node/core: add sysctls
Change-Id: I47b0d639a62f73f134430c5164a35eef2b5622d7
Reviewed-on: https://review.monogon.dev/c/monogon/+/2273
Tested-by: Jenkins CI
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/metropolis/pkg/sysctl/BUILD.bazel b/metropolis/pkg/sysctl/BUILD.bazel
new file mode 100644
index 0000000..a945a03
--- /dev/null
+++ b/metropolis/pkg/sysctl/BUILD.bazel
@@ -0,0 +1,8 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+ name = "sysctl",
+ srcs = ["options.go"],
+ importpath = "source.monogon.dev/metropolis/pkg/sysctl",
+ visibility = ["//visibility:public"],
+)
diff --git a/metropolis/pkg/sysctl/options.go b/metropolis/pkg/sysctl/options.go
new file mode 100644
index 0000000..b5e1e36
--- /dev/null
+++ b/metropolis/pkg/sysctl/options.go
@@ -0,0 +1,29 @@
+package sysctl
+
+import (
+ "fmt"
+ "os"
+ "path"
+ "strings"
+)
+
+// Options contains sysctl options to apply
+type Options map[string]string
+
+// Apply attempts to apply all options in Options. It aborts on the first
+// one which returns an error when applying.
+func (o Options) Apply() error {
+ for name, value := range o {
+ filePath := path.Join("/proc/sys/", strings.ReplaceAll(name, ".", "/"))
+ optionFile, err := os.OpenFile(filePath, os.O_WRONLY, 0)
+ if err != nil {
+ return fmt.Errorf("failed to set option %v: %w", name, err)
+ }
+ if _, err := optionFile.WriteString(value + "\n"); err != nil {
+ optionFile.Close()
+ return fmt.Errorf("failed to set option %v: %w", name, err)
+ }
+ optionFile.Close() // In a loop, defer'ing could open a lot of FDs
+ }
+ return nil
+}