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regexreplace(str, pattern, replace) replaces every match of pattern in str with replace. Uses RE2 regular expression syntax.

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Signature

regexreplace(str string, pattern string, replace string) string

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Example

Sanitize a git branch name for use as a Kubernetes namespace. Namespaces must be lowercase, alphanumeric, and hyphenated with no leading or trailing hyphens: 
variable "branch" {
  description = "Git branch name"
  type        = string
}

computed "namespace" {
  description = "Kubernetes namespace derived from the branch"
  expression  = lower(regexreplace(var.branch, "[^a-z0-9]", "-"))
}

task "deploy-preview" {
  description = "Deploy a preview environment for this branch"
  commands = [
    "kubectl create namespace ${computed.namespace} --dry-run=client -o yaml | kubectl apply -f -",
    "helm upgrade --install preview-${computed.namespace} ./chart --namespace ${computed.namespace}",
  ]
}
feature/My-Branch becomes feature-my-branch.

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Notes

  • The pattern must be a valid RE2 expression. RE2 does not support lookahead or backreferences.
  • replace can include $1, $2, etc. to reference capture groups.
  • For simple string substitution without regular expressions, use replace.