Support for RHEL 4.18 kernels

README.md

@@ -66,11 +66,12 @@ See [Documentation](https://grafana.com/docs/beyla/) and the [tutorials](https:/
  enabled. BTF became enabled by default on most Linux distributions with kernel 5.14 or higher. 
  You can check if your kernel has BTF enabled by verifying if `/sys/kernel/btf/vmlinux` exists on your system.
  If you need to recompile your kernel to enable BTF, the configuration option `CONFIG_DEBUG_INFO_BTF=y` must be
- set. 
-- eBPF enabled on the host
+ set.
+- Beyla supports Linux distributions running RedHat Enterprise Linux 4.18 kernels build 348 and above as they have the required kernel backports. These include CentOS, AlmaLinux, and Oracle Linux.
+- eBPF enabled on the host.
 - For instrumenting Go programs, they must have been compiled with at least Go 1.17. We currently
  support Go applications built with a major **Go version no earlier than 3 versions** behind the current
- stable major release. 
+ stable major release.
 - Some level of elevated permissions to execute the instrumenter:
  - On host systems, running Beyla requires `sudo`.
  - For Kubernetes we have detailed configuration example on how to run with minimum

docs/sources/_index.md

@@ -45,6 +45,7 @@ Beyla offers the following features:
  You can check if your kernel has BTF enabled by verifying if `/sys/kernel/btf/vmlinux` exists on your system.
  If you need to recompile your kernel to enable BTF, the configuration option `CONFIG_DEBUG_INFO_BTF=y` must be
  set.
+- Alternatively, RHEL 4.18 Linux kernels (at least build 348) are also supported, due to their heavily backported nature.
 - eBPF enabled in the host.
 - For instrumenting Go programs, they must have been compiled with at least Go 1.17. We currently
  support Go applications built with a major **Go version no earlier than 3 versions** behind the current

pkg/beyla/os.go

@@ -12,11 +12,15 @@ import (
  "github.com/grafana/beyla/pkg/internal/helpers"
 )
 
-// Minimum required Kernel version: 5.8
-const minKernMaj, minKernMin = 5, 8
+// Minimum required Kernel version: 4.18
+const minKernMaj, minKernMin = 4, 18
 
 var kernelVersion = ebpfcommon.KernelVersion
 
+func KernelVersion() (major, minor int) {
+ return kernelVersion()
+}
+
 // CheckOSSupport returns an error if the running operating system does not support
 // the minimum required Beyla features.
 func CheckOSSupport() error {

pkg/beyla/os_test.go

@@ -42,8 +42,8 @@ func TestCheckOSSupport_Unsupported(t *testing.T) {
  for _, tc := range []testCase{
  {maj: 0, min: 0},
  {maj: 3, min: 11},
- {maj: 5, min: 0},
- {maj: 5, min: 7},
+ {maj: 4, min: 0},
+ {maj: 4, min: 17},
  } {
  t.Run(fmt.Sprintf("%d.%d", tc.maj, tc.min), func(t *testing.T) {
  overrideKernelVersion(tc)

pkg/internal/ebpf/instrumenter.go

@@ -92,7 +92,11 @@ func (i *instrumenter) kprobes(p KprobesTracer) error {
  log.Debug("going to add kprobe to function", "function", kfunc, "probes", kprobes)
 
  if err := i.kprobe(kfunc, kprobes); err != nil {
- return fmt.Errorf("instrumenting function %q: %w", kfunc, err)
+ if kprobes.Required {
+ return fmt.Errorf("instrumenting function %q: %w", kfunc, err)
+ }
+
+ log.Debug("error instrumenting kprobe", "function", kfunc, "error", err)
  }
  p.AddCloser(i.closables...)
  }

pkg/internal/ebpf/ktracer/ktracer.go

@@ -250,7 +250,7 @@ func (p *Tracer) KProbes() map[string]ebpfcommon.FunctionPrograms {
  End: p.bpfObjects.KretprobeSysClone,
  },
  "sys_clone3": {
- Required: true,
+ Required: false,
  End: p.bpfObjects.KretprobeSysClone,
  },
  "sys_exit": {

test/integration/multiprocess_test.go

@@ -88,7 +88,7 @@ func TestMultiProcess(t *testing.T) {
  assert.Empty(t, results)
  })
 
- if kprobeTraces {
+ if kprobeTracesEnabled() {
  t.Run("Nested traces with kprobes: rust -> java -> node -> go -> python -> rails", func(t *testing.T) {
  testNestedHTTPTracesKProbes(t)
  })

test/integration/red_test_nodeclient.go

@@ -96,7 +96,7 @@ func testNodeClientWithMethodAndStatusCode(t *testing.T, method string, statusCo
  We check that the traceID has that 16 character 0 suffix and then we
  use the first 16 characters for looking up by Parent span.
  */
- if kprobeTraces {
+ if kprobeTracesEnabled() {
  assert.NotEmpty(t, span.TraceID)
  assert.Truef(t, strings.HasSuffix(span.TraceID, traceIDLookup),
  "string %q should have suffix %q", span.TraceID, traceIDLookup)

test/integration/red_test_rust.go

@@ -84,7 +84,7 @@ func testREDMetricsForRustHTTPLibrary(t *testing.T, url, comm, namespace string,
  require.Len(t, res, 1)
  parent := res[0]
  require.NotEmpty(t, parent.TraceID)
- if kprobeTraces {
+ if kprobeTracesEnabled() {
  require.Equal(t, traceID, parent.TraceID)
  // Validate that "parent" is a CHILD_OF the traceparent's "parent-id"
  childOfPID := trace.ChildrenOf(parentID)

test/integration/suites_test.go

@@ -11,10 +11,15 @@ import (
 
  "github.com/stretchr/testify/require"
 
+ "github.com/grafana/beyla/pkg/beyla"
  "github.com/grafana/beyla/test/integration/components/docker"
 )
 
-var kprobeTraces = true // allow tests to run distributed traces tests
+func kprobeTracesEnabled() bool {
+ major, minor := beyla.KernelVersion()
+
+ return major > 5 || (major == 5 && minor >= 17)
+}
 
 func TestSuite(t *testing.T) {
  compose, err := docker.ComposeSuite("docker-compose.yml", path.Join(pathOutput, "test-suite.log"))
@@ -492,6 +497,11 @@ func TestSuite_OverrideServiceName(t *testing.T) {
 }
 
 func TestSuiteNodeClient(t *testing.T) {
+ if !kprobeTracesEnabled() {
+ t.Skip("distributed traces not supported")
+ return
+ }
+
  compose, err := docker.ComposeSuite("docker-compose-nodeclient.yml", path.Join(pathOutput, "test-suite-nodeclient.log"))
  compose.Env = append(compose.Env, `BEYLA_EXECUTABLE_NAME=node`, `NODE_APP=client`)
  require.NoError(t, err)
@@ -505,6 +515,11 @@ func TestSuiteNodeClient(t *testing.T) {
 }
 
 func TestSuiteNodeClientTLS(t *testing.T) {
+ if !kprobeTracesEnabled() {
+ t.Skip("distributed traces not supported")
+ return
+ }
+
  compose, err := docker.ComposeSuite("docker-compose-nodeclient.yml", path.Join(pathOutput, "test-suite-nodeclient-tls.log"))
  compose.Env = append(compose.Env, `BEYLA_EXECUTABLE_NAME=node`, `NODE_APP=client_tls`)
  require.NoError(t, err)

test/integration/traces_test.go

@@ -370,7 +370,7 @@ func testHTTPTracesKProbes(t *testing.T) {
  require.Len(t, res, 1)
  parent := res[0]
  require.NotEmpty(t, parent.TraceID)
- if kprobeTraces {
+ if kprobeTracesEnabled() {
  require.Equal(t, traceID, parent.TraceID)
  // Validate that "parent" is a CHILD_OF the traceparent's "parent-id"
  childOfPID := trace.ChildrenOf(parentID)