feat: support Docker volume-based JAR mounting for Docker-in-Docker

When CAMELEER_JAR_DOCKER_VOLUME is set, the orchestrator mounts the
named volume at the jar storage path instead of using a host bind mount.
This solves the path translation issue in Docker-in-Docker setups where
the server runs inside a container and manages sibling containers.

The entrypoint is overridden to use the volume-mounted JAR path via
the CAMELEER_APP_JAR env var.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/java/com/cameleer3/server/app/runtime/DeploymentExecutor.java

@@ -58,6 +58,12 @@ public class DeploymentExecutor {
     @Value("${cameleer.runtime.server-url:}")
     private String globalServerUrl;
 
+    @Value("${cameleer.runtime.jar-docker-volume:}")
+    private String jarDockerVolume;
+
+    @Value("${cameleer.runtime.jar-storage-path:/data/jars}")
+    private String jarStoragePath;
+
     public DeploymentExecutor(RuntimeOrchestrator orchestrator,
                               DeploymentService deploymentService,
                               AppService appService,
@@ -122,8 +128,11 @@ public class DeploymentExecutor {
                 String containerName = env.slug() + "-" + app.slug() + "-" + i;
                 Long cpuQuota = config.cpuLimit() != null ? (long) (config.cpuLimit() * 100_000) : null;
 
+                String volumeName = jarDockerVolume != null && !jarDockerVolume.isBlank() ? jarDockerVolume : null;
                 ContainerRequest request = new ContainerRequest(
-                        containerName, baseImage, jarPath, primaryNetwork,
+                        containerName, baseImage, jarPath,
+                        volumeName, jarStoragePath,
+                        primaryNetwork,
                         envNet != null ? List.of(envNet) : List.of(),
                         baseEnvVars, labels,
                         config.memoryLimitBytes(), config.memoryReserveBytes(),

cameleer3-server-app/src/main/java/com/cameleer3/server/app/runtime/DockerRuntimeOrchestrator.java

@@ -60,16 +60,23 @@ public class DockerRuntimeOrchestrator implements RuntimeOrchestrator {
         List<String> envList = request.envVars().entrySet().stream()
                 .map(e -> e.getKey() + "=" + e.getValue()).toList();
 
-        Bind jarBind = new Bind(request.jarPath(), new Volume("/app/app.jar"), AccessMode.ro);
-
         HostConfig hostConfig = HostConfig.newHostConfig()
                 .withMemory(request.memoryLimitBytes())
                 .withMemorySwap(request.memoryLimitBytes())
                 .withCpuShares(request.cpuShares())
                 .withNetworkMode(request.network())
-                .withBinds(jarBind)
                 .withRestartPolicy(RestartPolicy.onFailureRestart(request.restartPolicyMaxRetries()));
 
+        // JAR mounting: volume mount (Docker-in-Docker) or bind mount (host path)
+        if (request.jarVolumeName() != null && !request.jarVolumeName().isBlank()) {
+            // Mount the named volume at the jar storage base path
+            Bind volumeBind = new Bind(request.jarVolumeName(), new Volume(request.jarVolumeMountPath()), AccessMode.ro);
+            hostConfig.withBinds(volumeBind);
+        } else {
+            Bind jarBind = new Bind(request.jarPath(), new Volume("/app/app.jar"), AccessMode.ro);
+            hostConfig.withBinds(jarBind);
+        }
+
         if (request.memoryReserveBytes() != null) {
             hostConfig.withMemoryReservation(request.memoryReserveBytes());
         }
@@ -77,6 +84,12 @@ public class DockerRuntimeOrchestrator implements RuntimeOrchestrator {
             hostConfig.withCpuQuota(request.cpuQuota());
         }
 
+        // When using volume mount, the JAR is at the original path, not /app/app.jar
+        if (request.jarVolumeName() != null && !request.jarVolumeName().isBlank()) {
+            envList = new ArrayList<>(envList);
+            envList.add("CAMELEER_APP_JAR=" + request.jarPath());
+        }
+
         var createCmd = dockerClient.createContainerCmd(request.baseImage())
                 .withName(request.containerName())
                 .withEnv(envList)
@@ -90,6 +103,22 @@ public class DockerRuntimeOrchestrator implements RuntimeOrchestrator {
                         .withRetries(3)
                         .withStartPeriod(30_000_000_000L));
 
+        // Override entrypoint to use the volume-mounted JAR path
+        if (request.jarVolumeName() != null && !request.jarVolumeName().isBlank()) {
+            createCmd.withEntrypoint("sh", "-c",
+                    "exec java -javaagent:/app/agent.jar " +
+                    "-Dcameleer.export.type=${CAMELEER_EXPORT_TYPE:-HTTP} " +
+                    "-Dcameleer.export.endpoint=${CAMELEER_EXPORT_ENDPOINT} " +
+                    "-Dcameleer.agent.name=${HOSTNAME} " +
+                    "-Dcameleer.agent.application=${CAMELEER_APPLICATION_ID:-default} " +
+                    "-Dcameleer.agent.environment=${CAMELEER_ENVIRONMENT_ID:-default} " +
+                    "-Dcameleer.routeControl.enabled=${CAMELEER_ROUTE_CONTROL_ENABLED:-false} " +
+                    "-Dcameleer.replay.enabled=${CAMELEER_REPLAY_ENABLED:-false} " +
+                    "-Dcameleer.health.enabled=true " +
+                    "-Dcameleer.health.port=9464 " +
+                    "-jar ${CAMELEER_APP_JAR}");
+        }
+
         if (request.exposedPorts() != null && !request.exposedPorts().isEmpty()) {
             var ports = request.exposedPorts().stream()
                     .map(p -> com.github.dockerjava.api.model.ExposedPort.tcp(p))

cameleer3-server-app/src/main/resources/application.yml

@@ -52,6 +52,7 @@ cameleer:
     routing-mode: ${CAMELEER_ROUTING_MODE:path}
     routing-domain: ${CAMELEER_ROUTING_DOMAIN:localhost}
     server-url: ${CAMELEER_SERVER_URL:}
+    jar-docker-volume: ${CAMELEER_JAR_DOCKER_VOLUME:}
   body-size-limit: ${CAMELEER_BODY_SIZE_LIMIT:16384}
   indexer:
     debounce-ms: ${CAMELEER_INDEXER_DEBOUNCE_MS:2000}

cameleer3-server-core/src/main/java/com/cameleer3/server/core/runtime/ContainerRequest.java

@@ -7,6 +7,8 @@ public record ContainerRequest(
         String containerName,
         String baseImage,
         String jarPath,
+        String jarVolumeName,
+        String jarVolumeMountPath,
         String network,
         List<String> additionalNetworks,
         Map<String, String> envVars,