Initial commit

.formatter.exs

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+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

.github/workflows/ci.yml

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+name: Test suite
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    env:
+      MIX_ENV: test
+    strategy:
+      matrix:
+        include:
+          - pair:
+              elixir: '1.7'
+              otp: '20.3'
+          - pair:
+              elixir: '1.11'
+              otp: '23.2'
+            check_format: true
+
+    name: elixir-${{ matrix.pair.elixir }}-otp-${{ matrix.pair.otp }}
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - uses: erlef/setup-elixir@v1
+      with:
+        otp-version: ${{matrix.pair.otp}}
+        elixir-version: ${{matrix.pair.elixir}}
+
+    - name: Install Dependencies
+      run: |
+        mix local.rebar --force
+        mix local.hex --force
+        mix deps.get --only test
+
+    - name: Check format
+      if: matrix.check_format
+      run: mix format --check-formatted
+
+    - name: Run Tests
+      run: mix test

.gitignore

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+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where third-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+goodo-*.tar
+
+# Temporary files for e.g. tests
+/tmp

LICENSE

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+Copyright 2021 Fishbrain
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+# Goodoo
+
+Goodoo is a simple, robust, and highly customizable health check solution written in Elixir.
+
+## Installation
+
+Add `:goodoo` to your Mix project.
+
+```elixir
+def deps() do
+  [{:goodoo, "~> 0.1"}]
+end
+```
+
+## Overview
+
+Full documentation can be found on [Hex][hex-doc].
+
+Goodoo works by periodically checking the availablity of the sub-systems based
+on your configuration, and provides a few APIs to retrieves the report.
+
+To start using Goodoo, create a module:
+
+```elixir
+defmodule MyHealthCheck do
+  use Goodoo
+end
+```
+
+After that, add the module with the desired checkers to the supervisor tree.
+Please see the "Checkers" section for all currently supported checkers.
+
+```elixir
+checkers = %{
+  "primary" => {Goodoo.Checker.EctoSQL, repo: MyPrimaryRepo},
+  "replica" => {Goodoo.Checker.EctoSQL, repo: MyReplicaRepo},
+  "persistent_cache" => {Goodoo.Checker.Redix, connection: MyCache}
+}
+
+children = [
+  MyPrimaryRepo,
+  MyReplicaRepo,
+  MyCache,
+  ...,
+  {MyHealthCheck, checkers},
+  MyEndpoint
+]
+
+Supervisor.start_link(children, strategy: :one_for_one, name: MyApp)
+```
+
+Allez, hop! You are "goodoo" to go. To retrieve the health check report,
+`list_health_states/1` and `get_health_state/2` can be used.
+
+Usually you might want to expose an HTTP endpoint for some uptime checkers e.g.
+AWS ALB, Pingdom, etc. It can be easily done with Plug or Phoenix controller.
+
+### Plug integration
+
+```elixir
+defmodule MyRouter do
+  use Plug.Router
+
+  plug :match
+  plug :dispatch
+
+  get "/health" do
+    healthy? =
+      Enum.all?(
+        Goodoo.list_health_states(MyHealthCheck),
+        fn {_checker_name, {state, _last_checked_at}} ->
+          state == :healthy
+        end
+      )
+
+    if healthy? do
+      send_resp(conn, 200, "Everything is 200 OK")
+    else
+      send_resp(conn, 503, "Something is on fire!")
+    end
+  end
+
+  get "/health/:checker_name" do
+    case Goodoo.get_health_state(MyHealthCheck, checker_name) do
+      nil ->
+        send_resp(conn, 404, "Not found")
+
+      {state, _last_checked_at} ->
+        if state == :healthy do
+          send_resp(conn, 200, "Service is doing fine")
+        else
+          send_resp(conn, 503, "Service is on fire")
+        end
+    end
+  end
+end
+```
+
+### Phoenix integration
+
+```elixir
+defmodule HealthController do
+  use MyWeb, :controller
+
+  def index(conn, _params) do
+    healthy? =
+      Enum.all?(
+        Goodoo.list_health_states(MyHealthCheck),
+        fn {_checker_name, {state, _last_checked_at}} ->
+          state == :healthy
+        end
+      )
+
+    conn = put_status(conn, 200)
+
+    if healthy? do
+      text(conn, "Everything is 200 OK")
+    else
+      text(conn, "Something is on fire!")
+    end
+  end
+end
+```
+
+### "Goodoo" to know
+
+Goodoo is the local name of [Murray Cod][murray-cod] in Australia. Here is a picture of it.
+
+![goodoo](./goodoo.jpg)
+
+## Development
+
+Make sure you have [Elixir installed][elixir-installation-guide].
+
+1. Fork the project.
+2. Run `mix deps.get` to fetch dependencies.
+3. Run `mix test`.
+
+## Contributing
+
+If you have any ideas or suggestions, feel free to submit [an
+issue][goodoo-issue] or [a pull request][goodoo-pr].
+
+## License
+
+MIT
+
+
+[elixir-installation-guide]: https://elixir-lang.org/install.html
+[hex-doc]: https://hexdocs.pm/goodoo
+[goodoo-issue]: https://github.com/fishbrain/goodoo/issues
+[goodoo-pr]: https://github.com/fishbrain/goodoo/pulls
+[murray-cod]: https://en.wikipedia.org/wiki/Murray_cod

lib/goodoo.ex

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+defmodule Goodoo do
+  @moduledoc """
+  Goodoo is a simple, robust, and highly customizable health check solution written in Elixir.
+
+  Goodoo works by periodically checking the availablity of the sub-systems based
+  on your configuration, and provides a few APIs to retrieves the report.
+
+  To start using Goodoo, create a module:
+
+      defmodule MyHealthCheck do
+        use Goodoo
+      end
+
+  After that, add the module with the desired checkers to the supervisor tree.
+  Please see the "Checkers" section for all currently supported checkers.
+
+      checkers = %{
+        "primary" => {Goodoo.Checker.EctoSQL, repo: MyPrimaryRepo},
+        "replica" => {Goodoo.Checker.EctoSQL, repo: MyReplicaRepo},
+        "persistent_cache" => {Goodoo.Checker.Redix, connection: MyCache}
+      }
+
+      children = [
+        MyPrimaryRepo,
+        MyReplicaRepo,
+        MyCache,
+        ...,
+        {MyHealthCheck, checkers},
+        MyEndpoint
+      ]
+
+      Supervisor.start_link(children, strategy: :one_for_one, name: MyApp)
+
+  Allez, hop! You are "goodoo" to go. To retrieve the health check report,
+  `list_health_states/1` and `get_health_state/2` can be used.
+
+  Usually you might want to expose an HTTP endpoint for some uptime checkers e.g.
+  AWS ALB, Pingdom, etc. It can be easily done with Plug.
+
+      defmodule MyRouter do
+        use Plug.Router
+
+        plug :match
+        plug :dispatch
+
+        get "/health" do
+          healthy? =
+            Enum.all?(
+              Goodoo.list_health_states(MyHealthCheck),
+              fn {_checker_name, {state, _last_checked_at}} ->
+                state == :healthy
+              end
+            )
+
+          if healthy? do
+            send_resp(conn, 200, "Everything is 200 OK")
+          else
+            send_resp(conn, 503, "Something is on fire!")
+          end
+        end
+
+        get "/health/:checker_name" do
+          case Goodoo.get_health_state(MyHealthCheck, checker_name) do
+            nil ->
+              send_resp(conn, 404, "Not found")
+
+            {state, _last_checked_at} ->
+              if state == :healthy do
+                send_resp(conn, 200, "Service is doing fine")
+              else
+                send_resp(conn, 503, "Service is on fire")
+              end
+          end
+        end
+      end
+
+  ### Checkers
+
+  Goodoo implemented a few common checkers:
+
+  * `Goodoo.Checker.EctoSQL` - checkers for works with `Ecto.Repo`.
+  * `Goodoo.Checker.Redix` - Checker that works with `Redix`.
+
+  For more information, please visit the documentation for them accordingly.
+
+  Goodoo supports customer checkers, please visit `Goodoo.Checker` for more information.
+
+  ### Checker scheduling/interval
+
+  Goodoo schedules checkers based on the last health state. The default intervals are:
+
+  * `:healthy` - next check will be in 30 seconds.
+  * `:degraded` - next check will be in 10 seconds.
+  * `:unhealthy` - next check will be in 3 seconds.
+
+  You can configure your own strategy with the following example. Please note that missing
+  intervals will fall back to the defaults.
+
+      # `:healthy` and `:degraded` will fall back to defaults.
+      repo_intervals = %{
+        unhealthy: 1_000
+      }
+
+      cache_intervals = %{
+        unhealthy: 1_000,
+        degraded: 5_000,
+        healthy: 15_000
+      }
+
+      checkers = %{
+        "repo" => {Goodoo.Checker.EctoSQL, repo: MyRepo, intervals: repo_intervals},
+        "cache" => {Goodoo.Checker.EctoSQL, connection: MyCache, intervals: cache_intervals}
+      }
+
+  """
+
+  defmacro __using__(_) do
+    quote location: :keep do
+      import Goodoo
+
+      def child_spec(checkers) do
+        Goodoo.Supervisor.child_spec({__MODULE__, checkers})
+      end
+    end
+  end
+
+  @doc """
+  Retrieves all checker statuses of a healthcheck module.
+  """
+  @spec list_health_states(module()) :: %{
+          Goodoo.Checker.name() => {Goodoo.Checker.health_state(), DateTime.t()}
+        }
+  def list_health_states(module) do
+    module
+    |> Goodoo.Storage.get_storage_name()
+    |> Goodoo.Storage.list()
+  end
+
+  @doc """
+  Retrieve the checker status by its name of a healthcheck module
+  """
+  @spec get_health_state(module(), Goodoo.Checker.name()) ::
+          {Goodoo.Checker.health_state(), DateTime.t()} | nil
+  def get_health_state(module, name) do
+    module
+    |> Goodoo.Storage.get_storage_name()
+    |> Goodoo.Storage.get(name)
+  end
+end