README.md

lerna-semver-sync

Problem

Lerna seems to have some trouble with different dependency versions, even if they both "resolve" to the same version. For example, both ^4.1.0 and ^4.2.0 may end up installing 4.5.6, but Lerna doesn't de-duplicate the dependencies because the semver declaration is not identical. This leads to slower install times, particularly in a CI/CD environment where this is done many times per day.

Solution

For each package, collect the different dependency version declarations. Then find the intersection of those declared ranges for each dependency. Modify the package.json for each package in your monorepo to be that common semver declaration.

Notes

• ^4.1.0 and ^4.2.0 would be modified to all be ^4.2.0
• ^3.1.0, ~3.7.0, and ^3.6.0 would be modified to all be ~3.7.0
• ~3.6.0 and ~3.8.0 are incompatible and an error is thrown Range >=3.8.0 is not compatible with <3.7.0
• Exact ranges are kept unaltered. 4.0.0 and ^4.0.0 will not de-duplicate to 4.0.0
• Each component of a compound ranges separated by || are de-duplicated separately and must have a unique major version number. For example, ~0.14.0 || ^15.0.0 || ^16.0.0 is fine, ~15.0.0 || ~15.5.0 will throw an error.

Note that you'll want to verify the changes (git diff, etc.). You may want to relax some changes manually rather than modify all your dependency versions. In the above example, maybe ~3.7.0 is better off as ^3.7.0.

Before

// packages/foo/package.json         // packages/bar/package.json                // packages/baz/package.json
{                                    {                                           {
  "dependencies": {                    "dependencies": {                           "dependencies": {
    "classnames": "^2.3.6",              "classnames": "^2.3.0",                     "classnames": "^2.0.0",
    "create-react-class": "^15.0.0",     "create-react-class": "^15.5.0",            "create-react-class": "^15.5.1",
    "debug": "^2.1.1",                   "debug": "^2.0.0",                          "debug": "^2.0.0",
    "immutable": "^3.6.4",               "immutable": "~3.6.0",                      "immutable": "^3.6.0",
    "prop-types": "^15.5.8",             "prop-types": "^15.5.0",                    "prop-types": "^15.5.0",
    "react-intl": "^2.0.0",              "react-intl": "^2.0.0 || 2.0.0-beta.1",     "react-intl": "^2.0.0",
    "sinon": "^1.17.7",                  "sinon": "^1.0.2"                           "sinon": "^1.0.0",
  }                                    }                                           }
}                                    }                                           }

After

// packages/foo/package.json         // packages/bar/package.json                // packages/baz/package.json
{                                    {                                           {
  "dependencies": {                    "dependencies": {                           "dependencies": {
    "classnames": "^2.3.6",              "classnames": "^2.3.6",                     "classnames": "^2.3.6",
    "create-react-class": "^15.5.2",     "create-react-class": "^15.5.2",            "create-react-class": "^15.5.2",
    "debug": "^2.1.1",                   "debug": "^2.1.1",                          "debug": "^2.1.1",
    "immutable": "~3.6.4",               "immutable": "~3.6.4",                      "immutable": "~3.6.4",
    "prop-types": "^15.5.8",             "prop-types": "^15.5.8",                    "prop-types": "^15.5.8",
    "react-intl": "^2.0.0",              "react-intl": "^2.0.0 || 2.0.0-beta.1",     "react-intl": "^2.0.0",
    "sinon": "^1.17.7"                   "sinon": "^1.17.7"                          "sinon": "^1.17.7"
  }                                    }                                           }
}                                    }                                           }

Use

A script, lerna-semver-sync.js should be available in your node_modules/.bin folder. Running it will clean up all the duplicate versions it can, then output any that it couldn't de-duplicate.

$ ./node_modules/bin/lerna-semver-sync.js
The following packages have duplicate versions that I can't de-duplicate
classnames: ^2.2.5, ^1.0.0
react-intl: ^2.0.0 || 2.0.0-beta-1, ^2.0.0
react-addons-perf: ~0.14.0 || ^15.0.0, ^15.0.0
react-addons-pure-render-mixin: ~0.14.3 || ^15.0.0, ^15.0.0
react-addons-shallow-compare: ~0.14.0 || ^15.0.0, ^15.0.0