feat: add post about git conditional config

Author: confusedalex

content/blog/git-conditional-config/index.md

@@ -0,0 +1,67 @@
++++
+title= "TIL: git conditional config with and without home-manager"
+date = 2025-02-19
+[taxonomies]
+tags = ["til", "git", "nix"]
++++
+
+Today I learnt how to use git conditional config to use multiple identities easily.  
+I use git for my private project and the projects I need to work at my day job.  
+To keep these two projects apart, I have a `~/projects` folder in my home directory with the two subfolder `~/projects/work` and `~/projects/personal`.
+Now we can tell git to always use the one identity for all projects under `~/projects/personal` and another for `~/projects/work`.
+We just add two includeIfs in our git config. With includeIf we can specify other files to source if the condition is met. The prepended "gitdir:" just means every git repository under this directory. [^1]
+
+```
+[includeIf "gitdir:~/projects/personal/"]
+	path = "./personal"
+
+[includeIf "gitdir:~/projects/work/"]
+	path = "./work"
+```
+
+In the personal config, we specify our personal identity
+
+```
+[user]
+	email = "[email protected]"
+	name = "confusedalex"
+	signingKey = "05AF71643F6E2ED3"
+```
+
+and do the same for the work config.
+
+## Integrating with home-manager
+
+Because I use [home-manager](https://nix-community.github.io/home-manager/index.xhtml) I want to specify these conditionals with nix. We just need to add a list we attributes sets for every include.
+
+> Everything under contents must follow the structure as in git-config.
+
+```nix
+{
+  programs.git = {
+    enable = true;
+    # ...
+    includes = [
+      {
+        condition = "gitdir:~/projects/personal/";
+        contents = {
+          user = {
+            name = "confusedalex";
+            email = "[email protected]";
+            signingKey = "05AF71643F6E2ED3";
+          };
+          gpg.format = "openpgp";
+        };
+      }
+      {
+        condition = "gitdir:~/projects/work/";
+        contents = {
+            #...
+        };
+      }
+    ];
+  };
+}
+```
+
+[^1]: [ https://git-scm.com/docs/git-config#\_includes ](https://git-scm.com/docs/git-config#_includes)