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DockMon Bot edited this page Apr 30, 2026 · 2 revisions

Container Operations

DockMon provides comprehensive container management capabilities, from basic lifecycle operations to advanced batch actions and detailed inspection.

Overview

Container operations in DockMon allow you to:

  • Control container lifecycle (start, stop, restart)
  • View real-time logs from running containers
  • Inspect configurations and environment variables
  • Monitor resource usage (CPU, memory, network I/O)
  • Manage container tags for organization
  • Configure policies (auto-restart, desired state, auto-update)
  • Perform bulk operations on multiple containers simultaneously

Container Table

The container table is your primary interface for viewing and managing containers.

Columns

Column Description
Select Checkbox for bulk operations
Status Visual indicator of container state (running, stopped, etc.)
Name Container name with clickable tags
Policy Auto-restart, desired state, and auto-update icons
Alerts Active alert count by severity (critical/error/warning/info)
Updates Update availability indicator
Host Docker host where container runs
Uptime Time since container creation
CPU% Current CPU usage percentage
RAM Current memory usage
Actions Start, stop, restart, logs, view details buttons

Status Indicators

Containers display color-coded status icons:

Status Color Icon Description
Running Green Filled circle Container is actively running
Stopped/Exited Red Filled circle Container has exited
Created Gray Filled circle Container created but never started
Paused Yellow Filled circle Container is paused (frozen)
Restarting Blue Spinning circle Container is currently restarting
Dead Red Filled circle Container is in dead state (unrecoverable)

Policy Icons

Three icons indicate container automation policies:

Auto-Restart Icon:

  • Blue refresh icon: Auto-restart enabled
  • Gray crossed-out refresh: Auto-restart disabled
  • Hover for tooltip with current status

Desired State Icon:

  • Green filled play: Should be running (and currently running)
  • Black play: Should be running (but currently stopped)
  • Yellow warning triangle: Should be running but is exited (attention needed!)
  • Gray clock: On-demand (no desired state)

Auto-Update Icon:

  • Amber package icon: Auto-update enabled
  • No icon: Auto-update disabled
  • Hover for tooltip with current status

Basic Operations

Start Container

Requirements: Container must be in stopped/exited/created state

Methods:

  1. Quick action: Click green Play icon in Actions column
  2. Details modal: Open container → Actions tab → Start button
  3. Bulk action: Select multiple containers → Bulk Actions bar → Start

Behavior:

  • Starts container using Docker API
  • Updates status in real-time via WebSocket
  • Shows success/error toast notification
  • If auto-restart enabled, monitoring begins immediately

Stop Container

Requirements: Container must be running

Methods:

  1. Quick action: Click red Stop icon in Actions column
  2. Details modal: Open container → Actions tab → Stop button
  3. Bulk action: Select multiple containers → Bulk Actions bar → Stop

Behavior:

  • Sends SIGTERM signal (graceful shutdown)
  • Waits 10 seconds for graceful exit
  • Forces stop (SIGKILL) if container doesn't exit
  • Updates status in real-time via WebSocket

Note: Stopping a container with desired_state: should_run will trigger a warning icon, as the container will likely be auto-restarted if auto-restart is enabled.

Restart Container

Requirements: Container must be running

Methods:

  1. Quick action: Click blue Restart icon in Actions column
  2. Details modal: Open container → Actions tab → Restart button
  3. Bulk action: Select multiple containers → Bulk Actions bar → Restart

Behavior:

  • Stops container gracefully (SIGTERM + 10s timeout)
  • Starts container with same configuration
  • Useful for applying environment changes or clearing memory leaks
  • Resets uptime counter

Use cases:

  • Apply configuration changes that require restart
  • Clear memory leaks in long-running containers
  • Recover from hung state
  • Force reload of application code

Container Details

Opening Details View

Default behavior (Simplified Workflow enabled):

  • Click container card to open full-screen details view with all tabs

Alternative behavior (Simplified Workflow disabled):

  • Click container card to open drawer (quick view from the side)
  • The drawer provides quick access to container information

Toggle workflow: Settings → Dashboard → Simplified Workflow

Details Tabs

Info Tab

Displays comprehensive container information:

Container Metadata:

  • Container ID (12-character short ID)
  • Image name and tag
  • Created timestamp
  • Host assignment

Configuration:

  • Environment variables (with masking for sensitive values)
  • Volumes and mounts
  • Network settings
  • Port mappings
  • Labels

Runtime State:

  • Current status
  • Exit code (if stopped)
  • PID (process ID)
  • Restart count

Stats Charts:

  • CPU Usage, Memory Usage, and Network I/O charts for this container
  • By default, charts show live data (real-time WebSocket stream, last few minutes only)
  • When historical stats persistence is enabled (Settings → System), a time-range selector appears above the charts (5m / 1h / 24h / 7d / 30d / 60d / 90d). The charts can then render historical data at any of those depths, with older data downsampled into cascade tiers
  • For containers on agent-based hosts, historical charts require agent v1.0.8 or newer. Older agents continue to deliver live stats but won't contribute to history

Logs Tab

Real-time container log viewer:

Features:

  • Live streaming: Logs update in real-time via WebSocket
  • Tail options: Last 100, 500, 1000 lines, or all
  • Search/filter: Find specific log entries
  • Copy to clipboard: Export logs for analysis
  • Auto-scroll: Toggle automatic scrolling to latest entries
  • Timestamps: Show/hide log timestamps
  • Color coding: ANSI color support for formatted logs

Best practices:

  • Start with 100 lines for quick debugging
  • Use search to find error patterns
  • Disable auto-scroll when analyzing historical logs
  • Copy logs before container restart (logs are ephemeral)

Events Tab

Container event history:

Displays:

  • All events for this specific container
  • Event type (start, stop, die, restart, etc.)
  • Timestamp with millisecond precision
  • Exit codes (for stop/die events)
  • Context information

Useful for:

  • Diagnosing crash loops
  • Understanding restart patterns
  • Audit trail for container lifecycle

Tags Tab

Container tag management:

Features:

  • View all tags (derived + custom)
  • Add custom tags
  • Remove custom tags
  • Tag autocomplete (suggests existing tags)

Tag types:

  • Derived tags (automatic, cannot be removed):
    • Docker Compose project tags (from com.docker.compose.project label)
    • Docker Swarm service tags (from com.docker.swarm.service.name label)
  • Custom tags (user-defined, can be removed):
    • Any user-added tags via UI or bulk operations

Use cases:

  • Organize containers by environment (production, staging, dev)
  • Group by purpose (web, database, cache)
  • Mark for specific alert rules
  • Enable tag-based filtering in dashboard

Health Check Tab

Configure HTTP/HTTPS health checks:

Configuration:

  • Endpoint URL (e.g., http://localhost:8080/health)
  • Check interval (seconds)
  • Timeout (seconds)
  • Failure threshold (consecutive failures before action)
  • Auto-restart on failure (toggle)

Status:

  • Last check time
  • Last check result (success/failure)
  • Failure count
  • Next check time (countdown)

Use cases:

  • Monitor web application availability
  • Auto-restart services that hang but don't crash
  • Detect and recover from deadlocks
  • Ensure critical services remain responsive

Auto-Restart Tab

Configure automatic restart behavior:

Settings:

  • Enable/Disable: Toggle auto-restart for this container
  • Max retries: Maximum restart attempts before giving up (0-10)
  • Retry delay: Seconds to wait between restart attempts (5-300)
  • Backoff strategy: Linear or exponential delay increase

Status:

  • Current restart attempt count
  • Last restart time
  • Next retry time (if in retry loop)

Best practices:

  • Always-on services: Enable with 5+ retries
  • One-shot tasks: Disable auto-restart
  • Flaky services: Use exponential backoff with longer delays
  • Critical infrastructure: Enable with alerts on failures

Updates Tab

Container image update management:

Displays:

  • Current image tag
  • Available image tag (if update exists)
  • Last update check time
  • Update history

Actions:

  • Check for updates now
  • Update to latest version
  • View update changelog (if available)
  • Configure auto-update settings

Auto-update configuration:

  • Enable auto-update: Automatically update when new version available
  • Floating tag mode: How to handle version tags
    • allow: Allow updates for floating tags (e.g., latest, stable)
    • prevent: Skip updates for floating tags (only update pinned versions)
  • Update schedule: When to check and apply updates

Bulk Operations

Select multiple containers to perform batch actions efficiently.

Selecting Containers

Methods:

  1. Individual: Click checkbox next to each container
  2. All visible: Click checkbox in table header
  3. Filter + select all: Apply search/filter → Select all visible

Selection count: Displayed in floating bulk action bar

Bulk Action Bar

When containers are selected, a bar appears at the bottom with:

Actions:

  • Start: Start all selected stopped containers
  • Stop: Stop all selected running containers
  • Restart: Restart all selected running containers
  • Clear selection: Deselect all containers

Tag management:

  • Add tags: Apply tags to all selected containers
  • Remove tags: Remove tags from all selected containers

Policy management:

  • Enable auto-restart: Turn on auto-restart for all selected
  • Disable auto-restart: Turn off auto-restart for all selected
  • Set desired state: Set to "Should Run" or "On-Demand"
  • Configure auto-update: Enable/disable for all selected

Batch Job Progress

Bulk operations run as background jobs with progress tracking:

Progress panel displays:

  • Overall progress percentage
  • Succeeded container count
  • Failed container count
  • Per-container status (pending, running, success, failed)
  • Error messages for failures

Features:

  • Real-time progress updates
  • Cancellable operations
  • Detailed error reporting
  • Success/failure summary

Best practices:

  • Start with small batches (5-10 containers) to verify behavior
  • Monitor first batch job before scheduling larger operations
  • Review failed containers and retry manually if needed
  • Don't close browser during batch operations (job continues server-side)

Search and Filtering

Global Search

The search box filters containers by:

  • Container name
  • Image name
  • Host name
  • Tags

Examples:

  • nginx - Find all nginx containers
  • production - Find all containers tagged "production"
  • web-server - Find containers on host named "web-server"

Advanced Filtering

Filter by status:

  • Click column header → Sort by status
  • Groups running/stopped containers together

Filter by host:

  • Click host name in container row
  • Shows only containers on that host
  • URL updates to include ?hostId=<id> for shareable links

Filter by tag:

  • Click tag chip on container
  • Shows only containers with that tag
  • Useful for environment-based views

Common Workflows

Troubleshooting a Crashed Container

  1. Identify the problem:

    • Check status column for exit code
    • Look for red "exited" status
    • Check alerts for error notifications

  2. Review logs:

    • Open container details → Logs tab
    • Search for "error", "exception", "fatal"
    • Note timestamp of last successful operation

  3. Inspect configuration:

    • Info tab → Check environment variables
    • Verify volume mounts are correct
    • Check port conflicts

  4. Review events:

    • Events tab → Look for restart loops
    • Check frequency of crashes
    • Note exit codes

  5. Fix and restart:

    • Address root cause (config, resources, dependencies)
    • Click Restart to test fix
    • Monitor logs for successful startup

Rolling Restart for Updates

When config changes require restart without downtime:

  1. Tag containers by instance role (e.g., "web-1", "web-2", "web-3")

  2. Restart in batches:

    • Select containers with tag "web-1"
    • Bulk Actions → Restart
    • Wait for completion and health check success
    • Repeat for "web-2", "web-3", etc.

  3. Monitor:

    • Watch for successful startup in logs
    • Verify health checks pass
    • Check error rates in application metrics

Maintenance Window

Prepare for scheduled maintenance:

  1. Enable blackout window (Settings → Alerts → Blackout Windows)

  2. Stop non-critical services:

    • Filter by tag "non-critical"
    • Select all
    • Bulk Actions → Stop

  3. Perform maintenance (database migration, host updates, etc.)

  4. Restart services:

    • Select all stopped containers
    • Bulk Actions → Start
    • Verify all containers started successfully

  5. Disable blackout window when complete

Best Practices

Container Lifecycle

DO:

  • Use descriptive container names (include purpose and instance number)
  • Tag containers by environment, purpose, and team
  • Set desired state for always-on services
  • Enable auto-restart for critical services
  • Monitor logs during first 5 minutes after start

DON'T:

  • Restart containers without checking logs first
  • Stop containers without understanding impact on dependent services
  • Enable auto-restart for one-shot jobs or migration tasks
  • Ignore yellow warning icons (desired state mismatch)

Log Management

DO:

  • Use structured logging (JSON) in applications for easy parsing
  • Implement log rotation in containers (prevent disk fill)
  • Copy important logs before container restart
  • Search logs before requesting full output (performance)

DON'T:

  • Stream all logs for high-traffic containers (resource intensive)
  • Store sensitive data in logs (passwords, tokens, PII)
  • Rely on logs as persistent storage (use external logging service)

Tag Organization

DO:

  • Use consistent tag naming (lowercase, hyphen-separated)
  • Create tag hierarchy (environment → purpose → instance)
  • Document tag meanings in team wiki
  • Remove obsolete tags to keep system clean

DON'T:

  • Create too many tags (hard to manage)
  • Use special characters in tags (can break filtering)
  • Tag every container with every category (loses meaning)

Troubleshooting

Container Won't Start

Possible causes:

  1. Port conflict: Another container using same port
  2. Volume conflict: Volume mounted by another container
  3. Missing dependency: Database or service not ready
  4. Resource limits: Insufficient CPU/RAM on host
  5. Image missing: Image pulled incorrectly or deleted

Solutions:

  • Check logs for specific error message
  • Review Info tab → Port mappings for conflicts
  • Verify host resource availability
  • Check Events tab for repeated crash pattern

Container Stuck in Restarting State

Possible causes:

  1. Crash loop: Application crashes immediately after start
  2. Auto-restart loop: Auto-restart enabled with low retry delay
  3. Health check failure: Container stops due to failed health checks

Solutions:

  • Disable auto-restart temporarily
  • Check logs for error during startup
  • Review health check configuration (URL, timeout, threshold)
  • Increase retry delay to allow debugging time

Logs Not Updating

Possible causes:

  1. WebSocket disconnected: Connection lost to backend
  2. Container stopped: Can't stream logs from stopped container
  3. Browser tab inactive: Browser throttles inactive tabs
  4. Log buffer full: Too many logs, reaching rate limit

Solutions:

  • Check WebSocket connection indicator (green dot in header)
  • Verify container is running
  • Refresh browser tab
  • Reduce log tail size (100 instead of 1000)

Related Documentation

Getting Started

User Guide

Configuration

Remote Monitoring

Access Control

Advanced

Development

Help

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