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12 <h1><a href="../cli/npm-shrinkwrap.html">npm-shrinkwrap</a></h1> <p>Lock down dependency versions</p>
13 <h2 id="synopsis">SYNOPSIS</h2>
14 <pre><code>npm shrinkwrap
15 </code></pre><h2 id="description">DESCRIPTION</h2>
16 <p>This command locks down the versions of a package's dependencies so
17 that you can control exactly which versions of each dependency will be
18 used when your package is installed. The <code>package.json</code> file is still
19 required if you want to use <code>npm install</code>.</p>
20 <p>By default, <code>npm install</code> recursively installs the target's
21 dependencies (as specified in <code>package.json</code>), choosing the latest
22 available version that satisfies the dependency's semver pattern. In
23 some situations, particularly when shipping software where each change
24 is tightly managed, it's desirable to fully specify each version of
25 each dependency recursively so that subsequent builds and deploys do
26 not inadvertently pick up newer versions of a dependency that satisfy
27 the semver pattern. Specifying specific semver patterns in each
28 dependency's <code>package.json</code> would facilitate this, but that's not always
29 possible or desirable, as when another author owns the npm package.
30 It's also possible to check dependencies directly into source control,
31 but that may be undesirable for other reasons.</p>
32 <p>As an example, consider package A:</p>
34 "name": "A",
35 "version": "0.1.0",
36 "dependencies": {
37 "B": "<0.1.0"
40 </code></pre><p>package B:</p>
42 "name": "B",
43 "version": "0.0.1",
44 "dependencies": {
45 "C": "<0.1.0"
48 </code></pre><p>and package C:</p>
50 "name": "C",
51 "version": "0.0.1"
53 </code></pre><p>If these are the only versions of A, B, and C available in the
54 registry, then a normal <code>npm install A</code> will install:</p>
58 </code></pre><p>However, if B@0.0.2 is published, then a fresh <code>npm install A</code> will
63 </code></pre><p>assuming the new version did not modify B's dependencies. Of course,
64 the new version of B could include a new version of C and any number
65 of new dependencies. If such changes are undesirable, the author of A
66 could specify a dependency on B@0.0.1. However, if A's author and B's
67 author are not the same person, there's no way for A's author to say
68 that he or she does not want to pull in newly published versions of C
69 when B hasn't changed at all.</p>
70 <p>In this case, A's author can run</p>
71 <pre><code>npm shrinkwrap
72 </code></pre><p>This generates <code>npm-shrinkwrap.json</code>, which will look something like this:</p>
74 "name": "A",
75 "version": "0.1.0",
76 "dependencies": {
78 "version": "0.0.1",
79 "dependencies": {
81 "version": "0.0.1"
87 </code></pre><p>The shrinkwrap command has locked down the dependencies based on
88 what's currently installed in node_modules. When <code>npm install</code>
89 installs a package with an <code>npm-shrinkwrap.json</code> in the package
90 root, the shrinkwrap file (rather than <code>package.json</code> files) completely
91 drives the installation of that package and all of its dependencies
92 (recursively). So now the author publishes A@0.1.0, and subsequent
93 installs of this package will use B@0.0.1 and C@0.0.1, regardless the
94 dependencies and versions listed in A's, B's, and C's <code>package.json</code>
96 <h3 id="using-shrinkwrapped-packages">Using shrinkwrapped packages</h3>
97 <p>Using a shrinkwrapped package is no different than using any other
98 package: you can <code>npm install</code> it by hand, or add a dependency to your
99 <code>package.json</code> file and <code>npm install</code> it.</p>
100 <h3 id="building-shrinkwrapped-packages">Building shrinkwrapped packages</h3>
101 <p>To shrinkwrap an existing package:</p>
103 <li>Run <code>npm install</code> in the package root to install the current
104 versions of all dependencies.</li>
105 <li>Validate that the package works as expected with these versions.</li>
106 <li>Run <code>npm shrinkwrap</code>, add <code>npm-shrinkwrap.json</code> to git, and publish
109 <p>To add or update a dependency in a shrinkwrapped package:</p>
111 <li>Run <code>npm install</code> in the package root to install the current
112 versions of all dependencies.</li>
113 <li>Add or update dependencies. <code>npm install</code> each new or updated
114 package individually and then update <code>package.json</code>. Note that they
115 must be explicitly named in order to be installed: running <code>npm
116 install</code> with no arguments will merely reproduce the existing
118 <li>Validate that the package works as expected with the new
120 <li>Run <code>npm shrinkwrap</code>, commit the new <code>npm-shrinkwrap.json</code>, and
121 publish your package.</li>
123 <p>You can use <a href="../cli/npm-outdated.html">npm-outdated(1)</a> to view dependencies with newer versions
125 <h3 id="other-notes">Other Notes</h3>
126 <p>A shrinkwrap file must be consistent with the package's <code>package.json</code>
127 file. <code>npm shrinkwrap</code> will fail if required dependencies are not
128 already installed, since that would result in a shrinkwrap that
129 wouldn't actually work. Similarly, the command will fail if there are
130 extraneous packages (not referenced by <code>package.json</code>), since that would
131 indicate that <code>package.json</code> is not correct.</p>
132 <p>Since <code>npm shrinkwrap</code> is intended to lock down your dependencies for
133 production use, <code>devDependencies</code> will not be included unless you
134 explicitly set the <code>--dev</code> flag when you run <code>npm shrinkwrap</code>. If
135 installed <code>devDependencies</code> are excluded, then npm will print a
136 warning. If you want them to be installed with your module by
137 default, please consider adding them to <code>dependencies</code> instead.</p>
138 <p>If shrinkwrapped package A depends on shrinkwrapped package B, B's
139 shrinkwrap will not be used as part of the installation of A. However,
140 because A's shrinkwrap is constructed from a valid installation of B
141 and recursively specifies all dependencies, the contents of B's
142 shrinkwrap will implicitly be included in A's shrinkwrap.</p>
143 <h3 id="caveats">Caveats</h3>
144 <p>If you wish to lock down the specific bytes included in a package, for
145 example to have 100% confidence in being able to reproduce a
146 deployment or build, then you ought to check your dependencies into
147 source control, or pursue some other mechanism that can verify
148 contents rather than versions.</p>
149 <h2 id="see-also">SEE ALSO</h2>
151 <li><a href="../cli/npm-install.html">npm-install(1)</a></li>
152 <li><a href="../files/package.json.html">package.json(5)</a></li>
153 <li><a href="../cli/npm-ls.html">npm-ls(1)</a></li>
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167 <p id="footer">npm-shrinkwrap — npm@2.14.4</p>