NFTables.Formatter (NFTables v0.8.2)

Convert nftables JSON expressions to nft command syntax strings.

This module provides formatting functions to convert structured JSON expressions (generated by Match) into human-readable nft syntax strings for debugging, display, and documentation purposes.

Examples

# Format a single expression
expr = %{"drop" => nil}
Formatter.format_expr(expr)
#=> "drop"

# Format an expression list
expr_list = [
  %{"match" => %{...}},
  %{"counter" => nil},
  %{"drop" => nil}
]
Formatter.format_expr_list(expr_list)
#=> "ip saddr 192.168.1.1 counter drop"

Note

This formatter covers 90%+ of common use cases. For complex or uncommon expressions, it may produce simplified output or fall back to JSON representation.

Summary

Functions

format_expr(expr)

Format a single JSON expression to nft syntax.

format_expr_list(expr_list)

Format a list of JSON expressions to nft syntax.

Functions

format_expr(expr)

@spec format_expr(map()) :: String.t()

Format a single JSON expression to nft syntax.

Examples

format_expr(%{"accept" => nil})
#=> "accept"

format_expr(%{"match" => %{
  "left" => %{"payload" => %{"protocol" => "tcp", "field" => "dport"}},
  "right" => 80,
  "op" => "=="
}})
#=> "tcp dport 80"

format_expr_list(expr_list)

@spec format_expr_list(list()) :: String.t()

Format a list of JSON expressions to nft syntax.

Examples

format_expr_list([
  %{"match" => %{...}},
  %{"counter" => nil},
  %{"drop" => nil}
])
#=> "ip saddr 192.168.1.1 counter drop"