From ed3e2e7bd48191177c21955a22e51696ebd93737 Mon Sep 17 00:00:00 2001
From: Cecil Singh <54638818+Cecilsingh@users.noreply.github.com>
Date: Wed, 25 Sep 2024 09:21:02 +1000
Subject: [PATCH] Create memoryBalancing.R

---
 loadBalancing/memoryBalancing.R | 44 +++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 loadBalancing/memoryBalancing.R

diff --git a/loadBalancing/memoryBalancing.R b/loadBalancing/memoryBalancing.R
new file mode 100644
index 0000000..82cee07
--- /dev/null
+++ b/loadBalancing/memoryBalancing.R
@@ -0,0 +1,44 @@
+#!/usr/bin/Rscript
+
+get_nodes <- function(nodes = Sys.getenv("RSTUDIO_NODES")) {
+  unlist(strsplit(nodes, ",", fixed = TRUE))
+}
+
+get_health_check <- function(node_address) {
+  con <- url(sprintf("http://%s/health-check", node_address))
+  on.exit(close(con))
+  readLines(con)
+}
+
+parse_health_check <- function(health_check) {
+  fields <- unlist(strsplit(health_check, "\n|,"))
+
+  keys <- sub(
+    ":",
+    "",
+    regmatches(fields, regexpr("^[a-z\\-]+:", fields))
+  )
+
+  values <- sub(
+    ": ",
+    "",
+    regmatches(fields, regexpr(":.+$", fields))
+  )
+  data.frame(keys, values, stringsAsFactors = FALSE)
+}
+
+get_value <- function(hc_table, hc_value) {
+  as.double(hc_table[hc_table[["keys"]] == hc_value, "values"])
+}
+
+main <- function() {
+  nodes <- get_nodes()
+  named_hc <- setNames(lapply(nodes, get_health_check), nodes)
+  parsed_hc <- lapply(named_hc, parse_health_check)
+  mem_percent <- lapply(parsed_hc, get_value, "memory-percent")
+  least_mem <- names(which.min(unlist(mem_percent)))
+
+  least_mem
+}
+
+cat(main())