JavaScript / ECMAScript

Dockerfile ENV Instruction in JS

Match Dockerfile `ENV KEY=value` (or `ENV KEY value`) instructions, capturing key and value.

Try it in the JS tester →

Pattern

regexJS
^ENV\s+([A-Z_][A-Z0-9_]*)(?:[=\s]+)(.+)$   (flags: gm)

JavaScript / ECMAScript code

jsJavaScript
const re = new RegExp("^ENV\\s+([A-Z_][A-Z0-9_]*)(?:[=\\s]+)(.+)$", "gm");
const input = "ENV NODE_VERSION=20.10.0\\nENV PORT 3000";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));

Uses `String.prototype.matchAll` for global iteration (Node 12+ / all modern browsers).

How the pattern works

^ENV anchors to the line start (m flag enables per-line). \s+ requires whitespace. ([A-Z_][A-Z0-9_]*) captures the key (uppercase + underscores by convention). [=\s]+ matches either the modern `=` separator or the legacy whitespace separator. (.+)$ captures the rest of the line as the value.

Examples

Input

ENV NODE_VERSION=20.10.0\nENV PORT 3000

Matches

  • ENV NODE_VERSION=20.10.0
  • ENV PORT 3000

Input

ENV DATABASE_URL=postgres://localhost/db

Matches

  • ENV DATABASE_URL=postgres://localhost/db

Input

FROM node:20

No match

—

Same pattern, other engines

Python (re)

Supported

See how this pattern looks (and behaves) in Python's stdlib `re` module.

Go (RE2)

Supported

See how this pattern looks (and behaves) in Go's `regexp` package (RE2 engine).

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