A Technical I.T./DevOps Blog
Problem scenario
The server you have is a RHEL (RedHat Enterprise Linux) or Ubuntu instance. You are in a Docker container that you pulled from the internet for Nginx. Inside this Docker container you cannot use vi because it is not a recognized command. What do you do to install a text editor in the Docker container?
Solution for non-SUSE Linux
#1 Inside the Docker container,
…
Continue reading “How Do You Edit Text inside a Docker Container?”
Problem scenario
Normally the Nginx web service logs operations (e.g., a user going to a website with a web browser). By default Nginx Docker containers do not have good logging for web server usage. You want regular Nginx logging inside the Docker container. What do you do?
Solution
1. Go inside the Docker container (e.g., docker exec -it <containerName> bash). Go to /etc/nginx/
2.
…
Problem scenario
You have inherited several Docker containers to manage. They were assigned IP addresses and assigned user-defined networks when they were created. You do not know what IP addresses that they were given. You want to know the IP addresses so you can add them to a load balancer. The external IP address of the Docker host combined with identifying port numbers of the containers can create sockets that are unique.
…
Problem scenario
You are trying to create a Docker image and assign it an IP address with the –ip flag. But you get this error: “/usr/bin/docker-current: Error response from daemon: User specified IP address is supported only when connecting to networks with user configured subnets.” How do you get your Docker command to work and resolve this problem?
Solution
#1 From the Linux server,
…
Problem scenario
You want to deploy Apache Tomcat in a Docker container on an AWS instance of Ubuntu Linux. How do you do this?
Solution
1. Install Docker. See this link if you need assistance.
2. Start the Docker service with this command: sudo service docker start
3. Run these two commands:
docker pull consol/tomcat-8.0
docker run consol/tomcat-8.0
4.
…
Updated on 11/7/17
Problem scenario
You want a computer server (e.g., an AWS instance) to be a reverse proxy (a type of landing page users do not see that acts as a portal). You want it to relay traffic to other IP addresses. How do you get a server with Docker to distribute traffic to other IP endpoints?
Solution
Prerequisites
This assumes that Docker has already been installed.
…
Continue reading “How Do You Configure Nginx in a Docker Container to Be an HTTP Load Balancer?”
Problem scenario
You want web page refreshes to happen more quickly for your website when a user clicks “Reload” in her web browser. The website you manage is powered by Nginx configured as an HTTP load balancer (aka a reverse proxy). This Nginx configuration is in a Docker container too. The rule you want is that clients’ inbound connection requests from a specific IP address should be relayed to the same Nginx server every time that client reloads the web page in the web browser.
…
Problem scenario
You are using Nginx as a reverse proxy (a server that is essentially a landing page that is invisible to users and passes connection requests to other web servers like a router). You noticed that when you added the “ip_hash;” directive in the “upstream server {}” section (also known as a block) of the /etc/nginx/conf.d/default.conf file, you lose the Docker container. That is if you stop the Docker container once the Nginx default.conf file has this “ip_hash;” directive,
…
Problem scenario
To improve performance of your HTTP load balancing mechanism, you want to configure how failed members of the load balancer are dealt with. Some Nginx instances may fail in your environment. You do not want attempts to send web traffic to these instances immediately after several failures. How do you granularly keep track of failed attempts and remove the instance from the distribution algorithm after a certain limit has been reach to improve performance by attempting only more reliable instances?
…
Problem scenario
You want to create several Docker containers each supporting Nginx. You want to be able to browse to the different instances of Nginx from a web browser. How do you have multiple Docker containers support Nginx on one RedHat Enterprise Linux host server?
Solution
These directions are geared toward a RHEL host server instance in AWS.
#1 Install Docker.
…