通过分析nginx upstream源码来看动态配置upstream模块
2022/1/19 7:11:16
本文主要是介绍通过分析nginx upstream源码来看动态配置upstream模块，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！
upstream回源处理流程
代码围绕着ngx_http_upstream.c展开，该模块主要为创建mainconf函数：
static void *
ngx_http_upstream_create_main_conf(ngx_conf_t *cf)
{
...
//创建main conf
umcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_main_conf_t));
//创建upstream数组，每一个ngx_http_upstream_srv_conf_t对应一个upstream
ngx_array_init(&umcf->upstreams, cf->pool, 4,
sizeof(ngx_http_upstream_srv_conf_t *)
//创建implicit_upstreams链表，用来存放proxy_pass创建出来的upstream，真正创建upstream的时候用
ngx_list_init(&umcf->implicit_upstreams, cf->pool, 4,
sizeof(ngx_http_upstream_srv_conf_t *)
//创建rbtree。
ngx_rbtree_init(&umcf->rbtree, &umcf->sentinel,
ngx_http_upstream_rbtree_insert_value);
...
}
配置中的upstream会触发ngx_http_upstream函数，该配置作用于mainconf的配置
static char *
ngx_http_upstream(ngx_conf_t *cf, ngx_command_t *cmd, void *dummy)
{
...
// upstream的name
value = cf->args->elts;
u.host = value[1];
//生成uscf结构体
uscf = ngx_http_upstream_add(cf, &u, flag);
//创建配置指针，保存当前http块的配置，将生成配置的main_conf指向http块
ctx = ngx_pcalloc(cf->pool, sizeof(ngx_http_conf_ctx_t));
http_ctx = cf->ctx;
ctx->main_conf = http_ctx->main_conf;
//将生成的uscf放在upstream module对应srv配置上，因为这个模块没有create srv conf
ctx->srv_conf = ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module);
ctx->srv_conf[ngx_http_upstream_module.ctx_index] = uscf;
uscf->srv_conf = ctx->srv_conf;
//接下来是生成loc conf并且将全部的模块过滤一次，生成对应的srv conf和loc conf，不用merge的是因为在ups里的配置不可能出现在别的地方了，这些生成的conf会在接下来使用
uscf->servers = ngx_array_create(cf->pool, 4,
sizeof(ngx_http_upstream_server_t));
// 接下来开始解析里面的配置，主要是servers
pcf = *cf;
cf->ctx = ctx;
cf->cmd_type = NGX_HTTP_UPS_CONF;
rv = ngx_conf_parse(cf, NULL);
...
}
ngx_http_upstream_add函数是当前的upstream加进去，这个函数在遇到“upstream”的时候，是带着create标志位的，这个就是正了八经的创建，如果遇到proxy_pass,带的标志位是0
ngx_http_upstream_srv_conf_t *
ngx_http_upstream_add(ngx_conf_t *cf, ngx_url_t *u, ngx_uint_t flags)
{
...
// 红黑树里寻找uscf，对应upstream的配置
umcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_upstream_module);
uscf = ngx_http_upstream_rbtree_lookup(umcf, &u->host);
// not found的时候，再找找看有没有proxy_pass搞出来的part
not_found:
part = &umcf->implicit_upstreams.part;
uscfp = part->elts;
// 最后的创建，先看是否带标志位，如果带则删掉part，insert进红黑树
if (flags & NGX_HTTP_UPSTREAM_CREATE) {
uscfp[i]->flags = flags;
#if (NGX_HTTP_UPSTREAM_RBTREE)
uscf = uscfp[i];
ngx_rbtree_insert(&umcf->rbtree, &uscfp[i]->node);
ngx_list_delete(&umcf->implicit_upstreams, &uscfp[i]);
return uscf;
#endif
}
...
}
分析完回源upstream处理流程，再来看dyups是怎么工作的？
dyups_module
动态修改upstream不reload nginx模块，ngx_http_dyups_module分析。
围绕ngx_http_dyups_module.c进行分析：
在create main conf的时候初始化这个数组
static void *
ngx_http_dyups_create_main_conf(ngx_conf_t *cf)
{
...
if (ngx_array_init(&dmcf->dy_upstreams, cf->pool, 1024,
sizeof(ngx_http_dyups_srv_conf_t))
!= NGX_OK)
{
return NULL;
}
...
}
ngx_http_dyups_init
在dyups init的时候将upstream中的conf全部取出来放进去
//初始化dy_upstream链以及全局ngx_http_dyups_deleted_upstream
static ngx_int_t
ngx_http_dyups_init(ngx_conf_t *cf)
{
...
dmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_dyups_module);
umcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_upstream_module);
uscfp = umcf->upstreams.elts;
for (i = 0; i < umcf->upstreams.nelts; i++) {
duscf = ngx_array_push(&dmcf->dy_upstreams);
// 清零
ngx_memzero(duscf, sizeof(ngx_http_dyups_srv_conf_t));
duscf->pool = NULL;
// 赋值
duscf->upstream = uscfp[i];
duscf->dynamic = (uscfp[i]->port == 0
&& uscfp[i]->srv_conf && uscfp[i]->servers
&& uscfp[i]->flags & NGX_HTTP_UPSTREAM_CREATE);
duscf->deleted = 0;
// 赋值index
duscf->idx = i;
}
...
}
dyups share memory同步机制
shm初始化在ngx_http_dyups_init_main_conf函数中，同时设置了read_mesg的超时时间，并且指定了大小。
static char *
ngx_http_dyups_init_main_conf(ngx_conf_t *cf, void *conf)
{
...
if (dmcf->read_msg_timeout == NGX_CONF_UNSET_MSEC) {
// 一秒一次
dmcf->read_msg_timeout = 1000;
}
if (dmcf->shm_size == NGX_CONF_UNSET_UINT) {
dmcf->shm_size = 2 * 1024 * 1024;
}
return ngx_http_dyups_init_shm(cf, conf);
...
}
static char *
ngx_http_dyups_init_shm(ngx_conf_t *cf, void *conf)
{
...
shm_zone = ngx_shared_memory_add(cf, &dmcf->shm_name, dmcf->shm_size,
&ngx_http_dyups_module);
shm_zone->data = cf->pool;
// 加进去的这个名头的共享内存块的init函数会在初始化的时候统一调用
shm_zone->init = ngx_http_dyups_init_shm_zone;
...
}
static ngx_int_t
ngx_http_dyups_init_shm_zone(ngx_shm_zone_t *shm_zone, void *data)
{
...
shpool = (ngx_slab_pool_t *) shm_zone->shm.addr;
sh = ngx_slab_alloc(shpool, sizeof(ngx_dyups_shctx_t));
if (sh == NULL) {
return NGX_ERROR;
}
// 全局变量，sh和shpool
ngx_dyups_global_ctx.sh = sh;
ngx_dyups_global_ctx.shpool = shpool;
// 初始化msg->queue
ngx_queue_init(&sh->msg_queue);
sh->version = 0;
sh->status = NULL;
...
}
dyups init process
该函数在启动进程时候调用，设定定时器。
//初始化共享内存状态，判断如果是非正常退出，则重新加载upstream配置
static ngx_int_t
ngx_http_dyups_init_process(ngx_cycle_t *cycle)
{
...
// 设定定时器来定时read msg，同步信息
timer = &ngx_dyups_global_ctx.msg_timer;
timer->handler = ngx_http_dyups_read_msg;
ngx_add_timer(timer, dmcf->read_msg_timeout);
// 拿到全局的pool和sh
shpool = ngx_dyups_global_ctx.shpool;
sh = ngx_dyups_global_ctx.sh;
ngx_shmtx_lock(&shpool->mutex);
// 初始化的时候肯定是NULL，，申请对应数量进程数的内存
if (sh->status == NULL) {
sh->status = ngx_slab_alloc_locked(shpool,
sizeof(ngx_dyups_status_t) * ccf->worker_processes);
if (sh->status == NULL) {
ngx_shmtx_unlock(&shpool->mutex);
return NGX_ERROR;
}
ngx_memzero(sh->status,
sizeof(ngx_dyups_status_t) * ccf->worker_processes);
ngx_shmtx_unlock(&shpool->mutex);
return NGX_OK;
}
ngx_shmtx_unlock(&shpool->mutex);
// 判断version，如果不是0的话，说明version已经在同步中被++了，所以是进程挂掉再被拉起来
if (sh->version != 0) {
// 这里后续再看...
}
最核心的是ngx_http_dyups_read_msg函数里的ngx_http_dyups_read_msg_locked函数
static void
ngx_http_dyups_read_msg_locked(ngx_event_t *ev)
{
...
sh = ngx_dyups_global_ctx.sh;
shpool = ngx_dyups_global_ctx.shpool;
for (i = 0; i < ccf->worker_processes; i++) {
status = &sh->status[i];
if (status->pid == 0 || status->pid == ngx_pid) {
ngx_log_debug2(NGX_LOG_DEBUG_HTTP, ev->log, 0,
"[dyups] process %P update time %ui",
status->pid, status->time);
// 遍历全部进程，将对应的pid赋值
status->pid = ngx_pid;
status->time = now;
break;
}
}
// 遍历消息队列
for (q = ngx_queue_last(&sh->msg_queue);
q != ngx_queue_sentinel(&sh->msg_queue);
q = ngx_queue_prev(q))
{
// 如果该msg的count和进程数一致，就是大家都同步过了，把这个msg删掉
if (msg->count == ccf->worker_processes) {
t = ngx_queue_next(q); ngx_queue_remove(q); q = t;
ngx_log_debug2(NGX_LOG_DEBUG_HTTP, ev->log, 0,
"[dyups] destroy msg %V:%V",
&msg->name, &msg->content);
ngx_dyups_destroy_msg(shpool, msg);
continue;
}
found = 0;
for (i = 0; i < msg->count; i++) {
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, ev->log, 0,
"[dyups] msg pids [%P]", msg->pid[i]);
if (msg->pid[i] == ngx_pid) {
found = 1;
break;
}
}
// 如果发现该进程了，就说明已经同步过了，继续
if (found) {
ngx_log_debug2(NGX_LOG_DEBUG_HTTP, ev->log, 0,
"[dyups] msg %V count %ui found",
&msg->name, msg->count);
continue;
}
// 如果没发现的话，count++,pid更新
msg->pid[i] = ngx_pid;
msg->count++;
ngx_log_debug2(NGX_LOG_DEBUG_HTTP, ev->log, 0,
"[dyups] msg %V count %ui", &msg->name, msg->count);
// 取出来name和content
name = msg->name;
content = msg->content;
// 执行同步
rc = ngx_dyups_sync_cmd(pool, &name, &content, msg->flag);
if (rc != NGX_OK) {
ngx_log_error(NGX_LOG_ALERT, ev->log, 0,
"[dyups] read msg error, may cause the "
"config inaccuracy, name:%V, content:%V",
&name, &content);
}
}
...
}
static ngx_int_t
ngx_dyups_sync_cmd(ngx_pool_t *pool, ngx_str_t *name, ngx_str_t *content,
ngx_uint_t flag)
{
...
} else if (flag == NGX_DYUPS_ADD) {
body.start = body.pos = content->data;
body.end = body.last = content->data + content->len;
body.temporary = 1;
rc = ngx_dyups_do_update(name, &body, &rv);
ngx_log_error(NGX_LOG_INFO, ngx_cycle->log, 0,
"[dyups] sync add: %V rv: %V rc: %i",
name, &rv, rc);
if (rc != NGX_HTTP_OK) {
return NGX_ERROR;
}
return NGX_OK;
}
...
}
接下来就是ngx_dyups_do_update
同步其他进程接收的信息，如果是当前进程处理的，要把信息添加到消息队列中。
dyups update
ngx_dyups_update_upstream
ngx_int_t
ngx_dyups_update_upstream(ngx_str_t *name, ngx_buf_t *buf, ngx_str_t *rv)
{
...
// 先检查有没有需要做的操作
ngx_http_dyups_read_msg_locked(timer);
// 沙箱测试配置
status = ngx_dyups_sandbox_update(buf, rv);
if (status != NGX_HTTP_OK) {
goto finish;
}
status = ngx_dyups_do_update(name, buf, rv);
if (status == NGX_HTTP_OK) {
//关键的是把操作发到队列中去
if (ngx_http_dyups_send_msg(name, buf, NGX_DYUPS_ADD)) {
ngx_str_set(rv, "alert: update success "
"but not sync to other process");
status = NGX_HTTP_INTERNAL_SERVER_ERROR;
}
}
...
}
接下来就是ngx_http_dyups_send_msg函数
static ngx_int_t
ngx_http_dyups_send_msg(ngx_str_t *name, ngx_buf_t *body, ngx_uint_t flag)
{
...
// 这个函数还是挺简单的，就是初始化整个msg，将name和body填充进去。
sh->version++;
ngx_queue_insert_head(&sh->msg_queue, &msg->queue);
...
}
dyups ngx_dyups_do_update
update之前先find寻找对应的upstream。
static ngx_http_dyups_srv_conf_t *
ngx_dyups_find_upstream(ngx_str_t *name, ngx_int_t *idx)
{
...
duscfs = dumcf->dy_upstreams.elts;
for (i = 0; i < dumcf->dy_upstreams.nelts; i++) {
duscf = &duscfs[i];
uscf = duscf->upstream;
if (uscf->host.len != name->len
|| ngx_strncasecmp(uscf->host.data, name->data, uscf->host.len)
!= 0)
{
continue;
}
*idx = i;
return duscf;
}
...
}
如果寻找到了则对idx赋值，一旦发现寻找到了对应name的dy_upstream进行判断。
调用的是ngx_dyups_mark_upstream_delete函数
static void
ngx_dyups_mark_upstream_delete(ngx_http_dyups_srv_conf_t *duscf)
{
...
// 获取umcf和uscf
uscf = duscf->upstream;
umcf = ngx_http_cycle_get_module_main_conf(ngx_cycle,
ngx_http_upstream_module);
// us获取这个dynamic upstream下的servers
us = uscf->servers->elts;
for (i = 0; i < uscf->servers->nelts; i++) {
// 标志位置1
us[i].down = 1;
#if (NGX_HTTP_UPSTREAM_CHECK)
if (us[i].addrs) {
// 关闭peer，看宏定义主要关闭健康检查的peer
ngx_http_upstream_check_delete_dynamic_peer(&uscf->host,
us[i].addrs);
}
#endif
}
// 将upstream对应的index的配置变成一个dummy配置
uscfp[duscf->idx] = &ngx_http_dyups_deleted_upstream;
#if (NGX_HTTP_UPSTREAM_RBTREE)
ngx_rbtree_delete(&umcf->rbtree, &uscf->node);
#endif
duscf->deleted = NGX_DYUPS_DELETING;
...
}
这里最重要的是check_delete_dynamic_peer
void
ngx_http_upstream_check_delete_dynamic_peer(ngx_str_t *name,
ngx_addr_t *peer_addr)
{
...
/* 一堆比较 找到choosen*/
chosen = &peer[i];
chosen->shm->ref--;
if (chosen->shm->ref <= 0 && chosen->shm->delete != PEER_DELETED) {
ngx_http_upstream_check_clear_dynamic_peer_shm(chosen->shm);
chosen->shm->delete = PEER_DELETED;
}
ngx_shmtx_unlock(&chosen->shm->mutex);
ngx_http_upstream_check_clear_peer(chosen);
...
}
删完一次之后再find一次，idx大概率就变成-1了，然后就进行创建了。
static ngx_int_t
ngx_dyups_do_update(ngx_str_t *name, ngx_buf_t *buf, ngx_str_t *rv)
{
...
if (idx == -1) {
duscf = ngx_array_push(&dumcf->dy_upstreams);
// 这个uscfp是没有用处的，只为了给这个数组加一
uscfp = ngx_array_push(&umcf->upstreams);
ngx_memzero(duscf, sizeof(ngx_http_dyups_srv_conf_t));
// 这块是为了获取在umcf中的新upstream的index值。
idx = umcf->upstreams.nelts - 1;
}
duscf->idx = idx;
rc = ngx_dyups_init_upstream(duscf, name, idx);
rc = ngx_dyups_add_server(duscf, buf);
...
}
最重要的就是init_upstream和add_server。
init upstream的传参是dy_srv_conf_t、upstream的name，以及upstream链表中对应的index。
static ngx_int_t
ngx_dyups_init_upstream(ngx_http_dyups_srv_conf_t *duscf, ngx_str_t *name,
ngx_uint_t index)
{
...
umcf = ngx_http_cycle_get_module_main_conf(ngx_cycle,
ngx_http_upstream_module);
uscfp = umcf->upstreams.elts;
/*初始化uscf 也就是upstream的各个结构体*/
uscfp[index] = uscf; // 赋值
duscf->dynamic = 1;
duscf->upstream = uscf;
ctx = ngx_pcalloc(duscf->pool, sizeof(ngx_http_conf_ctx_t));
// 存放ctx
duscf->ctx = ctx;
// insert进去uscf
uscf->node.key = ngx_crc32_short(uscf->host.data, uscf->host.len);
ngx_rbtree_insert(&umcf->rbtree, &uscf->node);
...
}
static ngx_int_t
ngx_dyups_add_server(ngx_http_dyups_srv_conf_t *duscf, ngx_buf_t *buf)
{
...
ngx_dyups_parse_upstream(&cf, buf)
...
}
static char *
ngx_dyups_parse_upstream(ngx_conf_t *cf, ngx_buf_t *buf)
{
...
b = *buf;
ngx_memzero(&conf_file, sizeof(ngx_conf_file_t));
conf_file.file.fd = NGX_INVALID_FILE;
conf_file.buffer = &b;
cf->conf_file = &conf_file;
return ngx_conf_parse(cf, NULL);
...
}
ngx_dyups_do_delete
static ngx_int_t
ngx_dyups_do_delete(ngx_str_t *name, ngx_str_t *rv)
{
...
duscf = ngx_dyups_find_upstream(name, &dumy);
// 如查出来是NULL or 被标记删除 or 彻底删除，说明要删的这个有问题
if (duscf == NULL || duscf->deleted) {
ngx_log_error(NGX_LOG_DEBUG, ngx_cycle->log, 0,
"[dyups] not find upstream %V %p", name, duscf);
ngx_str_set(rv, "not found uptream");
return NGX_HTTP_NOT_FOUND;
}
// 没问题的话就这样正常删除
ngx_dyups_mark_upstream_delete(duscf);
...
}
ngx_dyups_find_upstream
find upstream主要做了查找、删除工作。
static ngx_http_dyups_srv_conf_t *
ngx_dyups_find_upstream(ngx_str_t *name, ngx_int_t *idx)
{
...
dumcf = ngx_http_cycle_get_module_main_conf(ngx_cycle, ngx_http_dyups_module);
duscfs = dumcf->dy_upstreams.elts;
for (i = 0; i < dumcf->dy_upstreams.nelts; i++) {
// 这块是在mark_upstream中被标记的
if (duscf->deleted == NGX_DYUPS_DELETING) {
// 确认可以删除，主要看这个ref的引用计数
if (*(duscf->ref) == 0) {
ngx_log_error(NGX_LOG_INFO, ngx_cycle->log, 0,
"[dyups] free dynamic upstream in find upstream"
" %ui", duscf->idx);
duscf->deleted = NGX_DYUPS_DELETED;
if (duscf->pool) {
ngx_destroy_pool(duscf->pool);
duscf->pool = NULL;
}
}
}
// 如果是deleted或者是deleting
// 如果遍历完啥也没找到就返回一个deleted
if (duscf->deleted == NGX_DYUPS_DELETING) {
continue;
}
if (duscf->deleted == NGX_DYUPS_DELETED) {
*idx = i;
duscf_del = duscf;
continue;
}
// 如果找到了就正常返回
if (uscf->host.len != name->len
|| ngx_strncasecmp(uscf->host.data, name->data, uscf->host.len)
!= 0)
{
continue;
}
*idx = i;
return duscf;
}
...
}
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