diff --git a/config/config.exs b/config/config.exs
index 0df80bc..768a042 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -3,5 +3,5 @@ import Config
config :ha_handler,
http_port: 4000,
acme_challenge_path: "acme-challenge",
- haproxy_socket: System.get_env("HAPROXY_SOCKET") || "/var/run/haproxy.sock"
-
+ haproxy_socket: System.get_env("HAPROXY_SOCKET") || "/var/run/haproxy.sock",
+ pgsql_instances: []
diff --git a/lib/ha_handler.ex b/lib/ha_handler.ex
index 8ab75e7..2700fc0 100644
--- a/lib/ha_handler.ex
+++ b/lib/ha_handler.ex
@@ -11,6 +11,8 @@ defmodule HAHandler do
def http_port, do: Application.get_env(@otp_app, :http_port)
def haproxy_socket, do: Application.get_env(@otp_app, :haproxy_socket)
+ def pgsql_instances, do: Application.get_env(@otp_app, :pgsql_instances, [])
+
def acme_challenge_path, do: Application.get_env(@otp_app, :acme_challenge_path)
def static_path(), do: Application.app_dir(@otp_app, "priv/static/")
diff --git a/lib/ha_handler/application.ex b/lib/ha_handler/application.ex
index bb02cbf..d928238 100644
--- a/lib/ha_handler/application.ex
+++ b/lib/ha_handler/application.ex
@@ -5,12 +5,13 @@ defmodule HAHandler.Application do
use Application
- import HAHandler
+ alias HAHandler
@impl true
def start(_type, _args) do
children = [
- {Plug.Cowboy, scheme: :http, plug: HAHandler.Web.Router, options: [port: http_port()]}
+ {Plug.Cowboy, scheme: :http, plug: HAHandler.Web.Router, options: [port: HAHandler.http_port()]},
+ {HAHandler.PGSQL.Supervisor, HAHandler.pgsql_instances()}
]
# See https://hexdocs.pm/elixir/Supervisor.html
diff --git a/lib/ha_handler/pgsql.ex b/lib/ha_handler/pgsql.ex
new file mode 100644
index 0000000..3107d83
--- /dev/null
+++ b/lib/ha_handler/pgsql.ex
@@ -0,0 +1,10 @@
+defmodule HAHandler.PGSQL do
+ @supervisor HAHandler.PGSQL.Supervisor
+
+ def status() do
+ watchers = Supervisor.which_children(@supervisor)
+ for {_id, pid, _type, _modules} <- watchers do
+ GenServer.call(pid, :status)
+ end
+ end
+end
diff --git a/lib/ha_handler/pgsql/supervisor.ex b/lib/ha_handler/pgsql/supervisor.ex
new file mode 100644
index 0000000..8c826ac
--- /dev/null
+++ b/lib/ha_handler/pgsql/supervisor.ex
@@ -0,0 +1,17 @@
+defmodule HAHandler.PGSQL.Supervisor do
+ use Supervisor
+
+ alias HAHandler.PGSQL.Watcher, as: PGSQLWatcher
+
+ def start_link(opts) do
+ Supervisor.start_link(__MODULE__, opts, name: __MODULE__)
+ end
+
+ @impl true
+ def init(instances) do
+ children = Enum.map(instances, fn conf -> {PGSQLWatcher, conf} end)
+
+ opts = [ strategy: :one_for_one ]
+ Supervisor.init(children, opts)
+ end
+end
diff --git a/lib/ha_handler/pgsql/watcher.ex b/lib/ha_handler/pgsql/watcher.ex
new file mode 100644
index 0000000..e3ce328
--- /dev/null
+++ b/lib/ha_handler/pgsql/watcher.ex
@@ -0,0 +1,42 @@
+defmodule HAHandler.PGSQL.Watcher do
+ use GenServer
+ require Logger
+
+ def start_link(opts) do
+ GenServer.start_link(__MODULE__, opts, name: __MODULE__)
+ end
+
+ @impl true
+ def init(opts) do
+ # Starts a Postgrex child but does not means the connection was
+ # successful.
+ # TODO: set dbconnections backoff and connect hooks
+ # See https://github.com/elixir-ecto/db_connection/blob/master/lib/db_connection.ex#L343
+ {:ok, pid} = Postgrex.start_link(opts)
+
+ state = %{
+ backend: pid,
+ hostname: Keyword.get(opts, :hostname)
+ }
+
+ {:ok, state}
+ end
+
+ @impl true
+ def handle_call(:status, _from, %{backend: backend, hostname: hostname} = state) do
+ result = case Postgrex.query(backend, "SELECT version();", []) do
+ {:ok, %Postgrex.Result{rows: [[raw_version_string]]}} ->
+ version = case Regex.run(~r/^PostgreSQL (\d+\.\d+)/, raw_version_string) do
+ [_, version_number] -> version_number
+ _ -> "unknown"
+ end
+ %{hostname: hostname, version: version, status: "up"}
+ {:error, %DBConnection.ConnectionError{message: _msg, reason: err}} ->
+ %{hostname: hostname, version: "unknown", status: err}
+ _ ->
+ %{hostname: hostname, version: "unknown", status: "Unhandled error"}
+ end
+
+ {:reply, result, state}
+ end
+end
diff --git a/lib/ha_handler/web/controller.ex b/lib/ha_handler/web/controller.ex
index 01b7d4f..448af9c 100644
--- a/lib/ha_handler/web/controller.ex
+++ b/lib/ha_handler/web/controller.ex
@@ -1,7 +1,7 @@
defmodule HAHandler.Web.Controller do
import Plug.Conn
- alias HAHandler.HAProxy
+ alias HAHandler.{HAProxy, PGSQL}
@templates_dir "lib/ha_handler/web/templates"
@@ -22,6 +22,7 @@ defmodule HAHandler.Web.Controller do
assigns = [
haproxy_stats: stats,
+ pgsql_status: PGSQL.status(),
hostname: hostname,
otp_app: HAHandler.otp_app(),
version: HAHandler.version(),
diff --git a/lib/ha_handler/web/templates/index.html.eex b/lib/ha_handler/web/templates/index.html.eex
index 3e62aa7..629d172 100644
--- a/lib/ha_handler/web/templates/index.html.eex
+++ b/lib/ha_handler/web/templates/index.html.eex
@@ -98,6 +98,29 @@
<% end %>
+
+
+
+ PostgreSQL
+
+
+
+
+ | Hostname |
+ Version |
+ Status |
+
+
+
+ <%= for entry <- pgsql_status do %>
+
+ | <%= entry[:hostname] %> |
+ <%= entry[:version] %> |
+ <%= entry[:status] %> |
+
+ <% end %>
+
+