# Example Elixir Pods
```elixir
Mix.install([
{:pods, path: "./pods"},
{:pod_lispyclouds_sqlite, path: "./pods/example"},
{:erlexec, "~> 2.0"},
{:jason, "~> 1.4"},
{:bento, "~> 1.0"}
])
require Logger
```
## Example Client
The example process manager uses https://github.com/saleyn/erlexec/
but you can implement the pod services using `System.cmd` or `Erlang Ports`
or any other solution if you want.
The only requirement is that it can allow `stdin` and `stdout` interactions.
```elixir
defmodule Decoder do
use Pods.Decoder
def decode(message, "bencode"), do: Bento.decode(message)
def decode(message, "json"), do: Jason.decode(message)
def decode!(message, "bencode"), do: Bento.decode!(message)
def decode!(message, "json"), do: Jason.decode!(message)
end
defmodule Encoder do
use Pods.Encoder
def encode(message, "bencode"), do: Bento.encode(message)
def encode(message, "json"), do: Jason.encode(message)
def encode!(message, "bencode"), do: Bento.encode!(message)
def encode!(message, "json"), do: Jason.encode!(message)
end
defmodule Handler do
use Pods.Handler
def event(payload, type) do
Logger.info("Got Pod Event #{type}")
Logger.debug(payload)
end
def success(payload) do
Logger.info("Got Pod Success Response")
Logger.debug(payload)
end
def error(payload) do
Logger.info("Got Pod Error Response")
Logger.debug(payload)
end
def exception(payload) do
Logger.info("Got Pod Exception")
Logger.debug(payload)
end
end
defmodule Manager do
use Pods.Manager
def init() do
Logger.info("Manager started")
:exec.start()
end
def stop(pod) do
Logger.info("Stopping Pod #{pod.module}")
:exec.stop(pod.pid)
end
def send(pod, message) do
Logger.info("Sending Message to Pod #{pod.module}")
:exec.send(pod.pid, message)
end
def start(executable, decoder, out_handler, exception_handler, opts \\ []) do
temp_dir = System.tmp_dir!()
temp_file_stdout = Path.join([temp_dir, Path.basename(executable) <> ".stdout"])
# Some processes may write a lot of text (streams), so we try to decode a cache
# until it works and then send the data to the handler
# maybe a better solution exists, but it works for now.
# can be a genserver? or maybe mnesia?
stdout_watcher = fn origin, pid, response ->
File.write!(temp_file_stdout, response, [:append])
case decoder.decode(String.trim(File.read!(temp_file_stdout)), "bencode") do
{:ok, _data} ->
out_handler.(%{origin: origin, pid: pid, response: response})
File.rm_rf!(temp_file_stdout)
_ ->
nil
end
end
# exceptions may not be in bencode, so we send the raw response
stderr_watcher = fn origin, pid, response ->
exception_handler.(%{origin: origin, pid: pid, response: response})
end
# start the process with ELIXIR_POD in the env
case :exec.run_link(
executable,
[
:stdin,
{:stdout, stdout_watcher},
{:stderr, stderr_watcher},
:monitor,
{:env, [{"ELIXIR_POD", "1"}]}
] ++ opts
) do
{:ok, _, pid} -> {:ok, pid}
_ = error -> {:error, error}
end
end
end
```
<!-- livebook:{"output":true} -->
```
{:module, Manager, <<70, 79, 82, 49, 0, 0, 20, ...>>, {:start, 5}}
```
## Example Pod Usage
```elixir
# Start the Pods Services
pods =
Pods.start(
# Available Pods List
[Pod.LispyClouds.SQLite],
# Pod Manager
Manager,
# Message Encoder
Encoder,
# Message Decoder
Decoder,
# stdout and stderr handler
Handler
)
# Use the Pods
pods
|> Pod.LispyClouds.SQLite.execute!("create table if not exists foo ( int foo )")
|> Pod.LispyClouds.SQLite.execute!("delete from foo")
|> Pod.LispyClouds.SQLite.execute!("insert into foo values (1), (2)")
|> Pod.LispyClouds.SQLite.execute!("select * from foo")
|> then(fn pods ->
# Give a little time to complete the operations
receive do
after
2000 ->
Pods.stop(pods, :all)
end
end)
```
<!-- livebook:{"output":true} -->
```
16:01:26.921 [info] Manager started
16:01:26.925 [info] Got Pod Event before_op
16:01:26.925 [debug] [args: [], command: "", id: "018f35bf-658d-744e-90dd-36a92005b5f7", message: "d2:id36:018f35bf-658d-744e-90dd-36a92005b5f72:op8:describee", op: "describe", result: %{}, pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:26.925 [info] Sending Message to Pod Elixir.Pod.LispyClouds.SQLite
16:01:26.925 [info] Got Pod Event ready
16:01:26.925 [debug] [args: [], command: "", id: "018f35bf-658d-744e-90dd-36a92005b5f7", message: "d2:id36:018f35bf-658d-744e-90dd-36a92005b5f72:op8:describee", op: "describe", result: :ok, pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:26.926 [info] Invoke command in Pod
16:01:26.926 [debug] [args: ["create table if not exists foo ( int foo )"], command: "execute!", module: Pod.LispyClouds.SQLite]
16:01:26.926 [info] Got Pod Event before_op
16:01:26.926 [debug] [args: ["create table if not exists foo ( int foo )"], command: "pod.lispyclouds.sqlite/execute!", id: "018f35bf-658e-7ac6-ad20-3eaadd97065d", message: "d4:args46:[\"create table if not exists foo ( int foo )\"]2:id36:018f35bf-658e-7ac6-ad20-3eaadd97065d2:op6:invoke3:var31:pod.lispyclouds.sqlite/execute!e", op: "invoke", result: %{}, pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:26.926 [info] Sending Message to Pod Elixir.Pod.LispyClouds.SQLite
16:01:26.927 [info] Got Pod Event after_op
16:01:26.927 [debug] [args: ["create table if not exists foo ( int foo )"], command: "pod.lispyclouds.sqlite/execute!", id: "018f35bf-658e-7ac6-ad20-3eaadd97065d", message: "d4:args46:[\"create table if not exists foo ( int foo )\"]2:id36:018f35bf-658e-7ac6-ad20-3eaadd97065d2:op6:invoke3:var31:pod.lispyclouds.sqlite/execute!e", op: "invoke", result: :ok, pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:26.927 [info] Invoke command in Pod
16:01:26.927 [debug] [args: ["delete from foo"], command: "execute!", module: Pod.LispyClouds.SQLite]
16:01:26.927 [info] Got Pod Event before_op
16:01:26.927 [debug] [args: ["delete from foo"], command: "pod.lispyclouds.sqlite/execute!", id: "018f35bf-658f-761a-ad35-f9da6d1a0384", message: "d4:args19:[\"delete from foo\"]2:id36:018f35bf-658f-761a-ad35-f9da6d1a03842:op6:invoke3:var31:pod.lispyclouds.sqlite/execute!e", op: "invoke", result: %{}, pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:26.927 [info] Sending Message to Pod Elixir.Pod.LispyClouds.SQLite
16:01:26.928 [info] Got Pod Event after_op
16:01:26.928 [debug] [args: ["delete from foo"], command: "pod.lispyclouds.sqlite/execute!", id: "018f35bf-658f-761a-ad35-f9da6d1a0384", message: "d4:args19:[\"delete from foo\"]2:id36:018f35bf-658f-761a-ad35-f9da6d1a03842:op6:invoke3:var31:pod.lispyclouds.sqlite/execute!e", op: "invoke", result: :ok, pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:26.928 [info] Invoke command in Pod
16:01:26.928 [debug] [args: ["insert into foo values (1), (2)"], command: "execute!", module: Pod.LispyClouds.SQLite]
16:01:26.928 [info] Got Pod Event before_op
16:01:26.928 [debug] [args: ["insert into foo values (1), (2)"], command: "pod.lispyclouds.sqlite/execute!", id: "018f35bf-6590-7694-a2f5-b45d6c1f3396", message: "d4:args35:[\"insert into foo values (1), (2)\"]2:id36:018f35bf-6590-7694-a2f5-b45d6c1f33962:op6:invoke3:var31:pod.lispyclouds.sqlite/execute!e", op: "invoke", result: %{}, pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:26.928 [info] Sending Message to Pod Elixir.Pod.LispyClouds.SQLite
16:01:26.928 [info] Got Pod Event after_op
16:01:26.928 [debug] [args: ["insert into foo values (1), (2)"], command: "pod.lispyclouds.sqlite/execute!", id: "018f35bf-6590-7694-a2f5-b45d6c1f3396", message: "d4:args35:[\"insert into foo values (1), (2)\"]2:id36:018f35bf-6590-7694-a2f5-b45d6c1f33962:op6:invoke3:var31:pod.lispyclouds.sqlite/execute!e", op: "invoke", result: :ok, pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:26.929 [info] Invoke command in Pod
16:01:26.938 [debug] [args: ["select * from foo"], command: "execute!", module: Pod.LispyClouds.SQLite]
16:01:26.938 [info] Got Pod Event before_op
16:01:26.938 [debug] [args: ["select * from foo"], command: "pod.lispyclouds.sqlite/execute!", id: "018f35bf-659a-7bf8-b912-098a0b14c8dc", message: "d4:args21:[\"select * from foo\"]2:id36:018f35bf-659a-7bf8-b912-098a0b14c8dc2:op6:invoke3:var31:pod.lispyclouds.sqlite/execute!e", op: "invoke", result: %{}, pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:26.939 [info] Sending Message to Pod Elixir.Pod.LispyClouds.SQLite
16:01:26.939 [info] Got Pod Event after_op
16:01:26.939 [debug] [args: ["select * from foo"], command: "pod.lispyclouds.sqlite/execute!", id: "018f35bf-659a-7bf8-b912-098a0b14c8dc", message: "d4:args21:[\"select * from foo\"]2:id36:018f35bf-659a-7bf8-b912-098a0b14c8dc2:op6:invoke3:var31:pod.lispyclouds.sqlite/execute!e", op: "invoke", result: :ok, pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:27.047 [info] Got Pod Success Response
16:01:27.048 [debug] [id: 7915, raw: %{pid: 7915, origin: :stdout, response: "d6:format4:json10:namespacesld4:name22:pod.lispyclouds.sqlite4:varsld4:name8:execute!eeeee"}, status: :ok, result: [], pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:27.050 [info] Got Pod Success Response
16:01:27.050 [debug] [id: "018f35bf-658e-7ac6-ad20-3eaadd97065d", raw: %{pid: 7915, origin: :stdout, response: "d2:id36:018f35bf-658e-7ac6-ad20-3eaadd97065d6:statusl4:donee5:value2:[]e"}, status: :ok, result: [], pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:27.052 [info] Got Pod Success Response
16:01:27.052 [debug] [id: "018f35bf-658f-761a-ad35-f9da6d1a0384", raw: %{pid: 7915, origin: :stdout, response: "d2:id36:018f35bf-658f-761a-ad35-f9da6d1a03846:statusl4:donee5:value2:[]e"}, status: :ok, result: [], pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:27.055 [info] Got Pod Success Response
16:01:27.055 [debug] [id: "018f35bf-6590-7694-a2f5-b45d6c1f3396", raw: %{pid: 7915, origin: :stdout, response: "d2:id36:018f35bf-6590-7694-a2f5-b45d6c1f33966:statusl4:donee5:value2:[]e"}, status: :ok, result: [], pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:27.058 [info] Got Pod Success Response
16:01:27.058 [debug] [id: "018f35bf-659a-7bf8-b912-098a0b14c8dc", raw: %{pid: 7915, origin: :stdout, response: "d2:id36:018f35bf-659a-7bf8-b912-098a0b14c8dc6:statusl4:donee5:value10:[[1], [2]]e"}, status: :ok, result: [[1], [2]], pod: %{module: Pod.LispyClouds.SQLite, pid: 7915, manifest: Pod.LispyClouds.SQLite.Manifest}]
16:01:28.940 [info] Stopping all pods
16:01:28.940 [info] Stopping Pod Elixir.Pod.LispyClouds.SQLite
```
<!-- livebook:{"output":true} -->
```
[%{pid: 7915, stop: :ok, pod: Pod.LispyClouds.SQLite}]
```
