How to Use Newlines in an Environment Variable File for Docker
source link: https://www.dannyguo.com/blog/how-to-use-newlines-in-an-environment-variable-file-for-docker/
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How to Use Newlines in an Environment Variable File for Docker
When you run a Docker container, you can pass environment
variables
to the run command.
However, the --env-file option has a limitation in that it doesn’t handle
newline characters. See this GitHub
issue and this comment on a
separate
issue.
This can be problematic if you need newlines for something like a public or
private key for public-key
cryptography. I tried
adding double quotes around the value and using \n for the newlines:
FOO=bar
PRIVATE_KEY="-----BEGIN PRIVATE KEY-----\nFOO\nBAR\nBAZ\n-----END PRIVATE KEY-----"
But that didn’t work, using single quotes didn’t work, and actually breaking the
value across multiple lines in my .env file didn’t work either. As a
workaround, I found that I could detect the situation and modify the value in
code. For a Node.js server, I did this:
let PRIVATE_KEY = process.env.PRIVATE_KEY;
if (PRIVATE_KEY?.startsWith(`"`)) {
PRIVATE_KEY =
PRIVATE_KEY.replaceAll(`"`, ``).replaceAll(`\\n`, `\n`);
}
So I removed the double quotes and replaced every occurrence of a literal
backslash (the \\ is necesssary for
escaping the backslash)
followed by a n with a newline character. This worked for my use case.
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