blob: b426f96c039c9991329cd97d7bb72f7df8bf69da [file] [log] [blame]
/*
* Wrapper to make haproxy systemd-compliant.
*
* Copyright 2013 Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*/
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#define REEXEC_FLAG "HAPROXY_SYSTEMD_REEXEC"
#define SD_DEBUG "<7>"
#define SD_NOTICE "<5>"
static volatile sig_atomic_t caught_signal;
static char *pid_file = "/run/haproxy.pid";
static int wrapper_argc;
static char **wrapper_argv;
static void setup_signal_handler();
static void pause_signal_handler();
static void reset_signal_handler();
/* returns the path to the haproxy binary into <buffer>, whose size indicated
* in <buffer_size> must be at least 1 byte long.
*/
static void locate_haproxy(char *buffer, size_t buffer_size)
{
char *end = NULL;
int len;
len = readlink("/proc/self/exe", buffer, buffer_size - 1);
if (len == -1)
goto fail;
buffer[len] = 0;
end = strrchr(buffer, '/');
if (end == NULL)
goto fail;
if (strcmp(end + strlen(end) - 16, "-systemd-wrapper") == 0) {
end[strlen(end) - 16] = '\0';
return;
}
end[1] = '\0';
strncpy(end + 1, "haproxy", buffer + buffer_size - (end + 1));
buffer[buffer_size - 1] = '\0';
return;
fail:
strncpy(buffer, "/usr/sbin/haproxy", buffer_size);
buffer[buffer_size - 1] = '\0';
return;
}
/* Note: this function must not exit in case of error (except in the child), as
* it is only dedicated the starting a new haproxy process. By keeping the
* process alive it will ensure that future signal delivery may get rid of
* the issue. If the first startup fails, the wrapper will notice it and
* return an error thanks to wait() returning ECHILD.
*/
static void spawn_haproxy(char **pid_strv, int nb_pid)
{
char haproxy_bin[512];
pid_t pid;
int main_argc;
char **main_argv;
int pipefd[2];
char fdstr[20];
int ret;
main_argc = wrapper_argc - 1;
main_argv = wrapper_argv + 1;
if (pipe(pipefd) != 0) {
fprintf(stderr, SD_NOTICE "haproxy-systemd-wrapper: failed to create a pipe, please try again later.\n");
return;
}
pid = fork();
if (!pid) {
char **argv;
int i;
int argno = 0;
/* 3 for "haproxy -Ds -sf" */
argv = calloc(4 + main_argc + nb_pid + 1, sizeof(char *));
if (!argv) {
fprintf(stderr, SD_NOTICE "haproxy-systemd-wrapper: failed to calloc(), please try again later.\n");
exit(1);
}
reset_signal_handler();
close(pipefd[0]); /* close the read side */
snprintf(fdstr, sizeof(fdstr), "%d", pipefd[1]);
if (setenv("HAPROXY_WRAPPER_FD", fdstr, 1) != 0) {
fprintf(stderr, SD_NOTICE "haproxy-systemd-wrapper: failed to setenv(), please try again later.\n");
exit(1);
}
locate_haproxy(haproxy_bin, 512);
argv[argno++] = haproxy_bin;
for (i = 0; i < main_argc; ++i)
argv[argno++] = main_argv[i];
argv[argno++] = "-Ds";
if (nb_pid > 0) {
argv[argno++] = "-sf";
for (i = 0; i < nb_pid; ++i)
argv[argno++] = pid_strv[i];
}
argv[argno] = NULL;
fprintf(stderr, SD_DEBUG "haproxy-systemd-wrapper: executing ");
for (i = 0; argv[i]; ++i)
fprintf(stderr, "%s ", argv[i]);
fprintf(stderr, "\n");
execv(argv[0], argv);
fprintf(stderr, SD_NOTICE "haproxy-systemd-wrapper: execv(%s) failed, please try again later.\n", argv[0]);
exit(1);
}
else if (pid == -1) {
fprintf(stderr, SD_NOTICE "haproxy-systemd-wrapper: failed to fork(), please try again later.\n");
}
/* The parent closes the write side and waits for the child to close it
* as well. Also deal the case where the fd would unexpectedly be 1 or 2
* by silently draining all data.
*/
close(pipefd[1]);
do {
char c;
ret = read(pipefd[0], &c, sizeof(c));
} while ((ret > 0) || (ret == -1 && errno == EINTR));
/* the child has finished starting up */
close(pipefd[0]);
}
static int read_pids(char ***pid_strv)
{
FILE *f = fopen(pid_file, "r");
int read = 0, allocated = 8;
char pid_str[10];
if (!f)
return 0;
*pid_strv = malloc(allocated * sizeof(char *));
while (1 == fscanf(f, "%s\n", pid_str)) {
if (read == allocated) {
allocated *= 2;
*pid_strv = realloc(*pid_strv, allocated * sizeof(char *));
}
(*pid_strv)[read++] = strdup(pid_str);
}
fclose(f);
return read;
}
static void signal_handler(int signum)
{
if (caught_signal != SIGINT && caught_signal != SIGTERM)
caught_signal = signum;
}
static void setup_signal_handler()
{
struct sigaction sa;
memset(&sa, 0, sizeof(struct sigaction));
sa.sa_handler = &signal_handler;
sigaction(SIGUSR2, &sa, NULL);
sigaction(SIGHUP, &sa, NULL);
sigaction(SIGINT, &sa, NULL);
sigaction(SIGTERM, &sa, NULL);
}
static void pause_signal_handler()
{
signal(SIGUSR2, SIG_IGN);
signal(SIGHUP, SIG_IGN);
signal(SIGINT, SIG_DFL);
signal(SIGTERM, SIG_DFL);
}
static void reset_signal_handler()
{
signal(SIGUSR2, SIG_DFL);
signal(SIGHUP, SIG_DFL);
signal(SIGINT, SIG_DFL);
signal(SIGTERM, SIG_DFL);
}
/* handles SIGUSR2 and SIGHUP only */
static void do_restart(int sig)
{
setenv(REEXEC_FLAG, "1", 1);
fprintf(stderr, SD_NOTICE "haproxy-systemd-wrapper: re-executing on %s.\n",
sig == SIGUSR2 ? "SIGUSR2" : "SIGHUP");
/* don't let the other process take one of those signals by accident */
pause_signal_handler();
execv(wrapper_argv[0], wrapper_argv);
/* failed, let's reinstall the signal handler and continue */
setup_signal_handler();
fprintf(stderr, SD_NOTICE "haproxy-systemd-wrapper: re-exec(%s) failed.\n", wrapper_argv[0]);
}
/* handles SIGTERM and SIGINT only */
static void do_shutdown(int sig)
{
int i, pid;
char **pid_strv = NULL;
int nb_pid = read_pids(&pid_strv);
for (i = 0; i < nb_pid; ++i) {
pid = atoi(pid_strv[i]);
if (pid > 0) {
fprintf(stderr, SD_DEBUG "haproxy-systemd-wrapper: %s -> %d.\n",
sig == SIGTERM ? "SIGTERM" : "SIGINT", pid);
kill(pid, sig);
free(pid_strv[i]);
}
}
free(pid_strv);
}
static void init(int argc, char **argv)
{
while (argc > 1) {
if ((*argv)[0] == '-' && (*argv)[1] == 'p') {
pid_file = *(argv + 1);
}
--argc; ++argv;
}
}
int main(int argc, char **argv)
{
int status;
setup_signal_handler();
wrapper_argc = argc;
wrapper_argv = argv;
--argc; ++argv;
init(argc, argv);
if (getenv(REEXEC_FLAG) != NULL) {
/* We are being re-executed: restart HAProxy gracefully */
int i;
char **pid_strv = NULL;
int nb_pid = read_pids(&pid_strv);
unsetenv(REEXEC_FLAG);
spawn_haproxy(pid_strv, nb_pid);
for (i = 0; i < nb_pid; ++i)
free(pid_strv[i]);
free(pid_strv);
}
else {
/* Start a fresh copy of HAProxy */
spawn_haproxy(NULL, 0);
}
status = -1;
while (caught_signal || wait(&status) != -1 || errno == EINTR) {
int sig = caught_signal;
if (caught_signal == SIGUSR2 || caught_signal == SIGHUP) {
caught_signal = 0;
do_restart(sig);
}
else if (caught_signal == SIGINT || caught_signal == SIGTERM) {
caught_signal = 0;
do_shutdown(sig);
}
}
fprintf(stderr, SD_NOTICE "haproxy-systemd-wrapper: exit, haproxy RC=%d\n",
status);
return status;
}