Dockerfile.mount_cache: readonly is a flag, not a boolean

edwintorok · MisterDA · commit 969de8495da8 · 2025-07-03T15:24:45.000-03:00
Attempting to set `readonly:true` results in this error:
`readonly: must not provide an argument for option`

`readonly` is chosen by the presence of the flag, so use `optional_flag`
instead.

Signed-off-by: Edwin Török &lt;edwin.torok@cloud.com&gt;
diff --git a/src/dockerfile.ml b/src/dockerfile.ml
@@ -308,7 +308,7 @@ let string_of_mount { typ } =
       String.concat ","
         ([ "--mount=type=cache" ] @ optional "id" id
         @ [ sprintf "target=%s" target ]
-        @ optional_bool "readonly" readonly
+        @ optional_flag "readonly" readonly
         @ (match sharing with
           | None -> []
           | Some `Shared -> [ "sharing=shared" ]
