Feature 57 (config and provisioning): modules declare config and provisions, their files rendered from templates; synced with main (issues of feature 57, 874)

modules/memory-pressure/cmd/memory-pressure/templates_test.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+// The module's directory, where its manifest and its files/ are.
+const moduleDir = "../.."
+
+// templateText is the text a file resource places on the machine: its template's, in the module's files/
+// (novox/hq ADR 0349 §2). A resource that names no template, or a template that is not there, fails the test.
+func templateText(t *testing.T, r map[string]any) string {
+	t.Helper()
+	name, _ := r["template"].(string)
+	if name == "" {
+		t.Fatalf("resource %v names no template", r["id"])
+	}
+	raw, err := os.ReadFile(filepath.Join(moduleDir, filepath.FromSlash(name)))
+	if err != nil {
+		t.Fatalf("resource %v names %s: %v", r["id"], name, err)
+	}
+	return string(raw)
+}
+
+// No file resource carries its text inline: each names its template in files/, and the build packs files/
+// into the one archive the controller reads the templates back from (novox/hq ADR 0349 §2).
+func TestEveryFileTakesItsTextFromATemplate(t *testing.T) {
+	raw, err := os.ReadFile(filepath.Join(moduleDir, "module.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m struct {
+		Resources []map[string]any `json:"resources"`
+		Build     struct {
+			Artifacts []map[string]any `json:"artifacts"`
+		} `json:"build"`
+	}
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatal(err)
+	}
+	for _, r := range m.Resources {
+		if _, inline := r["content"]; inline {
+			t.Errorf("resource %v keeps its text inline: keep it in files/ and name it as the template", r["id"])
+		}
+		if r["type"] == "file" {
+			templateText(t, r)
+		}
+	}
+	packs := 0
+	for _, a := range m.Build.Artifacts {
+		if a["kind"] == "archive" && a["from"] == "files" {
+			packs++
+			if a["name"] != "files" {
+				t.Errorf("the templates archive is named %v, not files", a["name"])
+			}
+		}
+	}
+	if packs != 1 {
+		t.Errorf("the build packs files/ into %d archives, not one", packs)
+	}
+}

modules/memory-pressure/files/oomd.conf

@@ -0,0 +1,8 @@
+# Managed by the mesh (module memory-pressure). Replaced on every push; edit the catalogue instead.
+#
+# systemd-oomd kills the worst unit before the kernel's OOM killer freezes the machine: when swap is
+# 90 % used, or when a watched unit stalls on memory for 20 s above its limit.
+[OOM]
+SwapUsedLimit=90%
+DefaultMemoryPressureLimit=60%
+DefaultMemoryPressureDurationSec=20s

modules/memory-pressure/files/root-slice.conf

@@ -0,0 +1,5 @@
+# Managed by the mesh (module memory-pressure). Replaced on every push; edit the catalogue instead.
+#
+# systemd-oomd may act on swap exhaustion across the whole machine.
+[Slice]
+ManagedOOMSwap=kill

modules/memory-pressure/files/sysctl.conf

@@ -0,0 +1,9 @@
+# Managed by the mesh (module memory-pressure). Replaced on every push; edit the catalogue instead.
+#
+# Swap-in reads one page, not eight: read-ahead exists to amortise a disk's seek, and compressed swap in
+# RAM has none — the speculation only costs decompression and memory.
+vm.page-cluster = 0
+#
+# vm.swappiness is deliberately left alone. The usual zram advice (150-180) holds only while the
+# compressed swap has room; once it is full, a higher swappiness moves pages to the disk swap, the thing
+# being avoided. Raise it only together with zram-size.

modules/memory-pressure/files/user-manager.conf

@@ -0,0 +1,7 @@
+# Managed by the mesh (module memory-pressure). Replaced on every push; edit the catalogue instead.
+#
+# systemd-oomd may kill the worst unit in a person's service manager when its memory pressure stays
+# above 80 % — instead of the kernel freezing the machine.
+[Service]
+ManagedOOMMemoryPressure=kill
+ManagedOOMMemoryPressureLimit=80%

modules/memory-pressure/files/zram-generator.conf

@@ -0,0 +1,11 @@
+# Managed by the mesh (module memory-pressure). Replaced on every push; edit the catalogue instead.
+#
+# Compressed swap in RAM: fast, at a higher priority than any swap on disk, so it takes the everyday
+# pressure before anything spills to a disk. Half the RAM, at most 16 GiB, compressed with zstd.
+# The swap on disk, its size and whether one exists at all are the machine's, not this module's.
+#
+# Read by the generator at boot: a change applies at the next boot.
+[zram0]
+zram-size = min(ram / 2, 16384)
+compression-algorithm = zstd
+swap-priority = 100

modules/memory-pressure/module.json

@@ -28,7 +28,7 @@
       "type": "file",
       "path": "/etc/systemd/zram-generator.conf",
       "mode": "0644",
-      "content": "# Managed by the mesh (module memory-pressure). Replaced on every push; edit the catalogue instead.\n#\n# Compressed swap in RAM: fast, at a higher priority than any swap on disk, so it takes the everyday\n# pressure before anything spills to a disk. Half the RAM, at most 16 GiB, compressed with zstd.\n# The swap on disk, its size and whether one exists at all are the machine's, not this module's.\n#\n# Read by the generator at boot: a change applies at the next boot.\n[zram0]\nzram-size = min(ram / 2, 16384)\ncompression-algorithm = zstd\nswap-priority = 100\n"
+      "template": "files/zram-generator.conf"
     },
     {
       "id": "sysctl-drop-ins",
@@ -41,7 +41,7 @@
       "type": "file",
       "path": "/etc/sysctl.d/90-memory-pressure.conf",
       "mode": "0644",
-      "content": "# Managed by the mesh (module memory-pressure). Replaced on every push; edit the catalogue instead.\n#\n# Swap-in reads one page, not eight: read-ahead exists to amortise a disk's seek, and compressed swap in\n# RAM has none — the speculation only costs decompression and memory.\nvm.page-cluster = 0\n#\n# vm.swappiness is deliberately left alone. The usual zram advice (150-180) holds only while the\n# compressed swap has room; once it is full, a higher swappiness moves pages to the disk swap, the thing\n# being avoided. Raise it only together with zram-size.\n"
+      "template": "files/sysctl.conf"
     },
     {
       "id": "sysctl",
@@ -62,7 +62,7 @@
       "type": "file",
       "path": "/etc/systemd/oomd.conf.d/memory-pressure.conf",
       "mode": "0644",
-      "content": "# Managed by the mesh (module memory-pressure). Replaced on every push; edit the catalogue instead.\n#\n# systemd-oomd kills the worst unit before the kernel's OOM killer freezes the machine: when swap is\n# 90 % used, or when a watched unit stalls on memory for 20 s above its limit.\n[OOM]\nSwapUsedLimit=90%\nDefaultMemoryPressureLimit=60%\nDefaultMemoryPressureDurationSec=20s\n"
+      "template": "files/oomd.conf"
     },
     {
       "id": "root-slice-drop-ins",
@@ -75,7 +75,7 @@
       "type": "file",
       "path": "/etc/systemd/system/-.slice.d/10-oomd.conf",
       "mode": "0644",
-      "content": "# Managed by the mesh (module memory-pressure). Replaced on every push; edit the catalogue instead.\n#\n# systemd-oomd may act on swap exhaustion across the whole machine.\n[Slice]\nManagedOOMSwap=kill\n"
+      "template": "files/root-slice.conf"
     },
     {
       "id": "user-manager-drop-ins",
@@ -88,7 +88,7 @@
       "type": "file",
       "path": "/etc/systemd/system/user@.service.d/10-oomd.conf",
       "mode": "0644",
-      "content": "# Managed by the mesh (module memory-pressure). Replaced on every push; edit the catalogue instead.\n#\n# systemd-oomd may kill the worst unit in a person's service manager when its memory pressure stays\n# above 80 % — instead of the kernel freezing the machine.\n[Service]\nManagedOOMMemoryPressure=kill\nManagedOOMMemoryPressureLimit=80%\n"
+      "template": "files/user-manager.conf"
     },
     {
       "id": "oomd",
@@ -115,6 +115,11 @@
         "loads": [
           "memory-pressure"
         ]
+      },
+      {
+        "name": "files",
+        "kind": "archive",
+        "from": "files"
       }
     ]
   }