fix: Dockerfile template substitution fails with multi-line profile installations

[b00y0h]

Summary

• Fix awk -v failing on multi-line $profile_installations values by switching to ENVIRON array, which correctly handles newlines and special characters
• Fix guard check syntax broken in 634a40d (missing || between grep commands)

Root cause

awk -v pi="$profile_installations" does not support literal newlines in variable assignments. When profile functions return multi-line RUN commands containing &&, the substitution fails with awk: newline in string errors, leaving {{PROFILE_INSTALLATIONS}} placeholders in the generated Dockerfile.

The ENVIRON array reads variables from the process environment, which has no issues with newlines or special characters like &.

Before (broken)

RUN apt-get update {{PROFILE_INSTALLATIONS}}{{PROFILE_INSTALLATIONS}} apt-get install -y nginx {{PROFILE_INSTALLATIONS}}{{PROFILE_INSTALLATIONS}} apt-get clean

After (fixed)

RUN apt-get update && apt-get install -y nginx && apt-get clean

Test

profile_installations="# Python profile
RUN apt-get update && apt-get install -y nginx && apt-get clean"

# Using ENVIRON (this PR)
final=$(PI="$profile_installations" awk '
/\{\{[[:space:]]*PROFILE_INSTALLATIONS[[:space:]]*\}\}/ { print ENVIRON["PI"]; next }
{ print }
' <<<"{{PROFILE_INSTALLATIONS}}")

echo "$final"
# Output: correct multi-line content with && preserved

Fixes #91

Summary by Sourcery

Fix Dockerfile template substitution to correctly handle multi-line profile installation blocks and restore the guard that detects unreplaced placeholders.

Bug Fixes:

• Resolve failure of Dockerfile template substitution when profile installations contain multi-line commands or special characters by switching awk variable injection to use environment variables.
• Fix the placeholder guard condition so it properly detects remaining PROFILE_INSTALLATIONS or LABELS placeholders in the generated Dockerfile.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Refactors the Dockerfile template substitution logic to pass profile installations and labels into awk via environment variables instead of -v (fixing multi-line handling) and corrects the guard that checks for unreplaced placeholders.

Sequence diagram for Dockerfile generation with ENVIRON-based substitution

sequenceDiagram
    participant User
    participant main_sh as main.sh
    participant Awk as awk
    participant Env as ENVIRON

    User->>main_sh: Invoke Dockerfile generation
    main_sh->>main_sh: Prepare base_dockerfile
    main_sh->>Env: Set PI=profile_installations
    main_sh->>Env: Set LBS=labels
    main_sh->>Awk: Execute awk with here-string base_dockerfile
    Awk->>Env: Read PI via ENVIRON[PI]
    Awk->>Env: Read LBS via ENVIRON[LBS]
    Awk->>Awk: For each line
    Awk-->>main_sh: Return final_dockerfile
    main_sh->>main_sh: grep for unreplaced placeholders
    alt Placeholders remain
        main_sh-->>User: error Unreplaced placeholders remain
    else All placeholders replaced
        main_sh->>main_sh: Write final_dockerfile to Dockerfile
        main_sh-->>User: Dockerfile generation successful
    end

Loading

File-Level Changes

Change	Details	Files
Switch awk variable passing to ENVIRON-based environment variables to properly handle multi-line profile_installations and labels.	Stop assigning base_dockerfile to final_dockerfile before substitution and instead capture awk output directly into final_dockerfile. Replace awk -v pi and -v lbs arguments with environment variable exports PI and LBS before invoking awk. Update awk script to read injected blocks from ENVIRON["PI"] and ENVIRON["LBS"] while preserving placeholder-matching regexes and passthrough behavior.	main.sh
Fix guard logic that verifies no unreplaced placeholders remain in the generated Dockerfile.	Correct the if condition to use a line continuation and

Assessment against linked issues

Issue	Objective	Addressed	Explanation
#91	Ensure Dockerfile template substitution for {{PROFILE_INSTALLATIONS}} works correctly with multi-line profile installation commands so that container rebuilds succeed after adding profiles.	✅

Possibly linked issues

• Unable to rebuild container after adding profiles #91: PR changes awk usage to ENVIRON and fixes guards, resolving the newline-in-string Dockerfile substitution error.
• Unable to rebuild container after adding profiles #91: PR fixes awk substitution so PROFILE_INSTALLATIONS placeholders are correctly expanded, preventing broken Dockerfile RUN lines seen in issue.
• Unable to rebuild container after adding profiles #91: PR changes awk substitution and guard logic so {{PROFILE_INSTALLATIONS}} placeholders are correctly expanded, fixing the reported build failure.

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[sourcery-ai]

Hey - I've left some high level feedback:

• The guard that checks for unreplaced placeholders only looks for the exact {{PROFILE_INSTALLATIONS}} and {{LABELS}} strings, but your awk pattern allows optional whitespace inside the braces, so you might want to update the grep patterns (e.g., use grep -E '\{\{[[:space:]]*PROFILE_INSTALLATIONS[[:space:]]*\}\}') to consistently catch all unreplaced forms.
• Since you’re now relying on ENVIRON, consider briefly noting in a code comment that the PI= and LBS= prefixes are intentional and required for the awk ENVIRON lookup, so future changes don’t inadvertently switch back to -v or remove those environment assignments.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- The guard that checks for unreplaced placeholders only looks for the exact `{{PROFILE_INSTALLATIONS}}` and `{{LABELS}}` strings, but your awk pattern allows optional whitespace inside the braces, so you might want to update the grep patterns (e.g., use `grep -E '\{\{[[:space:]]*PROFILE_INSTALLATIONS[[:space:]]*\}\}'`) to consistently catch all unreplaced forms.
- Since you’re now relying on ENVIRON, consider briefly noting in a code comment that the `PI=` and `LBS=` prefixes are intentional and required for the awk ENVIRON lookup, so future changes don’t inadvertently switch back to `-v` or remove those environment assignments.

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