Add `--no-trunc` option to `docker stack deploy` for full error messages

Description

Problem

When running docker stack deploy, deployment errors (especially scheduling constraint failures) are truncated in the CLI output. For example:

1/1: no suitable node (scheduling constraints not satisfied on 1 node; host-mod…
overall progress: 0 out of 1 tasks

This truncation makes it difficult to understand why a service could not be scheduled, as the most relevant part of the message is often cut off. This behavior appears to be hardcoded and does not respect terminal width or environment variables like COLUMNS.

Workarounds

• Manually running docker service ps <service> --no-trunc after deployment
• Inspecting tasks individually with docker inspect
• Writing custom scripts to combine deployment and diagnostic commands

These add friction and delay in understanding deployment issues.

Proposal

Add a --no-trunc flag to docker stack deploy, similar to the one already available in docker service ps, which disables truncation of deployment status and error messages.

Other alternatives could include:

• Respecting the actual terminal width or COLUMNS environment variable
• Automatically disabling truncation when output is non-interactive (e.g. in CI pipelines)
• Supporting full output when --verbose or --debug is enabled

Benefits

• Immediate visibility into deployment failures without requiring follow-up commands
• Better support for CI/CD pipelines where error visibility is critical
• Makes docker stack deploy consistent with other CLI commands that support --no-trunc

Related

• docker service ps already supports --no-trunc and behaves as expected
• No current CLI flags exist to control truncation during stack deployment

Start at the docker stack deploy CLI entry point and compare its output handling with the existing docker service ps --no-trunc implementation. Trace the deployment status and error output, then verify that the new option preserves full messages and that the relevant CLI tests pass.