Add alt-text for the diagram

python · dstufft · 47fc562bdb2e793e8edbac47d97f3c9b38a9d04b
commit 47fc562bdb2e793e8edbac47d97f3c9b38a9d04b
@@ -1067,7 +1067,29 @@ Installing a package from an index
 
 .. figure:: pep-0817/conceptual_diagram_installers.svg
     :target: _images/conceptual_diagram_installers.svg
-    :alt: TODO.
+    :alt: A diagram showing installing a package including variant wheel
+          building. It is split into three columns: Developer, Installer
+          and Install-time providers. The diagram starts with Develop
+          initiating package install. The subsequent steps involve
+          installer, in order: resolver selects package version;
+          determine if release has variant wheels. If there are no
+          variant wheels, jump to installing package and report success.
+          If the version has variant wheels, check user's variant
+          preferences. In parallel, download JSON from index, then
+          extract variant provider configuration. If it uses AoT
+          providers only, converge to determine optimal variant
+          immediately. If it requires install-time providers, the
+          further path depends on whether non-vendored providers are
+          included. If they are not, query install-time providers
+          immediately and converge to determine optimal variant. If
+          non-vendored providers are included, they are installed if not
+          present in env and then queried. Querying providers involves
+          an exchange of data with different providers (in the diagram,
+          "provider 1" and "provider 2" are given as examples), each
+          filtering and ordering supported configurations for the
+          current environment. All the variant paths converge on
+          determining optimal variant, which is following by installing
+          package and reporting success.
 
     A conceptual diagram of installing a wheel.