Multiline YAML Values to ENV Conversion

Multiline values are one of the trickiest aspects of YAML-to-ENV conversion. YAML supports elegant multiline string formatting with literal (|) and folded (>) block scalars, but ENV files are line-oriented -- each line is a separate variable.

YAML with multiline values:

ssl_cert: |
  -----BEGIN CERTIFICATE-----
  MIIBxTCCAWugAwIBAgIJALP2kEZ0gN3vMA
  oGCCqGSM49BAMCMDkxCzAJBgNVBAYTAlVT
  -----END CERTIFICATE-----

welcome_message: >
  Welcome to our application.
  Please read the documentation
  before getting started.

query: |
  SELECT u.name, u.email
  FROM users u
  WHERE u.active = true
  ORDER BY u.created_at DESC;

ENV conversion strategy 1: Escaped newlines in double quotes

SSL_CERT="-----BEGIN CERTIFICATE-----\nMIIBxTCCAWugAwIBAgIJALP2kEZ0gN3vMA\noGCCqGSM49BAMCMDkxCzAJBgNVBAYTAlVT\n-----END CERTIFICATE-----"
WELCOME_MESSAGE="Welcome to our application. Please read the documentation before getting started."
QUERY="SELECT u.name, u.email\nFROM users u\nWHERE u.active = true\nORDER BY u.created_at DESC;"

ENV conversion strategy 2: Single quotes with actual newlines

SSL_CERT='-----BEGIN CERTIFICATE-----
MIIBxTCCAWugAwIBAgIJALP2kEZ0gN3vMA
oGCCqGSM49BAMCMDkxCzAJBgNVBAYTAlVT
-----END CERTIFICATE-----'

How each YAML block style affects the output:

1. Literal block (|) preserves every newline. Each line break becomes \n in the ENV value. This is critical for certificates, SSH keys, and SQL queries where line breaks matter.

2. Folded block (>) joins lines with spaces, producing a single-line value. This is simpler for ENV conversion since the result is naturally a single line.

3. Chomping modifiers (|-, |+, >-, >+) control trailing newlines. |- strips the final newline (usually what you want for ENV values), while |+ keeps all trailing newlines.

Compatibility concerns:

• Docker/docker-compose supports multi-line ENV values with escaped newlines in double quotes.
• systemd environment files do NOT support multi-line values at all.
• dotenv libraries vary: Node.js dotenv supports multi-line in double quotes, Python dotenv supports them in both quote styles.
• Shell export supports $'...' syntax with literal \n on Bash, but not all shells.

Recommendation: For maximum portability, use escaped \n within double-quoted values. For certificates and keys, consider Base64-encoding the entire value instead.