今天前端遇到一个问题，前端部署的[反向代理]](/posts/nginx-proxy/)到后端的upstream一直pending。
timeout？#
以为是后端服务压力大，来不及响应，所以更新upstream配置，加上timeout。 立竿见影，没问题了。
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| location /api/ {
proxy_set_header Host $http_host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection 'upgrade';
rewrite ^/api/(.*)$ /$1 break;
proxy_pass http://api_server/;
proxy_connect_timeout 5s;
proxy_send_timeout 10s;
proxy_read_timeout 10s;
}
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一段时间后，后端又接受不到前端请求了，nginx一直报错499。
DNS !#
调查了一段时间后发现根本问题是nginx的dns cache机制的问题。
原来后端每次更新k8s后端deployment的时候，也会重建service从而导致 service的 IP发生了变化。
和后端沟通修改了后端更新流水线脚本，不再重建service 后，问题解决 :)
dubug#
force nginx to resolve DNS (of a dynamic hostname) everytime when doing proxy_pass?
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| server {
#...
resolver 127.0.0.1;
set $backend "http://dynamic.example.com:80";
proxy_pass $backend;
#...
}
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resolver
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| resolver 10.0.0.1;
upstream dynamic {
zone upstream_dynamic 64k;
server backend1.example.com weight=5;
server backend2.example.com:8080 fail_timeout=5s slow_start=30s;
server 192.0.2.1 max_fails=3;
server backend3.example.com resolve;
server backend4.example.com service=http resolve;
server backup1.example.com:8080 backup;
server backup2.example.com:8080 backup;
}
server {
location / {
proxy_pass http://dynamic;
health_check;
}
}
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use enviroment (not working)#
/etc/nginx/templates/*.template
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| # build stage
FROM node:lts-alpine as build-front
ARG front
WORKDIR /app
COPY package*.json ./
RUN npm config set registry https://mirrors.my-dear-company.com/npm-ok/
RUN npm install
COPY . ./
RUN npm run build
FROM nginx:stable
COPY nginx.template.conf /etc/nginx/templates/api.conf.template
COPY --from=build-front /app/build /usr/share/nginx/html
EXPOSE 80
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