fix(web/blog): make base URL configurable for atom feeds

This was previously hardcoded to tazj.in, which is not going to work
of course.

Instead it now takes the blog config which has a new baseUrl
parameter. For ease of use, the configs of my and the TVL blog have
been moved into a location that is accessible in the tree for reuse.

Change-Id: I94e71aaa7859db4380eb7013740a17f6b6a02620
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3777
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>

web/blog/default.nix

@@ -40,8 +40,8 @@ let
   fragments = import ./fragments.nix args;
 
   # Functions for generating feeds for these blogs using //web/atom-feed.
-  toFeedEntry = defun [ post atom-feed.entry ] (post: rec {
-    id = "https://tazj.in/blog/${post.key}";
+  toFeedEntry = { baseUrl, ...}: defun [ post atom-feed.entry ] (post: rec {
+    id = "${baseUrl}/${post.key}";
     title = post.title;
     content = readFile (renderMarkdown post.content);
     published = post.date;
@@ -52,7 +52,6 @@ let
       href = id;
     };
   });
-
 in {
   inherit post toFeedEntry;
   inherit (fragments) renderPost;

web/blog/fragments.nix

@@ -59,7 +59,7 @@ let
     <hr>
   '';
 
-  renderPost = { name, footer }: post: runCommandNoCC "${post.key}.html" {} ''
+  renderPost = { name, footer, ... }: post: runCommandNoCC "${post.key}.html" {} ''
     cat ${writeText "header.html" (header name post.title)} > $out
 
     # Write the post title & date