refactor(web/cgit-tvl): Move cgit config back out of module r/4254

It occured to me yesterday that with the config inside of the module
it is kind of difficult to test cgit locally.

This moves it back to a separate location (//web/cgit-tvl) and makes
the most important things configurable via overrides.

Change-Id: I9b0f4c60b75c31441e1718e63b5b55aba3100aae
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5893
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>

2 files changed, 86 insertions, 0 deletions

diff --git a/web/cgit-tvl/default.nix b/web/cgit-tvl/default.nix
new file mode 100644
index 0000000000..d26de9a5eb
--- /dev/null
+++ b/web/cgit-tvl/default.nix
@@ -0,0 +1,73 @@
+# Wrapper for running cgit through thttpd with TVL-specific
+# configuration.
+#
+# In practice this is only used for //ops/modules/cgit, but exposing
+# it here makes it easy to experiment with cgit locally.
+{ depot, lib, pkgs, ... }:
+
+let
+  cgitConfig = repo: pkgs.writeText "cgitrc" ''
+    # Global configuration
+    virtual-root=/
+    enable-http-clone=0
+    readme=:README.md
+    about-filter=${depot.tools.cheddar.about-filter}/bin/cheddar-about
+    source-filter=${depot.tools.cheddar}/bin/cheddar
+    enable-log-filecount=1
+    enable-log-linecount=1
+    enable-follow-links=1
+    enable-blame=1
+    mimetype-file=${pkgs.mime-types}/etc/mime.types
+    logo=https://static.tvl.fyi/${depot.web.static.drvHash}/logo-animated.svg
+
+    # Repository configuration
+    repo.url=depot
+    repo.path=${repo}
+    repo.desc=monorepo for the virus lounge
+    repo.owner=The Virus Lounge
+    repo.clone-url=https://code.tvl.fyi/depot.git
+  '';
+
+  thttpdConfig = port: pkgs.writeText "thttpd.conf" ''
+    port=${toString port}
+    dir=${depot.third_party.cgit}/cgit
+    nochroot
+    novhost
+    cgipat=**.cgi
+  '';
+
+  # Patched version of thttpd that serves cgit.cgi as the index and
+  # sets the environment variable for pointing cgit at the correct
+  # configuration.
+  #
+  # Things are done this way because recompilation of thttpd is much
+  # faster than cgit.
+  thttpdConfigPatch = repo: pkgs.writeText "thttpd_cgit_conf.patch" ''
+    diff --git a/libhttpd.c b/libhttpd.c
+    index c6b1622..eef4b73 100644
+    --- a/libhttpd.c
+    +++ b/libhttpd.c
+    @@ -3055,4 +3055,6 @@ make_envp( httpd_conn* hc )
+
+         envn = 0;
+    +    // force cgit to load the correct configuration
+    +    envp[envn++] = "CGIT_CONFIG=${cgitConfig repo}";
+         envp[envn++] = build_env( "PATH=%s", CGI_PATH );
+     #ifdef CGI_LD_LIBRARY_PATH
+  '';
+
+  thttpdCgit = repo: pkgs.thttpd.overrideAttrs (old: {
+    patches = [
+      ./thttpd_cgi_idx.patch
+      (thttpdConfigPatch repo)
+    ];
+  });
+
+in
+lib.makeOverridable
+  ({ port ? 2448
+   , repo ? "/var/lib/gerrit/git/depot.git/"
+   }: pkgs.writeShellScript "cgit-launch" ''
+    exec ${thttpdCgit repo}/bin/thttpd -D -C ${thttpdConfig port}
+  '')
+{ }
diff --git a/web/cgit-tvl/thttpd_cgi_idx.patch b/web/cgit-tvl/thttpd_cgi_idx.patch
new file mode 100644
index 0000000000..67dbc0c7ab
--- /dev/null
+++ b/web/cgit-tvl/thttpd_cgi_idx.patch
@@ -0,0 +1,13 @@
+diff --git a/config.h b/config.h
+index 65ab1e3..cde470f 100644
+--- a/config.h
++++ b/config.h
+@@ -327,7 +327,7 @@
+ /* CONFIGURE: A list of index filenames to check.  The files are searched
+ ** for in this order.
+ */
+-#define INDEX_NAMES "index.html", "index.htm", "index.xhtml", "index.xht", "Default.htm", "index.cgi"
++#define INDEX_NAMES "cgit.cgi"
+ 
+ /* CONFIGURE: If this is defined then thttpd will automatically generate
+ ** index pages for directories that don't have an explicit index file.