Add metadata to identify Python and Ruby processes (#1868)

- Add identifier metadata for Ruby and Python
- Introduce runtime package for common functionality

depends: #1867

### Why?
This additional metadata helps us to query Python and Ruby specific
profiles from executable of the running processes.
Right now, we took a naive approach and check for the common symbols of
interpreters across the versions.

Further iterations will come.

### What?
<!--
copilot:summary
-->
### <samp>🤖 Generated by Copilot at 3dfad75</samp>

This pull request adds metadata providers for Python and Ruby processes,
and refactors the existing Java provider. It also introduces new
functions in `pkg/runtime` to detect Python and Ruby processes based on
ELF symbols. The `hsperfdata` package is moved and renamed to `java` in
`pkg/runtime` to improve code organization.

### How?
<!--
copilot:walkthrough
-->
### <samp>🤖 Generated by Copilot at 3dfad75</samp>

* Add metadata providers for Python and Ruby processes
([link](https://github.com/parca-dev/parca-agent/pull/1868/files?diff=unified&w=0#diff-57833d176ed681886b67a7fa2e4dc2f68d5e00cb1db269e7854fb3dafb45f54eL664-R666),
[link](https://github.com/parca-dev/parca-agent/pull/1868/files?diff=unified&w=0#diff-b5bcdce21d9b76af9586cf79fa08cba39b460e8afdae697b0c372a660812fd31R1-R96),
[link](https://github.com/parca-dev/parca-agent/pull/1868/files?diff=unified&w=0#diff-47648631ed7788443bfebfb8c3a943990bca4c75647c9c45416c349d483b0b55R1-R96))
* Rename `java_process.go` to `java.go` and `JavaProcess` to `Java` in
`pkg/metadata`
([link](https://github.com/parca-dev/parca-agent/pull/1868/files?diff=unified&w=0#diff-35835b1e76e2185d9ae1138faf6c0b347ce295ca3f965b004c8e8b64ce34a8f3L24-R29))
* Move `hsperfdata.go` from `pkg/hsperfdata` to `pkg/runtime/java` and
rename package to `java`
([link](https://github.com/parca-dev/parca-agent/pull/1868/files?diff=unified&w=0#diff-bffa53f69a05fb77178a7088b45cc22da039ad07dcf9f4de99762e508c620bc6L15-R15))
* Rename `Cache` to `HSPerfDataCache` and update related functions and
methods in `pkg/runtime/java/hsperfdata.go`
([link](https://github.com/parca-dev/parca-agent/pull/1868/files?diff=unified&w=0#diff-bffa53f69a05fb77178a7088b45cc22da039ad07dcf9f4de99762e508c620bc6L37-R37),
[link](https://github.com/parca-dev/parca-agent/pull/1868/files?diff=unified&w=0#diff-bffa53f69a05fb77178a7088b45cc22da039ad07dcf9f4de99762e508c620bc6L54-R55),
[link](https://github.com/parca-dev/parca-agent/pull/1868/files?diff=unified&w=0#diff-bffa53f69a05fb77178a7088b45cc22da039ad07dcf9f4de99762e508c620bc6L67-R67),
[link](https://github.com/parca-dev/parca-agent/pull/1868/files?diff=unified&w=0#diff-bffa53f69a05fb77178a7088b45cc22da039ad07dcf9f4de99762e508c620bc6L80-R80))
* Add `IsPython` and `IsRuby` functions to `pkg/runtime` to check ELF
files for Python and Ruby identifiers
([link](https://github.com/parca-dev/parca-agent/pull/1868/files?diff=unified&w=0#diff-7ef2d85bbb21b340c4273db9f8c50c07d567cce478d6e2b2fbd3e8e5fe67d915R1-R70),
[link](https://github.com/parca-dev/parca-agent/pull/1868/files?diff=unified&w=0#diff-e446dd52ecce11cbc98b8dc12cc36fff325aca8d376f2353192e153f59028e77R1-R72))

### Test Plan
1. Local tests (using containers with different versions of
interpreters)
2. CI intergration tests
![CleanShot 2023-07-18 at 19 53
26](https://github.com/parca-dev/parca-agent/assets/536449/2b9a3af5-526e-4fb3-bb7a-52e068739d50)
![CleanShot 2023-07-18 at 19 53
08](https://github.com/parca-dev/parca-agent/assets/536449/5a336bb3-7bc7-40c6-b899-4de242425f06)

cmd/parca-agent/main.go

@@ -661,7 +661,9 @@ func run(logger log.Logger, reg *prometheus.Registry, flags flags) error {
 			metadata.Target(flags.Node, flags.Metadata.ExternalLabels),
 			metadata.Compiler(logger, reg, ofp),
 			metadata.Process(pfs),
-			metadata.JavaProcess(logger, nsCache),
+			metadata.Java(logger, nsCache),
+			metadata.Ruby(pfs, reg, ofp),
+			metadata.Python(pfs, reg, ofp),
 			metadata.System(),
 			metadata.PodHosts(),
 		},

pkg/metadata/java_process.go → pkg/metadata/java.go

@@ -21,12 +21,12 @@ import (
 	"github.com/go-kit/log"
 	"github.com/prometheus/common/model"
 
-	"github.com/parca-dev/parca-agent/pkg/hsperfdata"
 	"github.com/parca-dev/parca-agent/pkg/namespace"
+	"github.com/parca-dev/parca-agent/pkg/runtime/java"
 )
 
-func JavaProcess(logger log.Logger, nsCache *namespace.Cache) Provider {
-	cache := hsperfdata.NewCache(logger, nsCache)
+func Java(logger log.Logger, nsCache *namespace.Cache) Provider {
+	cache := java.NewHSPerfDataCache(logger, nsCache)
 
 	return &StatelessProvider{"java process", func(ctx context.Context, pid int) (model.LabelSet, error) {
 		if ctx.Err() != nil {

pkg/metadata/python.go

@@ -0,0 +1,97 @@
+// Copyright 2022-2023 The Parca Authors
+// 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.
+//
+
+//nolint:dupl
+package metadata
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/common/model"
+	"github.com/prometheus/procfs"
+
+	"github.com/parca-dev/parca-agent/pkg/cache"
+	"github.com/parca-dev/parca-agent/pkg/objectfile"
+	"github.com/parca-dev/parca-agent/pkg/runtime"
+)
+
+func Python(procfs procfs.FS, reg prometheus.Registerer, objFilePool *objectfile.Pool) Provider {
+	cache := cache.NewLRUCache[string, bool](
+		prometheus.WrapRegistererWith(prometheus.Labels{"cache": "metadata_python"}, reg),
+		512,
+	)
+	return &StatelessProvider{"python", func(ctx context.Context, pid int) (model.LabelSet, error) {
+		if ctx.Err() != nil {
+			return nil, ctx.Err()
+		}
+
+		p, err := procfs.Proc(pid)
+		if err != nil {
+			return nil, fmt.Errorf("failed to instantiate procfs for PID %d: %w", pid, err)
+		}
+
+		executable, err := p.Executable()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get executable for PID %d: %w", pid, err)
+		}
+
+		if python, ok := cache.Get(executable); ok {
+			if !python {
+				return nil, nil
+			}
+			return model.LabelSet{
+				"python": model.LabelValue(fmt.Sprintf("%t", true)),
+			}, nil
+		}
+
+		comm, err := p.Comm()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get comm for PID %d: %w", pid, err)
+		}
+
+		if strings.HasPrefix(comm, "python") {
+			cache.Add(executable, true)
+			return model.LabelSet{
+				"python": model.LabelValue(fmt.Sprintf("%t", true)),
+			}, nil
+		}
+
+		obj, err := objFilePool.Open(executable)
+		if err != nil {
+			return nil, fmt.Errorf("failed to open ELF file for process %d: %w", pid, err)
+		}
+
+		ef, release, err := obj.ELF()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get ELF file for process %d: %w", pid, err)
+		}
+		defer release()
+
+		python, err := runtime.IsPython(ef)
+		if err != nil {
+			return nil, fmt.Errorf("failed to determine if PID %d belongs to a python process: %w", pid, err)
+		}
+
+		cache.Add(executable, python)
+		if !python {
+			return nil, nil
+		}
+		return model.LabelSet{
+			"python": model.LabelValue(fmt.Sprintf("%t", true)),
+		}, nil
+	}}
+}

pkg/metadata/ruby.go

@@ -0,0 +1,97 @@
+// Copyright 2022-2023 The Parca Authors
+// 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.
+//
+
+//nolint:dupl
+package metadata
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/common/model"
+	"github.com/prometheus/procfs"
+
+	"github.com/parca-dev/parca-agent/pkg/cache"
+	"github.com/parca-dev/parca-agent/pkg/objectfile"
+	"github.com/parca-dev/parca-agent/pkg/runtime"
+)
+
+func Ruby(procfs procfs.FS, reg prometheus.Registerer, objFilePool *objectfile.Pool) Provider {
+	cache := cache.NewLRUCache[string, bool](
+		prometheus.WrapRegistererWith(prometheus.Labels{"cache": "metadata_ruby"}, reg),
+		512,
+	)
+	return &StatelessProvider{"ruby", func(ctx context.Context, pid int) (model.LabelSet, error) {
+		if ctx.Err() != nil {
+			return nil, ctx.Err()
+		}
+
+		p, err := procfs.Proc(pid)
+		if err != nil {
+			return nil, fmt.Errorf("failed to instantiate procfs for PID %d: %w", pid, err)
+		}
+
+		executable, err := p.Executable()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get executable for PID %d: %w", pid, err)
+		}
+
+		if ruby, ok := cache.Get(executable); ok {
+			if !ruby {
+				return nil, nil
+			}
+			return model.LabelSet{
+				"ruby": model.LabelValue(fmt.Sprintf("%t", true)),
+			}, nil
+		}
+
+		comm, err := p.Comm()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get comm for PID %d: %w", pid, err)
+		}
+
+		if strings.HasPrefix(comm, "ruby") {
+			cache.Add(executable, true)
+			return model.LabelSet{
+				"ruby": model.LabelValue(fmt.Sprintf("%t", true)),
+			}, nil
+		}
+
+		obj, err := objFilePool.Open(executable)
+		if err != nil {
+			return nil, fmt.Errorf("failed to open ELF file for process %d: %w", pid, err)
+		}
+
+		ef, release, err := obj.ELF()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get ELF file for process %d: %w", pid, err)
+		}
+		defer release()
+
+		ruby, err := runtime.IsRuby(ef)
+		if err != nil {
+			return nil, fmt.Errorf("failed to determine if PID %d belongs to a ruby process: %w", pid, err)
+		}
+
+		cache.Add(executable, ruby)
+		if !ruby {
+			return nil, nil
+		}
+		return model.LabelSet{
+			"ruby": model.LabelValue(fmt.Sprintf("%t", true)),
+		}, nil
+	}}
+}

pkg/hsperfdata/hsperfdata.go → pkg/runtime/java/hsperfdata.go

@@ -12,7 +12,7 @@
 // limitations under the License.
 //
 
-package hsperfdata
+package java
 
 import (
 	"errors"
@@ -34,7 +34,7 @@ import (
 
 const hsperfdata = "/tmp/hsperfdata_*"
 
-type Cache struct {
+type HSPerfDataCache struct {
 	fs     fs.FS
 	logger log.Logger
 
@@ -51,8 +51,8 @@ func (f *realfs) Open(name string) (fs.File, error) {
 	return os.Open(name)
 }
 
-func NewCache(logger log.Logger, nsCache *namespace.Cache) *Cache {
-	return &Cache{
+func NewHSPerfDataCache(logger log.Logger, nsCache *namespace.Cache) *HSPerfDataCache {
+	return &HSPerfDataCache{
 		fs:     &realfs{},
 		logger: logger,
 
@@ -64,7 +64,7 @@ func NewCache(logger log.Logger, nsCache *namespace.Cache) *Cache {
 	}
 }
 
-func (c *Cache) Exists(pid int) bool {
+func (c *HSPerfDataCache) Exists(pid int) bool {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
@@ -77,7 +77,7 @@ func (c *Cache) Exists(pid int) bool {
 // running on host and then searches in /proc/{pid}/root/tmp for processes
 // running in containers. Note that pids are assumed to be unique regardless
 // of username.
-func (c *Cache) IsJavaProcess(pid int) (bool, error) {
+func (c *HSPerfDataCache) IsJavaProcess(pid int) (bool, error) {
 	// Check if the pid is in the cache.
 	if c.Exists(pid) {
 		return true, nil

pkg/runtime/python.go

@@ -0,0 +1,71 @@
+// Copyright 2022-2023 The Parca Authors
+// 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 runtime
+
+import (
+	"debug/elf"
+	"errors"
+	"fmt"
+)
+
+func IsPython(ef *elf.File) (bool, error) {
+	python := false
+
+	syms, err := ef.Symbols()
+	if err != nil && !errors.Is(err, elf.ErrNoSymbols) {
+		return python, fmt.Errorf("failed to get symbols: %w", err)
+	}
+	for _, sym := range syms {
+		if isPythonIdentifyingSymbol(sym.Name) {
+			python = true
+			break
+		}
+	}
+
+	if !python {
+		dynSyms, err := ef.DynamicSymbols()
+		if err != nil {
+			return python, fmt.Errorf("failed to get dynamic symbols: %w", err)
+		}
+		for _, sym := range dynSyms {
+			if isPythonIdentifyingSymbol(sym.Name) {
+				python = true
+				break
+			}
+		}
+	}
+
+	return python, nil
+}
+
+/*
+Python symbols to look for:
+
+	2.7:`Py_Main`
+
+	3.2:`Py_Main`
+	3.3:`Py_Main`
+	3.4:`Py_Main`
+	3.5:`Py_Main`
+	3.6:`Py_Main`
+	3.7:`_Py_UnixMain`
+	3.8:`Py_BytesMain`
+	3.9:`Py_BytesMain`
+	3.10:`Py_BytesMain`
+	3.11:`Py_BytesMain`
+*/
+func isPythonIdentifyingSymbol(sym string) bool {
+	return sym == "Py_Main" || sym == "_Py_UnixMain" || sym == "Py_BytesMain"
+}