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db6870e06d
nginx/src/http/modules/ngx_http_upstream_zone_module.c
Ruslan Ermilov db6870e06d Upstream: re-resolvable servers. 
Specifying the upstream server by a hostname together with the
"resolve" parameter will make the hostname to be periodically
resolved, and upstream servers added/removed as necessary.

This requires a "resolver" at the "http" configuration block.

The "resolver_timeout" parameter also affects when the failed
DNS requests will be attempted again.  Responses with NXDOMAIN
will be attempted again in 10 seconds.

Upstream has a configuration generation number that is incremented each
time servers are added/removed to the primary/backup list.  This number
is remembered by the peer.init method, and if peer.get detects a change
in configuration, it returns NGX_BUSY.

Each server has a reference counter.  It is incremented by peer.get and
decremented by peer.free.  When a server is removed, it is removed from
the list of servers and is marked as "zombie".  The memory allocated by
a zombie peer is freed only when its reference count becomes zero.

Co-authored-by: Roman Arutyunyan <arut@nginx.com>
Co-authored-by: Sergey Kandaurov <pluknet@nginx.com>
Co-authored-by: Vladimir Homutov <vl@nginx.com>
2024-11-07 07:57:42 -08:00

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/*
* Copyright (C) Ruslan Ermilov
* Copyright (C) Nginx, Inc.
*/
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>
static char *ngx_http_upstream_zone(ngx_conf_t *cf, ngx_command_t *cmd,
void *conf);
static ngx_int_t ngx_http_upstream_init_zone(ngx_shm_zone_t *shm_zone,
void *data);
static ngx_http_upstream_rr_peers_t *ngx_http_upstream_zone_copy_peers(
ngx_slab_pool_t *shpool, ngx_http_upstream_srv_conf_t *uscf);
static ngx_http_upstream_rr_peer_t *ngx_http_upstream_zone_copy_peer(
ngx_http_upstream_rr_peers_t *peers, ngx_http_upstream_rr_peer_t *src);
static void ngx_http_upstream_zone_set_single(
ngx_http_upstream_srv_conf_t *uscf);
static void ngx_http_upstream_zone_remove_peer_locked(
ngx_http_upstream_rr_peers_t *peers, ngx_http_upstream_rr_peer_t *peer);
static ngx_int_t ngx_http_upstream_zone_init_worker(ngx_cycle_t *cycle);
static void ngx_http_upstream_zone_resolve_timer(ngx_event_t *event);
static void ngx_http_upstream_zone_resolve_handler(ngx_resolver_ctx_t *ctx);
static ngx_command_t ngx_http_upstream_zone_commands[] = {
{ ngx_string("zone"),
NGX_HTTP_UPS_CONF|NGX_CONF_TAKE12,
ngx_http_upstream_zone,
0,
0,
NULL },
ngx_null_command
};
static ngx_http_module_t ngx_http_upstream_zone_module_ctx = {
NULL, /* preconfiguration */
NULL, /* postconfiguration */
NULL, /* create main configuration */
NULL, /* init main configuration */
NULL, /* create server configuration */
NULL, /* merge server configuration */
NULL, /* create location configuration */
NULL /* merge location configuration */
};
ngx_module_t ngx_http_upstream_zone_module = {
NGX_MODULE_V1,
&ngx_http_upstream_zone_module_ctx, /* module context */
ngx_http_upstream_zone_commands, /* module directives */
NGX_HTTP_MODULE, /* module type */
NULL, /* init master */
NULL, /* init module */
ngx_http_upstream_zone_init_worker, /* init process */
NULL, /* init thread */
NULL, /* exit thread */
NULL, /* exit process */
NULL, /* exit master */
NGX_MODULE_V1_PADDING
};
static char *
ngx_http_upstream_zone(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
ssize_t size;
ngx_str_t *value;
ngx_http_upstream_srv_conf_t *uscf;
ngx_http_upstream_main_conf_t *umcf;
uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module);
umcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_upstream_module);
value = cf->args->elts;
if (!value[1].len) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"invalid zone name \"%V\"", &value[1]);
return NGX_CONF_ERROR;
}
if (cf->args->nelts == 3) {
size = ngx_parse_size(&value[2]);
if (size == NGX_ERROR) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"invalid zone size \"%V\"", &value[2]);
return NGX_CONF_ERROR;
}
if (size < (ssize_t) (8 * ngx_pagesize)) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"zone \"%V\" is too small", &value[1]);
return NGX_CONF_ERROR;
}
} else {
size = 0;
}
uscf->shm_zone = ngx_shared_memory_add(cf, &value[1], size,
&ngx_http_upstream_module);
if (uscf->shm_zone == NULL) {
return NGX_CONF_ERROR;
}
uscf->shm_zone->init = ngx_http_upstream_init_zone;
uscf->shm_zone->data = umcf;
uscf->shm_zone->noreuse = 1;
return NGX_CONF_OK;
}
static ngx_int_t
ngx_http_upstream_init_zone(ngx_shm_zone_t *shm_zone, void *data)
{
size_t len;
ngx_uint_t i;
ngx_slab_pool_t *shpool;
ngx_http_upstream_rr_peers_t *peers, **peersp;
ngx_http_upstream_srv_conf_t *uscf, **uscfp;
ngx_http_upstream_main_conf_t *umcf;
shpool = (ngx_slab_pool_t *) shm_zone->shm.addr;
umcf = shm_zone->data;
uscfp = umcf->upstreams.elts;
if (shm_zone->shm.exists) {
peers = shpool->data;
for (i = 0; i < umcf->upstreams.nelts; i++) {
uscf = uscfp[i];
if (uscf->shm_zone != shm_zone) {
continue;
}
uscf->peer.data = peers;
peers = peers->zone_next;
}
return NGX_OK;
}
len = sizeof(" in upstream zone \"\"") + shm_zone->shm.name.len;
shpool->log_ctx = ngx_slab_alloc(shpool, len);
if (shpool->log_ctx == NULL) {
return NGX_ERROR;
}
ngx_sprintf(shpool->log_ctx, " in upstream zone \"%V\"%Z",
&shm_zone->shm.name);
/* copy peers to shared memory */
peersp = (ngx_http_upstream_rr_peers_t **) (void *) &shpool->data;
for (i = 0; i < umcf->upstreams.nelts; i++) {
uscf = uscfp[i];
if (uscf->shm_zone != shm_zone) {
continue;
}
peers = ngx_http_upstream_zone_copy_peers(shpool, uscf);
if (peers == NULL) {
return NGX_ERROR;
}
*peersp = peers;
peersp = &peers->zone_next;
}
return NGX_OK;
}
static ngx_http_upstream_rr_peers_t *
ngx_http_upstream_zone_copy_peers(ngx_slab_pool_t *shpool,
ngx_http_upstream_srv_conf_t *uscf)
{
ngx_str_t *name;
ngx_uint_t *config;
ngx_http_upstream_rr_peer_t *peer, **peerp;
ngx_http_upstream_rr_peers_t *peers, *backup;
config = ngx_slab_calloc(shpool, sizeof(ngx_uint_t));
if (config == NULL) {
return NULL;
}
peers = ngx_slab_alloc(shpool, sizeof(ngx_http_upstream_rr_peers_t));
if (peers == NULL) {
return NULL;
}
ngx_memcpy(peers, uscf->peer.data, sizeof(ngx_http_upstream_rr_peers_t));
name = ngx_slab_alloc(shpool, sizeof(ngx_str_t));
if (name == NULL) {
return NULL;
}
name->data = ngx_slab_alloc(shpool, peers->name->len);
if (name->data == NULL) {
return NULL;
}
ngx_memcpy(name->data, peers->name->data, peers->name->len);
name->len = peers->name->len;
peers->name = name;
peers->shpool = shpool;
peers->config = config;
for (peerp = &peers->peer; *peerp; peerp = &peer->next) {
/* pool is unlocked */
peer = ngx_http_upstream_zone_copy_peer(peers, *peerp);
if (peer == NULL) {
return NULL;
}
*peerp = peer;
(*peers->config)++;
}
for (peerp = &peers->resolve; *peerp; peerp = &peer->next) {
peer = ngx_http_upstream_zone_copy_peer(peers, *peerp);
if (peer == NULL) {
return NULL;
}
*peerp = peer;
(*peers->config)++;
}
if (peers->next == NULL) {
goto done;
}
backup = ngx_slab_alloc(shpool, sizeof(ngx_http_upstream_rr_peers_t));
if (backup == NULL) {
return NULL;
}
ngx_memcpy(backup, peers->next, sizeof(ngx_http_upstream_rr_peers_t));
backup->name = name;
backup->shpool = shpool;
backup->config = config;
for (peerp = &backup->peer; *peerp; peerp = &peer->next) {
/* pool is unlocked */
peer = ngx_http_upstream_zone_copy_peer(backup, *peerp);
if (peer == NULL) {
return NULL;
}
*peerp = peer;
(*backup->config)++;
}
for (peerp = &backup->resolve; *peerp; peerp = &peer->next) {
peer = ngx_http_upstream_zone_copy_peer(backup, *peerp);
if (peer == NULL) {
return NULL;
}
*peerp = peer;
(*backup->config)++;
}
peers->next = backup;
done:
uscf->peer.data = peers;
return peers;
}
static ngx_http_upstream_rr_peer_t *
ngx_http_upstream_zone_copy_peer(ngx_http_upstream_rr_peers_t *peers,
ngx_http_upstream_rr_peer_t *src)
{
ngx_slab_pool_t *pool;
ngx_http_upstream_rr_peer_t *dst;
pool = peers->shpool;
dst = ngx_slab_calloc_locked(pool, sizeof(ngx_http_upstream_rr_peer_t));
if (dst == NULL) {
return NULL;
}
if (src) {
ngx_memcpy(dst, src, sizeof(ngx_http_upstream_rr_peer_t));
dst->sockaddr = NULL;
dst->name.data = NULL;
dst->server.data = NULL;
dst->host = NULL;
}
dst->sockaddr = ngx_slab_calloc_locked(pool, sizeof(ngx_sockaddr_t));
if (dst->sockaddr == NULL) {
goto failed;
}
dst->name.data = ngx_slab_calloc_locked(pool, NGX_SOCKADDR_STRLEN);
if (dst->name.data == NULL) {
goto failed;
}
if (src) {
ngx_memcpy(dst->sockaddr, src->sockaddr, src->socklen);
ngx_memcpy(dst->name.data, src->name.data, src->name.len);
dst->server.data = ngx_slab_alloc_locked(pool, src->server.len);
if (dst->server.data == NULL) {
goto failed;
}
ngx_memcpy(dst->server.data, src->server.data, src->server.len);
if (src->host) {
dst->host = ngx_slab_calloc_locked(pool,
sizeof(ngx_http_upstream_host_t));
if (dst->host == NULL) {
goto failed;
}
dst->host->name.data = ngx_slab_alloc_locked(pool,
src->host->name.len);
if (dst->host->name.data == NULL) {
goto failed;
}
dst->host->peers = peers;
dst->host->peer = dst;
dst->host->name.len = src->host->name.len;
ngx_memcpy(dst->host->name.data, src->host->name.data,
src->host->name.len);
}
}
return dst;
failed:
if (dst->host) {
ngx_slab_free_locked(pool, dst->host);
}
if (dst->server.data) {
ngx_slab_free_locked(pool, dst->server.data);
}
if (dst->name.data) {
ngx_slab_free_locked(pool, dst->name.data);
}
if (dst->sockaddr) {
ngx_slab_free_locked(pool, dst->sockaddr);
}
ngx_slab_free_locked(pool, dst);
return NULL;
}
static void
ngx_http_upstream_zone_set_single(ngx_http_upstream_srv_conf_t *uscf)
{
ngx_http_upstream_rr_peers_t *peers;
peers = uscf->peer.data;
if (peers->number == 1
&& (peers->next == NULL || peers->next->number == 0))
{
peers->single = 1;
} else {
peers->single = 0;
}
}
static void
ngx_http_upstream_zone_remove_peer_locked(ngx_http_upstream_rr_peers_t *peers,
ngx_http_upstream_rr_peer_t *peer)
{
peers->total_weight -= peer->weight;
peers->number--;
peers->tries -= (peer->down == 0);
(*peers->config)++;
peers->weighted = (peers->total_weight != peers->number);
ngx_http_upstream_rr_peer_free(peers, peer);
}
static ngx_int_t
ngx_http_upstream_zone_init_worker(ngx_cycle_t *cycle)
{
ngx_uint_t i;
ngx_event_t *event;
ngx_http_upstream_rr_peer_t *peer;
ngx_http_upstream_rr_peers_t *peers;
ngx_http_upstream_srv_conf_t *uscf, **uscfp;
ngx_http_upstream_main_conf_t *umcf;
if (ngx_process != NGX_PROCESS_WORKER
&& ngx_process != NGX_PROCESS_SINGLE)
{
return NGX_OK;
}
umcf = ngx_http_cycle_get_module_main_conf(cycle, ngx_http_upstream_module);
if (umcf == NULL) {
return NGX_OK;
}
uscfp = umcf->upstreams.elts;
for (i = 0; i < umcf->upstreams.nelts; i++) {
uscf = uscfp[i];
if (uscf->shm_zone == NULL) {
continue;
}
peers = uscf->peer.data;
do {
ngx_http_upstream_rr_peers_wlock(peers);
for (peer = peers->resolve; peer; peer = peer->next) {
if (peer->host->worker != ngx_worker) {
continue;
}
event = &peer->host->event;
ngx_memzero(event, sizeof(ngx_event_t));
event->data = uscf;
event->handler = ngx_http_upstream_zone_resolve_timer;
event->log = cycle->log;
event->cancelable = 1;
ngx_add_timer(event, 1);
}
ngx_http_upstream_rr_peers_unlock(peers);
peers = peers->next;
} while (peers);
}
return NGX_OK;
}
static void
ngx_http_upstream_zone_resolve_timer(ngx_event_t *event)
{
ngx_resolver_ctx_t *ctx;
ngx_http_upstream_host_t *host;
ngx_http_upstream_srv_conf_t *uscf;
host = (ngx_http_upstream_host_t *) event;
uscf = event->data;
ctx = ngx_resolve_start(uscf->resolver, NULL);
if (ctx == NULL) {
goto retry;
}
if (ctx == NGX_NO_RESOLVER) {
ngx_log_error(NGX_LOG_ERR, event->log, 0,
"no resolver defined to resolve %V", &host->name);
return;
}
ctx->name = host->name;
ctx->handler = ngx_http_upstream_zone_resolve_handler;
ctx->data = host;
ctx->timeout = uscf->resolver_timeout;
ctx->cancelable = 1;
if (ngx_resolve_name(ctx) == NGX_OK) {
return;
}
retry:
ngx_add_timer(event, ngx_max(uscf->resolver_timeout, 1000));
}
static void
ngx_http_upstream_zone_resolve_handler(ngx_resolver_ctx_t *ctx)
{
time_t now;
in_port_t port;
ngx_msec_t timer;
ngx_uint_t i, j;
ngx_event_t *event;
ngx_resolver_addr_t *addr;
ngx_http_upstream_host_t *host;
ngx_http_upstream_rr_peer_t *peer, *template, **peerp;
ngx_http_upstream_rr_peers_t *peers;
ngx_http_upstream_srv_conf_t *uscf;
host = ctx->data;
event = &host->event;
uscf = event->data;
peers = host->peers;
template = host->peer;
ngx_http_upstream_rr_peers_wlock(peers);
now = ngx_time();
if (ctx->state) {
ngx_log_error(NGX_LOG_ERR, event->log, 0,
"%V could not be resolved (%i: %s)",
&ctx->name, ctx->state,
ngx_resolver_strerror(ctx->state));
if (ctx->state != NGX_RESOLVE_NXDOMAIN) {
ngx_http_upstream_rr_peers_unlock(peers);
ngx_resolve_name_done(ctx);
ngx_add_timer(event, ngx_max(uscf->resolver_timeout, 1000));
return;
}
/* NGX_RESOLVE_NXDOMAIN */
ctx->naddrs = 0;
}
#if (NGX_DEBUG)
{
u_char text[NGX_SOCKADDR_STRLEN];
size_t len;
for (i = 0; i < ctx->naddrs; i++) {
len = ngx_sock_ntop(ctx->addrs[i].sockaddr, ctx->addrs[i].socklen,
text, NGX_SOCKADDR_STRLEN, 0);
ngx_log_debug3(NGX_LOG_DEBUG_HTTP, event->log, 0,
"name %V was resolved to %*s", &host->name, len, text);
}
}
#endif
for (peerp = &peers->peer; *peerp; /* void */ ) {
peer = *peerp;
if (peer->host != host) {
goto next;
}
for (j = 0; j < ctx->naddrs; j++) {
addr = &ctx->addrs[j];
if (addr->name.len == 0
&& ngx_cmp_sockaddr(peer->sockaddr, peer->socklen,
addr->sockaddr, addr->socklen, 0)
== NGX_OK)
{
addr->name.len = 1;
goto next;
}
}
*peerp = peer->next;
ngx_http_upstream_zone_remove_peer_locked(peers, peer);
ngx_http_upstream_zone_set_single(uscf);
continue;
next:
peerp = &peer->next;
}
for (i = 0; i < ctx->naddrs; i++) {
addr = &ctx->addrs[i];
if (addr->name.len == 1) {
addr->name.len = 0;
continue;
}
ngx_shmtx_lock(&peers->shpool->mutex);
peer = ngx_http_upstream_zone_copy_peer(peers, NULL);
ngx_shmtx_unlock(&peers->shpool->mutex);
if (peer == NULL) {
ngx_log_error(NGX_LOG_ERR, event->log, 0,
"cannot add new server to upstream \"%V\", "
"memory exhausted", peers->name);
break;
}
ngx_memcpy(peer->sockaddr, addr->sockaddr, addr->socklen);
port = ((struct sockaddr_in *) template->sockaddr)->sin_port;
switch (peer->sockaddr->sa_family) {
#if (NGX_HAVE_INET6)
case AF_INET6:
((struct sockaddr_in6 *) peer->sockaddr)->sin6_port = port;
break;
#endif
default: /* AF_INET */
((struct sockaddr_in *) peer->sockaddr)->sin_port = port;
}
peer->socklen = addr->socklen;
peer->name.len = ngx_sock_ntop(peer->sockaddr, peer->socklen,
peer->name.data, NGX_SOCKADDR_STRLEN, 1);
peer->host = template->host;
peer->server = template->server;
peer->weight = template->weight;
peer->effective_weight = peer->weight;
peer->max_conns = template->max_conns;
peer->max_fails = template->max_fails;
peer->fail_timeout = template->fail_timeout;
peer->down = template->down;
*peerp = peer;
peerp = &peer->next;
peers->number++;
peers->tries += (peer->down == 0);
peers->total_weight += peer->weight;
peers->weighted = (peers->total_weight != peers->number);
(*peers->config)++;
ngx_http_upstream_zone_set_single(uscf);
}
ngx_http_upstream_rr_peers_unlock(peers);
timer = (ngx_msec_t) 1000 * (ctx->valid > now ? ctx->valid - now + 1 : 1);
ngx_resolve_name_done(ctx);
ngx_add_timer(event, timer);
}
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