diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
index cd9b5afe..56ca1e0f 100644
--- a/.devcontainer/devcontainer.json
+++ b/.devcontainer/devcontainer.json
@@ -22,11 +22,16 @@
   // Use 'postCreateCommand' to run commands after the container is created.
   "postCreateCommand": ".devcontainer/post-create.sh",
 
-  // HACK: Out of the box, this dev container doesn't allow installation to the
-  // default GEM_HOME, because of a weird thing going on with RVM. Instead, we
-  // set a custom GEM_HOME and GEM_PATH in our home directory!
-  // https://github.com/devcontainers/templates/issues/188
   "containerEnv": {
+    // Because the database is hosted on the local network at the hostname `db`,
+    // we partially override `config/database.yml` to connect to `db`!
+    "DATABASE_URL_PRIMARY_DEV": "mysql2://db",
+    "DATABASE_URL_OPENNEO_ID_DEV": "mysql2://db",
+
+    // HACK: Out of the box, this dev container doesn't allow installation to
+    // the default GEM_HOME, because of a weird thing going on with RVM.
+    // Instead, we set a custom GEM_HOME and GEM_PATH in our home directory!
+    // https://github.com/devcontainers/templates/issues/188
     "GEM_HOME": "~/.rubygems",
     "GEM_PATH": "~/.rubygems"
   }
diff --git a/config/database.yml b/config/database.yml
index 2fbc7152..81a389e9 100644
--- a/config/database.yml
+++ b/config/database.yml
@@ -1,7 +1,9 @@
 development:
   primary:
+    # You can override these default settings with this environment variable,
+    # fully or partially. We do this in the .devcontainer setup!
+    url: <%= ENV['DATABASE_URL_PRIMARY_DEV'] %>
     adapter: mysql2
-    host: db
     database: openneo_impress
     username: impress_dev
     password: impress_dev
@@ -10,8 +12,10 @@ development:
       sql_mode: TRADITIONAL
 
   openneo_id:
+    # You can override these default settings with this environment variable,
+    # fully or partially. We do this in the .devcontainer setup!
+    url: <%= ENV['DATABASE_URL_OPENNEO_ID_DEV'] %>
     adapter: mysql2
-    host: db
     database: openneo_id
     username: impress_dev
     password: impress_dev