envsync-le

Compare the dotenv files in a tree and say which keys are missing from which, before a deploy finds out for you.

npx envsync-le
npx envsync-le --template .env.example
npx envsync-le --file .env --file .env.production

This is the same command line as the Rust crate envsync-le, and it behaves identically: same flags, same walk, same output, same exit codes. Install whichever toolchain you already have.

What it reads

Key names, and nothing else. A dotenv file is where credentials live and the answer does not need them, so no value is parsed, compared or reported, and a line that cannot be parsed is named by its line number rather than quoted.

.env, .env.* and *.env files are found anywhere under the directory, including the git-ignored ones: a dotenv file is ignored by design, and a walk that honoured that would compare .env.example against nothing and call it in sync. Hidden directories are skipped unless you pass --hidden.

Two questions

Without a template the reference is the union of every key found, so a key present anywhere must be present everywhere. With --template, that file is the contract and a key it does not have is extra, which is the question a deploy asks.

Output

stdout carries one JSON report for the whole run whenever it is piped or redirected, and nothing when it is a terminal. stderr carries the human summary.

$ envsync-le --template .env.example
.env: missing DB_PORT (in .env.example)
.env: extra DEBUG (not in .env.example)
out of sync — 1 file with mismatches across 3 files

{"status":"missing-keys","mode":"template","files":[{"path":".env","type":"base","keys":3},{"path":".env.example","type":"example","keys":3},{"path":".env.production","type":"production","keys":3}],"missingKeys":[{"filepath":".env","keys":["DB_PORT"],"reference":".env.example"}],"extraKeys":[{"filepath":".env","keys":["DEBUG"],"reference":".env.example"}],"diagnostics":[],"summary":{"files":3,"missing":1,"extra":1}}

Exit codes

• 0: in sync, or no dotenv files at all, since there is nothing to be out of sync with.
• 1: out of sync.
• 2: the question was malformed, or --strict and a file could not be read.

For agents

envsync-le mcp serves the Model Context Protocol on stdio with two tools: compare_env_files for file contents and envsync_le_check for a directory. Hosts that want the server alone can install envsync-le-mcp.

envsync-le --help lists every option.

MIT licensed. Part of letools.