How to declare unique users in R+Shiny - r

Question

For debugging purposes, I'd like to log in to my shiny app as user1, user2, ..., user6. I have tried 2 methods without success. Getting any method working be good, and getting all working would be great.
Preferred Method
Declare user from url inside server.R and access outside of observe
In Web-Browser
http://127.0.0.1:XXXX?username=JA1
server.R
user <- parseQueryString(session$clientData$url_search)[['username']]
## Outside of any function ->
cat( file=stderr(), "User: ", user, "\n")
2nd Method
How do turn url parameters into R variables in shiny? This is similar to https://github.com/daattali/advanced-shiny/tree/master/url-inputs ,but I would prefer to use the new variable outside of an observer (see above)
server.R
shinyServer( function( input, output, session){
observe({
query <- parseQueryString(session$clientData$url_search)
if (!is.null(query[['user']])) {
## The New User [declared in the URL]
user <- query[['user']]
} else {
## The Default User
user <- "user1"
}
})
## Some Code that executes based on `user`
if(user=="user3") cat( file=stderr(), user, " Working Now\n")
3rd Method
How to have each user log in with a sequentially assigned ID?
server.R
## Global Reactives to Count Sequential Users
Debug <- reactiveValues(UserCount=6)
shinyServer( function( input, output, session){
observe(Debug$userCount, {
cat(Debug$userCount)
user <- paste0("user", Debug$UserCount)
Debug$UserCount <<- Debug$UserCount -1
})
if(user=="user3") cat( file=stderr(), user, " Working Now\n")
Other Methods
With Authorized access for ShinyServerPro, I can just use
user <- session$user
For small numbers of users, I can just resample a userID when I refresh the page
user <- paste0("user", sample(1:2,1))