feat: add functions to common.libsonnet for warpstream (#14123)

Author: grobinson-grafana

production/ksonnet/loki/common.libsonnet

@@ -44,6 +44,45 @@ local k = import 'ksonnet-util/kausal.libsonnet';
       container.mixin.readinessProbe.httpGet.withPort($._config.http_listen_port) +
       container.mixin.readinessProbe.withInitialDelaySeconds(15) +
       container.mixin.readinessProbe.withTimeoutSeconds(1),
+
+    // parseCPU is used for conversion of Kubernetes CPU units to the corresponding float value of CPU cores.
+    // Moreover, the function assumes the input is in a correct Kubernetes format, i.e., an integer, a float,
+    // a string representation of an integer or a float, or a string containing a number ending with 'm'
+    // representing a number of millicores.
+    // Examples:
+    // parseCPU(10) = parseCPU("10") = 10
+    // parseCPU(4.5) = parse("4.5") = 4.5
+    // parseCPU("3000m") = 3000 / 1000
+    // parseCPU("3580m") = 3580 / 1000
+    // parseCPU("3980.7m") = 3980.7 / 1000
+    // parseCPU(0.5) = parse("0.5") = parse("500m") = 0.5
+    parseCPU(v)::
+      if std.isString(v) && std.endsWith(v, 'm') then std.parseJson(std.rstripChars(v, 'm')) / 1000
+      else if std.isString(v) then std.parseJson(v)
+      else if std.isNumber(v) then v
+      else 0,
+
+    // siToBytes is used to convert Kubernetes byte units to bytes.
+    // Only works for limited set of SI prefixes: Ki, Mi, Gi, Ti.
+    siToBytes(str):: (
+      // Utility converting the input to a (potentially decimal) number of bytes
+      local siToBytesDecimal(str) = (
+        if std.endsWith(str, 'Ki') then (
+          std.parseJson(std.rstripChars(str, 'Ki')) * std.pow(2, 10)
+        ) else if std.endsWith(str, 'Mi') then (
+          std.parseJson(std.rstripChars(str, 'Mi')) * std.pow(2, 20)
+        ) else if std.endsWith(str, 'Gi') then (
+          std.parseJson(std.rstripChars(str, 'Gi')) * std.pow(2, 30)
+        ) else if std.endsWith(str, 'Ti') then (
+          std.parseJson(std.rstripChars(str, 'Ti')) * std.pow(2, 40)
+        ) else (
+          std.parseJson(str)
+        )
+      );
+
+      // Round down to nearest integer
+      std.floor(siToBytesDecimal(str))
+    ),
   },
 
   // functions for k8s objects