tinytex - after install, set the CTAN mirror to the one resolved by h…

…ttps://mirror.ctan.org

This will make sure any user installing TinyTeX with quarto does not end up with a US-based mirror.

news/changelog-1.5.md

@@ -126,3 +126,4 @@ All changes included in 1.5:
 - Resolve data URIs in Pandoc's mediabag when rendering documents.
 - Increase v8's max heap size by default, to avoid out-of-memory errors when rendering large documents (also cf. https://github.com/denoland/deno/issues/18935).
 - Upgrade Deno to 1.41.0
+- `quarto install tinytex` will now try to set the default CTAN repository to the nearest mirror resolved from https://mirror.ctan.org.

src/tools/impl/tinytex.ts

@@ -329,7 +329,7 @@ async function afterInstall(context: InstallContext) {
 
     // Set the default repo to an https repo
     let restartRequired = false;
-    const defaultRepo = textLiveRepo();
+    const defaultRepo = await textLiveRepo();
     await context.withSpinner(
       {
         message: `Setting default repository`,
@@ -471,9 +471,24 @@ function exec(path: string, cmd: string[]) {
 
 const kTlMgrKey = "tlmgr";
 
-function textLiveRepo(): string {
-  const randomInt = Math.floor(Math.random() * kDefaultRepos.length);
-  return kDefaultRepos[randomInt];
+async function textLiveRepo() {
+  // We don't set the default to `ctan` because one caveat of mirror.ctan.org
+  // is that it resolves to many different hosts, and they are not perfectly synchronized;
+  // Recommendation is to update only daily (at most), and not more often, which we don't want.
+  // So:
+  // 1. Try to get the automatic CTAN mirror returned from mirror.ctan.org
+  // 2. If that fails, use one of the selected mirrors
+  let autoUrl;
+  try {
+    const url = "https://mirror.ctan.org/systems/texlive/tlnet";
+    const response = await fetch(url, { redirect: "follow" });
+    autoUrl = response.url;
+  } catch (_e) {}
+  if (!autoUrl) {
+    const randomInt = Math.floor(Math.random() * kDefaultRepos.length);
+    autoUrl = kDefaultRepos[randomInt];
+  }
+  return autoUrl;
 }
 
 function tinyTexPkgName(base?: string, ver?: string) {