view release on metacpan or  search on metacpan

lib/API/Docker/API/Exec.pm  view on Meta::CPAN

    # Create an exec instance
    my $exec = $docker->exec->create($container_id,
        Cmd         => ['/bin/sh', '-c', 'echo hello'],
        AttachStdout => 1,
        AttachStderr => 1,
    );

    # Start the exec -- ArrayRef of { stream => ..., data => ... } frames
    my $frames = $docker->exec->start($exec->{Id});
    my $output = join '', map { $_->{data} } @$frames;

    # The exit status comes from a separate call
    my $exit = $docker->exec->inspect($exec->{Id})->{ExitCode};

    # Inspect exec instance
    my $info = $docker->exec->inspect($exec->{Id});

=head1 DESCRIPTION

This module provides methods for executing commands inside running containers
using the Docker Exec API.

Accessed via C<< $docker->exec >>, or through
L<API::Docker::Role::Using/using> for a run of calls that needs its own
transport bound: C<< $docker->exec->using(read_timeout => 5) >>.

=head2 client

Reference to L<API::Docker> client. Weak reference to avoid circular dependencies.

=head2 create

    my $exec = $exec->create($container_id,
        Cmd          => ['/bin/sh', '-c', 'echo hello'],
        AttachStdout => 1,
        AttachStderr => 1,
        Tty          => 0,
    );

Create an exec instance. Returns hashref with C<Id>.

Required config: C<Cmd> (ArrayRef of command and arguments).

Common config keys: C<AttachStdin>, C<AttachStdout>, C<AttachStderr>, C<Tty>,
C<Env>, C<User>, C<WorkingDir>.

The boolean flags (C<AttachStdin>, C<AttachStdout>, C<AttachStderr>, C<Tty>,
C<Privileged>) may be given as a Perl C<1>/C<0> or as a JSON boolean; either
goes out as a real JSON C<true>/C<false>, which the engine's body type-check
requires. Passing C<1> where the daemon wants a boolean would otherwise be
rejected.

=head2 start

    my $frames = $exec->start($exec_id, Detach => 0);

    my $output = join '', map { $_->{data} } @$frames;

Start an exec instance. Returns an ArrayRef of frames in the same shape as
L<API::Docker::API::Containers/logs>:

    [ { stream => 'stdout', data => "OUT\n" },
      { stream => 'stderr', data => "ERR\n" } ]

An exec instance created without a TTY multiplexes stdout and stderr into one
framed stream, which this method demultiplexes. One created with a TTY has no
frame headers and its output arrives as a single C<< stream => 'raw' >> frame.
A detached start produces no output, so it returns an empty ArrayRef.

The exit status is B<not> part of this response. It comes from a separate call
once the exec has finished:

    my $exit = $exec->inspect($exec_id)->{ExitCode};

Options:

=over

=item * C<Detach> - Run detached; the engine returns immediately and no output
is streamed

=item * C<Tty> - Declares that this exec instance was created with a TTY. It is
sent in the request body, where the engine expects it to match the C<Tty> given
to L</create>, and it also suppresses demultiplexing of the response. Framing is
otherwise detected from the response bytes -- see
L<API::Docker::Role::HTTP/"Detecting a framed stream">

=item * C<on_frame> - CodeRef called with each frame as it arrives, instead of
the ArrayRef being collected and returned; see below

=back

=head2 Watching the output as it is produced

Without a callback this returns when the command has finished and the daemon
has closed the stream -- a command that runs for a minute is a minute of
silence, and one that never finishes never returns. Pass C<on_frame> and the
frames are handed over as they arrive:

    my $summary = $exec->start($exec_id,
        on_frame => sub {
            my ($frame, $stop) = @_;
            print $frame->{data};
            $stop->() if $frame->{data} =~ /ready/;
        },
    );

    $summary;   # { delivered => 9, stopped => 1 }

With a callback the return value is that summary HashRef, not the frames:
C<delivered> is how many went to the callback, C<stopped> is 1 when the
callback ended the stream and 0 when the daemon did. Nothing is accumulated,
so joining the output is the callback's job. See
L<API::Docker::Role::HTTP/"Streaming a response as it arrives">.

A detached start produces no output, so its summary is
C<< { delivered => 0, stopped => 0 } >> where the buffered call returns an
empty ArrayRef.

C<Tty> means something stronger on this path. The buffered path decides