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/*
* cgroup_test.go - Tests for cgroup CPU and memory limit reading.
*
* Copyright 2026 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package cgroup
import (
"encoding/json"
"errors"
"math"
"os"
"path/filepath"
"strconv"
"testing"
)
func writeFile(t *testing.T, path, content string) {
t.Helper()
if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
t.Fatal(err)
}
if err := os.WriteFile(path, []byte(content), 0644); err != nil {
t.Fatal(err)
}
}
func TestCgroupV1Unsupported(t *testing.T) {
content := `12:memory:/docker/abc123
11:cpu,cpuacct:/docker/abc123
`
root := t.TempDir()
writeFile(t, filepath.Join(root, "proc/self/cgroup"), content)
_, err := NewFromRoot(root)
if !errors.Is(err, ErrV1Detected) {
t.Fatalf("NewFromRoot() error = %v, want %v", err, ErrV1Detected)
}
}
// testdataExpected holds the expected values from a testdata/*/expected.json.
// Null fields indicate that ErrNoLimit is expected.
type testdataExpected struct {
CPUQuota *float64 `json:"cpu_quota"`
MemoryLimit *int64 `json:"memory_limit"`
}
// TestWithRootFromTestdata runs NewFromRoot, CPUQuota, and MemoryLimit
// against filesystem snapshots captured from real Docker containers by
// bin/snapshot-cgroup. Each subdirectory of testdata/ is a separate test
// case containing a proc/ and sys/ tree plus an expected.json.
//
// Regenerate with: bin/gen-cgroup-testdata
func TestWithRootFromTestdata(t *testing.T) {
entries, err := os.ReadDir("testdata")
if err != nil {
t.Fatalf("no testdata directory: %v", err)
}
for _, entry := range entries {
if !entry.IsDir() {
continue
}
name := entry.Name()
root := filepath.Join("testdata", name)
t.Run(name, func(t *testing.T) {
data, err := os.ReadFile(filepath.Join(root, "expected.json"))
if err != nil {
t.Fatalf("reading expected.json: %v", err)
}
var want testdataExpected
if err := json.Unmarshal(data, &want); err != nil {
t.Fatalf("parsing expected.json: %v", err)
}
cg, err := NewFromRoot(root)
if err != nil {
t.Fatalf("NewFromRoot(%q): %v", root, err)
}
gotCPU, err := cg.CPUQuota()
if want.CPUQuota == nil {
if !errors.Is(err, ErrNoLimit) {
t.Errorf("CPUQuota() error = %v, want ErrNoLimit", err)
}
} else if err != nil {
t.Fatalf("CPUQuota(): %v", err)
} else if math.Abs(gotCPU-*want.CPUQuota) > 0.001 {
t.Errorf("CPUQuota() = %v, want %v", gotCPU, *want.CPUQuota)
}
gotMem, err := cg.MemoryLimit()
if want.MemoryLimit == nil {
if !errors.Is(err, ErrNoLimit) {
t.Errorf("MemoryLimit() error = %v, want ErrNoLimit", err)
}
} else if err != nil {
t.Fatalf("MemoryLimit(): %v", err)
} else if gotMem != *want.MemoryLimit {
t.Errorf("MemoryLimit() = %v, want %v", gotMem, *want.MemoryLimit)
}
})
}
}
// TestIntegrationCgroupLimits calls the real New(), CPUQuota(), and
// MemoryLimit() against the live kernel cgroup interface. It is intended to
// run inside a Docker container started with --cpus and --memory flags.
//
// The test is skipped unless CGROUP_EXPECTED_CPU_QUOTA and
// CGROUP_EXPECTED_MEMORY_LIMIT are set in the environment.
func TestIntegrationCgroupLimits(t *testing.T) {
cpuStr := os.Getenv("CGROUP_EXPECTED_CPU_QUOTA")
memStr := os.Getenv("CGROUP_EXPECTED_MEMORY_LIMIT")
if cpuStr == "" && memStr == "" {
t.Skip("set CGROUP_EXPECTED_CPU_QUOTA and CGROUP_EXPECTED_MEMORY_LIMIT to run")
}
cg, err := New()
if err != nil {
t.Fatalf("New() error: %v", err)
}
if cpuStr != "" {
wantCPU, err := strconv.ParseFloat(cpuStr, 64)
if err != nil {
t.Fatalf("bad CGROUP_EXPECTED_CPU_QUOTA %q: %v", cpuStr, err)
}
gotCPU, err := cg.CPUQuota()
if err != nil {
t.Fatalf("CPUQuota() error: %v", err)
}
if math.Abs(gotCPU-wantCPU) > 0.001 {
t.Errorf("CPUQuota() = %v, want %v", gotCPU, wantCPU)
}
}
if memStr != "" {
wantMem, err := strconv.ParseInt(memStr, 10, 64)
if err != nil {
t.Fatalf("bad CGROUP_EXPECTED_MEMORY_LIMIT %q: %v", memStr, err)
}
gotMem, err := cg.MemoryLimit()
if err != nil {
t.Fatalf("MemoryLimit() error: %v", err)
}
if gotMem != wantMem {
t.Errorf("MemoryLimit() = %v, want %v", gotMem, wantMem)
}
}
}
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