test(preload): build once, then test against both libc flavors

The previous build & test setup was invalid: So far we have built
_different_ libdash0envhook.so binaries for the LD_PRELOAD hook per
libc flavor. With this, the binary works in the target system.

But actually this approach is not not possible in the real world. We
can set one binary as LD_PRELOAD when instrumenting a container and we
do not know which libc flavor it is ahead of time. Thus we ultimately
need to build a libdash0envhook.so binary that works independently of
which libc flavor the target system uses.

This commit only fixes the test setup. The binary does not yet support
both libc flavors. This will be handled in a follow up commit.

[skip ci]

images/dash0-instrumentation/preload/Makefile

@@ -1,13 +1,15 @@
 # SPDX-FileCopyrightText: Copyright 2024 Dash0 Inc.
 # SPDX-License-Identifier: Apache-2.0
 
+ARCH := $(shell uname -m)
 CFLAGS ?= -Wall -Werror -Wextra -O2
+LIB_LINKER_FLAGS ?= -nostdlib -rdynamic -shared -ldl
 
 SRC_DIR := src
-BIN_DIR := bin
 OBJ_DIR := obj
 LIB_DIR := lib
 TEST_DIR := test
+TESTBIN_DIR := testbin/$(ARCH)
 SRC_EXT := c
 
 OS := $(shell uname -s)
@@ -17,21 +19,25 @@ NAMES := $(notdir $(basename $(wildcard $(SRC_DIR)/*.$(SRC_EXT))))
 OBJECTS :=$(patsubst %,$(OBJ_DIR)/%.o,$(NAMES))
 
 TEST_NAMES := $(notdir $(basename $(wildcard $(TEST_DIR)/*.$(SRC_EXT))))
-TEST_OBJECTS :=$(patsubst %,$(OBJ_DIR)/%.o,$(TEST_NAMES))
+TEST_OBJECTS :=$(patsubst %,$(TESTBIN_DIR)/%.o,$(TEST_NAMES))
 
-all: $(OBJECTS) $(TEST_OBJECTS) testbin/appundertest.so
-	$(CC) $(CFLAGS) -rdynamic -shared -ldl $(OBJECTS) -o $(LIB_DIR)/libdash0envhook.so
+all: $(LIB_DIR)/libdash0envhook.so
+
+$(LIB_DIR)/libdash0envhook.so: $(OBJECTS)
+	$(CC) $(CFLAGS) $(LIB_LINKER_FLAGS) $(OBJECTS) -o $(LIB_DIR)/libdash0envhook.so
 
 $(OBJ_DIR)/%.o: $(SRC_DIR)/%.$(SRC_EXT)
 	$(CC) -c -fPIC $^ -o $@ $(DEBUG) $(CFLAGS) $(LIBS)
 
-$(OBJ_DIR)/%.o: $(TEST_DIR)/%.$(SRC_EXT)
-	$(CC) -c $^ -o $@ $(DEBUG) $(CFLAGS) $(LIBS)
+clean: clean-test
+	@rm -f $(OBJECTS) $(LIB_DIR)/libdash0envhook.so
+
+clean-test:
+	@rm -f $(TEST_OBJECTS)
 
-testbin/appundertest.so: test/appundertest.c
-	$(CC) $(CFLAGS) -o $@ test/appundertest.c
+build-test: $(TEST_OBJECTS)
 
-clean:
-	@rm -f $(OBJECTS) $(OBJ_DIR)/*.o $(TEST_OBJECTS) $(LIB_DIR)/*.so testbin/appundertest.so
+$(TESTBIN_DIR)/%.o: $(TEST_DIR)/%.$(SRC_EXT)
+	$(CC) $(CFLAGS) -o $@ $(DEBUG) $^
 
-.PHONY: all clean install
+.PHONY: all clean install clean-test build-test

images/dash0-instrumentation/preload/docker/Dockerfile-build

@@ -0,0 +1,12 @@
+# SPDX-FileCopyrightText: Copyright 2024 Dash0 Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+FROM ubuntu:24.10
+
+RUN apt update && \
+  apt-get install -y \
+    build-essential
+
+WORKDIR /usr/src/dash0/preload/
+
+CMD ["scripts/make-clean.sh"]

images/dash0-instrumentation/preload/Dockerfile-glibc → images/dash0-instrumentation/preload/docker/Dockerfile-test-glibc

@@ -9,4 +9,4 @@ RUN apt update && \
 
 WORKDIR /usr/src/dash0/preload/
 
-CMD ["test/smoke-test.sh"]
+CMD ["test/run-tests.sh"]

images/dash0-instrumentation/preload/Dockerfile-musl → images/dash0-instrumentation/preload/docker/Dockerfile-test-musl

@@ -7,4 +7,4 @@ RUN apk add --no-cache build-base
 
 WORKDIR /usr/src/dash0/preload/
 
-CMD ["test/smoke-test.sh"]
+CMD ["test/run-tests.sh"]

images/dash0-instrumentation/preload/scripts/build-in-container.sh

@@ -0,0 +1,54 @@
+#!/usr/bin/env sh
+
+# SPDX-FileCopyrightText: Copyright 2024 Dash0 Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+set -eu
+
+cd "$(dirname "$0")"/..
+
+# TODO build multi platform image
+
+if [ -z "${ARCH:-}" ]; then
+  ARCH=arm64
+fi
+if [ "$ARCH" = arm64 ]; then
+  docker_platform=linux/arm64
+elif [ "$ARCH" = x86_64 ]; then
+  docker_platform=linux/amd64
+else
+  echo "The architecture $ARCH is not supported."
+  exit 1
+fi
+
+dockerfile_name=docker/Dockerfile-build
+image_name=dash0-env-hook-builder
+container_name=$image_name
+
+docker_run_extra_arguments=""
+if [ "${INTERACTIVE:-}" = "true" ]; then
+  docker_run_extra_arguments=/bin/bash
+fi
+
+echo
+echo
+echo ">>> Building the library on $ARCH <<<"
+
+docker rm -f "$container_name"
+docker build \
+  --platform "$docker_platform" \
+  . \
+  -f "$dockerfile_name" \
+  -t "$image_name"
+
+# note: building one image for both platforms is not supported by Docker desktop's standard "docker build" command.
+# docker build --platform linux/amd64,linux/arm64 . -f $dockerfile_name -t dash0-env-hook-builder-all-$LIBC
+
+docker run \
+  --platform "$docker_platform" \
+  --name "$container_name" \
+  -it \
+  --volume "$(pwd):/usr/src/dash0/preload/" \
+  "$image_name" \
+  $docker_run_extra_arguments
+

images/dash0-instrumentation/preload/scripts/make-clean.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env sh
+
+# SPDX-FileCopyrightText: Copyright 2024 Dash0 Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+set -eu
+
+cd "$(dirname "$0")"/..
+
+make clean
+make
+

images/dash0-instrumentation/preload/build-and-test.sh → images/dash0-instrumentation/preload/scripts/run-tests-in-container.sh

@@ -5,7 +5,7 @@
 
 set -eu
 
-cd "$(dirname "$0")"
+cd "$(dirname "$0")"/..
 
 if [ -z "${ARCH:-}" ]; then
   ARCH=arm64
@@ -25,17 +25,13 @@ if [ -z "${LIBC:-}" ]; then
   LIBC=glibc
 fi
 
-echo
-echo
-echo ">>> Building and testing for $ARCH and $LIBC <<<"
-
-dockerfile_name="Dockerfile-$LIBC"
+dockerfile_name="docker/Dockerfile-test-$LIBC"
 if [ ! -f "$dockerfile_name" ]; then
   echo "The file \"$dockerfile_name\" does not exist, the libc flavor $LIBC is not supported."
   exit 1
 fi
 
-image_name=dash0-env-hook-builder-$ARCH-$LIBC
+image_name=dash0-env-hook-test-$ARCH-$LIBC
 container_name=$image_name
 
 docker_run_extra_arguments=""
@@ -50,11 +46,16 @@ if [ "${INTERACTIVE:-}" = "true" ]; then
   fi
 fi
 
-docker rm -f "$container_name"
-docker build --platform "$docker_platform" . -f "$dockerfile_name" -t "$image_name"
+echo
+echo
+echo ">>> Testing the library on $ARCH and $LIBC <<<"
 
-# note: building one image for both platforms is not suppored on Docker desktop
-# docker build --platform linux/amd64,linux/arm64 . -f $dockerfile_name -t dash0-env-hook-builder-all-$LIBC
+docker rm -f "$container_name"
+docker build \
+  --platform "$docker_platform" \
+  . \
+  -f "$dockerfile_name" \
+  -t "$image_name"
 
 docker run \
   --platform "$docker_platform" \

images/dash0-instrumentation/preload/scripts/test-all.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env sh
+
+# SPDX-FileCopyrightText: Copyright 2024 Dash0 Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+set -eu
+
+cd "$(dirname "$0")"/..
+
+scripts/build-in-container.sh
+
+ARCH=arm64 LIBC=glibc scripts/run-tests-in-container.sh
+ARCH=x86_64 LIBC=glibc scripts/run-tests-in-container.sh
+ARCH=arm64 LIBC=musl scripts/run-tests-in-container.sh
+ARCH=x86_64 LIBC=musl scripts/run-tests-in-container.sh
+

images/dash0-instrumentation/preload/src/libdash0envhook.c

@@ -22,7 +22,6 @@ Entry map[1];
 
 char* default_node_options_value = "--require /opt/dash0/instrumentation/node.js/node_modules/@dash0/opentelemetry/src/index.js";
 
-
 __attribute__((constructor)) static void setup(void) {
   Entry node_options_entry = { .key = "NODE_OPTIONS", .value = NULL };
   map[0] = node_options_entry;

images/dash0-instrumentation/preload/src/map.c

@@ -1,13 +1,12 @@
 // SPDX-FileCopyrightText: Copyright 2024 Dash0 Inc.
 // SPDX-License-Identifier: Apache-2.0
 
-#include <stdlib.h>
 #include <string.h>
 
 #include "map.h"
 
 Entry* find(Entry map[], int len, const char* key) {
- for (int i = 0; i < len; i++) {
+  for (int i = 0; i < len; i++) {
     Entry* e = &map[i];
     if (strcmp(e->key, key) == 0) {
       return e;

images/dash0-instrumentation/preload/src/map.h

@@ -9,3 +9,4 @@ typedef struct Entry {
 char* get_map_entry(Entry map[], int len, const char* key);
 
 void put_map_entry(Entry* map, int len, const char* key, char* value);
+

images/dash0-instrumentation/preload/test/appundertest.c

@@ -33,8 +33,7 @@ void echo_env_var_secure(const char* name) {
 
 int main(int argc, char* argv[]) {
   if (argc < 2) {
-    fputs("not enough arguments, the name of the test case needs to be specifed", stdout);
-    fputs("\n", stdout);
+    fputs("error: not enough arguments, the name of the test case needs to be specifed\n", stdout);
     exit(1);
   }
   char* test_case = argv[1];

images/dash0-instrumentation/preload/test/smoke-test.sh → images/dash0-instrumentation/preload/test/run-tests.sh

@@ -34,16 +34,25 @@ else
   printf "${GREEN}verifying CPU architecture %s successful${NC}\n" "$EXPECTED_CPU_ARCHITECTURE"
 fi
 
+preload_lib=$directory/lib/libdash0envhook.so
+if [ ! -f $preload_lib ]; then
+  printf "${RED}error: $preload_lib does not exist, not running any tests.${NC}\n"
+  exit 1
+fi
+
+appundertest=testbin/"${arch_output}"/appundertest.o
+echo appundertest: $appundertest
+
 run_test_case() {
   test_case=$1
   command=$2
   expected=$3
   existing_node_options_value=${4:-}
   set +e
   if [ "$existing_node_options_value" != "" ]; then
-    test_output=$(LD_PRELOAD="$directory/lib/libdash0envhook.so" NODE_OPTIONS="$existing_node_options_value" ./testbin/appundertest.so "$command")
+    test_output=$(LD_PRELOAD="$preload_lib" NODE_OPTIONS="$existing_node_options_value" "$appundertest" "$command")
   else
-    test_output=$(LD_PRELOAD="$directory/lib/libdash0envhook.so" ./testbin/appundertest.so "$command")
+    test_output=$(LD_PRELOAD="$preload_lib" "$appundertest" "$command")
   fi
   test_exit_code=$?
   set -e
@@ -62,8 +71,9 @@ run_test_case() {
   fi
 }
 
-make clean
-make
+# We always need to clean out the old appundertest.o, it might have been built for a different libc flavor.
+make clean-test
+make build-test
 
 exit_code=0
 

images/dash0-instrumentation/preload/testbin/aarch64/.gitignore

@@ -0,0 +1 @@
+*.o

images/dash0-instrumentation/preload/testbin/x86_64/.gitignore

@@ -0,0 +1 @@
+*.o