Groovy: Idiomatic way to replace captured groups

Question

I've a string like this: docker login -u username -p password docker-registry-url.

I execute the command in a Groovy script with execute. For debugging purposes, I print the command before execution, but since it contains sensitive data, I obfuscate the username and password.

def printableCmd = cmd.toString()

def m = printableCmd =~ /(?:.+) -u (.+) -p (.+) (?:.+)/

if (m.matches() && m[0].size() >= 3) {
  printableCmd = m[0][-1..-2].inject(m[0][0]) { acc, val -> acc.replaceAll(val, "***") }
}

The above works as expected and prints docker login -u *** -p *** docker-registry-url, but I'm wondering if there is a more idiomatic way to do this. Note that I don't want to delete the captured groups, just replace them with asterisks, thus making it very clear that the command is not wrong, but obfuscated for security purposes.

daggett · Accepted Answer · 2017-08-03 05:25:43Z

14

def cmd='docker login -u username -p password docker-registry-url'
println cmd.replaceAll(/(\s-[up]\s+)(\S+)/,'$1***')

Output:

docker login -u *** -p *** docker-registry-url

answered Aug 3, 2017 at 5:25

daggett

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Comments

Abhijit Sarkar · Accepted Answer · 2017-08-03 06:01:45Z

1

I found the following solution myself using positive look-behind:

def cmd = "docker login -u username -p password docker-registry-url"
println cmd.replaceAll(/(?<=-[up]\s)(\S+)/,"***")

answered Aug 3, 2017 at 6:01

Abhijit Sarkar

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2 Comments

Wiktor Stribiżew Over a year ago

If there are 2 or more spaces between -u and 1+ non-whitespace chars, your lookbehind approach will fail. Capturing group approach is the correct one. You might use /(?<=-[up]\s{1,100})(\S+)/, but it is rather a hacky feature in a Java regex.

Abhijit Sarkar Over a year ago

@WiktorStribiżew perhaps you are referring to the fact that look-behind in java has to be of known length, so \s+ wouldn't work. I used \s{1,10} instead. The reason I prefer this over daggett's answer is because, IMO, it expresses the requirement clearer.

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