Only build favicons locally (r-lib#2563)

And fix bug introduced by use of fs everywhere. Fixes r-lib#2553.

Tested by re-buidling pkgdown's favicons.

NEWS.md

@@ -1,5 +1,6 @@
 # pkgdown (development version)
 
+* `init_site()` will no longer automatically build favicons on CI systems (e.g. GHA). This is an expensive operation that uses an external service so it should only be run locally (#2553).
 * `build_home_index()` now reports when rendering the home page (#2544).
 * Bootstrap 3 has been deprecated. It was superseded in December 2021, and now we're starting to more directly encourage folks to move away from it.
 * Improve HTML5 compliance (#2369):

R/build-favicons.R

@@ -84,11 +84,11 @@ build_favicons <- function(pkg = ".", overwrite = FALSE) {
     cli::cli_abort("API request failed.", .internal = TRUE)
   }
 
-  tmp <- withr::local_tempdir()
+  tmp <- withr::local_tempfile()
   result <- httr::RETRY(
     "GET",
     result$favicon$package_url,
-    httr::write_disk(tmp),
+    httr::write_disk(tmp, overwrite = TRUE),
     quiet = TRUE
   )
 

R/init.R

@@ -40,8 +40,8 @@ init_site <- function(pkg = ".") {
     build_bslib(pkg)
   }
 
-  if (has_logo(pkg) && !has_favicons(pkg)) {
-    # Building favicons is expensive, so we hopefully only do it once.
+  # Building favicons is expensive, so we hopefully only do it once, locally
+  if (has_logo(pkg) && !has_favicons(pkg) && !on_ci()) {
     build_favicons(pkg)
   }
   copy_favicons(pkg)

R/utils.R

@@ -181,6 +181,10 @@ section_id <- function(section) {
   xml2::xml_attr(h, "id")
 }
 
+on_ci <- function() {
+  isTRUE(as.logical(Sys.getenv("CI", "false")))
+}
+
 # yaml ------------------------------------------------------------
 
 print_yaml <- function(x) {