<!DOCTYPE HTML> <html lang="en"> <head> <meta charset="UTF-8"> <title>Source Replacement - The Cargo Book</title> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> <meta name="description" content=""> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="theme-color" content="#ffffff" /> <base href="../"> <link rel="stylesheet" href="book.css"> <link href="https://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800" rel="stylesheet" type="text/css"> <link href="https://fonts.googleapis.com/css?family=Source+Code+Pro:500" rel="stylesheet" type="text/css"> <link rel="shortcut icon" href="favicon.png"> <!-- Font Awesome --> <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css"> <link rel="stylesheet" href="highlight.css"> <link rel="stylesheet" href="tomorrow-night.css"> <link rel="stylesheet" href="ayu-highlight.css"> <!-- Custom theme --> <!-- Fetch Clipboard.js from CDN but have a local fallback --> <script src="https://cdn.jsdelivr.net/clipboard.js/1.6.1/clipboard.min.js"></script> <script> if (typeof Clipboard == 'undefined') { document.write(unescape("%3Cscript src='clipboard.min.js'%3E%3C/script%3E")); 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} catch(e) { } sidebar = sidebar || 'visible'; } document.querySelector('html').classList.add("sidebar-" + sidebar); </script> <nav id="sidebar" class="sidebar" aria-label="Table of contents"> <ol class="chapter"><li class="affix"><a href="index.html">Introduction</a></li><li><a href="getting-started/index.html"><strong aria-hidden="true">1.</strong> Getting Started</a></li><li><ol class="section"><li><a href="getting-started/installation.html"><strong aria-hidden="true">1.1.</strong> Installation</a></li><li><a href="getting-started/first-steps.html"><strong aria-hidden="true">1.2.</strong> First Steps with Cargo</a></li></ol></li><li><a href="guide/index.html"><strong aria-hidden="true">2.</strong> Cargo Guide</a></li><li><ol class="section"><li><a href="guide/why-cargo-exists.html"><strong aria-hidden="true">2.1.</strong> Why Cargo Exists</a></li><li><a href="guide/creating-a-new-project.html"><strong aria-hidden="true">2.2.</strong> Creating a New Project</a></li><li><a href="guide/working-on-an-existing-project.html"><strong aria-hidden="true">2.3.</strong> Working on an Existing Project</a></li><li><a href="guide/dependencies.html"><strong aria-hidden="true">2.4.</strong> Dependencies</a></li><li><a href="guide/project-layout.html"><strong aria-hidden="true">2.5.</strong> Project Layout</a></li><li><a href="guide/cargo-toml-vs-cargo-lock.html"><strong aria-hidden="true">2.6.</strong> Cargo.toml vs Cargo.lock</a></li><li><a href="guide/tests.html"><strong aria-hidden="true">2.7.</strong> Tests</a></li><li><a href="guide/continuous-integration.html"><strong aria-hidden="true">2.8.</strong> Continuous Integration</a></li><li><a href="guide/build-cache.html"><strong aria-hidden="true">2.9.</strong> Build Cache</a></li></ol></li><li><a href="reference/index.html"><strong aria-hidden="true">3.</strong> Cargo Reference</a></li><li><ol class="section"><li><a href="reference/specifying-dependencies.html"><strong aria-hidden="true">3.1.</strong> Specifying Dependencies</a></li><li><a href="reference/manifest.html"><strong aria-hidden="true">3.2.</strong> The Manifest Format</a></li><li><a href="reference/config.html"><strong aria-hidden="true">3.3.</strong> Configuration</a></li><li><a href="reference/environment-variables.html"><strong aria-hidden="true">3.4.</strong> Environment Variables</a></li><li><a href="reference/build-scripts.html"><strong aria-hidden="true">3.5.</strong> Build Scripts</a></li><li><a href="reference/publishing.html"><strong aria-hidden="true">3.6.</strong> Publishing on crates.io</a></li><li><a href="reference/pkgid-spec.html"><strong aria-hidden="true">3.7.</strong> Package ID Specifications</a></li><li><a href="reference/source-replacement.html" class="active"><strong aria-hidden="true">3.8.</strong> Source Replacement</a></li><li><a href="reference/external-tools.html"><strong aria-hidden="true">3.9.</strong> External Tools</a></li></ol></li><li><a href="faq.html"><strong aria-hidden="true">4.</strong> FAQ</a></li></ol> </nav> <div id="page-wrapper" class="page-wrapper"> <div class="page"> <div id="menu-bar" class="menu-bar"> <div id="menu-bar-sticky-container"> <div class="left-buttons"> <button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar"> <i class="fa fa-bars"></i> </button> <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list"> <i class="fa fa-paint-brush"></i> </button> <ul id="theme-list" class="theme-popup" aria-label="submenu"> <li><button class="theme" id="light">Light <span class="default">(default)</span></button></li> <li><button class="theme" id="rust">Rust</button></li> <li><button class="theme" id="coal">Coal</button></li> <li><button class="theme" id="navy">Navy</button></li> <li><button class="theme" id="ayu">Ayu</button></li> </ul> </div> <h1 class="menu-title">The Cargo Book</h1> <div class="right-buttons"> <a href="print.html" title="Print this book" aria-label="Print this book"> <i id="print-button" class="fa fa-print"></i> </a> </div> </div> </div> <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM --> <script type="text/javascript"> document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible'); document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible'); Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) { link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1); }); </script> <div id="content" class="content"> <main> <a class="header" href="reference/source-replacement.html#source-replacement" id="source-replacement"><h2>Source Replacement</h2></a> <p>Cargo supports the ability to <strong>replace one source with another</strong> to express strategies along the lines of mirrors or vendoring dependencies. Configuration is currently done through the <a href="reference/config.html"><code>.cargo/config</code> configuration</a> mechanism, like so:</p> <pre><code class="language-toml"># The `source` table is where all keys related to source-replacement # are stored. [source] # Under the `source` table are a number of other tables whose keys are a # name for the relevant source. For example this section defines a new # source, called `my-awesome-source`, which comes from a directory # located at `vendor` relative to the directory containing this `.cargo/config` # file [source.my-awesome-source] directory = "vendor" # Git sources can optionally specify a branch/tag/rev as well git = "https://example.com/path/to/repo" # branch = "master" # tag = "v1.0.1" # rev = "313f44e8" # The crates.io default source for crates is available under the name # "crates-io", and here we use the `replace-with` key to indicate that it's # replaced with our source above. [source.crates-io] replace-with = "my-awesome-source" </code></pre> <p>With this configuration Cargo attempts to look up all crates in the directory "vendor" rather than querying the online registry at crates.io. Using source replacement Cargo can express:</p> <ul> <li> <p>Vendoring - custom sources can be defined which represent crates on the local filesystem. These sources are subsets of the source that they're replacing and can be checked into projects if necessary.</p> </li> <li> <p>Mirroring - sources can be replaced with an equivalent version which acts as a cache for crates.io itself.</p> </li> </ul> <p>Cargo has a core assumption about source replacement that the source code is exactly the same from both sources. In our above example Cargo assumes that all of the crates coming from <code>my-awesome-source</code> are the exact same as the copies from <code>crates-io</code>. Note that this also means that <code>my-awesome-source</code> is not allowed to have crates which are not present in the <code>crates-io</code> source.</p> <p>As a consequence, source replacement is not appropriate for situations such as patching a dependency or a private registry. Cargo supports patching dependencies through the usage of <a href="reference/manifest.html#the-replace-section">the <code>[replace]</code> key</a>, and private registry support is planned for a future version of Cargo.</p> <a class="header" href="reference/source-replacement.html#configuration" id="configuration"><h3>Configuration</h3></a> <p>Configuration of replacement sources is done through <a href="reference/config.html"><code>.cargo/config</code></a> and the full set of available keys are:</p> <pre><code class="language-toml"># Each source has its own table where the key is the name of the source [source.the-source-name] # Indicate that `the-source-name` will be replaced with `another-source`, # defined elsewhere replace-with = "another-source" # Available kinds of sources that can be specified (described below) registry = "https://example.com/path/to/index" local-registry = "path/to/registry" directory = "path/to/vendor" </code></pre> <p>The <code>crates-io</code> represents the crates.io online registry (default source of crates) and can be replaced with:</p> <pre><code class="language-toml">[source.crates-io] replace-with = 'another-source' </code></pre> <a class="header" href="reference/source-replacement.html#registry-sources" id="registry-sources"><h3>Registry Sources</h3></a> <p>A "registry source" is one that is the same as crates.io itself. That is, it has an index served in a git repository which matches the format of the <a href="https://github.com/rust-lang/crates.io-index">crates.io index</a>. That repository then has configuration indicating where to download crates from.</p> <p>Currently there is not an already-available project for setting up a mirror of crates.io. Stay tuned though!</p> <a class="header" href="reference/source-replacement.html#local-registry-sources" id="local-registry-sources"><h3>Local Registry Sources</h3></a> <p>A "local registry source" is intended to be a subset of another registry source, but available on the local filesystem (aka vendoring). Local registries are downloaded ahead of time, typically sync'd with a <code>Cargo.lock</code>, and are made up of a set of <code>*.crate</code> files and an index like the normal registry is.</p> <p>The primary way to manage and crate local registry sources is through the <a href="https://crates.io/crates/cargo-local-registry"><code>cargo-local-registry</code></a> subcommand, available on crates.io and can be installed with <code>cargo install cargo-local-registry</code>.</p> <p>Local registries are contained within one directory and contain a number of <code>*.crate</code> files downloaded from crates.io as well as an <code>index</code> directory with the same format as the crates.io-index project (populated with just entries for the crates that are present).</p> <a class="header" href="reference/source-replacement.html#directory-sources" id="directory-sources"><h3>Directory Sources</h3></a> <p>A "directory source" is similar to a local registry source where it contains a number of crates available on the local filesystem, suitable for vendoring dependencies. Also like local registries, directory sources can primarily be managed by an external subcommand, <a href="https://crates.io/crates/cargo-vendor"><code>cargo-vendor</code></a>, which can be installed with <code>cargo install cargo-vendor</code>.</p> <p>Directory sources are distinct from local registries though in that they contain the unpacked version of <code>*.crate</code> files, making it more suitable in some situations to check everything into source control. A directory source is just a directory containing a number of other directories which contain the source code for crates (the unpacked version of <code>*.crate</code> files). Currently no restriction is placed on the name of each directory.</p> <p>Each crate in a directory source also has an associated metadata file indicating the checksum of each file in the crate to protect against accidental modifications.</p> </main> <nav class="nav-wrapper" aria-label="Page navigation"> <!-- Mobile navigation buttons --> <a rel="prev" href="reference/pkgid-spec.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a rel="next" href="reference/external-tools.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> <div style="clear: both"></div> </nav> </div> </div> <nav class="nav-wide-wrapper" aria-label="Page navigation"> <a href="reference/pkgid-spec.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a href="reference/external-tools.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> </nav> </div> <!-- Local fallback for Font Awesome --> <script> if (getComputedStyle(document.querySelector(".fa")).fontFamily !== "FontAwesome") { var link = document.createElement('link'); link.rel = 'stylesheet'; link.type = 'text/css'; link.href = '_FontAwesome/css/font-awesome.css'; document.head.insertBefore(link, document.head.firstChild) } </script> <script src="highlight.js"></script> <script src="book.js"></script> <!-- Custom JS script --> </body> </html>