Yellow text color + unsyncronized help text when clock is out of sync

lib/nerves_motd.ex

@@ -84,7 +84,7 @@ defmodule NervesMOTD do
     [
       [{"Serial", serial_number()}],
       [{"Uptime", uptime()}],
-      [{"Clock", Utils.formatted_local_time()}],
+      [clock_cell()],
       temperature_row(),
       [],
       [firmware_cell(), applications_cell(apps)],
@@ -135,6 +135,18 @@ defmodule NervesMOTD do
   defp format_cell_value(value, 0, width), do: Utils.fit_ansidata(value, width)
   defp format_cell_value(value, 1, _width), do: value
 
+  @spec clock_cell() :: cell()
+  defp clock_cell() do
+    formatted_clock =
+      if runtime_mod().time_synchronized?() do
+        Utils.formatted_local_time()
+      else
+        [:yellow, Utils.formatted_local_time(), " (unsynchronized)", :reset]
+      end
+
+    {"Clock", formatted_clock}
+  end
+
   @spec firmware_cell() :: cell()
   defp firmware_cell() do
     fw_active = runtime_mod().active_partition()

lib/nerves_motd/runtime.ex

@@ -21,6 +21,7 @@ defmodule NervesMOTD.Runtime do
                  used_percent: non_neg_integer()
                }}
               | :error
+  @callback time_synchronized?() :: boolean()
 end
 
 defmodule NervesMOTD.Runtime.Target do
@@ -112,4 +113,12 @@ defmodule NervesMOTD.Runtime.Target do
     # In case the `df` command is not available or any of the out parses incorrectly
     _error -> :error
   end
+
+  if Code.ensure_loaded?(NervesTime) do
+    @impl NervesMOTD.Runtime
+    def time_synchronized?(), do: apply(NervesTime, :synchronized?, [])
+  else
+    @impl NervesMOTD.Runtime
+    def time_synchronized?(), do: true
+  end
 end

mix.exs

@@ -33,6 +33,7 @@ defmodule NervesMOTD.MixProject do
   defp deps do
     [
       {:nerves_runtime, "~> 0.8"},
+      {:nerves_time, "~> 0.4", optional: true},
       {:credo, "~> 1.5", only: [:dev, :test], runtime: false},
       {:dialyxir, "~> 1.1", only: [:dev, :test], runtime: false},
       {:ex_doc, "~> 0.25", only: :docs, runtime: false},

mix.lock

@@ -13,8 +13,10 @@
   "makeup_erlang": {:hex, :makeup_erlang, "0.1.1", "3fcb7f09eb9d98dc4d208f49cc955a34218fc41ff6b84df7c75b3e6e533cc65f", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "174d0809e98a4ef0b3309256cbf97101c6ec01c4ab0b23e926a9e17df2077cbb"},
   "mix_test_watch": {:hex, :mix_test_watch, "1.1.0", "330bb91c8ed271fe408c42d07e0773340a7938d8a0d281d57a14243eae9dc8c3", [:mix], [{:file_system, "~> 0.2.1 or ~> 0.3", [hex: :file_system, repo: "hexpm", optional: false]}], "hexpm", "52b6b1c476cbb70fd899ca5394506482f12e5f6b0d6acff9df95c7f1e0812ec3"},
   "mox": {:hex, :mox, "1.0.2", "dc2057289ac478b35760ba74165b4b3f402f68803dd5aecd3bfd19c183815d64", [:mix], [], "hexpm", "f9864921b3aaf763c8741b5b8e6f908f44566f1e427b2630e89e9a73b981fef2"},
+  "muontrap": {:hex, :muontrap, "1.0.0", "53a05c37f71cc5070aaa0858a774ae1f500160b7186a70565521a14ef7843c5a", [:make, :mix], [{:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "0d3cd6e335986f9c2af1b61f583375b0f0d91cea95b7ec7bc720f330b4dc9b49"},
   "nerves_logging": {:hex, :nerves_logging, "0.2.0", "4099b860f41a0171ff49fbc1e86ee0ce4576c24c1cf318a0fd0bf227355e8c12", [:make, :mix], [{:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "07cfb9fe9d21b908da51b81a1ced858288c68519204aca7aa2c1fcd531d5e059"},
-  "nerves_runtime": {:hex, :nerves_runtime, "0.13.3", "378d6dda56291c0144567f24eb2d4ade314012443ce5d03542adec93091ad9b7", [:mix], [{:nerves_logging, "~> 0.2.0", [hex: :nerves_logging, repo: "hexpm", optional: false]}, {:nerves_uevent, "~> 0.1.0", [hex: :nerves_uevent, repo: "hexpm", optional: false]}, {:uboot_env, "~> 1.0 or ~> 0.3.0", [hex: :uboot_env, repo: "hexpm", optional: false]}], "hexpm", "00b51d9675cae78cc82910e18508e5c8b8a032dad7a83d417c4d061d802e3107"},
+  "nerves_runtime": {:hex, :nerves_runtime, "0.13.3", "378d6dda56291c0144567f24eb2d4ade314012443ce5d03542adec93091ad9b7", [:mix], [{:nerves_logging, "~> 0.2.0", [hex: :nerves_logging, repo: "hexpm", optional: false]}, {:nerves_uevent, "~> 0.1.0", [hex: :nerves_uevent, repo: "hexpm", optional: false]}, {:uboot_env, "~> 0.3.0 or ~> 1.0", [hex: :uboot_env, repo: "hexpm", optional: false]}], "hexpm", "00b51d9675cae78cc82910e18508e5c8b8a032dad7a83d417c4d061d802e3107"},
+  "nerves_time": {:hex, :nerves_time, "0.4.5", "038d6754421b20f21eff8918f006d26a2c3e7440dc6954c4164030427e9228d8", [:make, :mix], [{:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}, {:muontrap, "~> 0.5 or ~> 1.0", [hex: :muontrap, repo: "hexpm", optional: false]}], "hexpm", "cbe4593bb63ba6fd66f09c321f558037ca9de6ad8b93bc0dc77c4209c4734a88"},
   "nerves_time_zones": {:hex, :nerves_time_zones, "0.3.1", "0ccb71faf9db9de37ad40a2f75ea0d7f5e7a24ac6e07c19a369e485ba709205c", [:make, :mix], [{:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}, {:zoneinfo, "~> 0.1.2", [hex: :zoneinfo, repo: "hexpm", optional: false]}], "hexpm", "69d026322fb8062315fc8c28e24de4600fcee2b6d0b5abba83a355ff62290c53"},
   "nerves_uevent": {:hex, :nerves_uevent, "0.1.0", "651111a46be9a238560cbf7946989fc500e5f33d7035fd9ea7194d07a281bc19", [:make, :mix], [{:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}, {:property_table, "~> 0.2.0", [hex: :property_table, repo: "hexpm", optional: false]}], "hexpm", "cb0b1993c3ed3cefadbcdb534e910af0661f95c3445796ce8a7c8be3519a4e5f"},
   "nimble_parsec": {:hex, :nimble_parsec, "1.2.3", "244836e6e3f1200c7f30cb56733fd808744eca61fd182f731eac4af635cc6d0b", [:mix], [], "hexpm", "c8d789e39b9131acf7b99291e93dae60ab48ef14a7ee9d58c6964f59efb570b0"},

test/nerves_motd_test.exs

@@ -113,6 +113,17 @@ defmodule NervesMOTDTest do
     assert capture_motd() =~ ~r/Clock        : \d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2} \w{3}/
   end
 
+  test "Clock gets highlighted when not synchronized" do
+    NervesMOTD.MockRuntime
+    |> Mox.expect(:applications, 1, default_applications_code())
+    |> Mox.expect(:active_partition, 1, fn -> "A" end)
+    |> Mox.expect(:firmware_validity, 1, fn -> :valid end)
+    |> Mox.expect(:time_synchronized?, 1, fn -> false end)
+
+    assert capture_motd() =~
+             ~r/Clock        : \d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2} \w{3} \(unsynchronized\)/
+  end
+
   test "Temperature when available" do
     NervesMOTD.MockRuntime
     |> Mox.expect(:applications, 1, default_applications_code())

test/support/runtime.ex

@@ -38,4 +38,7 @@ defmodule NervesMOTD.Runtime.Host do
     # Raise if the path isn't the expected one for the unit tests
     {:ok, %{size_mb: 14_619, used_mb: 37, used_percent: 0}}
   end
+
+  @impl NervesMOTD.Runtime
+  def time_synchronized?(), do: true
 end