AstarteExport: Add Cassandra host/port and update README

- Modified export_realm_data/3 to accept db_host_and_port as an argument.
- Set Cassandra host and port as env variables
- Updated the run/1 function to reflect the new parameters for exporting.
- Enhanced documentation to include the new db_host_and_port argument.
- Updated README to reflect the changes in function usage and parameters.

Signed-off-by: Jusuf <jusuf.avdic@secomind.com>

Author: Jusuf95

tools/astarte_export/README.md

@@ -3,7 +3,7 @@
 Astarte Export is an easy to use tool that allows to exporting all the devices and data from an existing Astarte realm to XML format.
 
 ```iex
-iex(astarte_export@127.0.0.1)6> Astarte.Export.export_realm_data("test", "test.xml")
+iex(astarte_export@127.0.0.1)6> Astarte.Export.export_realm_data("test", "test.xml", [{:device_id, "ogmcilZpRDe"}, {:db_host_and_port, "localhost:9042"}])
 level=info ts=2020-02-03T03:57:21.412+00:00 msg="Export started." module=Astarte.Export function=generate_xml/2 realm=test tag=export_started
 level=info ts=2020-02-03T03:57:21.413+00:00 msg="Connecting to \"172.23.0.3\":\"9042\" cassandra database." module=Astarte.Export.FetchData.Queries function=get_connection/0
 level=info ts=2020-02-03T03:57:21.414+00:00 msg="Connected to database." module=Astarte.Export.FetchData.Queries function=get_connection/0
@@ -40,12 +40,26 @@ To export data for all devices in a realm:
 To export data for a single device in a realm:
 
 ```bash
-mix astarte.export <REALM> <FILE_XML> <DEVICE_ID>
+mix astarte.export <REALM> <FILE_XML> --device_id <DEVICE_ID>
 ```
 
 - `<REALM>`: The name of the Astarte realm.
 - `<FILE_XML>`: The output file path where the exported data will be saved.
-- `<DEVICE_ID>`: The unique identifier of the device (e.g., "ogmcilZpRDeDWwuNfJr0yA").
+- `--device_id <DEVICE_ID>`(optional): The unique identifier of the device (e.g., "ogmcilZpRDeDWwuNfJr0yA").
+
+## Export Data for a Realm with a Custom Database Host and Port
+
+To export data from a specific Astarte realm with a custom database host and port:
+
+```bash
+mix astarte.export <REALM> <FILE_XML> --device_id <DEVICE_ID> --db_host_and_port <DB_HOST_AND_PORT>
+```
+
+- `<REALM>`: The name of the Astarte realm.
+- `<FILE_XML>`: The output file path where the exported data will be saved.
+- `--device_id  <DEVICE_ID>` (optional): The unique identifier of the device (e.g., "ogmcilZpRDeDWwuNfJr0yA").
+- `--db_host_and_port <DB_HOST_AND_PORT>` (optional): 
+  The host and port of the database in the format host:port (e.g., "localhost:9042"").
 
 ## Example Commands
 

tools/astarte_export/lib/astarte/export.ex

@@ -37,7 +37,14 @@ defmodule Astarte.Export do
     - options   -> options to export the realm data.
   """
 
-  @spec export_realm_data(String.t(), String.t(), keyword()) ::
+  @spec export_realm_data(
+          String.t(),
+          String.t(),
+          [{:db_host_and_port, String.t()} | {:device_id, String.t()}] | []
+        ) ::
+          :ok | {:error, :invalid_parameters} | {:error, any()}
+
+  @spec export_realm_data(String.t(), String.t()) ::
           :ok | {:error, :invalid_parameters} | {:error, any()}
 
   def export_realm_data(realm, file, opts \\ []) do
@@ -54,7 +61,7 @@ defmodule Astarte.Export do
     with {:ok, state} <- XMLGenerate.xml_write_default_header(fd),
          {:ok, state} <- XMLGenerate.xml_write_start_tag(fd, {"astarte", []}, state),
          {:ok, state} <- XMLGenerate.xml_write_start_tag(fd, {"devices", []}, state),
-         {:ok, conn} <- FetchData.db_connection_identifier(),
+         {:ok, conn} <- FetchData.db_connection_identifier(opts),
          {:ok, state} <- process_devices(conn, realm, fd, state, opts),
          {:ok, state} <- XMLGenerate.xml_write_end_tag(fd, state),
          {:ok, _state} <- XMLGenerate.xml_write_end_tag(fd, state),

tools/astarte_export/lib/astarte/fetchdata/fetchdata.ex

@@ -13,8 +13,8 @@ defmodule Astarte.Export.FetchData do
     booleanarray: :boolean
   }
 
-  def db_connection_identifier() do
-    with {:ok, conn_ref} <- Queries.get_connection() do
+  def db_connection_identifier(opts \\ []) do
+    with {:ok, conn_ref} <- Queries.get_connection(opts) do
       {:ok, conn_ref}
     else
       _ -> {:error, :connection_setup_failed}

tools/astarte_export/lib/astarte/fetchdata/queries/queries.ex

@@ -6,12 +6,22 @@ defmodule Astarte.Export.FetchData.Queries do
 
   require Logger
 
-  def get_connection() do
-    host = System.get_env("CASSANDRA_DB_HOST")
-    port = System.get_env("CASSANDRA_DB_PORT")
-    Logger.info("Connecting to #{inspect(host)}:#{inspect(port)} cassandra database.")
+  def get_connection(opts \\ []) do
+    db_host_and_port = Keyword.get(opts, :db_host_and_port)
 
-    with {:ok, xandra_conn} <- Xandra.start_link(nodes: ["#{host}:#{port}"], atom_keys: true) do
+    [db_host, db_port] =
+      case db_host_and_port do
+        nil ->
+          [System.get_env("CASSANDRA_DB_HOST"), System.get_env("CASSANDRA_DB_PORT")]
+
+        _ ->
+          String.split(db_host_and_port, ":")
+      end
+
+    Logger.info("Connecting to #{inspect(db_host)}:#{inspect(db_port)} cassandra database.")
+
+    with {:ok, xandra_conn} <-
+           Xandra.start_link(nodes: ["#{db_host}:#{db_port}"], atom_keys: true) do
       Logger.info("Connected to database.")
       {:ok, xandra_conn}
     else

tools/astarte_export/lib/mix/tasks/astarte_export.ex

@@ -5,34 +5,43 @@ defmodule Mix.Tasks.Astarte.Export do
   require Logger
 
   @impl Mix.Task
-  @shortdoc "export data from an existing Astarte realm"
+  @shortdoc "Export data from an existing Astarte realm"
   def run(args) do
-    case args do
-      [realm, file_name] ->
-        Logger.info("Exporting data from realm #{realm} to file #{file_name}")
+    {realm, file_name, device_id, db_host_and_port} = parse_args(args)
 
-        case Application.ensure_all_started(:astarte_export) do
-          {:ok, _} ->
-            Export.export_realm_data(realm, file_name)
+    Logger.info("Exporting data from realm #{realm} to file #{file_name}")
 
-          {:error, reason} ->
-            Logger.error("Cannot start applications: #{inspect(reason)}")
-        end
+    options =
+      case {db_host_and_port, device_id} do
+        {nil, nil} -> []
+        {nil, _} -> [device_id: device_id]
+        {_, nil} -> [db_host_and_port: db_host_and_port]
+        {_, _} -> [db_host_and_port: db_host_and_port, device_id: device_id]
+      end
 
-      [realm, file_name, device_id] ->
-        Logger.info(
-          "Exporting data for device #{device_id} from realm #{realm} to file #{file_name}"
-        )
+    case Application.ensure_all_started(:astarte_export) do
+      {:ok, _} ->
+        Export.export_realm_data(realm, file_name, options)
 
-        options = [device_id: device_id]
+      {:error, reason} ->
+        Logger.error("Cannot start applications: #{inspect(reason)}")
+    end
+  end
 
-        case Application.ensure_all_started(:astarte_export) do
-          {:ok, _} ->
-            Export.export_realm_data(realm, file_name, options)
+  defp parse_args([realm, file_name | opts]) do
+    {device_id, db_host_and_port} = parse_optional_args(opts)
+    {realm, file_name, device_id, db_host_and_port}
+  end
 
-          {:error, reason} ->
-            Logger.error("Cannot start applications: #{inspect(reason)}")
-        end
-    end
+  defp parse_optional_args([]), do: {nil, nil}
+
+  defp parse_optional_args(["--device_id", device_id | rest]) do
+    {device_id, parse_optional_args(rest) |> elem(1)}
+  end
+
+  defp parse_optional_args(["--db_host_and_port", db_host_and_port | rest]) do
+    {parse_optional_args(rest) |> elem(0), db_host_and_port}
   end
+
+  defp parse_optional_args([_ | rest]), do: parse_optional_args(rest)
 end

tools/astarte_export/test/astarte_export_test.exs

@@ -5,6 +5,7 @@ defmodule Astarte.ExportTest do
   alias Astarte.Export.FetchData
   alias Astarte.DatabaseTestdata
   @realm "test"
+  @db_host_and_port "localhost:9042"
 
   @expected_xml """
   <?xml version="1.0" encoding="UTF-8"?>
@@ -77,12 +78,35 @@ defmodule Astarte.ExportTest do
     assert @expected_xml == File.read!(file)
   end
 
+  test "export realm data to xml file with db_host_and_port"  do
+    DatabaseTestdata.initialize_database()
+    assert {:ok, :export_completed} ==
+             Export.export_realm_data(@realm, "test.xml", [db_host_and_port: @db_host_and_port])
+    file = Path.expand("test.xml") |> Path.absname()
+    assert @expected_xml == File.read!(file)
+  end
+
   test "export realm data to xmlfile in a absolute path " do
     file = File.cwd!() <> "/test.xml"
     assert {:ok, :export_completed} == Export.export_realm_data(@realm, file)
     assert @expected_xml == File.read!(file)
   end
 
+  test "export realm data to xml file with db_host_and_port in absolute path" do
+    file = File.cwd!() <> "/test.xml"
+    assert {:ok, :export_completed} == Export.export_realm_data(@realm, file, [db_host_and_port: @db_host_and_port])
+    assert @expected_xml == File.read!(file)
+  end
+
+  test "export fails with invalid realm" do
+    assert {:error, :database_error} == Export.export_realm_data("invalid_realm", "test.xml")
+  end
+
+  test "export fails with database connection error" do
+    assert {:error, :database_connection_error} ==
+             Export.export_realm_data(@realm, "test.xml", [db_host_and_port: "invalid_host:0000"])
+  end
+
   test "test to export xml data " do
     {:ok, stdio} = read_stdio_output_on_port()
     {:ok, state} = XMLGenerate.xml_write_default_header(:standard_error)