Skip to content

Approx. date: Boot/console troubleshooting session (date not explicitly stated in chat) - Slow Login Prompt in qm terminal

Summary

A Proxmox VM was investigated for delayed login prompt visibility when accessed through qm terminal. Initial concern included a boot-time stall related to systemd-tmpfiles-setup.service, but the issue was later narrowed to console presentation rather than the VM failing to boot. The session focused on distinguishing between a true boot delay and a serial-console or getty presentation issue.

Environment

  • Proxmox VE
  • QEMU/KVM VM accessed with qm terminal
  • Linux guest using systemd
  • Likely Debian-based guest OS
  • Serial console context involving ttyS0
  • GRUB bootloader and serial-getty@ttyS0.service

Problem

The login prompt took a long time to appear when using qm terminal, even after the VM had already finished booting.

Symptoms

  • Boot output included: text Job systemd-tmpfiles-setup.service/start running (2min 32s / no limit)
  • Later clarification indicated the VM had already gotten past that stage and had finished booting.
  • qm terminal appeared blank or delayed before showing login:.

Actions Taken

  1. Considered whether boot was blocked by systemd-tmpfiles-setup.service.
  2. Reviewed likely causes of slow boot or delayed console availability:
  3. slow mounts
  4. tmpfiles rules
  5. network waits
  6. cloud-init work
  7. filesystem checks
  8. After clarification that boot had completed, the focus shifted to console behavior rather than boot performance.
  9. Identified likely causes:
  10. serial console not fully configured
  11. qm terminal attached to ttyS0 while login was on VGA/tty1
  12. serial-getty already running but not repainting until keypress
  13. Proposed enabling a serial login console and adding kernel console parameters.
  14. Noted that pressing Enter once after attaching may redraw an already-running getty prompt.

Key Findings

  • The observed systemd-tmpfiles-setup.service message indicated a boot job was running at one point, but it was not the root cause of the final user-facing issue.
  • Once the VM had fully booted, the remaining problem was more consistent with console mismatch than with actual system slowness.
  • qm terminal behavior depends on:
  • whether Proxmox is attached to a serial device such as ttyS0
  • whether the guest kernel logs to that console
  • whether a getty is active on that console
  • A blank or delayed screen in qm terminal can happen even when the VM is healthy.

Resolution

Current status: the issue was diagnosed conceptually as a serial console / getty configuration problem rather than a true boot hang.

Recommended fix path: - enable serial-getty@ttyS0.service - configure GRUB with: bash GRUB_CMDLINE_LINUX_DEFAULT="quiet console=tty0 console=ttyS0" - update GRUB and reboot - test whether Enter redraws the prompt when attaching with qm terminal

Validation

Suggested validation steps: - confirm serial-getty@ttyS0.service is active - reboot the VM - reconnect with: bash qm terminal 100 - verify that boot messages and the login: prompt appear on the serial console - if the screen is blank, press Enter once and confirm whether the prompt appears immediately

Follow-Up Tasks

  • Verify whether the VM has a configured serial port in Proxmox hardware settings.
  • Check whether Proxmox is set to use a serial console for the VM.
  • Confirm GRUB kernel command line includes both VGA and serial console targets.
  • Confirm the issue is present only in qm terminal and not in the Proxmox web console.
  • Capture systemctl status serial-getty@ttyS0.service and /etc/default/grub for documentation.

Lessons Learned

  • A blank qm terminal session does not always mean the VM is still booting.
  • Separate true boot delays from serial-console presentation issues.
  • For reliable headless troubleshooting, configure both kernel console output and a getty on ttyS0.
  • Pressing Enter can reveal an already-running login prompt on serial consoles.

Traefik Docker Provider API Version Mismatch

Summary

Traefik failed to start correctly because its Docker provider was using an outdated Docker client API version. The environment included a dockersocket sidecar proxy in front of the Docker socket. Troubleshooting focused on interpreting provider errors, separating root cause from shutdown noise, and identifying the correct remediation path.

Environment

  • Date from logs: [date removed]
  • Docker Engine
  • Docker Compose
  • Traefik container
  • dockersocket container acting as Docker socket proxy
  • Reverse proxy setup using Traefik Docker provider
  • HTTP entrypoint on port 80
  • HTTPS entrypoint on port 443

Problem

Traefik could not communicate with the Docker daemon because the Docker API version used by the Traefik binary was too old for the host Docker Engine.

Symptoms

Observed logs included:

traefik       | [date removed]-18T18:06:48Z ERR Provider error, retrying in 7.845389865s error="Error response from daemon: client version 1.24 is too old. Minimum supported API version is 1.44, please upgrade your client to a newer version" providerName=docker

Additional shutdown logs:

dockersocket  | [NOTICE]   (1) : haproxy version is 3.2.4-98813a1
dockersocket  | [WARNING]  (1) : Exiting Master process...
dockersocket  | Proxy dockerfrontend stopped (cumulated conns: FE: 81, BE: 0).
dockersocket  | Proxy dockerbackend stopped (cumulated conns: FE: 0, BE: 81).
dockersocket  | Proxy docker-events stopped (cumulated conns: FE: 0, BE: 0).
traefik       | [date removed]-18T18:06:55Z INF I have to go...
traefik       | [date removed]-18T18:06:55Z INF Stopping server gracefully
traefik       | [date removed]-18T18:06:55Z ERR error="accept tcp [::]:443: use of closed network connection" entryPointName=websecure
traefik       | [date removed]-18T18:06:55Z ERR error="accept tcp [::]:80: use of closed network connection" entryPointName=web
dockersocket  | [WARNING]  (1) : All workers exited. Exiting... (0)
dockersocket exited with code 0
traefik       | [date removed]-18T18:06:56Z INF Server stopped
traefik       | [date removed]-18T18:06:56Z INF Shutting down
traefik       | [date removed]-18T18:06:56Z ERR Cannot retrieve data error="context canceled" providerName=docker
traefik exited with code 0

Actions Taken

  1. Reviewed Traefik logs and isolated the first meaningful provider error.
  2. Distinguished the root cause from subsequent graceful shutdown messages.
  3. Determined that:
  4. the error was generated by Traefik as the Docker API client
  5. dockersocket was only proxying the connection and was not itself the version-mismatched client
  6. Identified the likely remediation:
  7. upgrade the Traefik image to a modern version
  8. Considered a temporary workaround:
  9. forcing DOCKER_API_VERSION=1.44
  10. Explicitly rejected Docker Engine downgrade as a preferred fix.

Key Findings

  • Root cause: text client version 1.24 is too old. Minimum supported API version is 1.44
  • This indicates a Docker API compatibility gap between:
  • the Traefik binary or embedded Docker client library
  • the installed Docker Engine version
  • The dockersocket container was not the source of the API version problem.
  • Messages such as: text use of closed network connection occurred during shutdown and were secondary symptoms, not the initiating fault.
  • Both Traefik and dockersocket exited with code 0, indicating controlled shutdown rather than a crash loop caused by signal failure or segmentation fault.

Resolution

Current status: root cause identified; recommended fix is to upgrade Traefik.

Recommended primary remediation: - update the Traefik image in Docker Compose to a current release, such as: yaml image: traefik:v3.1

Temporary workaround if an immediate upgrade is not possible: - set: yaml DOCKER_API_VERSION=1.44 - treat this only as an interim measure

Not recommended: - downgrading Docker Engine to preserve support for very old client API versions

Validation

Suggested validation steps after remediation: 1. Pull and deploy the updated Traefik image. 2. Start Traefik and dockersocket. 3. Review logs for absence of: text client version 1.24 is too old 4. Confirm Traefik successfully loads the Docker provider and discovers routers/services. 5. Confirm ports 80 and 443 remain bound and available after startup.

Follow-Up Tasks

  • Review the current Traefik image tag and document the exact version in use before and after remediation.
  • Verify whether other Compose stacks use similarly outdated pinned image tags.
  • Confirm compatibility of Traefik static flags and dynamic configuration with the target upgraded version.
  • Consider documenting a version policy for critical infrastructure containers such as Traefik.
  • Add a post-upgrade validation checklist for routes, TLS, and Docker provider discovery.

Lessons Learned

  • The first provider error is usually the most important line in the log stream.
  • Graceful-shutdown errors around entrypoints often follow the real issue and should not be mistaken for root cause.
  • A Docker socket proxy can be healthy while the client behind it is too old.
  • Infrastructure containers such as reverse proxies should be kept within a supported version range relative to the Docker Engine.

Command Reference

Command

journalctl -u systemd-tmpfiles-setup.service -b

Purpose

View logs for systemd-tmpfiles-setup.service from the current boot.

What it does

Queries the systemd journal for only this unit during the current boot session.

Important parts

  • -u systemd-tmpfiles-setup.service limits output to that service
  • -b limits output to the current boot

Why it was used

To determine whether boot delay was caused by tmpfiles processing.

Expected result

Logs showing whether the service completed normally, stalled on a path, or emitted errors.

What success or failure indicates

  • Normal completion suggests tmpfiles is not the current blocker.
  • Long pauses, filesystem errors, or path access failures indicate a real boot bottleneck.

Risk

Low risk. Read-only.

Command

systemd-analyze blame

Purpose

Show which services or units consumed the most time during boot.

What it does

Lists boot units sorted by initialization time.

Why it was used

To identify whether boot slowness was real and, if so, which unit was responsible.

Expected result

A ranked list of services and mounts by startup duration.

What success or failure indicates

  • Long times on mount units, network waits, or tmpfiles help pinpoint the delay.
  • If nothing significant appears, the issue may be console-related rather than a real boot hold-up.

Risk

Low risk. Read-only.

Command

systemd-analyze critical-chain

Purpose

Show the dependency path that controlled how long the system took to reach the boot target.

What it does

Displays the chain of units that gated boot progress.

Why it was used

To tell whether the login delay was caused by service dependencies instead of console behavior.

Expected result

A timing tree showing the key boot path.

What success or failure indicates

  • A long dependency chain confirms actual boot delay.
  • A normal chain suggests the system is up and the issue is likely with console access or getty behavior.

Risk

Low risk. Read-only.

Command

systemctl --failed

Purpose

List failed systemd units.

What it does

Shows services, mounts, or targets that failed during boot or runtime.

Why it was used

To identify failed boot components that could explain missing login or partial system initialization.

Expected result

Either no failed units or a short list of failed components.

What success or failure indicates

  • No failed units suggests the boot completed cleanly.
  • Failed getty, mount, or networking units may explain delayed or missing console login.

Risk

Low risk. Read-only.

Command

journalctl -b -u systemd-tmpfiles-setup.service | sed -n '1,80p'

Purpose

Show the first portion of tmpfiles logs from the current boot.

What it does

Reads service logs, then limits output to the first 80 printed lines.

Important parts

  • sed -n '1,80p' prints only lines 1 through 80

Why it was used

To quickly inspect early tmpfiles activity without dumping an excessively long log.

Expected result

Compact service output suitable for troubleshooting.

What success or failure indicates

Useful for spotting where processing slowed or failed.

Risk

Low risk. Read-only.

Command

qm terminal 100

Purpose

Attach to the Proxmox VM serial console for VM ID 100.

What it does

Opens a terminal session to the VM console managed by Proxmox.

Important parts

  • 100 is the VM ID

Why it was used

To observe boot behavior and check whether a login prompt appeared.

Expected result

Kernel messages, boot logs, or a login prompt if the guest is configured for serial console access.

What success or failure indicates

  • A visible prompt suggests serial console and getty are working.
  • A blank screen may indicate no serial output, missing getty on ttyS0, or only VGA console output.

Risk

Low risk. Interactive access only.

Platform note

In Proxmox, qm terminal is most useful when the guest is configured with a serial port and login on ttyS0.

Command

sudo systemctl enable --now serial-getty@ttyS0.service

Purpose

Enable and start a login prompt on the serial console.

What it does

Configures systemd to launch a getty on ttyS0 immediately and on future boots.

Important parts

  • enable persists across reboots
  • --now starts the service immediately
  • serial-getty@ttyS0.service targets the serial device commonly used by Proxmox serial console

Why it was used

To ensure qm terminal has a login prompt to display after boot.

Expected result

The service becomes active and starts listening on ttyS0.

What success or failure indicates

  • Success means the guest is now prepared to present login over serial.
  • Failure may indicate missing serial device support or guest console mismatch.

Risk

Low risk.

Command

sudo update-grub

Purpose

Regenerate GRUB configuration after editing kernel command-line settings.

What it does

Rebuilds the GRUB boot configuration based on /etc/default/grub and related scripts.

Why it was used

After adding console=tty0 console=ttyS0, GRUB must be updated so the next boot uses the new console parameters.

Expected result

New GRUB configuration written without errors.

What success or failure indicates

  • Success means the next reboot should use the updated kernel console settings.
  • Failure means serial console configuration changes will not take effect.

Risk

Moderate. Safe when done correctly, but mistakes in bootloader configuration can affect boot behavior.

Safer alternative

Back up /etc/default/grub before editing.

Command

cat /etc/default/grub | sed -n '1,20p'

Purpose

Review the beginning of the GRUB defaults file.

What it does

Prints the first 20 lines of the file for quick inspection.

Why it was used

To verify whether GRUB_CMDLINE_LINUX_DEFAULT includes the required console parameters.

Expected result

A readable snippet showing current GRUB defaults.

What success or failure indicates

Useful for validating whether serial console settings are correctly defined.

Risk

Low risk. Read-only.

Command

systemctl status serial-getty@ttyS0.service

Purpose

Check the state of the serial getty service.

What it does

Shows whether the service is active, enabled, failed, or inactive, along with recent log lines.

Why it was used

To confirm whether login should appear on the serial console.

Expected result

active (running) when properly configured.

What success or failure indicates

  • Active service supports qm terminal login visibility.
  • Inactive or failed status points to the root of the missing prompt.

Risk

Low risk. Read-only.

Command

cd /opt/compose/traefik_stack

Purpose

Change into the Traefik Compose project directory.

What it does

Sets the working directory so docker compose commands apply to the intended stack.

Why it was used

To manage the Traefik and dockersocket containers from the correct Compose context.

Expected result

Shell working directory changes successfully.

What success or failure indicates

  • Success means subsequent Compose commands target the right project.
  • Failure suggests the expected stack path may differ.

Risk

Low risk.

Command

docker compose pull traefik

Purpose

Download the updated Traefik image.

What it does

Pulls the latest version of the specified image tag defined for the traefik service.

Why it was used

To upgrade Traefik and resolve Docker API client compatibility issues.

Expected result

A successful image download for the configured Traefik tag.

What success or failure indicates

  • Success means the updated image is ready for deployment.
  • Failure may indicate network, registry, authentication, or tag issues.

Risk

Low risk, but it changes what image version will be used on the next deployment.

Platform note

For Docker Compose environments, image updates should be paired with controlled restart and post-change validation.

Command

docker compose up -d traefik dockersocket

Purpose

Start or recreate the Traefik and dockersocket services in detached mode.

What it does

Applies the current Compose configuration to the named services and runs them in the background.

Important parts

  • -d runs containers detached
  • service names restrict scope to Traefik-related components

Why it was used

To deploy the upgraded Traefik image and restore reverse proxy service.

Expected result

Containers start successfully and remain running.

What success or failure indicates

  • Stable running containers indicate the deployment likely succeeded.
  • Immediate exit or restart loops indicate remaining config or compatibility problems.

Risk

Moderate. This changes live reverse proxy components and can temporarily interrupt ingress traffic.

Safer alternative

Review the Compose diff and image tag changes before restarting production-facing proxy services.

Command

docker logs -f traefik

Purpose

Follow Traefik container logs in real time.

What it does

Streams stdout/stderr from the Traefik container continuously.

Important parts

  • -f follows the log stream

Why it was used

To verify whether the Docker provider initializes correctly after upgrade.

Expected result

Startup logs showing provider loading, router discovery, and absence of API version errors.

What success or failure indicates

  • No provider error indicates the compatibility issue is resolved.
  • Reappearance of the API version error means the old image, wrong tag, or another incompatible component is still in play.

Risk

Low risk. Read-only.

Command

image: traefik:v3.1

Purpose

Pin Traefik to a current major release in Compose configuration.

What it does

Tells Docker Compose which Traefik image version to deploy.

Why it was used

To replace an outdated Traefik version that embedded an old Docker client API.

Expected result

A newer Traefik binary with current Docker provider compatibility.

What success or failure indicates

  • Successful deployment suggests API compatibility should improve.
  • If startup still fails, review other static flags, provider settings, or whether the image actually changed.

Risk

Moderate. Major version upgrades can introduce config differences.

Safer alternative

Use a tested minor version pin and review Traefik release notes before upgrading.

Command

DOCKER_API_VERSION=1.44

Purpose

Force the Docker client library inside the container to negotiate with API version 1.44.

What it does

Overrides automatic API version selection through an environment variable.

Why it was used

As a temporary workaround when an immediate Traefik upgrade is not possible.

Expected result

The Docker provider may successfully talk to the Docker daemon if the client library can operate at that version.

What success or failure indicates

  • Success suggests temporary compatibility can be restored.
  • Failure means the binary itself is too old or otherwise incompatible.

Risk

Moderate. This is a workaround, not a long-term fix.

Safer alternative

Upgrade Traefik rather than relying on API version forcing.

Command

Likely command used: docker compose logs traefik dockersocket

Purpose

Review recent logs from the Traefik and dockersocket services together.

What it does

Shows log output for both containers in one view.

Why it was likely used

The troubleshooting relied on correlated logs from both services, which are commonly viewed this way in Compose environments.

Expected result

Interleaved container logs showing the provider error and controlled shutdown sequence.

What success or failure indicates

Useful for identifying which service emitted the first fault and which only reacted afterward.

Risk

Low risk. Read-only.