Env files

Each env file named by --env-file / DBMCP_ENV_FILE uses this format:

# Comments start with #
DBMCP_DB_BACKEND=postgres
DBMCP_DB_HOST: db.internal            # KEY: VAL also works
export DBMCP_DB_USER=app              # optional export prefix
DB_PASSWORD='p@ss #not a comment'     # single quotes are literal
GREETING="line one\nline two"         # double quotes support escapes
CERT="-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----"            # quoted values may span lines
DBMCP_DB_NAME=${APP_DB:-myapp}        # ${} expands from process env, then earlier keys
DBMCP_CONFIG_FILE=/srv/dbmcp.yaml     # may name the config files

• Unquoted values end at # (space, hash) and are trimmed.
• Single-quoted values are taken literally; double-quoted values support escapes such as \n and \".
• Unquoted and double-quoted values expand ${} against the process environment, then keys defined earlier in the same file, then earlier env files.
• A bare KEY with no value takes its value from the process environment, else from an earlier line or an earlier env file; if none sets it, the line is skipped.

Each env file plays two roles at once:

1. Its DBMCP_* keys set settings directly, between the process environment and the config files in precedence. An empty value is unset, as everywhere.
2. All of its keys, whatever their name, are available to ${} in the config files, after the process environment.

Errors are reported per line without echoing the file's contents (for example line 2: key cannot contain a space).

Multiple env filesCopy Anchor Link

Repeat --env-file (or list several files in DBMCP_ENV_FILE) to layer env files, the way docker compose --env-file a --env-file b does:

dbmcp --env-file /srv/dbmcp/base.env --env-file /srv/dbmcp/local.env
DBMCP_ENV_FILE=/srv/dbmcp/base.env,/srv/dbmcp/local.env dbmcp

• Files are read in list order, and a later file wins over an earlier one.
• A later file's ${} sees the keys of earlier files (after the process environment and its own earlier lines).
• The files fold into one set of keys. A later KEY= (empty) overwrites an earlier value with an empty one, so the setting is unset and falls through to the config files or the default, not to the earlier env file.
• The process environment beats every env file.
• The last file that sets DBMCP_CONFIG_FILE names the config files.
• Every non-empty DBMCP_* value in every file is checked, including values a later file overwrites.
• Loading stops at the first file that cannot be read or parsed, reporting all of that file's errors. The same file may be listed twice; each problem is reported once.