meilisearch: enable using search_key

Using only the admin key works as well currently
and Akkoma needs to know the admin key to be able
to add new entries etc. However the Meilisearch
key descriptions suggest the admin key is not
supposed to be used for searches, so let’s not.

For compatibility with existings configs, search_key remains optional.

CHANGELOG.md

@@ -14,6 +14,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## Added
 - Implement [FEP-67ff](https://codeberg.org/fediverse/fep/src/branch/main/fep/67ff/fep-67ff.md) (federation documentation)
 
+## Added
+- Meilisearch: it is now possible to use separate keys for search and admin actions
+
 ## Fixed
 - Meilisearch: order of results returned from our REST API now actually matches how Meilisearch ranks results
 

docs/docs/configuration/search.md

@@ -33,6 +33,7 @@ indexes faster when it can process many posts in a single batch.
 > config :pleroma, Pleroma.Search.Meilisearch,
 >    url: "http://127.0.0.1:7700/",
 >    private_key: "private key",
+>    search_key: "search key",
 >    initial_indexing_chunk_size: 100_000
 
 Information about setting up meilisearch can be found in the
@@ -45,7 +46,7 @@ is hardly usable on a somewhat big instance.
 ### Private key authentication (optional)
 
 To set the private key, use the `MEILI_MASTER_KEY` environment variable when starting. After setting the _master key_,
-you have to get the _private key_, which is actually used for authentication.
+you have to get the _private key_ and possibly _search key_, which are actually used for authentication.
 
 === "OTP"
     ```sh
@@ -57,7 +58,11 @@ you have to get the _private key_, which is actually used for authentication.
     mix pleroma.search.meilisearch show-keys <your master key here>
     ```
 
-You will see a "Default Admin API Key", this is the key you actually put into your configuration file.
+You will see a "Default Admin API Key", this is the key you actually put into
+your configuration file as `private_key`. You should also see a
+"Default Search API key", put this into your config as `search_key`.
+If your version of Meilisearch only showed the former,
+just leave `search_key` completely unset in Akkoma's config.
 
 ### Initial indexing
 

lib/pleroma/search/meilisearch.ex

@@ -8,11 +8,24 @@ defmodule Pleroma.Search.Meilisearch do
 
   @behaviour Pleroma.Search.SearchBackend
 
-  defp meili_headers do
-    private_key = Pleroma.Config.get([Pleroma.Search.Meilisearch, :private_key])
+  defp meili_headers(key) do
+    key_header =
+      if is_nil(key), do: [], else: [{"Authorization", "Bearer #{key}"}]
 
-    [{"Content-Type", "application/json"}] ++
-      if is_nil(private_key), do: [], else: [{"Authorization", "Bearer #{private_key}"}]
+    [{"Content-Type", "application/json"} | key_header]
+  end
+
+  defp meili_headers_admin do
+    private_key = Pleroma.Config.get([Pleroma.Search.Meilisearch, :private_key])
+    meili_headers(private_key)
+  end
+
+  defp meili_headers_search do
+    search_key =
+      Pleroma.Config.get([Pleroma.Search.Meilisearch, :search_key]) ||
+        Pleroma.Config.get([Pleroma.Search.Meilisearch, :private_key])
+
+    meili_headers(search_key)
   end
 
   def meili_get(path) do
@@ -21,7 +34,7 @@ def meili_get(path) do
     result =
       Pleroma.HTTP.get(
         Path.join(endpoint, path),
-        meili_headers()
+        meili_headers_admin()
       )
 
     with {:ok, res} <- result do
@@ -29,14 +42,14 @@ def meili_get(path) do
     end
   end
 
-  def meili_post(path, params) do
+  defp meili_search(params) do
     endpoint = Pleroma.Config.get([Pleroma.Search.Meilisearch, :url])
 
     result =
       Pleroma.HTTP.post(
-        Path.join(endpoint, path),
+        Path.join(endpoint, "/indexes/objects/search"),
         Jason.encode!(params),
-        meili_headers()
+        meili_headers_search()
       )
 
     with {:ok, res} <- result do
@@ -52,7 +65,7 @@ def meili_put(path, params) do
         :put,
         Path.join(endpoint, path),
         Jason.encode!(params),
-        meili_headers(),
+        meili_headers_admin(),
         []
       )
 
@@ -69,7 +82,7 @@ def meili_delete!(path) do
         :delete,
         Path.join(endpoint, path),
         "",
-        meili_headers(),
+        meili_headers_admin(),
         []
       )
   end
@@ -80,10 +93,7 @@ def search(user, query, options \\ []) do
     author = Keyword.get(options, :author)
 
     res =
-      meili_post(
-        "/indexes/objects/search",
-        %{q: query, offset: offset, limit: limit}
-      )
+      meili_search(%{q: query, offset: offset, limit: limit})
 
     with {:ok, result} <- res do
       hits = result["hits"] |> Enum.map(& &1["ap"])