modularized all source code (#4391)

* modularized all external plugins

* added README.md in plugins

* fixed title

* fixed typo

* relative link to external plugins

* external plugins configuration README

* added plugins link

* remove plugins link

* plugin names are links

* added links to external plugins

* removed unecessary spacing

* list to table

* added language

* fixed typo

* list to table on internal plugins

* added more documentation to internal plugins

* moved python, node, and bash code and configs into the external plugins

* added statsd README

* fix bug with corrupting config.h every 2nd compilation

* moved all config files together with their code

* more documentation

* diskspace info

* fixed broken links in apps.plugin

* added backends docs

* updated plugins readme

* move nc-backend.sh to backends

* created daemon directory

* moved all code outside src/

* fixed readme identation

* renamed plugins.d.plugin to plugins.d

* updated readme

* removed linux- from linux plugins

* updated readme

* updated readme

* updated readme

* updated readme

* updated readme

* updated readme

* fixed README.md links

* fixed netdata tree links

* updated codacy, codeclimate and lgtm excluded paths

* update CMakeLists.txt

* updated automake options at top directory

* libnetdata slit into directories

* updated READMEs

* updated READMEs

* updated ARL docs

* updated ARL docs

* moved /plugins to /collectors

* moved all external plugins outside plugins.d

* updated codacy, codeclimate, lgtm

* updated README

* updated url

* updated readme

* updated readme

* updated readme

* updated readme

* moved api and web into webserver

* web/api web/gui web/server

* modularized webserver

* removed web/gui/version.txt

6 files changed, 3958 insertions, 0 deletions

diff --git a/collectors/cgroups.plugin/Makefile.am b/collectors/cgroups.plugin/Makefile.am
new file mode 100644
index 0000000000..fd878049d0
--- /dev/null
+++ b/collectors/cgroups.plugin/Makefile.am
@@ -0,0 +1,20 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+CLEANFILES = \
+	cgroup-name.sh \
+	$(NULL)
+
+include $(top_srcdir)/build/subst.inc
+SUFFIXES = .in
+
+dist_plugins_SCRIPTS = \
+	cgroup-name.sh \
+	cgroup-network-helper.sh \
+	$(NULL)
+
+dist_noinst_DATA = \
+	cgroup-name.sh.in \
+	$(NULL)
diff --git a/collectors/cgroups.plugin/cgroup-name.sh.in b/collectors/cgroups.plugin/cgroup-name.sh.in
new file mode 100755
index 0000000000..53696a4bf9
--- /dev/null
+++ b/collectors/cgroups.plugin/cgroup-name.sh.in
@@ -0,0 +1,196 @@
+#!/usr/bin/env bash
+
+# netdata
+# real-time performance and health monitoring, done right!
+# (C) 2016 Costa Tsaousis <costa@tsaousis.gr>
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# Script to find a better name for cgroups
+#
+
+export PATH="${PATH}:/sbin:/usr/sbin:/usr/local/sbin"
+export LC_ALL=C
+
+# -----------------------------------------------------------------------------
+
+PROGRAM_NAME="$(basename "${0}")"
+
+logdate() {
+    date "+%Y-%m-%d %H:%M:%S"
+}
+
+log() {
+    local status="${1}"
+    shift
+
+    echo >&2 "$(logdate): ${PROGRAM_NAME}: ${status}: ${*}"
+
+}
+
+warning() {
+    log WARNING "${@}"
+}
+
+error() {
+    log ERROR "${@}"
+}
+
+info() {
+    log INFO "${@}"
+}
+
+fatal() {
+    log FATAL "${@}"
+    exit 1
+}
+
+debug=0
+debug() {
+    [ $debug -eq 1 ] && log DEBUG "${@}"
+}
+
+# -----------------------------------------------------------------------------
+
+[ -z "${NETDATA_USER_CONFIG_DIR}"  ] && NETDATA_USER_CONFIG_DIR="@configdir_POST@"
+[ -z "${NETDATA_STOCK_CONFIG_DIR}" ] && NETDATA_STOCK_CONFIG_DIR="@libconfigdir_POST@"
+
+DOCKER_HOST="${DOCKER_HOST:=/var/run/docker.sock}"
+CGROUP="${1}"
+NAME=
+
+# -----------------------------------------------------------------------------
+
+if [ -z "${CGROUP}" ]
+    then
+    fatal "called without a cgroup name. Nothing to do."
+fi
+
+for CONFIG in "${NETDATA_USER_CONFIG_DIR}/cgroups-names.conf" "${NETDATA_STOCK_CONFIG_DIR}/cgroups-names.conf"
+do
+    if [ -f "${CONFIG}" ]
+    then
+        NAME="$(grep "^${CGROUP} " "${CONFIG}" | sed "s/[[:space:]]\+/ /g" | cut -d ' ' -f 2)"
+        if [ -z "${NAME}" ]
+            then
+            info "cannot find cgroup '${CGROUP}' in '${CONFIG}'."
+        else
+            break
+        fi
+    #else
+    #   info "configuration file '${CONFIG}' is not available."
+    fi
+done
+
+function docker_get_name_classic {
+    local id="${1}"
+    info "Running command: docker ps --filter=id=\"${id}\" --format=\"{{.Names}}\""
+    NAME="$( docker ps --filter=id="${id}" --format="{{.Names}}" )"
+    return 0
+}
+
+function docker_get_name_api {
+    local id="${1}"
+    if [ ! -S "${DOCKER_HOST}" ]
+        then
+        warning "Can't find ${DOCKER_HOST}"
+        return 1
+    fi
+    info "Running API command: /containers/${id}/json"
+    JSON=$(echo -e "GET /containers/${id}/json HTTP/1.0\r\n" | nc -U ${DOCKER_HOST} | grep '^{.*')
+    NAME=$(echo $JSON | jq -r .Name,.Config.Hostname | grep -v null | head -n1 | sed 's|^/||')
+    return 0
+}
+
+function docker_get_name {
+    local id="${1}"
+    if hash docker 2>/dev/null
+        then
+        docker_get_name_classic "${id}"
+    else
+        docker_get_name_api "${id}" || docker_get_name_classic "${id}"
+    fi
+    if [ -z "${NAME}" ]
+        then
+        warning "cannot find the name of docker container '${id}'"
+        NAME="${id:0:12}"
+    else
+        info "docker container '${id}' is named '${NAME}'"
+    fi
+}
+
+if [ -z "${NAME}" ]
+    then
+    if [[ "${CGROUP}" =~ ^.*docker[-_/\.][a-fA-F0-9]+[-_\.]?.*$ ]]
+        then
+        # docker containers
+
+        DOCKERID="$( echo "${CGROUP}" | sed "s|^.*docker[-_/]\([a-fA-F0-9]\+\)[-_\.]\?.*$|\1|" )"
+        # echo "DOCKERID=${DOCKERID}"
+
+        if [ ! -z "${DOCKERID}" -a \( ${#DOCKERID} -eq 64 -o ${#DOCKERID} -eq 12 \) ]
+            then
+            docker_get_name "${DOCKERID}"
+        else
+            error "a docker id cannot be extracted from docker cgroup '${CGROUP}'."
+        fi
+    elif [[ "${CGROUP}" =~ ^.*kubepods[_/].*[_/]pod[a-fA-F0-9-]+[_/][a-fA-F0-9]+$ ]]
+        then
+        # kubernetes
+
+        DOCKERID="$( echo "${CGROUP}" | sed "s|^.*kubepods[_/].*[_/]pod[a-fA-F0-9-]\+[_/]\([a-fA-F0-9]\+\)$|\1|" )"
+        # echo "DOCKERID=${DOCKERID}"
+
+        if [ ! -z "${DOCKERID}" -a \( ${#DOCKERID} -eq 64 -o ${#DOCKERID} -eq 12 \) ]
+            then
+            docker_get_name "${DOCKERID}"
+        else
+            error "a docker id cannot be extracted from kubernetes cgroup '${CGROUP}'."
+        fi
+    elif [[ "${CGROUP}" =~ machine.slice[_/].*\.service ]]
+        then
+        # systemd-nspawn
+
+        NAME="$(echo ${CGROUP} | sed 's/.*machine.slice[_\/]\(.*\)\.service/\1/g')"
+
+    elif [[ "${CGROUP}" =~ machine.slice_machine.*-qemu ]]
+        then
+        # libvirtd / qemu virtual machines
+
+        # NAME="$(echo ${CGROUP} | sed 's/machine.slice_machine.*-qemu//; s/\/x2d//; s/\/x2d/\-/g; s/\.scope//g')"
+        NAME="qemu_$(echo ${CGROUP} | sed 's/machine.slice_machine.*-qemu//; s/\/x2d[[:digit:]]*//; s/\/x2d//g; s/\.scope//g')"
+
+    elif [[ "${CGROUP}" =~ machine_.*\.libvirt-qemu ]]
+        then
+        # libvirtd / qemu virtual machines
+        NAME="qemu_$(echo ${CGROUP} | sed 's/^machine_//; s/\.libvirt-qemu$//; s/-/_/;')"
+
+    elif [[ "${CGROUP}" =~ qemu.slice_([0-9]+).scope && -d /etc/pve ]]
+        then
+        # Proxmox VMs
+
+        FILENAME="/etc/pve/qemu-server/${BASH_REMATCH[1]}.conf"
+        if [[ -f $FILENAME && -r $FILENAME ]]
+            then
+            NAME="qemu_$(grep -e '^name: ' "/etc/pve/qemu-server/${BASH_REMATCH[1]}.conf" | head -1 | sed -rn 's|\s*name\s*:\s*(.*)?$|\1|p')"
+        else
+            error "proxmox config file missing ${FILENAME} or netdata does not have read access.  Please ensure netdata is a member of www-data group."
+        fi
+    elif [[ "${CGROUP}" =~ lxc_([0-9]+) && -d /etc/pve ]]
+        then
+        # Proxmox Containers (LXC)
+
+        FILENAME="/etc/pve/lxc/${BASH_REMATCH[1]}.conf"
+        if [[ -f ${FILENAME} && -r ${FILENAME} ]]
+            then
+            NAME=$(grep -e '^hostname: ' /etc/pve/lxc/${BASH_REMATCH[1]}.conf | head -1 | sed -rn 's|\s*hostname\s*:\s*(.*)?$|\1|p')
+        else
+            error "proxmox config file missing ${FILENAME} or netdata does not have read access.  Please ensure netdata is a member of www-data group."
+        fi
+    fi
+
+    [ -z "${NAME}" ] && NAME="${CGROUP}"
+    [ ${#NAME} -gt 100 ] && NAME="${NAME:0:100}"
+fi
+
+info "cgroup '${CGROUP}' is called '${NAME}'"
+echo "${NAME}"
diff --git a/collectors/cgroups.plugin/cgroup-network-helper.sh b/collectors/cgroups.plugin/cgroup-network-helper.sh
new file mode 100755
index 0000000000..666f02fc88
--- /dev/null
+++ b/collectors/cgroups.plugin/cgroup-network-helper.sh
@@ -0,0 +1,258 @@
+#!/usr/bin/env bash
+# shellcheck disable=SC1117
+
+# cgroup-network-helper.sh
+# detect container and virtual machine interfaces
+#
+# (C) 2017 Costa Tsaousis
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This script is called as root (by cgroup-network), with either a pid, or a cgroup path.
+# It tries to find all the network interfaces that belong to the same cgroup.
+#
+# It supports several method for this detection:
+#
+# 1. cgroup-network (the binary father of this script) detects veth network interfaces,
+#    by examining iflink and ifindex IDs and switching namespaces
+#    (it also detects the interface name as it is used by the container).
+#
+# 2. this script, uses /proc/PID/fdinfo to find tun/tap network interfaces.
+#
+# 3. this script, calls virsh to find libvirt network interfaces.
+#
+
+# -----------------------------------------------------------------------------
+
+# the system path is cleared by cgroup-network
+# shellcheck source=/dev/null
+[ -f /etc/profile ] && source /etc/profile
+
+export LC_ALL=C
+
+PROGRAM_NAME="$(basename "${0}")"
+
+logdate() {
+    date "+%Y-%m-%d %H:%M:%S"
+}
+
+log() {
+    local status="${1}"
+    shift
+
+    echo >&2 "$(logdate): ${PROGRAM_NAME}: ${status}: ${*}"
+
+}
+
+warning() {
+    log WARNING "${@}"
+}
+
+error() {
+    log ERROR "${@}"
+}
+
+info() {
+    log INFO "${@}"
+}
+
+fatal() {
+    log FATAL "${@}"
+    exit 1
+}
+
+debug=0
+debug() {
+    [ "${debug}" = "1" ] && log DEBUG "${@}"
+}
+
+# -----------------------------------------------------------------------------
+# check for BASH v4+ (required for associative arrays)
+
+[ $(( BASH_VERSINFO[0] )) -lt 4 ] && \
+    fatal "BASH version 4 or later is required (this is ${BASH_VERSION})."
+
+# -----------------------------------------------------------------------------
+# parse the arguments
+
+pid=
+cgroup=
+while [ ! -z "${1}" ]
+do
+    case "${1}" in
+        --cgroup) cgroup="${2}"; shift 1;;
+        --pid|-p) pid="${2}"; shift 1;;
+        --debug|debug) debug=1;;
+        *) fatal "Cannot understand argument '${1}'";;
+    esac
+
+    shift
+done
+
+if [ -z "${pid}" ] && [ -z "${cgroup}" ]
+then
+    fatal "Either --pid or --cgroup is required"
+fi
+
+# -----------------------------------------------------------------------------
+
+set_source() {
+    [ ${debug} -eq 1 ] && echo "SRC ${*}"
+}
+
+
+# -----------------------------------------------------------------------------
+# veth interfaces via cgroup
+
+# cgroup-network can detect veth interfaces by itself (written in C).
+# If you seek for a shell version of what it does, check this:
+# https://github.com/netdata/netdata/issues/474#issuecomment-317866709
+
+
+# -----------------------------------------------------------------------------
+# tun/tap interfaces via /proc/PID/fdinfo
+
+# find any tun/tap devices linked to a pid
+proc_pid_fdinfo_iff() {
+    local p="${1}" # the pid
+
+    debug "Searching for tun/tap interfaces for pid ${p}..."
+    set_source "fdinfo"
+    grep "^iff:.*" "${NETDATA_HOST_PREFIX}/proc/${p}/fdinfo"/* 2>/dev/null | cut -f 2
+}
+
+find_tun_tap_interfaces_for_cgroup() {
+    local c="${1}" # the cgroup path
+
+    # for each pid of the cgroup
+    # find any tun/tap devices linked to the pid
+    if [ -f "${c}/emulator/cgroup.procs" ]
+    then
+        local p
+        for p in $(< "${c}/emulator/cgroup.procs" )
+        do
+            proc_pid_fdinfo_iff "${p}"
+        done
+    fi
+}
+
+
+# -----------------------------------------------------------------------------
+# virsh domain network interfaces
+
+virsh_cgroup_to_domain_name() {
+    local c="${1}" # the cgroup path
+
+    debug "extracting a possible virsh domain from cgroup ${c}..."
+
+    # extract for the cgroup path
+    sed -n -e "s|.*/machine-qemu\\\\x2d[0-9]\+\\\\x2d\(.*\)\.scope$|\1|p" \
+           -e "s|.*/machine/\(.*\)\.libvirt-qemu$|\1|p" \
+           <<EOF
+${c}
+EOF
+}
+
+virsh_find_all_interfaces_for_cgroup() {
+    local c="${1}" # the cgroup path
+
+    # the virsh command
+    local virsh
+    # shellcheck disable=SC2230
+    virsh="$(which virsh 2>/dev/null || command -v virsh 2>/dev/null)"
+
+    if [ ! -z "${virsh}" ]
+    then
+        local d
+        d="$(virsh_cgroup_to_domain_name "${c}")"
+
+        if [ ! -z "${d}" ]
+        then
+            debug "running: virsh domiflist ${d}; to find the network interfaces"
+
+            # match only 'network' interfaces from virsh output
+
+            set_source "virsh"
+            "${virsh}" -r domiflist "${d}" |\
+                sed -n \
+                    -e "s|^\([^[:space:]]\+\)[[:space:]]\+network[[:space:]]\+\([^[:space:]]\+\)[[:space:]]\+[^[:space:]]\+[[:space:]]\+[^[:space:]]\+$|\1 \1_\2|p" \
+                    -e "s|^\([^[:space:]]\+\)[[:space:]]\+bridge[[:space:]]\+\([^[:space:]]\+\)[[:space:]]\+[^[:space:]]\+[[:space:]]\+[^[:space:]]\+$|\1 \1_\2|p"
+        else
+            debug "no virsh domain extracted from cgroup ${c}"
+        fi
+    else
+        debug "virsh command is not available"
+    fi
+}
+
+# -----------------------------------------------------------------------------
+
+find_all_interfaces_of_pid_or_cgroup() {
+    local p="${1}" c="${2}" # the pid and the cgroup path
+
+    if [ ! -z "${pid}" ]
+    then
+        # we have been called with a pid
+
+        proc_pid_fdinfo_iff "${p}"
+
+    elif [ ! -z "${c}" ]
+    then
+        # we have been called with a cgroup
+
+        info "searching for network interfaces of cgroup '${c}'"
+
+        find_tun_tap_interfaces_for_cgroup "${c}"
+        virsh_find_all_interfaces_for_cgroup "${c}"
+
+    else
+
+        error "Either a pid or a cgroup path is needed"
+        return 1
+
+    fi
+
+    return 0
+}
+
+# -----------------------------------------------------------------------------
+
+# an associative array to store the interfaces
+# the index is the interface name as seen by the host
+# the value is the interface name as seen by the guest / container
+declare -A devs=()
+
+# store all interfaces found in the associative array
+# this will also give the unique devices, as seen by the host
+last_src=
+# shellcheck disable=SC2162
+while read host_device guest_device
+do
+    [ -z "${host_device}" ] && continue
+
+    [ "${host_device}" = "SRC" ] && last_src="${guest_device}" && continue
+
+    # the default guest_device is the host_device
+    [ -z "${guest_device}" ] && guest_device="${host_device}"
+
+    # when we run in debug, show the source
+    debug "Found host device '${host_device}', guest device '${guest_device}', detected via '${last_src}'"
+
+    if [ -z "${devs[${host_device}]}" ] || [ "${devs[${host_device}]}" = "${host_device}" ]; then
+        devs[${host_device}]="${guest_device}"
+    fi
+
+done < <( find_all_interfaces_of_pid_or_cgroup "${pid}" "${cgroup}" )
+
+# print the interfaces found, in the format netdata expects them
+found=0
+for x in "${!devs[@]}"
+do
+    found=$((found + 1))
+    echo "${x} ${devs[${x}]}"
+done
+
+debug "found ${found} network interfaces for pid '${pid}', cgroup '${cgroup}', run as ${USER}, ${UID}"
+
+# let netdata know if we found any
+[ ${found} -eq 0 ] && exit 1
+exit 0
diff --git a/collectors/cgroups.plugin/cgroup-network.c b/collectors/cgroups.plugin/cgroup-network.c
new file mode 100644
index 0000000000..7fa7ee9608
--- /dev/null
+++ b/collectors/cgroups.plugin/cgroup-network.c
@@ -0,0 +1,682 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../../daemon/common.h"
+
+#ifdef HAVE_SETNS
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE             /* See feature_test_macros(7) */
+#endif
+#include <sched.h>
+#endif
+
+char environment_variable2[FILENAME_MAX + 50] = "";
+char *environment[] = {
+        "PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin",
+        environment_variable2,
+        NULL
+};
+
+
+// ----------------------------------------------------------------------------
+
+// callback required by fatal()
+void netdata_cleanup_and_exit(int ret) {
+    exit(ret);
+}
+
+// callbacks required by popen()
+void signals_block(void) {};
+void signals_unblock(void) {};
+void signals_reset(void) {};
+
+// callback required by eval()
+int health_variable_lookup(const char *variable, uint32_t hash, struct rrdcalc *rc, calculated_number *result) {
+    (void)variable;
+    (void)hash;
+    (void)rc;
+    (void)result;
+    return 0;
+};
+
+// required by get_system_cpus()
+char *netdata_configured_host_prefix = "";
+
+// ----------------------------------------------------------------------------
+
+struct iface {
+    const char *device;
+    uint32_t hash;
+
+    unsigned int ifindex;
+    unsigned int iflink;
+
+    struct iface *next;
+};
+
+unsigned int read_iface_iflink(const char *prefix, const char *iface) {
+    if(!prefix) prefix = "";
+
+    char filename[FILENAME_MAX + 1];
+    snprintfz(filename, FILENAME_MAX, "%s/sys/class/net/%s/iflink", prefix, iface);
+
+    unsigned long long iflink = 0;
+    int ret = read_single_number_file(filename, &iflink);
+    if(ret) error("Cannot read '%s'.", filename);
+
+    return (unsigned int)iflink;
+}
+
+unsigned int read_iface_ifindex(const char *prefix, const char *iface) {
+    if(!prefix) prefix = "";
+
+    char filename[FILENAME_MAX + 1];
+    snprintfz(filename, FILENAME_MAX, "%s/sys/class/net/%s/ifindex", prefix, iface);
+
+    unsigned long long ifindex = 0;
+    int ret = read_single_number_file(filename, &ifindex);
+    if(ret) error("Cannot read '%s'.", filename);
+
+    return (unsigned int)ifindex;
+}
+
+struct iface *read_proc_net_dev(const char *prefix) {
+    if(!prefix) prefix = "";
+
+    procfile *ff = NULL;
+    char filename[FILENAME_MAX + 1];
+
+    snprintfz(filename, FILENAME_MAX, "%s%s", prefix, (*prefix)?"/proc/1/net/dev":"/proc/net/dev");
+    ff = procfile_open(filename, " \t,:|", PROCFILE_FLAG_DEFAULT);
+    if(unlikely(!ff)) {
+        error("Cannot open file '%s'", filename);
+        return NULL;
+    }
+
+    ff = procfile_readall(ff);
+    if(unlikely(!ff)) {
+        error("Cannot read file '%s'", filename);
+        return NULL;
+    }
+
+    size_t lines = procfile_lines(ff), l;
+    struct iface *root = NULL;
+    for(l = 2; l < lines ;l++) {
+        if (unlikely(procfile_linewords(ff, l) < 1)) continue;
+
+        struct iface *t = callocz(1, sizeof(struct iface));
+        t->device = strdupz(procfile_lineword(ff, l, 0));
+        t->hash = simple_hash(t->device);
+        t->ifindex = read_iface_ifindex(prefix, t->device);
+        t->iflink  = read_iface_iflink(prefix, t->device);
+        t->next = root;
+        root = t;
+    }
+
+    procfile_close(ff);
+
+    return root;
+}
+
+void free_iface(struct iface *iface) {
+    freez((void *)iface->device);
+    freez(iface);
+}
+
+void free_host_ifaces(struct iface *iface) {
+    while(iface) {
+        struct iface *t = iface->next;
+        free_iface(iface);
+        iface = t;
+    }
+}
+
+int iface_is_eligible(struct iface *iface) {
+    if(iface->iflink != iface->ifindex)
+        return 1;
+
+    return 0;
+}
+
+int eligible_ifaces(struct iface *root) {
+    int eligible = 0;
+
+    struct iface *t;
+    for(t = root; t ; t = t->next)
+        if(iface_is_eligible(t))
+            eligible++;
+
+    return eligible;
+}
+
+static void continue_as_child(void) {
+    pid_t child = fork();
+    int status;
+    pid_t ret;
+
+    if (child < 0)
+        error("fork() failed");
+
+    /* Only the child returns */
+    if (child == 0)
+        return;
+
+    for (;;) {
+        ret = waitpid(child, &status, WUNTRACED);
+        if ((ret == child) && (WIFSTOPPED(status))) {
+            /* The child suspended so suspend us as well */
+            kill(getpid(), SIGSTOP);
+            kill(child, SIGCONT);
+        } else {
+            break;
+        }
+    }
+
+    /* Return the child's exit code if possible */
+    if (WIFEXITED(status)) {
+        exit(WEXITSTATUS(status));
+    } else if (WIFSIGNALED(status)) {
+        kill(getpid(), WTERMSIG(status));
+    }
+
+    exit(EXIT_FAILURE);
+}
+
+int proc_pid_fd(const char *prefix, const char *ns, pid_t pid) {
+    if(!prefix) prefix = "";
+
+    char filename[FILENAME_MAX + 1];
+    snprintfz(filename, FILENAME_MAX, "%s/proc/%d/%s", prefix, (int)pid, ns);
+    int fd = open(filename, O_RDONLY);
+
+    if(fd == -1)
+        error("Cannot open proc_pid_fd() file '%s'", filename);
+
+    return fd;
+}
+
+static struct ns {
+    int nstype;
+    int fd;
+    int status;
+    const char *name;
+    const char *path;
+} all_ns[] = {
+        // { .nstype = CLONE_NEWUSER,   .fd = -1, .status = -1, .name = "user",    .path = "ns/user"   },
+        // { .nstype = CLONE_NEWCGROUP, .fd = -1, .status = -1, .name = "cgroup",  .path = "ns/cgroup" },
+        // { .nstype = CLONE_NEWIPC,    .fd = -1, .status = -1, .name = "ipc",     .path = "ns/ipc"    },
+        // { .nstype = CLONE_NEWUTS,    .fd = -1, .status = -1, .name = "uts",     .path = "ns/uts"    },
+        { .nstype = CLONE_NEWNET,    .fd = -1, .status = -1, .name = "network", .path = "ns/net"    },
+        { .nstype = CLONE_NEWPID,    .fd = -1, .status = -1, .name = "pid",     .path = "ns/pid"    },
+        { .nstype = CLONE_NEWNS,     .fd = -1, .status = -1, .name = "mount",   .path = "ns/mnt"    },
+
+        // terminator
+        { .nstype = 0,               .fd = -1, .status = -1, .name = NULL,      .path = NULL        }
+};
+
+int switch_namespace(const char *prefix, pid_t pid) {
+    if(!prefix) prefix = "";
+
+#ifdef HAVE_SETNS
+
+    int i;
+    for(i = 0; all_ns[i].name ; i++)
+        all_ns[i].fd = proc_pid_fd(prefix, all_ns[i].path, pid);
+
+    int root_fd = proc_pid_fd(prefix, "root", pid);
+    int cwd_fd  = proc_pid_fd(prefix, "cwd", pid);
+
+    setgroups(0, NULL);
+
+    // 2 passes - found it at nsenter source code
+    // this is related CLONE_NEWUSER functionality
+
+    // This code cannot switch user namespace (it can all the other namespaces)
+    // Fortunately, we don't need to switch user namespaces.
+
+    int pass, errors = 0;
+    for(pass = 0; pass < 2 ;pass++) {
+        for(i = 0; all_ns[i].name ; i++) {
+            if (all_ns[i].fd != -1 && all_ns[i].status == -1) {
+                if(setns(all_ns[i].fd, all_ns[i].nstype) == -1) {
+                    if(pass == 1) {
+                        all_ns[i].status = 0;
+                        error("Cannot switch to %s namespace of pid %d", all_ns[i].name, (int) pid);
+                        errors++;
+                    }
+                }
+                else
+                    all_ns[i].status = 1;
+            }
+        }
+    }
+
+    setgroups(0, NULL);
+
+    if(root_fd != -1) {
+        if(fchdir(root_fd) < 0)
+            error("Cannot fchdir() to pid %d root directory", (int)pid);
+
+        if(chroot(".") < 0)
+            error("Cannot chroot() to pid %d root directory", (int)pid);
+
+        close(root_fd);
+    }
+
+    if(cwd_fd != -1) {
+        if(fchdir(cwd_fd) < 0)
+            error("Cannot fchdir() to pid %d current working directory", (int)pid);
+
+        close(cwd_fd);
+    }
+
+    int do_fork = 0;
+    for(i = 0; all_ns[i].name ; i++)
+        if(all_ns[i].fd != -1) {
+
+            // CLONE_NEWPID requires a fork() to become effective
+            if(all_ns[i].nstype == CLONE_NEWPID && all_ns[i].status)
+                do_fork = 1;
+
+            close(all_ns[i].fd);
+        }
+
+    if(do_fork)
+        continue_as_child();
+
+    return 0;
+
+#else
+
+    errno = ENOSYS;
+    error("setns() is missing on this system.");
+    return 1;
+
+#endif
+}
+
+pid_t read_pid_from_cgroup_file(const char *filename) {
+    int fd = open(filename, procfile_open_flags);
+    if(fd == -1) {
+        error("Cannot open pid_from_cgroup() file '%s'.", filename);
+        return 0;
+    }
+
+    FILE *fp = fdopen(fd, "r");
+    if(!fp) {
+        error("Cannot upgrade fd to fp for file '%s'.", filename);
+        return 0;
+    }
+
+    char buffer[100 + 1];
+    pid_t pid = 0;
+    char *s;
+    while((s = fgets(buffer, 100, fp))) {
+        buffer[100] = '\0';
+        pid = atoi(s);
+        if(pid > 0) break;
+    }
+
+    fclose(fp);
+    return pid;
+}
+
+pid_t read_pid_from_cgroup_files(const char *path) {
+    char filename[FILENAME_MAX + 1];
+
+    snprintfz(filename, FILENAME_MAX, "%s/cgroup.procs", path);
+    pid_t pid = read_pid_from_cgroup_file(filename);
+    if(pid > 0) return pid;
+
+    snprintfz(filename, FILENAME_MAX, "%s/tasks", path);
+    return read_pid_from_cgroup_file(filename);
+}
+
+pid_t read_pid_from_cgroup(const char *path) {
+    pid_t pid = read_pid_from_cgroup_files(path);
+    if (pid > 0) return pid;
+
+    DIR *dir = opendir(path);
+    if (!dir) {
+        error("cannot read directory '%s'", path);
+        return 0;
+    }
+
+    struct dirent *de = NULL;
+    while ((de = readdir(dir))) {
+        if (de->d_type == DT_DIR
+            && (
+                    (de->d_name[0] == '.' && de->d_name[1] == '\0')
+                    || (de->d_name[0] == '.' && de->d_name[1] == '.' && de->d_name[2] == '\0')
+            ))
+            continue;
+
+        if (de->d_type == DT_DIR) {
+            char filename[FILENAME_MAX + 1];
+            snprintfz(filename, FILENAME_MAX, "%s/%s", path, de->d_name);
+            pid = read_pid_from_cgroup(filename);
+            if(pid > 0) break;
+        }
+    }
+    closedir(dir);
+    return pid;
+}
+
+// ----------------------------------------------------------------------------
+// send the result to netdata
+
+struct found_device {
+    const char *host_device;
+    const char *guest_device;
+
+    uint32_t host_device_hash;
+
+    struct found_device *next;
+} *detected_devices = NULL;
+
+void add_device(const char *host, const char *guest) {
+    uint32_t hash = simple_hash(host);
+
+    if(guest && (!*guest || strcmp(host, guest) == 0))
+        guest = NULL;
+
+    struct found_device *f;
+    for(f = detected_devices; f ; f = f->next) {
+        if(f->host_device_hash == hash && strcmp(host, f->host_device) == 0) {
+
+            if(guest && !f->guest_device)
+                f->guest_device = strdupz(guest);
+
+            return;
+        }
+    }
+
+    f = mallocz(sizeof(struct found_device));
+    f->host_device = strdupz(host);
+    f->host_device_hash = hash;
+    f->guest_device = (guest)?strdupz(guest):NULL;
+    f->next = detected_devices;
+    detected_devices = f;
+}
+
+int send_devices(void) {
+    int found = 0;
+
+    struct found_device *f;
+    for(f = detected_devices; f ; f = f->next) {
+        found++;
+        printf("%s %s\n", f->host_device, (f->guest_device)?f->guest_device:f->host_device);
+    }
+
+    return found;
+}
+
+// ----------------------------------------------------------------------------
+// this function should be called only **ONCE**
+// also it has to be the **LAST** to be called
+// since it switches namespaces, so after this call, everything is different!
+
+void detect_veth_interfaces(pid_t pid) {
+    struct iface *host = NULL, *cgroup = NULL, *h, *c;
+
+    host = read_proc_net_dev(netdata_configured_host_prefix);
+    if(!host) {
+        errno = 0;
+        error("cannot read host interface list.");
+        goto cleanup;
+    }
+
+    if(!eligible_ifaces(host)) {
+        errno = 0;
+        error("there are no double-linked host interfaces available.");
+        goto cleanup;
+    }
+
+    if(switch_namespace(netdata_configured_host_prefix, pid)) {
+        errno = 0;
+        error("cannot switch to the namespace of pid %u", (unsigned int) pid);
+        goto cleanup;
+    }
+
+    cgroup = read_proc_net_dev(NULL);
+    if(!cgroup) {
+        errno = 0;
+        error("cannot read cgroup interface list.");
+        goto cleanup;
+    }
+
+    if(!eligible_ifaces(cgroup)) {
+        errno = 0;
+        error("there are not double-linked cgroup interfaces available.");
+        goto cleanup;
+    }
+
+    for(h = host; h ; h = h->next) {
+        if(iface_is_eligible(h)) {
+            for (c = cgroup; c; c = c->next) {
+                if(iface_is_eligible(c) && h->ifindex == c->iflink && h->iflink == c->ifindex) {
+                    add_device(h->device, c->device);
+                }
+            }
+        }
+    }
+
+cleanup:
+    free_host_ifaces(cgroup);
+    free_host_ifaces(host);
+}
+
+// ----------------------------------------------------------------------------
+// call the external helper
+
+#define CGROUP_NETWORK_INTERFACE_MAX_LINE 2048
+void call_the_helper(pid_t pid, const char *cgroup) {
+    if(setresuid(0, 0, 0) == -1)
+        error("setresuid(0, 0, 0) failed.");
+
+    char command[CGROUP_NETWORK_INTERFACE_MAX_LINE + 1];
+    if(cgroup)
+        snprintfz(command, CGROUP_NETWORK_INTERFACE_MAX_LINE, "exec " PLUGINS_DIR "/cgroup-network-helper.sh --cgroup '%s'", cgroup);
+    else
+        snprintfz(command, CGROUP_NETWORK_INTERFACE_MAX_LINE, "exec " PLUGINS_DIR "/cgroup-network-helper.sh --pid %d", pid);
+
+    info("running: %s", command);
+
+    pid_t cgroup_pid;
+    FILE *fp = mypopene(command, &cgroup_pid, environment);
+    if(fp) {
+        char buffer[CGROUP_NETWORK_INTERFACE_MAX_LINE + 1];
+        char *s;
+        while((s = fgets(buffer, CGROUP_NETWORK_INTERFACE_MAX_LINE, fp))) {
+            trim(s);
+
+            if(*s && *s != '\n') {
+                char *t = s;
+                while(*t && *t != ' ') t++;
+                if(*t == ' ') {
+                    *t = '\0';
+                    t++;
+                }
+
+                if(!*s || !*t) continue;
+                add_device(s, t);
+            }
+        }
+
+        mypclose(fp, cgroup_pid);
+    }
+    else
+        error("cannot execute cgroup-network helper script: %s", command);
+}
+
+int is_valid_path_s