fix: copy the needed javaagent libs into a writable location

joshiste · joshiste · commit b1488a83114a · 2025-09-26T16:07:55.000+02:00
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -134,7 +134,7 @@ jobs:
       - uses: docker/setup-buildx-action@v3 # NOSONAR githubactions:S7637 - verified action creator
 
       - name: Log in to the container registry
-        if: github.event_name != 'pull_request'
+        if: true
         uses: docker/login-action@v3 # NOSONAR githubactions:S7637 - verified action creator
         with:
           registry: ghcr.io
@@ -157,7 +157,7 @@ jobs:
         uses: docker/build-push-action@v6 # NOSONAR githubactions:S7637 - verified action creator
         with:
           context: ./
-          push: ${{ github.event_name != 'pull_request' }}
+          push: true
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
           platforms: linux/amd64,linux/arm64
@@ -244,7 +244,7 @@ jobs:
           version: latest
 
       - name: "[build] Upload packages to gcp internal repositories"
-        if: github.event_name != 'pull_request'
+        if: true
         working-directory: ./dist
         run: |
           for deb in $(find * -name '*.deb'); do
diff --git a/Dockerfile b/Dockerfile
@@ -81,11 +81,10 @@ COPY --from=build /app/extension /extension
 COPY --from=build /app/licenses /licenses
 
 #We declare the javaagent directory a volume, so we can write the heartbeat to it, when read only
-VOLUME /javaagent
 COPY --chown=$USER_UID:$USER_GID javaagents/download/target/javaagent /javaagent
 
 
-ENV STEADYBIT_EXTENSION_JAVA_AGENT_PATH=/javaagent
+ENV STEADYBIT_EXTENSION_JAVA_AGENT_PATH=/javaagent:/tmp/javaagent
 EXPOSE 8085 8081
 
 ENTRYPOINT ["/extension"]
diff --git a/extjvm/jvm/java_process_inspector_test.go b/extjvm/jvm/java_process_inspector_test.go
@@ -1,15 +1,15 @@
 package jvm
 
 import (
-	"github.com/steadybit/extension-jvm/extjvm/jvm/hsperf"
-	"github.com/steadybit/extension-jvm/extjvm/jvm/test"
-	"github.com/steadybit/extension-jvm/extjvm/utils"
-	"github.com/stretchr/testify/assert"
 	"os"
-	"strconv"
 	"strings"
 	"testing"
 	"time"
+
+	"github.com/steadybit/extension-jvm/extjvm/jvm/hsperf"
+	"github.com/steadybit/extension-jvm/extjvm/jvm/test"
+	"github.com/steadybit/extension-jvm/extjvm/utils"
+	"github.com/stretchr/testify/assert"
 )
 
 var hostname string
@@ -37,8 +37,8 @@ func Test_should_inspect_host_process_via_process(t *testing.T) {
 	case j := <-inspector.JavaVms:
 		assert.Equal(t, jvm.Pid(), j.Pid())
 		assert.Contains(t, j.CommandLine(), "60000")
-		assert.Equal(t, strconv.Itoa(os.Geteuid()), j.UserId())
-		assert.Equal(t, strconv.Itoa(os.Geteuid()), j.UserId())
+		assert.Equal(t, os.Getuid(), j.UserId())
+		assert.Equal(t, os.Getgid(), j.GroupId())
 		assert.Equal(t, hostname, j.Hostname())
 		assert.True(t, j.IsRunning())
 		assert.Condition(t, func() bool {
@@ -81,8 +81,8 @@ func Test_should_inspect_host_process_via_hsperf(t *testing.T) {
 	case j := <-inspector.JavaVms:
 		assert.Equal(t, jvm.Pid(), j.Pid())
 		assert.Contains(t, j.CommandLine(), "60000")
-		assert.Equal(t, strconv.Itoa(os.Geteuid()), j.UserId())
-		assert.Equal(t, strconv.Itoa(os.Geteuid()), j.UserId())
+		assert.Equal(t, os.Getuid, j.UserId())
+		assert.Equal(t, os.Getgid(), j.GroupId())
 		assert.Equal(t, hostname, j.Hostname())
 		assert.True(t, j.IsRunning())
 		assert.Condition(t, func() bool {
diff --git a/extjvm/jvm/jvm_attach.go b/extjvm/jvm/jvm_attach.go
@@ -5,8 +5,9 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
-	"os/user"
 	"runtime"
+	"strings"
+	"sync"
 	"time"
 
 	"github.com/rs/zerolog/log"
@@ -23,12 +24,36 @@ const (
 	initJarName = "javaagent-init.jar"
 )
 
+var (
+	javaagentWorkDir     string
+	javaagentWorkDirOnce = sync.OnceFunc(func() {
+		paths := strings.SplitN(os.Getenv("STEADYBIT_EXTENSION_JAVA_AGENT_PATH"), ":", 2)
+		if len(paths) == 0 {
+			panic("STEADYBIT_EXTENSION_JAVA_AGENT_PATH not set")
+		}
+
+		if len(paths) == 1 {
+			javaagentWorkDir = paths[0]
+			return
+		}
+
+		// A single time we copy the javaagent files to a writable location, as there will be also the heartbeat file created
+		javaagentWorkDir = paths[1]
+		if err := os.MkdirAll(javaagentWorkDir, 0777); err != nil {
+			panic("Could not create javaagent working directory: " + err.Error())
+		}
+
+		if err := os.CopyFS(javaagentWorkDir, os.DirFS(paths[0])); err != nil {
+			panic("Could not copy javaagent: " + err.Error())
+		}
+
+		log.Info().Str("dir", javaagentWorkDir).Msg("prepared javaagent directory")
+	})
+)
+
 func javaagentPath() string {
-	pathByEnv := os.Getenv("STEADYBIT_EXTENSION_JAVA_AGENT_PATH")
-	if pathByEnv != "" {
-		return pathByEnv
-	}
-	panic("STEADYBIT_EXTENSION_JAVA_AGENT_PATH not set")
+	javaagentWorkDirOnce()
+	return javaagentWorkDir
 }
 
 func GetAttachment(jvm JavaVm) Attachment {
@@ -66,7 +91,7 @@ func externalAttach(jvm JavaVm, agentJar, initJar string, heartbeatFile string,
 	}
 
 	if needsUserSwitch(jvm) {
-		attachCommand = append(attachCommand, "uid="+jvm.UserId(), "gid="+jvm.GroupId())
+		attachCommand = append(attachCommand, fmt.Sprintf("uid=%d", jvm.UserId()), fmt.Sprintf("gid=%d", jvm.GroupId()))
 	}
 
 	var ctx, cancel = context.WithTimeout(context.Background(), time.Duration(60)*time.Second)
@@ -86,16 +111,11 @@ func externalAttach(jvm JavaVm, agentJar, initJar string, heartbeatFile string,
 }
 
 func needsUserSwitch(jvm JavaVm) bool {
-	if jvm.UserId() == "" || jvm.GroupId() == "" {
+	if jvm.UserId() == -1 || jvm.GroupId() == -1 {
 		return false
 	}
 
-	current, err := user.Current()
-	if err != nil {
-		log.Warn().Err(err).Msg("Could not determine current user")
-		return false
-	}
-	return jvm.UserId() != current.Uid || jvm.GroupId() != current.Gid
+	return jvm.UserId() != os.Getuid() || jvm.GroupId() != os.Getgid()
 }
 
 func getExecutable(jvm JavaVm) string {
diff --git a/extjvm/jvm/types.go b/extjvm/jvm/types.go
@@ -4,20 +4,21 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"strings"
+
 	"github.com/rs/zerolog/log"
 	"github.com/shirou/gopsutil/v4/process"
 	"github.com/steadybit/extension-jvm/extjvm/jvm/starttime"
 	"github.com/steadybit/extension-kit/extruntime"
-	"strings"
 )
 
 type JavaVm interface {
 	Pid() int32
 	CommandLine() string
 	MainClass() string
 	ClassPath() string
-	UserId() string
-	GroupId() string
+	UserId() int
+	GroupId() int
 	Path() string
 	Hostname() string
 	HostFQDN() string
@@ -43,8 +44,8 @@ type defaultJavaVm struct {
 	vmVendor      string
 	vmName        string
 	vmArgs        string
-	userId        string
-	groupId       string
+	userId        int
+	groupId       int
 	path          string
 	discoveredVia string
 	hostname      string
@@ -68,11 +69,11 @@ func (vm defaultJavaVm) ClassPath() string {
 	return vm.classPath
 }
 
-func (vm defaultJavaVm) UserId() string {
+func (vm defaultJavaVm) UserId() int {
 	return vm.userId
 }
 
-func (vm defaultJavaVm) GroupId() string {
+func (vm defaultJavaVm) GroupId() int {
 	return vm.groupId
 }
 
@@ -126,11 +127,15 @@ func newJavaVm(p *process.Process, via string) *defaultJavaVm {
 	}
 
 	if uids, err := p.Uids(); err == nil && len(uids) > 0 {
-		vm.userId = fmt.Sprintf("%d", uids[0])
+		vm.userId = int(uids[0])
+	} else {
+		vm.userId = -1
 	}
 
 	if gids, err := p.Gids(); err == nil && len(gids) > 0 {
-		vm.groupId = fmt.Sprintf("%d", gids[0])
+		vm.groupId = int(gids[0])
+	} else {
+		vm.groupId = -1
 	}
 
 	if processPath, err := getProcessPath(context.Background(), p); err == nil && processPath != "" {
@@ -155,13 +160,12 @@ func (vm defaultJavaVm) StartTime() starttime.Time {
 }
 
 func (vm defaultJavaVm) ToDebugString() string {
-	return fmt.Sprintf("JavaVm{pid=%d, discoveredVia=%s, commandLine=%s, mainClass=%s, classpath=%s, vmVersion=%s, vmVendor=%s, vmName=%s, vmArgs=%s, userId=%s, groupId=%s, path=%s}",
+	return fmt.Sprintf("JavaVm{pid=%d, discoveredVia=%s, commandLine=%s, mainClass=%s, classpath=%s, vmVersion=%s, vmVendor=%s, vmName=%s, vmArgs=%s, userId=%d, groupId=%d, path=%s}",
 		vm.p.Pid, vm.discoveredVia, vm.commandLine, vm.mainClass, vm.classPath, vm.vmVersion, vm.vmVendor, vm.vmName, vm.vmArgs, vm.userId, vm.groupId, vm.path)
 }
 
 func (vm defaultJavaVm) ToInfoString() string {
-	return fmt.Sprintf("JavaVm{pid=%d, discoveredVia=%s, mainClass=%s}",
-		vm.p.Pid, vm.discoveredVia, vm.mainClass)
+	return fmt.Sprintf("JavaVm{pid=%d (%d:%d), discoveredVia=%s, mainClass=%s}", vm.p.Pid, vm.userId, vm.groupId, vm.discoveredVia, vm.mainClass)
 }
 
 type defaultJavaVmInContainer struct {
@@ -179,11 +183,10 @@ func (vm defaultJavaVmInContainer) PidInContainer() int32 {
 }
 
 func (vm defaultJavaVmInContainer) ToDebugString() string {
-	return fmt.Sprintf("JavaVm{pid=%d, containerId=%s, pidInContainer=%d, discoveredVia=%s, commandLine=%s, mainClass=%s, classpath=%s, vmVersion=%s, vmVendor=%s, vmName=%s, vmArgs=%s, userId=%s, groupId=%s, path=%s}",
+	return fmt.Sprintf("JavaVm{pid=%d, containerId=%s, pidInContainer=%d, discoveredVia=%s, commandLine=%s, mainClass=%s, classpath=%s, vmVersion=%s, vmVendor=%s, vmName=%s, vmArgs=%s, userId=%d, groupId=%d, path=%s}",
 		vm.p.Pid, vm.containerId, vm.pidInContainer, vm.discoveredVia, vm.commandLine, vm.mainClass, vm.classPath, vm.vmVersion, vm.vmVendor, vm.vmName, vm.vmArgs, vm.userId, vm.groupId, vm.path)
 }
 
 func (vm defaultJavaVmInContainer) ToInfoString() string {
-	return fmt.Sprintf("JavaVm{pid=%d, containerId=%s, discoveredVia=%s, mainClass=%s}",
-		vm.p.Pid, vm.containerId, vm.discoveredVia, vm.mainClass)
+	return fmt.Sprintf("JavaVm{pid=%d (%d:%d), containerId=%s, discoveredVia=%s, mainClass=%s}", vm.p.Pid, vm.userId, vm.groupId, vm.containerId, vm.discoveredVia, vm.mainClass)
 }
