Cloud 6.02

Avoid SCD on Both Phases

Understanding when and how to skip SCD, SKIP_SCD vs SCD_ON_DEMAND, and safe implementation strategies.

Exam Critical: Understanding when and how to skip SCD is important for development workflow optimization!

Avoiding SCD on Both Phases

mindmap root((Skip SCD)) Use Cases Speed up build Speed up deploy Development phase Faster code to Cloud SKIP_SCD Variable In magento env yaml Build and deploy nodes Preserves pub static Issues to Avoid Broken symlinks Manual deploy fails Production limitation Best Approach Use SCD_ON_DEMAND Or SKIP_SCD build only Then skip on deploy

Cases for Avoiding SCD

Why Skip Static Content Deployment?

Primary Benefits

  • Speed up build process - No time spent generating static content
  • Speed up deploy process - Faster deployment execution
  • Faster code to Cloud - Get code deployed quicker during development
  • Development efficiency - Ideal during development phase of a project

What Happens When You Skip SCD?

Static files from the previous build will still be present in pub/static directory. The existing content is preserved and reused.

Important Context

Skipping SCD is primarily useful during development when you need rapid deployments and haven't changed themes or static content. For production, you typically want SCD to run (preferably in build phase).

How to Skip SCD

Using SKIP_SCD Environment Variable

Specify the SKIP_SCD environment variable in .magento.env.yaml:

Option 1: Skip on Both Build and Deploy

stage:
  build:
    SKIP_SCD: true
  deploy:
    SKIP_SCD: true

Option 2: Skip Only on Build

stage:
  build:
    SKIP_SCD: true
  deploy:
    SKIP_SCD: false  # SCD runs in deploy phase

Option 3: Skip Only on Deploy

stage:
  build:
    SKIP_SCD: false  # SCD runs in build phase
  deploy:
    SKIP_SCD: true

Expected Results and Behavior

What Happens with SKIP_SCD

Configuration Build Phase Deploy Phase Result
SKIP_SCD: true (both) No SCD No SCD Uses previous static content
SKIP_SCD: true (build only) No SCD SCD runs SCD in deploy (default behavior)
SKIP_SCD: true (deploy only) SCD runs No SCD SCD in build (optimal!)

Static Content Preservation

The contents of pub/static directory will be preserved from the last run. This allows you to reuse previously generated static content.

Common Issues and Pitfalls

Problem 1: Broken Symlinks

Issue

If you previously were deploying static content in the build phase, your pub/static directory will contain three broken symlinks when you skip SCD.

Why This Happens

When SCD runs in build phase, symlinks are created to init/pub/static. When you skip SCD, these symlinks remain but point to non-existent content.

Problem 2: Manual Deployment Doesn't Work

Critical Limitation

Manually running bin/magento setup:static-content:deploy does NOT work in production!

Why?
  • Filesystem is read-only in production
  • pub/static is a mount point but restricted
  • You cannot manually generate static content on production servers

Best Approach: Safe Implementation

Recommended Strategy

Method 1: Use SCD_ON_DEMAND

The safest approach for skipping traditional SCD:

stage:
  deploy:
    SCD_ON_DEMAND: true
Benefits
  • No SCD during build or deploy
  • Static content generated on first request
  • No broken symlinks
  • Ideal for development environments

Method 2: Progressive SKIP_SCD Implementation

Step 1: Skip SCD on Build Phase First
stage:
  build:
    SKIP_SCD: true
  deploy:
    SKIP_SCD: false  # Allow SCD in deploy

Deploy this configuration. This generates static content in deploy phase and populates pub/static properly (no symlinks).

Step 2: After Content is in Environment

Once static content is in the environment and no symlinks are present, you can then enable SKIP_SCD on deploy phase:

stage:
  build:
    SKIP_SCD: true
  deploy:
    SKIP_SCD: true  # Now safe to skip

Result: Both phases skip SCD, using the existing static content from previous deployment.

Use Case Scenarios

When to Skip SCD

Good Use Cases
  • Development: Rapid code iterations without theme changes
  • Backend changes: PHP/logic changes that don't affect frontend
  • Integration environment: Frequent deployments for testing
  • Minor fixes: Bug fixes that don't touch static assets
  • Speed testing: Testing deployment performance
Avoid Skipping When
  • Production deploys: Always regenerate for production
  • Theme changes: Modified templates, CSS, JS
  • New locale: Added languages or stores
  • First deployment: No existing static content
  • Static asset updates: Changed images, fonts, etc.

Complete Workflow Example

Transitioning from Build-Phase SCD to Skip SCD

Current State: SCD in Build Phase

# Current .magento.env.yaml
stage:
  build:
    SKIP_SCD: false  # SCD runs in build
  deploy:
    SKIP_SCD: true   # Skip in deploy

Problem: pub/static contains symlinks to init/pub/static

Step 1: Move SCD to Deploy (Temporarily)

# Updated .magento.env.yaml
stage:
  build:
    SKIP_SCD: true   # Skip in build
  deploy:
    SKIP_SCD: false  # SCD runs in deploy

Deploy this. SCD generates files directly in pub/static, no symlinks.

Step 2: Skip SCD on Both Phases

# Final .magento.env.yaml
stage:
  build:
    SKIP_SCD: true   # Skip in build
  deploy:
    SKIP_SCD: true   # Skip in deploy

Deploy this. Both phases skip SCD, using existing content from Step 1.

Comparison: SKIP_SCD vs SCD_ON_DEMAND

Aspect SKIP_SCD SCD_ON_DEMAND
When Generated Uses previous deployment's static content Generated on first request
Build Time Fast (skipped) Fast (skipped)
Deploy Time Fast (skipped) Fast (skipped)
First Page Load Fast (content exists) Slow (must generate)
Requires Previous Deploy Yes No
Symlink Issues Possible if transitioning from build SCD No symlinks
Best For Backend-only changes in development Development with potential frontend changes

Exam Tips

Key Points to Remember

  • Use cases: Speed up build/deploy, development phase, faster code to Cloud
  • SKIP_SCD location: .magento.env.yaml (build and deploy nodes)
  • Preservation: pub/static content preserved from last run
  • Broken symlinks: Issue when transitioning from build-phase SCD
  • Manual deploy limitation: bin/magento setup:static-content:deploy does NOT work in production
  • Best approach 1: Use SCD_ON_DEMAND
  • Best approach 2: SKIP_SCD on build only first, then skip on deploy
  • Two-step process: 1) Skip build only, deploy once, 2) Skip both
  • Good for: Development, backend changes, minor fixes
  • Avoid for: Production, theme changes, new locales, first deployment
  • SKIP_SCD vs SCD_ON_DEMAND: SKIP uses previous content, ON_DEMAND generates on first request
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