refactor: enhance error reporting for Docker host connection failures

Author: jarlah

lib/connection/docker_host_strategy/docker_host_from_env.ex

@@ -14,7 +14,9 @@ defmodule Testcontainers.DockerHostFromEnvStrategy do
             {:ok, docker_host}
 
           {:error, reason} ->
-            {:error, docker_host_from_env: {reason, strategy.key}}
+            {:error,
+             docker_host_from_env:
+               {:ping_failed, key: strategy.key, value: docker_host, reason: reason}}
         end
       end
     end

lib/connection/docker_host_strategy/docker_host_from_properties.ex

@@ -20,7 +20,9 @@ defmodule Testcontainers.DockerHostFromPropertiesStrategy do
           {:ok, docker_host}
 
         {:error, reason} ->
-          {:error, testcontainer_host_from_properties: {reason, key}}
+          {:error,
+           testcontainer_host_from_properties:
+             {:ping_failed, key: key, value: docker_host, reason: reason}}
       end
     end
 

lib/testcontainers.ex

@@ -771,12 +771,17 @@ defmodule Testcontainers do
   end
 
   defp try_tcp_connect(host, port) do
-    :gen_tcp.connect(~c"#{host}", port, [
-      :binary,
-      active: false,
-      packet: :line,
-      send_timeout: 10_000
-    ], 5000)
+    :gen_tcp.connect(
+      ~c"#{host}",
+      port,
+      [
+        :binary,
+        active: false,
+        packet: :line,
+        send_timeout: 10_000
+      ],
+      5000
+    )
   end
 
   defp try_container_internal_connect(%Container{ip_address: ip}, internal_port, original_reason)

test/connection/docker_host_strategy/docker_host_from_env_test.exs

@@ -13,7 +13,7 @@ defmodule Testcontainers.Connection.DockerHostStrategy.DockerHostFromEnvTest do
       strategy = %DockerHostFromEnvStrategy{key: "X_DOCKER_HOST"}
 
       {:error,
-       "Failed to find docker host: [docker_host_from_env: {:econnrefused, \"X_DOCKER_HOST\"}]"} =
+       "Failed to find docker host: [docker_host_from_env: {:ping_failed, [key: \"X_DOCKER_HOST\", value: \"tcp://localhost:9999\", reason: :econnrefused]}]"} =
         DockerHostStrategyEvaluator.run_strategies([strategy], [])
     end
 

test/connection/docker_host_strategy/docker_host_from_properties_test.exs

@@ -14,7 +14,7 @@ defmodule Testcontainers.Connection.DockerHostStrategy.DockerHostFromPropertiesT
       }
 
       {:error,
-       "Failed to find docker host: [testcontainer_host_from_properties: {:econnrefused, \"tc.host\"}]"} =
+       "Failed to find docker host: [testcontainer_host_from_properties: {:ping_failed, [key: \"tc.host\", value: \"tcp://localhost:9999\", reason: :econnrefused]}]"} =
         DockerHostStrategyEvaluator.run_strategies([strategy], [])
     end
 

test/constants_test.exs

@@ -3,7 +3,9 @@ defmodule Testcontainers.ConstantsTest do
 
   test "have correct values" do
     assert Testcontainers.Constants.container_label() == "org.testcontainers"
-    assert Testcontainers.Constants.container_session_id_label() == "org.testcontainers.session-id"
+
+    assert Testcontainers.Constants.container_session_id_label() ==
+             "org.testcontainers.session-id"
 
     assert Testcontainers.Constants.container_reuse_hash_label() ==
              "org.testcontainers.reuse-hash"

test/docker/auth_test.exs

@@ -71,14 +71,18 @@ defmodule Testcontainers.Docker.AuthTest do
     end
 
     test "returns nil when the config file is missing" do
-      missing = Path.join(System.tmp_dir!(), "testcontainers-missing-#{System.unique_integer()}.json")
+      missing =
+        Path.join(System.tmp_dir!(), "testcontainers-missing-#{System.unique_integer()}.json")
+
       refute File.exists?(missing)
 
       assert Auth.resolve("library/redis:7", missing) == nil
     end
 
     test "returns nil when the config file is invalid JSON" do
-      path = Path.join(System.tmp_dir!(), "testcontainers-invalid-#{System.unique_integer()}.json")
+      path =
+        Path.join(System.tmp_dir!(), "testcontainers-invalid-#{System.unique_integer()}.json")
+
       File.write!(path, "this is not json")
 
       try do

test/testcontainers_test.exs

@@ -133,6 +133,7 @@ defmodule TestcontainersTest do
     {:ok, container} = Testcontainers.start_container(config, :name_test)
 
     conn = Connection.get_connection() |> Tuple.to_list() |> Kernel.hd()
+
     {:ok, %DockerEngineAPI.Model.ContainerInspectResponse{Name: assigned_name}} =
       DockerEngineAPI.Api.Container.container_inspect(conn, container.container_id)
 

test/util/properties_test.exs

@@ -55,14 +55,16 @@ defmodule Testcontainers.Util.PropertiesParserTest do
 
   describe "read_property_file/1" do
     test "reads properties from specified file" do
-      {:ok, props} = PropertiesParser.read_property_file("test/fixtures/.testcontainers.properties")
+      {:ok, props} =
+        PropertiesParser.read_property_file("test/fixtures/.testcontainers.properties")
 
       assert is_map(props)
       assert props["tc.host"] == "tcp://localhost:9999"
     end
 
     test "returns empty map for nonexistent file" do
-      {:ok, props} = PropertiesParser.read_property_file("/nonexistent/path/.testcontainers.properties")
+      {:ok, props} =
+        PropertiesParser.read_property_file("/nonexistent/path/.testcontainers.properties")
 
       assert props == %{}
     end

test/wait_strategy/http_wait_strategy_test.exs

@@ -28,9 +28,7 @@ defmodule Testcontainers.HttpWaitStrategyTest do
     config =
       %Container{image: "nginx:alpine"}
       |> Container.with_exposed_port(port)
-      |> Container.with_waiting_strategy(
-        HttpWaitStrategy.new("/", port, status_code: 200)
-      )
+      |> Container.with_waiting_strategy(HttpWaitStrategy.new("/", port, status_code: 200))
 
     assert {:ok, container} = Testcontainers.start_container(config)
     assert :ok = Testcontainers.stop_container(container.container_id)