Implemented Bionic/libc compatibility.

.github/workflows/release.yml

@@ -34,7 +34,8 @@ env:
   DEFAULT_NGINX_VERSIONS: "1.22.1 1.24.0 1.26.3 1.28.0 1.30.0"
   DEFAULT_TARGET_ARCHES: "linux-x86_64 linux-arm64 linux-armv7"
   MODULE_NAME: ngx_http_monitoring_module
-  RELEASE_BUILD_IMAGE: ubuntu:22.04
+  RELEASE_BUILD_IMAGE: ubuntu:18.04
+  RELEASE_LIBC_BASELINE: ubuntu-bionic-glibc-2.27
   NGINX_CONFIGURE_ARGS: >-
     --with-compat
     --with-http_ssl_module
@@ -226,6 +227,7 @@ jobs:
               -e NEXT_VERSION \
               -e NGINX_CONFIGURE_ARGS \
               -e RELEASE_BUILD_IMAGE \
+              -e RELEASE_LIBC_BASELINE \
               -e TARGET_ARCH="$target_arch" \
               -v "$GITHUB_WORKSPACE:/work" \
               -w /work \
@@ -306,6 +308,7 @@ jobs:
               printf 'target=%s\n' "$TARGET_ARCH"
               printf 'docker_platform=%s\n' "$DOCKER_PLATFORM"
               printf 'build_image=%s\n' "$RELEASE_BUILD_IMAGE"
+              printf 'libc_baseline=%s\n' "$RELEASE_LIBC_BASELINE"
               printf 'build_machine=%s\n' "$(uname -m)"
               printf 'runner=ubuntu-22.04\n'
               printf 'git_ref=%s\n' "$GITHUB_REF"
@@ -318,6 +321,7 @@ jobs:
               printf '# %s for Nginx %s\n\n' "$MODULE_NAME" "$nginx_version"
               printf 'Release: `%s`\n\n' "$NEXT_TAG"
               printf 'Target: `%s` (`%s`)\n\n' "$TARGET_ARCH" "$DOCKER_PLATFORM"
+              printf 'Libc baseline: `%s`\n\n' "$RELEASE_LIBC_BASELINE"
               printf 'This package contains a prebuilt Linux dynamic module:\n\n'
               printf '```text\n'
               printf 'modules/%s.so\n' "$MODULE_NAME"
@@ -326,8 +330,8 @@ jobs:
               printf '```nginx\n'
               printf 'load_module modules/%s.so;\n' "$MODULE_NAME"
               printf '```\n\n'
-              printf 'This binary is built with `--with-compat` against Nginx %s on Ubuntu 22.04 for %s. ' "$nginx_version" "$TARGET_ARCH"
+              printf 'This binary is built with `--with-compat` against Nginx %s on Ubuntu Bionic 18.04 for %s. ' "$nginx_version" "$TARGET_ARCH"
-              printf 'For safest production use, run the same Nginx version, CPU architecture, and a compatible Linux/glibc environment. '
+              printf 'For safest production use, run the same Nginx version, CPU architecture, and a Linux/glibc environment compatible with `%s`. ' "$RELEASE_LIBC_BASELINE"
               printf 'If your Nginx package has a materially different module ABI, rebuild from source with this repository.\n'
             } > "$package_dir/INSTALL.md"
 
@@ -354,6 +358,7 @@ jobs:
           {
             printf '# ngx_http_monitoring_module %s\n\n' "$NEXT_TAG"
             printf 'Previous tag: `%s`\n\n' "$LATEST_TAG"
+            printf 'Libc baseline: `%s`\n\n' "$RELEASE_LIBC_BASELINE"
             printf 'Prebuilt Linux dynamic module packages are attached for targets: `%s`.\n\n' "$NORMALIZED_TARGET_ARCHES"
             printf 'Each tarball is built against the Nginx version and target architecture in its filename and includes:\n\n'
             printf -- '- `modules/%s.so`\n' "$MODULE_NAME"
@@ -417,6 +422,9 @@ jobs:
           file: dockerized/Dockerfile
           platforms: ${{ steps.targets.outputs.docker_platforms }}
           push: true
+          build-args: |
+            BASE_IMAGE=ubuntu:18.04
+            OPENSSL_RUNTIME_PACKAGE=libssl1.1
           tags: |
             ${{ steps.image.outputs.repo }}:${{ steps.version.outputs.next_tag }}
             ${{ steps.image.outputs.repo }}:latest

.github/workflows/test.yml

@@ -13,7 +13,7 @@ permissions:
   contents: read
 
 env:
-  TEST_BUILD_IMAGE: ubuntu:22.04
+  TEST_BUILD_IMAGE: ubuntu:18.04
   NGINX_CONFIGURE_ARGS: >-
     --with-compat
     --with-http_ssl_module

README.md

@@ -36,6 +36,8 @@ The compiled module is written to:
 build/ngx_http_monitoring_module.so
 ```
 
+The source avoids glibc-only mount parsing APIs such as `getmntent()` and parses `/proc/mounts` directly, which keeps the collectors portable across Linux libc implementations that expose the required `/proc`, `statvfs()`, and `getifaddrs()` interfaces.
+
 ## Docker Image
 
 A Dockerized Nginx image is available in [dockerized](</dockerized>):

dockerized/Dockerfile

@@ -1,7 +1,7 @@
-ARG DEBIAN_VERSION=bookworm
+ARG BASE_IMAGE=debian:bookworm-slim
 ARG NGINX_VERSION=1.28.0
 
-FROM debian:${DEBIAN_VERSION}-slim AS builder
+FROM ${BASE_IMAGE} AS builder
 
 ARG NGINX_VERSION
 ARG NGINX_CONFIGURE_ARGS="--with-compat --with-http_ssl_module --with-http_stub_status_module --with-http_realip_module --with-http_v2_module --with-http_gzip_static_module"
@@ -48,9 +48,10 @@ RUN ./configure \
     && cp objs/ngx_http_monitoring_module.so /usr/local/nginx/modules/
 
 
-FROM debian:${DEBIAN_VERSION}-slim AS runtime
+FROM ${BASE_IMAGE} AS runtime
 
 ARG NGINX_VERSION
+ARG OPENSSL_RUNTIME_PACKAGE=libssl3
 
 LABEL org.opencontainers.image.title="ngx_http_monitoring_module nginx image" \
       org.opencontainers.image.description="Nginx built with ngx_http_monitoring_module and embedded monitoring dashboard" \
@@ -60,7 +61,7 @@ RUN apt-get update \
     && apt-get install -y --no-install-recommends \
         ca-certificates \
         libpcre2-8-0 \
-        libssl3 \
+        ${OPENSSL_RUNTIME_PACKAGE} \
         zlib1g \
     && rm -rf /var/lib/apt/lists/* \
     && groupadd --system --gid 101 nginx \

dockerized/README.md

@@ -22,6 +22,12 @@ To choose a different Nginx version:
 NGINX_VERSION=1.28.0 sh dockerized/build.sh
 ```
 
+To build the image on an Ubuntu Bionic 18.04 libc baseline:
+
+```sh
+BASE_IMAGE=ubuntu:18.04 OPENSSL_RUNTIME_PACKAGE=libssl1.1 sh dockerized/build.sh
+```
+
 ## Run
 
 ```sh

dockerized/build.sh

@@ -3,11 +3,15 @@ set -eu
 
 IMAGE="${IMAGE:-ngx-http-monitoring-module:local}"
 NGINX_VERSION="${NGINX_VERSION:-1.28.0}"
+BASE_IMAGE="${BASE_IMAGE:-debian:bookworm-slim}"
+OPENSSL_RUNTIME_PACKAGE="${OPENSSL_RUNTIME_PACKAGE:-libssl3}"
 
 cd "$(dirname "$0")/.."
 
 docker build \
     --build-arg "NGINX_VERSION=$NGINX_VERSION" \
+    --build-arg "BASE_IMAGE=$BASE_IMAGE" \
+    --build-arg "OPENSSL_RUNTIME_PACKAGE=$OPENSSL_RUNTIME_PACKAGE" \
     -f dockerized/Dockerfile \
     -t "$IMAGE" \
     .

dockerized/docker-compose.yml

@@ -4,7 +4,9 @@ services:
       context: ..
       dockerfile: dockerized/Dockerfile
       args:
+        BASE_IMAGE: "debian:bookworm-slim"
         NGINX_VERSION: "1.28.0"
+        OPENSSL_RUNTIME_PACKAGE: "libssl3"
     image: ngx-http-monitoring-module:local
     container_name: ngx-http-monitoring-module
     ports:

docs/ARCHITECTURE.md

@@ -58,3 +58,5 @@ Upstream metrics are passively observed from Nginx upstream state recorded on pr
 ## Compatibility
 
 The module is designed as an Nginx dynamic HTTP module and should be built with `--with-compat` against the target Nginx source tree. Stub-status counters are compiled in when the target Nginx build includes `--with-http_stub_status_module`; otherwise request counters still work but low-level active/reading/writing/waiting counters remain zero.
+
+Collectors avoid glibc-only helpers such as `getmntent()` and parse `/proc/mounts` directly. This keeps filesystem collection compatible with libc implementations that do not ship `<mntent.h>`, while still requiring Linux `/proc`, `statvfs()`, and `getifaddrs()`.

docs/RELEASES.md

@@ -1,6 +1,6 @@
 # Release Builds
 
-The GitHub Actions workflow in `.github/workflows/release.yml` builds ready-to-use Linux dynamic module packages for x86_64 and ARM targets.
+The GitHub Actions workflow in `.github/workflows/release.yml` builds ready-to-use Linux dynamic module packages for x86_64 and ARM targets. Release binaries are built in Ubuntu Bionic 18.04 containers, giving the module artifacts a `ubuntu-bionic-glibc-2.27` libc baseline.
 
 ## Manual Release Only
 
@@ -71,6 +71,13 @@ ghcr.io/<owner>/<repo>:latest
 
 The image is built with Docker Buildx for the same normalized target platforms requested by `target_arches`.
 
+The release image build passes:
+
+```text
+BASE_IMAGE=ubuntu:18.04
+OPENSSL_RUNTIME_PACKAGE=libssl1.1
+```
+
 ## Compatibility Warning
 
-Nginx dynamic modules are ABI-sensitive. The release packages are built with `--with-compat` on Ubuntu 22.04 against the Nginx version and CPU architecture in the filename. Use the matching Nginx version, CPU architecture, and a compatible Linux/glibc runtime. Rebuild locally when using a vendor Nginx package with materially different module ABI or hardening options.
+Nginx dynamic modules are ABI-sensitive. The release packages are built with `--with-compat` on Ubuntu Bionic 18.04 against the Nginx version and CPU architecture in the filename. Use the matching Nginx version, CPU architecture, and a Linux/glibc runtime compatible with `ubuntu-bionic-glibc-2.27`. Rebuild locally when using a vendor Nginx package with materially different module ABI or hardening options.

src/ngx_http_monitoring_collectors.c

@@ -5,7 +5,6 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <ifaddrs.h>
-#include <mntent.h>
 #include <net/if.h>
 #include <stdio.h>
 #include <string.h>
@@ -41,6 +40,9 @@ static ngx_atomic_uint_t ngx_http_monitoring_sum_disk(
 static ngx_atomic_uint_t ngx_http_monitoring_delta(ngx_atomic_uint_t now,
     ngx_atomic_uint_t prev);
 static ngx_uint_t ngx_http_monitoring_skip_fs(const char *type);
+static char *ngx_http_monitoring_next_mount_field(char **cursor);
+static void ngx_http_monitoring_copy_mount_field(u_char *dst, size_t size,
+    char *src);
 
 
 ngx_int_t
@@ -599,25 +601,45 @@ static void
 ngx_http_monitoring_collect_filesystems(ngx_http_monitoring_shctx_t *sh)
 {
     FILE             *fp;
-    struct mntent    *mnt;
+    char              line[4096], *cursor, *source, *mount, *type;
+    u_char            mount_path[4096], fs_type[NGX_HTTP_MONITORING_NAME_LEN];
     struct statvfs    st;
     ngx_uint_t        count;
     uint64_t          total, free_bytes, avail, used;
 
-    fp = setmntent("/proc/mounts", "r");
+    fp = fopen("/proc/mounts", "r");
     if (fp == NULL) {
         return;
     }
 
     count = 0;
-    while ((mnt = getmntent(fp)) != NULL
+    while (count < NGX_HTTP_MONITORING_FILESYSTEMS_MAX
-           && count < NGX_HTTP_MONITORING_FILESYSTEMS_MAX)
+           && fgets(line, sizeof(line), fp) != NULL)
     {
-        if (ngx_http_monitoring_skip_fs(mnt->mnt_type)) {
+        cursor = line;
+        source = ngx_http_monitoring_next_mount_field(&cursor);
+        mount = ngx_http_monitoring_next_mount_field(&cursor);
+        type = ngx_http_monitoring_next_mount_field(&cursor);
+
+        if (source == NULL || mount == NULL || type == NULL) {
             continue;
         }
 
-        if (statvfs(mnt->mnt_dir, &st) != 0 || st.f_blocks == 0) {
+        (void) source;
+
+        ngx_http_monitoring_copy_mount_field(mount_path, sizeof(mount_path),
+                                             mount);
+        ngx_http_monitoring_copy_mount_field(fs_type, sizeof(fs_type), type);
+
+        if (mount_path[0] == '\0' || fs_type[0] == '\0') {
+            continue;
+        }
+
+        if (ngx_http_monitoring_skip_fs((char *) fs_type)) {
+            continue;
+        }
+
+        if (statvfs((char *) mount_path, &st) != 0 || st.f_blocks == 0) {
             continue;
         }
 
@@ -626,9 +648,9 @@ ngx_http_monitoring_collect_filesystems(ngx_http_monitoring_shctx_t *sh)
         avail = (uint64_t) st.f_bavail * st.f_frsize;
         used = total - free_bytes;
 
-        ngx_cpystrn(sh->filesystems[count].path, (u_char *) mnt->mnt_dir,
+        ngx_cpystrn(sh->filesystems[count].path, mount_path,
                     NGX_HTTP_MONITORING_KEY_LEN);
-        ngx_cpystrn(sh->filesystems[count].type, (u_char *) mnt->mnt_type,
+        ngx_cpystrn(sh->filesystems[count].type, fs_type,
                     NGX_HTTP_MONITORING_NAME_LEN);
         sh->filesystems[count].total = (ngx_atomic_uint_t) total;
         sh->filesystems[count].used = (ngx_atomic_uint_t) used;
@@ -640,7 +662,7 @@ ngx_http_monitoring_collect_filesystems(ngx_http_monitoring_shctx_t *sh)
         count++;
     }
 
-    endmntent(fp);
+    fclose(fp);
     sh->fs_count = count;
 }
 
@@ -822,6 +844,72 @@ ngx_http_monitoring_delta(ngx_atomic_uint_t now, ngx_atomic_uint_t prev)
 }
 
 
+static char *
+ngx_http_monitoring_next_mount_field(char **cursor)
+{
+    char *p, *start;
+
+    p = *cursor;
+
+    while (*p == ' ' || *p == '\t') {
+        p++;
+    }
+
+    if (*p == '\0' || *p == '\n') {
+        *cursor = p;
+        return NULL;
+    }
+
+    start = p;
+
+    while (*p != '\0' && *p != '\n' && *p != ' ' && *p != '\t') {
+        p++;
+    }
+
+    if (*p != '\0') {
+        *p++ = '\0';
+    }
+
+    *cursor = p;
+
+    return start;
+}
+
+
+static void
+ngx_http_monitoring_copy_mount_field(u_char *dst, size_t size, char *src)
+{
+    u_char      *p, *last;
+    ngx_uint_t   value;
+
+    if (size == 0) {
+        return;
+    }
+
+    p = dst;
+    last = dst + size - 1;
+
+    while (*src != '\0' && p < last) {
+        if (src[0] == '\\'
+            && src[1] >= '0' && src[1] <= '7'
+            && src[2] >= '0' && src[2] <= '7'
+            && src[3] >= '0' && src[3] <= '7')
+        {
+            value = (ngx_uint_t) ((src[1] - '0') * 64
+                                  + (src[2] - '0') * 8
+                                  + (src[3] - '0'));
+            *p++ = (u_char) value;
+            src += 4;
+            continue;
+        }
+
+        *p++ = (u_char) *src++;
+    }
+
+    *p = '\0';
+}
+
+
 static ngx_uint_t
 ngx_http_monitoring_skip_fs(const char *type)
 {