akoutmos · michelboaventura · Apr 17, 2025
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
@@ -23,7 +23,7 @@ jobs:
           elixir-version: "1.17.2"
           otp-version: "27.0"
       - name: Restore cache
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: |
             deps
@@ -53,6 +53,7 @@ jobs:
       matrix:
         elixir:
           - "1.17"
+          - "1.18"
         otp:
           - "26.0"
           - "27.0"

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- PromEx now uses Elixir 1.18 default JSON module and falls back to Jason if it is not available.
+
 ## [1.11.0] - 2024-10-24
 
 ### Fixed

diff --git a/example_applications/web_app/config/config.exs b/example_applications/web_app/config/config.exs
@@ -50,8 +50,8 @@ config :logger, :console,
   format: "$time $metadata[$level] $message\n",
   metadata: [:request_id]
 
-# Use Jason for JSON parsing in Phoenix
-config :phoenix, :json_library, Jason
+# Use JSON falling back to Jason for JSON parsing in Phoenix
+config :phoenix, :json_library, PromEx.JSON
 
 # Import environment specific config. This must remain at the bottom
 # of this file so it overrides the configuration defined above.

diff --git a/example_applications/web_app/stress_test.exs b/example_applications/web_app/stress_test.exs
@@ -19,7 +19,7 @@ end
   |> Finch.build(users_path)
   |> Finch.request(StressTester)
 
-all_users = Jason.decode!(body)
+all_users = PromEx.JSON.decode!(body)
 
 # Level up all the users slowly
 all_users
@@ -78,7 +78,7 @@ task_2 =
         age = Faker.random_between(18, 75)
 
         data = %{first_name: first_name, last_name: last_name, age: age, points: 0}
-        payload = Jason.encode!(data)
+        payload = PromEx.JSON.encode!(data)
 
         :post
         |> Finch.build(users_path, [{"content-type", "application/json"}], payload)
@@ -98,7 +98,7 @@ Task.await_many([task_1, task_2], 60_000)
   |> Finch.build(users_path)
   |> Finch.request(StressTester)
 
-all_users = Jason.decode!(body)
+all_users = PromEx.JSON.decode!(body)
 
 all_users
 |> Enum.shuffle()

diff --git a/lib/prom_ex/dashboard_renderer.ex b/lib/prom_ex/dashboard_renderer.ex
@@ -107,16 +107,16 @@ defmodule PromEx.DashboardRenderer do
   end
 
   @doc """
-  This function will decode the JSON dashboard using `Jason`. If any errors occur during the decoding process,
-  the struct will be marked as having invalid JSON.
+  This function will decode the JSON dashboard using JSON if available and fallback to Jason. If any errors
+  occur during the decoding process, the struct will be marked as having invalid JSON.
   """
   @spec decode_dashboard(__MODULE__.t()) :: __MODULE__.t()
   def decode_dashboard(%__MODULE__{valid_file?: false} = dashboard_render) do
     dashboard_render
   end
 
   def decode_dashboard(%__MODULE__{rendered_file: json_definition} = dashboard_render) do
-    case Jason.decode(json_definition) do
+    case PromEx.JSON.decode(json_definition) do
       {:ok, decoded_dashboard} ->
         %{dashboard_render | decoded_dashboard: decoded_dashboard, valid_json?: true}
 

diff --git a/lib/prom_ex/dashboard_uploader.ex b/lib/prom_ex/dashboard_uploader.ex
@@ -126,7 +126,7 @@ defmodule PromEx.DashboardUploader do
   end
 
   defp upload_dashboard(dashboard_definition, grafana_conn, upload_opts, full_dashboard_path) do
-    dashboard_contents = Jason.encode!(dashboard_definition)
+    dashboard_contents = PromEx.JSON.encode!(dashboard_definition)
 
     case GrafanaClient.upload_dashboard(grafana_conn, dashboard_contents, upload_opts) do
       {:ok, _response_payload} ->

diff --git a/lib/prom_ex/grafana_client.ex b/lib/prom_ex/grafana_client.ex
@@ -73,7 +73,7 @@ defmodule PromEx.GrafanaClient do
 
     dashboard_uid =
       dashboard_contents
-      |> Jason.decode!()
+      |> PromEx.JSON.decode!()
       |> Map.get("uid")
 
     :get
@@ -94,7 +94,7 @@ defmodule PromEx.GrafanaClient do
     headers = grafana_headers(:post, grafana_conn.authorization)
 
     payload =
-      Jason.encode!(%{
+      PromEx.JSON.encode!(%{
         uid: folder_uid,
         title: title
       })
@@ -136,7 +136,7 @@ defmodule PromEx.GrafanaClient do
         overwrite: true
       }
       |> Map.merge(attrs)
-      |> Jason.encode!()
+      |> PromEx.JSON.encode!()
 
     :put
     |> Finch.build("#{grafana_conn.base_url}/api/folders/#{folder_uid}", headers, payload)
@@ -193,7 +193,7 @@ defmodule PromEx.GrafanaClient do
         {:time_end, v} -> {:timeEnd, v}
         {k, v} -> {k, v}
       end)
-      |> Jason.encode!()
+      |> PromEx.JSON.encode!()
 
     :post
     |> Finch.build("#{grafana_conn.base_url}/api/annotations", headers, payload)
@@ -204,7 +204,7 @@ defmodule PromEx.GrafanaClient do
   defp handle_grafana_response(finch_response) do
     case finch_response do
       {:ok, %Finch.Response{status: status_code, body: body}} when status_code in [200, 201] ->
-        {:ok, Jason.decode!(body)}
+        {:ok, PromEx.JSON.decode!(body)}
 
       {:ok, %Finch.Response{status: status_code} = response} ->
         Logger.warning("Received a #{status_code} from Grafana because: #{inspect(response)}")
@@ -236,12 +236,12 @@ defmodule PromEx.GrafanaClient do
   end
 
   defp generate_payload(dashboard_definition, opts) do
-    dashboard = Jason.decode!(dashboard_definition)
+    dashboard = PromEx.JSON.decode!(dashboard_definition)
 
     opts
     |> Map.new()
     |> Map.put(:dashboard, dashboard)
-    |> Jason.encode!()
+    |> PromEx.JSON.encode!()
   end
 
   defp lookup_status_code(status_code) do

diff --git a/lib/prom_ex/json.ex b/lib/prom_ex/json.ex
@@ -0,0 +1,21 @@
+defmodule PromEx.JSON do
+  @moduledoc false
+
+  # Delegates to JSON in Elixir v1.18+ or Jason for earlier versions
+
+  cond do
+    Code.ensure_loaded?(JSON) ->
+      defdelegate decode!(data), to: JSON
+      defdelegate decode(data), to: JSON
+      defdelegate encode!(data), to: JSON
+
+    Code.ensure_loaded?(Jason) ->
+      defdelegate decode!(data), to: Jason
+      defdelegate encode!(data), to: Jason
+
+    true ->
+      message = "Missing a compatible JSON library, add `:jason` to your deps."
+
+      IO.warn(message, Macro.Env.stacktrace(__ENV__))
+  end
+end
diff --git a/mix.exs b/mix.exs
@@ -55,7 +55,7 @@ defmodule PromEx.MixProject do
   defp deps do
     [
       # Required dependencies
-      {:jason, "~> 1.4"},
+      {:jason, "~> 1.4", optional: true},
       {:finch, "~> 0.18"},
       {:telemetry, ">= 1.0.0"},
       {:telemetry_poller, "~> 1.1"},

diff --git a/test/prom_ex/dashboard_uploader_test.exs b/test/prom_ex/dashboard_uploader_test.exs
@@ -161,7 +161,7 @@ defmodule PromEx.DashboardUploaderTest do
       {:ok, body, conn} = Plug.Conn.read_body(conn, [])
 
       assert body
-             |> Jason.decode!()
+             |> PromEx.JSON.decode!()
              |> get_in(["dashboard", "title"]) == "My really cool custom title"
 
       Plug.Conn.resp(conn, 200, response_payload)

diff --git a/test/prom_ex/grafana_client_test.exs b/test/prom_ex/grafana_client_test.exs
@@ -45,7 +45,7 @@ defmodule PromEx.GrafanaClientTest do
     Bypass.expect(bypass, "POST", "/api/annotations", fn conn ->
       {:ok, body, conn} = Plug.Conn.read_body(conn, [])
 
-      details = Jason.decode!(body)
+      details = PromEx.JSON.decode!(body)
       assert details["time"] == 1_640_995_200_000
       assert details["tags"] == ["some", "tags"]
       assert details["text"] == "message"
@@ -86,7 +86,7 @@ defmodule PromEx.GrafanaClientTest do
     Bypass.expect(bypass, "POST", "/api/annotations", fn conn ->
       {:ok, body, conn} = Plug.Conn.read_body(conn, [])
 
-      details = Jason.decode!(body)
+      details = PromEx.JSON.decode!(body)
       assert details["dashboardId"] == 1
       assert details["panelId"] == 2
       assert details["time"] == 1_640_995_200_000

diff --git a/test/support/test_app_router.ex b/test/support/test_app_router.ex
@@ -56,14 +56,14 @@ defmodule TestApp.PlugRouter do
 
   plug PromEx.Plug, prom_ex_module: TestApp.PromEx, path: "/metrics"
   plug Plug.Telemetry, event_prefix: [:testapp, :plug, :router]
-  plug Plug.Parsers, parsers: [:json], json_decoder: Jason
+  plug Plug.Parsers, parsers: [:json], json_decoder: PromEx.JSON
   plug :match
   plug :dispatch
 
   get "/users/:id" do
     conn
     |> put_resp_content_type("application/json")
-    |> send_resp(200, Jason.encode!(%{"id" => conn.params["id"]}))
+    |> send_resp(200, PromEx.JSON.encode!(%{"id" => conn.params["id"]}))
     |> halt()
   end