Erlexec 2.6.0: new features - run_container/1 and run_graph/2

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The following two features were added to erlexec.

Container: exec:run_container/1: run a command in a container

You describe the container in a map, and erlexec builds the podman or docker command line and runs it:

exec:run_container(#{
  image        => "alpine:3.20",
  command      => "echo hello",
  env          => #{"FOO" => "bar"},
  volumes      => [{"/tmp", "/work", "ro"}],
  ports        => [{"127.0.0.1", 8080, 80}],
  cpu_limit    => "500m",
  memory_limit => "256M",
  timeout      => 5000
}).
  • The runtime defaults to auto, which prefers podman and falls back to docker. You can also name one explicitly or give a path to an executable.
  • Runtime paths are cached in persistent_term. A cached path that no longer exists is dropped and looked up again.
  • remove defaults to true, so containers are removed when they exit.
  • timeout uses the normal exec timeout. Only on_timeout => kill is supported.
  • exec_options passes extra options through to exec:run_link/2.

The full list of spec keys is in the exec_container module docs.

Graph: exec:run_graph/2: run a pipeline of commands

A graph is a list of tasks. Each task’s stdout or stderr can be routed to another task’s stdin, to one or more tasks, or to a file:

Graph = [
  #{id     => producer,
    cmd    => "printf 'a\nb\nc\n'",
    stdout => [filter],

  #{id     => filter,
    cmd    => "grep '^b$'"}
],
{ok, [{stdout, [<<"b\n">>]}]} = exec:run_graph(Graph, [sync, stdout]).
  • sync blocks the caller and returns the collected output. Without it, run_graph/2 returns {ok, Worker, GraphOsPid} and sends messages to the caller.
  • In async mode, monitor reports when the whole graph finishes, and task_monitor reports each task as it finishes.
  • A per-task timeout can be set in the task map. timeout in the graph options limits the whole graph’s run time.
  • stats returns resource usage per task.
  • Options that aren’t graph-specific, such as timeout and stats, are passed to every task.

Feedback is welcome, especially on the graph options and the container spec keys. If you try either one, tell me what didn’t behave as you expected.

Github: erlexec
Hex.pm: erlexec

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