About the problem that the container will hang up after starting nginx in the docker container

Recently tried based on nginx Made a mirror image , stay Dockerfile Call a script in , This script is used to modify... According to the parameters passed in at startup nginx Default profile , And then restart nginx service .Dockerfile It's about ：

FROM nginx:alpine
ENV backend_api_url xxx
ADD launch.sh /launch.sh
EXPOSE 80
ENTRYPOINT [ "sh", "/launch.sh" ]

then launch.sh The main content of the script is to modify nginx.conf Configuration in file , perform nginx Start command . But after writing, the deployment found that the image can build success , But when you start a container, it always fails , Tried all kinds of start-up methods, but it didn't work .

Finally, after consulting the data, we found an effective method ： Use... In scripts nginx -g "daemon off;" To start up nginx.

Principle analysis

stay docker In the container pid=1 After the process of hangs up, the whole container will hang up , Based on nginx In terms of containers , Default pid=1 This is the process of nginx, But once you are Dockerfile Use in CMD perhaps ENTRYPOINT after , The corresponding program will replace nginx Turn into pid=1 The process of , For example, in my example above launch.sh, And once the script is executed, exit , The container will stop . When using nginx -g "daemon off;" Then tell me nginx Do not exit after startup , So as to ensure the normal operation of the generated container .