Nginx – Copy files from /var/www/html while they are used by nginx

copycpdockernginx

I have a lot of data in /var/www/html.
It's more than 2GB.
Now I have the possibility to host the website on the host (nginx is using /var/www/html) or I can use docker.

For the user of docker I am copying the content of /var/www/html to another folder (src/) and I mount src/ inside my container:

Steps:

stop nginx
copy files /var/www/html --> xxx/src/
start docker

The copy takes some minutes so there is some downtime.
Is it a bad idea to do the following:

copy files /var/www/html --> xxx/src/ (while nginx is running)
stop nginx
start docker

Can there be an issue?

Best Answer

It entirely depends on your use-case. Let me try to describe the possible scenarios and corresponding solutions.

If the data doesn't change fast or doesn't grow in size during the time it gets copied to another location, then there is no need to worry about the state (running / stopped) of the web server. Just copy the data and then switch the web server (from Nginx to Apache / Docker, for example).

If the data only grows in size (rather than change of content), then you may use rsync a couple of times before switching the web server. For the first time, rsync would copy the entire data (2GB or whatever). When rsync runs the second time, it'd only copy the new data (that was added when rsync was run the first time). In this situation, you'd want to stop the web server when rsync was run the second time. In this way, you'd minimize the downtime. It takes very less time to copy the newly added data than copying the entire data.

If the data changes (rather than grow in size), then you should definitely stop, copy and then start the web server.

If the data changes and also grows in size, then you should certainly stop, copy and then start the server too.

Whatever your scenario is, I highly recommend using rsync to reduce the downtime by copying most of the existing data to the new location.

I hope that helps.

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How does Docker work as far as being able to edit Apache config files and similar stuff?

Pretty much however you would like it to work. :)

If I understand correctly this is to allow outside folder/files of websites to exist on the server outside of the Docker image so that Docker is basically just to handle the actual server software?

Yes, that's correct.

Would things like Apache Virtualhost records for adding domains exist inside the docker image or on the server outside of it and be editable?

If you want/need them to exist outside the container, then build it that way.

As you've no doubt noticed, my answers to your questions have been fairly nebulous. There's a good reason for that. Just because you're using docker doesn't mean that there is one single good way to do things. Your use case will dictate to a large degree how you want to use docker.

In my environment, we have chosen to store all configuration and all application state outside of the container. For configuration, that means that we maintain an "etc" directory on the host that contains all configuration for each type of container running on that host. Likewise, we store state (database files, etc.) on the host's filesystem instead of using data volumes. Both configuration directories and data storage locations are mounted into running containers using the -v runtime flag. This architecture has worked out very well for us, but it may not be what your organization needs.

There are plenty of valid use cases for using completely self-contained docker images that include configuration, along with using data volumes for application state. You'll just need to enumerate your requirements and then work out a design that fulfills your requirements.

Docker is a tool for you to use. It's up to the user to determine how they're going to use it.

Docker stack deploy without downtime

You should put restart policy and stop_grace_period on your compose file:

version: "3.1"
services:
    web:
        stop_grace_period: 10s
        deploy:
             replicas: 2
             restart_policy:
               condition: on-failure

Best Answer

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