Timezone is unset after 2nd visit to Shiny app

[michael-dewar]

Describe the problem

Running a Shiny app that uses bslib twice will unset my TZ environment variable. For example, when I restart my R session, Sys.getenv('TZ') shows that I have a correctly set timezone. Then if I source the following code, hit escape to stop the app, and then run the app again, then Sys.getenv('TZ') returns "".

library(shiny)

ui <- fluidPage(
	theme = bslib::bs_theme(
		version = 5,
		primary = "#002FA7"
	)
)

server <- function(input, output, session) {}

shinyApp(ui, server)

If I try this with a skeleton app without the theme then I do not have this timezone problem.

Session Info

Details

─ Session info ──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
 setting  value
 version  R version 4.2.1 (2022-06-23)
 os       macOS Monterey 12.6
 system   x86_64, darwin17.0
 ui       RStudio
 language (EN)
 collate  en_US.UTF-8
 ctype    en_US.UTF-8
 tz       Asia/Taipei
 date     2022-09-27
 rstudio  2022.07.1+554 Spotted Wakerobin (desktop)
 pandoc   NA
─ Packages ──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────

package     * version date (UTC) lib source

brio          1.1.3   2021-11-30 [1] CRAN (R 4.2.0)

cachem        1.0.6   2021-08-19 [1] CRAN (R 4.2.0)

callr         3.7.2   2022-08-22 [1] CRAN (R 4.2.0)

cli           3.4.0   2022-09-08 [1] CRAN (R 4.2.0)

crayon        1.5.1   2022-03-26 [1] CRAN (R 4.2.0)

devtools    * 2.4.4   2022-07-20 [1] CRAN (R 4.2.0)

digest        0.6.29  2021-12-01 [1] CRAN (R 4.2.0)

ellipsis      0.3.2   2021-04-29 [1] CRAN (R 4.2.0)

fastmap       1.1.0   2021-01-25 [1] CRAN (R 4.2.0)

fs            1.5.2   2021-12-08 [1] CRAN (R 4.2.0)

glue          1.6.2   2022-02-24 [1] CRAN (R 4.2.0)

htmltools     0.5.3   2022-07-18 [1] CRAN (R 4.2.0)

htmlwidgets   1.5.4   2021-09-08 [1] CRAN (R 4.2.0)

httpuv        1.6.6   2022-09-08 [1] CRAN (R 4.2.0)

later         1.3.0   2021-08-18 [1] CRAN (R 4.2.0)

lifecycle     1.0.2   2022-09-01 [1] Github (r-lib/lifecycle@f92faf7)

magrittr      2.0.3   2022-03-30 [1] CRAN (R 4.2.0)

memoise       2.0.1   2021-11-26 [1] CRAN (R 4.2.0)

mime          0.12    2021-09-28 [1] CRAN (R 4.2.0)

miniUI        0.1.1.1 2018-05-18 [1] CRAN (R 4.2.0)

pkgbuild      1.3.1   2021-12-20 [1] CRAN (R 4.2.0)

pkgload       1.3.0   2022-06-27 [1] CRAN (R 4.2.0)

prettyunits   1.1.1   2020-01-24 [1] CRAN (R 4.2.0)

processx      3.7.0   2022-07-07 [1] CRAN (R 4.2.0)

profvis       0.3.7   2020-11-02 [1] CRAN (R 4.2.0)

promises      1.2.0.1 2021-02-11 [1] CRAN (R 4.2.0)

ps            1.7.1   2022-06-18 [1] CRAN (R 4.2.0)

purrr         0.3.4   2020-04-17 [1] CRAN (R 4.2.0)

R6            2.5.1   2021-08-19 [1] CRAN (R 4.2.0)

Rcpp          1.0.9   2022-07-08 [1] CRAN (R 4.2.0)

remotes       2.4.2   2021-11-30 [1] CRAN (R 4.2.0)

rlang         1.0.6   2022-09-24 [1] CRAN (R 4.2.0)

rstudioapi    0.14    2022-08-22 [1] CRAN (R 4.2.0)

sessioninfo   1.2.2   2021-12-06 [1] CRAN (R 4.2.0)

shiny         1.7.2   2022-07-19 [1] CRAN (R 4.2.0)

stringi       1.7.8   2022-07-11 [1] CRAN (R 4.2.0)

stringr       1.4.1   2022-08-20 [1] CRAN (R 4.2.0)

testthat    * 3.1.4   2022-04-26 [1] CRAN (R 4.2.0)

urlchecker    1.0.1   2021-11-30 [1] CRAN (R 4.2.0)

usethis     * 2.1.6   2022-05-25 [1] CRAN (R 4.2.0)

xtable        1.8-4   2019-04-21 [1] CRAN (R 4.2.0)
[1] /Library/Frameworks/R.framework/Versions/4.2/Resources/library
─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────

[cpsievert]

Huh, weird, this appears to be some strange interaction with shiny....I can render a page statically without encountering the issue:

library(shiny)
library(bslib)
library(htmltools)

Sys.setenv(TZ = "America/Sao_Paulo")

ui <- fluidPage(
    theme = bs_theme(
        version = 5,
        primary = "#002FA7"
    ), 
    "Foo bar"
)

browsable(ui)

Sys.getenv('TZ')
#> [1] "America/Sao_Paulo"

[wch]

I was able to reproduce this by running the app twice. Note that, at first, TZ is not set to anything. But then after running the app twice, it is set to "".

# Initially, TZ is not set
Sys.getenv("TZ", unset = "UNSET")
#> [1] "UNSET"

# Set to some value
Sys.setenv(TZ="America/Chicago")
Sys.getenv("TZ", unset = "UNSET")
#> [1] "America/Chicago"



library(shiny)
ui <- fluidPage(theme = bslib::bs_theme())
server <- function(input, output, session) {
  stopApp()  # Close the app as soon as the browser connects
}
app <- shinyApp(ui, server)


# Run first time: No change
app
Sys.getenv("TZ", unset = "UNSET")
#> [1] "America/Chicago"


# Run second time: TZ is set to ""
app
Sys.getenv("TZ", unset = "UNSET")
#> [1] ""

[wch]

I'm also finding that:

• This happens only when using bslib.
• The un-setting happens very late: after Shiny calls renderPage() but before it executes the server function (when the browser connects).
• If no browser visits the app (by launching the app with runApp(app, launch.browser = F)), then TZ does not get unset.

The fact that it happens on the second visit makes me wonder if it has something to do with bslib or sass's caching mechanism.

[cpsievert]

FWIW, it doesn't seem related to caching since I can repro with setting options(sass.cache = F) and/or shiny::devmode(F)

[cpsievert]

After some more investigation, It appears as though this issue is not specific to bslib (or sass). It can be reproduced with a fairly simple htmlDependency():

library(shiny)
library(htmltools)

Sys.getenv("TZ", unset = "UNSET")
#> [1] "UNSET"

Sys.setenv(TZ = "America/Chicago")

writeLines("body{background: red}", "styles.css")
dep <- htmlDependency(
  "foo", "1.0",
  src = getwd(),
  stylesheet = "styles.css",
  all_files = FALSE
)

app <- shinyApp(div(dep), \(...) stopApp())

app
Sys.getenv("TZ", unset = "UNSET")
#> [1] "America/Chicago"

app
Sys.getenv("TZ", unset = "UNSET")
#> [1] ""

[cpsievert]

It also appears as though this issue was introduced by #2280 (cc @wch), so a fix will likely have to come via shiny (and/or httpuv)

[cpsievert]

rstudio/httpuv#300 also seems to be relevant here. Particularly this line

https://github.com/rstudio/httpuv/pull/300/files#diff-d1af179c785afd6abd8c6ed56932093da07ee7d3b0f5f7858f5f424761e32284R40