Command output

Execute a command in a running container and read decoded output.

<?php

require __DIR__ . '/vendor/autoload.php';

use Docker\API\Model\ContainersIdExecPostBody;
use Docker\API\Model\ExecIdStartPostBody;
use Docker\Docker;

$docker = Docker::create();

$command = new ContainersIdExecPostBody();
$command->setCmd(['sh', '-c', 'printf "hello\n"']);
$command->setAttachStdout(true);
$command->setAttachStderr(true);
$command->setTty(false);

$exec = $docker->containerExec('my-container', $command);

$start = new ExecIdStartPostBody();
$start->setDetach(false);
$start->setTty(false);

$output = $docker->execStart($exec->getId(), $start);
$output->onStdout(function (string $chunk): void {
    echo $chunk;
});
$output->onStderr(function (string $chunk): void {
    fwrite(STDERR, $chunk);
});
$output->wait();

Replace my-container with an existing running container. Detach must be false to consume attached output. Use the same Tty value when creating and starting the exec command.

For non-TTY commands, stdout and stderr are separate. TTY commands combine both streams on onStdout. Callbacks receive chunks that may contain partial lines.

To check the exit status after consuming the output, use execInspect($exec->getId()) and inspect getRunning() and getExitCode().

Exit status is separate from HTTP success

Continue with the $exec created above, after $output->wait():

$result = $docker->execInspect($exec->getId());
if ($result->getRunning() !== false) {
    throw new RuntimeException('The command has not finished yet');
}
$exitCode = $result->getExitCode();
if ($exitCode === null) {
    throw new RuntimeException('No exit status was returned');
}
if ($exitCode !== 0) {
    throw new RuntimeException('The command failed with exit status '.$exitCode);
}

An HTTP-successful start can still run a command which exits non-zero. Do not infer success from the presence of output, the absence of stderr, or HTTP 200. If a connection ends early, inspect the exec state before deciding whether it finished or retrying a command with side effects.

Detached execution

For a background command, set Detach to true on the start model. Do not register callbacks or call wait() on its result; a detached start can return null on success. Poll execInspect() with a bounded interval/deadline in your application if you need completion and an exit code. This is a different lifecycle from the attached example, not an asynchronous PHP promise.

TTY and upgraded connections

The attached wrapper handles HTTP 200 and HTTP 101 responses when their media type identifies Docker raw or multiplexed output. Set Tty explicitly and consistently at creation and start; do not try to autodetect it from the bytes. A TTY combines stdout/stderr and may produce terminal control sequences.

Custom transports and proxies must preserve upgraded connections and provide an unbuffered body. A normal buffered HTTP response adapter may pass list or inspect calls but fail on exec output.

This recipe is output-only: it does not implement interactive stdin or a terminal UI. onStdin() on DockerRawStream is not a write method. See attach limitations.

Raw response bodies can contain binary frame headers. See Container logs before working with raw fetch modes.