feat: add dockfmt formatter (#388)

Author: theobori

README.md

@@ -221,7 +221,7 @@ functions.
 <!-- `> bash ./supported-programs.sh` -->
 
 <!-- BEGIN mdsh -->
-`treefmt-nix` currently supports 109 formatters:
+`treefmt-nix` currently supports 110 formatters:
 
 * [actionlint](programs/actionlint.nix)
 * [alejandra](programs/alejandra.nix)
@@ -245,6 +245,7 @@ functions.
 * [deno](programs/deno.nix)
 * [dhall](programs/dhall.nix)
 * [dnscontrol](programs/dnscontrol.nix)
+* [dockfmt](programs/dockfmt.nix)
 * [dos2unix](programs/dos2unix.nix)
 * [dprint](programs/dprint.nix)
 * [efmt](programs/efmt.nix)

examples/formatter-dockfmt.toml

@@ -0,0 +1,6 @@
+# Example generated by ../examples.sh
+[formatter.dockfmt]
+command = "dockfmt"
+excludes = []
+includes = ["Dockerfile", "*.Dockerfile", "Dockerfile.*"]
+options = ["fmt", "-w"]

programs/dockfmt.nix

@@ -0,0 +1,19 @@
+{ mkFormatterModule, ... }:
+{
+  meta.maintainers = [ "theobori" ];
+
+  imports = [
+    (mkFormatterModule {
+      name = "dockfmt";
+      args = [
+        "fmt"
+        "-w"
+      ];
+      includes = [
+        "Dockerfile"
+        "*.Dockerfile"
+        "Dockerfile.*"
+      ];
+    })
+  ];
+}