server_status.R

setwd("/srv/shiny-server/server_status")
RData <- "sysLoad.RData"

if (!file.exists(RData)) {
  Dat <- NULL
} else {
  load(RData)
}

I <- 0

repeat{
  system("top -n 1 -b -u shiny > top.log")
  dat <- readLines("top.log")
  id <- grep("R *$", dat)
  Names <- strsplit(gsub("^ +|%|\\+", "", dat[7]), " +")[[1]]
  if (length(id) > 0) {
    # 'top' data frame;
    L <- strsplit(gsub("^ *", "", dat[id]), " +")
    dat <- data.frame(matrix(unlist(L), ncol = 12, byrow = T))
    names(dat) <- Names
    dat <- data.frame(Time = Sys.time(), dat[, -ncol(dat)], usr = NA, app = NA)
    dat$CPU <- as.numeric(as.character(dat$CPU))
    dat$MEM <- as.numeric(as.character(dat$MEM))
    # Check if connection number changed;
    for (i in 1:length(dat$PID)) {
      PID <- dat$PID[i]
      system(paste("sudo netstat -p | grep", PID, "> netstat.log"))
      system(paste("sudo netstat -p | grep", PID, ">> netstat.log2"))
      system(paste("sudo lsof -p", PID, "| grep /srv > lsof.log"))
      netstat <- readLines("netstat.log")
      lsof <- readLines("lsof.log")
      dat$usr[i] <- length(grep("ESTABLISHED", netstat) & grep("tcp", netstat))
      dat$app[i] <- regmatches(lsof, regexec("srv/(.*)", lsof))[[1]][2]
    }
    if (!is.null(Dat)) {
      dat.a <- Dat[which(Dat$Time == max(Dat$Time)),]
      con.a <- dat.a$usr[order(dat.a$app)]
      con.b <- dat$usr[order(dat$app)]
      if (paste(con.a, collapse = "") == paste(con.b, collapse = "")) {
        changed <- FALSE
      } else {
        changed <- TRUE
      }
    } else {
      changed <- TRUE
    }
    # Keep only the lines containing important information to same storage space;
    if (any(dat$CPU > 5) | any(dat$MEM > 50) | changed) {
      Dat <- rbind(Dat, dat)
      Dat <- Dat[which(Dat$Time > (max(Dat$Time)-30*24*60*60)), ]
      save(Dat, file = RData)
    }
  }
  Sys.sleep(5)
  I <- I + 5
  if (I >= 60) {break}
}