fix an issue with baseurl processing

Author: mgwalker

.eleventy.js

@@ -5,6 +5,7 @@ const markdownItAttrs = require("markdown-it-attrs");
 const yaml = require("js-yaml");
 const svgSprite = require("eleventy-plugin-svg-sprite");
 const { headingLinks } = require("./config/headingLinks");
+const baseurl = require("./config/baseurl");
 
 const HandbookPlugin = require("./config/HandbookPlugin.js");
 
@@ -59,7 +60,7 @@ module.exports = function (config) {
     templateFormats: ["md", "html", "njk"],
     markdownTemplateEngine: "liquid",
     htmlTemplateEngine: "liquid",
-    pathPrefix: process.env.BASEURL ?? "/",
+    pathPrefix: baseurl,
 
     dir: {
       input: "pages",

check-links.js

@@ -1,6 +1,7 @@
-const cheerio = require("cheerio");
 const fs = require("fs/promises");
 const path = require("path");
+const baseurl = require("./config/baseurl");
+const cheerio = require("cheerio");
 
 const SITE_ROOT = path.join(__dirname, "_site");
 
@@ -51,7 +52,7 @@ const getDom = async (file) => {
       SITE_ROOT,
       // Strip off any URL hashes and remove the base URL portion to get down
       // to just the target file.
-      realFile.replace(/\#.*$/, "").replace(process.env.BASEURL, ""),
+      realFile.replace(/\#.*$/, "").replace(baseurl, ""),
       path.basename(file)
     );
 
@@ -103,7 +104,7 @@ const run = async () => {
 
         // if(/^\/(images|))
 
-        pathComponents.push(url.pathname.replace(process.env.BASEURL, ""));
+        pathComponents.push(url.pathname.replace(baseurl, ""));
 
         // If the link does not include a file path, append index.html
         if (!/\.[a-z]+/i.test(url.pathname)) {

config/baseurl.js

@@ -0,0 +1,19 @@
+// This bit of logic was being used in several places, and that's silly.
+// Especially when it turns out it's a little more complex than I thought it
+// was, and resulted in these issues:
+//
+// https://github.com/18F/handbook/issues/3615
+// https://github.com/18F/handbook/issues/3623
+// https://github.com/18F/handbook/issues/3630
+
+if (!process.env.BASEURL) {
+  // If the BASEURL set is falsey, then our actual baseurl is the root.
+  module.exports = "/";
+  // If the BASEURL is set but it's a string of just whitespace, we want to use
+  // the root for that too.
+} else if (process.env.BASEURL.trim().length === 0) {
+  module.exports = "/";
+} else {
+  // But if the BASEURL is set to a real value, then that's our base.
+  module.exports = process.env.BASEURL;
+}

config/shortcodes/download.js

@@ -1,5 +1,6 @@
 const fs = require("fs/promises");
 const path = require("path");
+const baseurl = require("../baseurl");
 
 // Given a path to a file that should be downloadable, copy that path into the
 // output's assets directory so it'll be available. Return the resulting URL
@@ -17,5 +18,5 @@ module.exports = async (downloadPath) => {
 
   // The resulting URL should include the base URL, if any. This is necessary
   // for cloud.gov Pages previews to work correctly.
-  return `${process.env.BASEURL ?? ""}/assets/downloads/${filename}`;
+  return `${baseurl}/assets/downloads/${filename}`;
 };

config/shortcodes/imageWithClass.js

@@ -1,5 +1,6 @@
 const Image = require("@11ty/eleventy-img");
 const path = require("path");
+const baseurl = require("../baseurl");
 
 // Given an image path, copies the file to the assets/images directory so it is
 // available on the web. Returns the text for an <img> element that has the
@@ -31,7 +32,7 @@ module.exports = async (imagePath, cssClass, altText) => {
   // unexpected, hard-to-debug ways that do not break the build.
   const attributes = {
     // We need to honor BASEURL to support cloud.gov Pages preview builds.
-    src: `${process.env.BASEURL ?? ""}/${url}`,
+    src: `${baseurl}/${url}`,
     class: cssClass ?? false,
     alt: altText ?? false,
     loading: "lazy",

config/shortcodes/link.js

@@ -1,7 +1,8 @@
 const path = require("path");
+const baseurl = require("../baseurl");
 
 // Given text that should be a link, guarantee that it becomes one. If it's
 // already a link that begins with http/https, leave it alone. Otherwise, add
 // the site BASEURL to it.
 module.exports = (link) =>
-  link.startsWith("http") ? link : path.join(process.env.BASEURL ?? "/", link);
+  link.startsWith("http") ? link : path.join(baseurl, link);

config/shortcodes/page.js

@@ -1,4 +1,5 @@
 const path = require("path");
+const baseurl = require("../baseurl");
 
 // Given a page reference, turn it into a link on the published site.
-module.exports = (link) => path.join(process.env.BASEURL ?? "/", link);
+module.exports = (link) => path.join(baseurl, link);