After
projectLayer=application && taskToolchain=node

Webhooks

• Removed the tool.* events. Use toolchain.* events instead.
• Removed the runtime field from dependencies.* events. Use the toolchain field instead.