Passing Host vs. Container Environment Variables to docker exec

Take a look at below example, on how to use environment variable from host machine vs. container while running _docker exec_:

# pull the image
docker pull goyalmunish/devenv

# fetching env. variable from host machine
docker exec -it devenv /bin/bash -c "echo $HOME"      # /home/ubuntu
# fetching env. variable from container
# use single quotes to escape parsing of environment variable from host machine itself
docker exec -it devenv /bin/bash -c 'echo $HOME'      # /root

As we can see, the first case passes host’s environment variable as part of the command, whereas the second case uses container’s environment variable are used.

…and this is obvious if you recall the difference between bash’s single quotes (full-quoting) and double quotes (partial-quoting).

#docker-cli #environment-variables #docker #bash #exec

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Passing Host vs. Container Environment Variables to docker exec

Passing Host vs. Container Environment Variables to docker exec

Take a look at below example, on how to use environment variable from host machine vs. container while running _docker exec_:

# pull the image
docker pull goyalmunish/devenv

# fetching env. variable from host machine
docker exec -it devenv /bin/bash -c "echo $HOME"      # /home/ubuntu
# fetching env. variable from container
# use single quotes to escape parsing of environment variable from host machine itself
docker exec -it devenv /bin/bash -c 'echo $HOME'      # /root

As we can see, the first case passes host’s environment variable as part of the command, whereas the second case uses container’s environment variable are used.

…and this is obvious if you recall the difference between bash’s single quotes (full-quoting) and double quotes (partial-quoting).

#docker-cli #environment-variables #docker #bash #exec

Iliana  Welch

Iliana Welch

1595249460

Docker Explained: Docker Architecture | Docker Registries

Following the second video about Docker basics, in this video, I explain Docker architecture and explain the different building blocks of the docker engine; docker client, API, Docker Daemon. I also explain what a docker registry is and I finish the video with a demo explaining and illustrating how to use Docker hub

In this video lesson you will learn:

  • What is Docker Host
  • What is Docker Engine
  • Learn about Docker Architecture
  • Learn about Docker client and Docker Daemon
  • Docker Hub and Registries
  • Simple demo to understand using images from registries

#docker #docker hub #docker host #docker engine #docker architecture #api

Mikel  Okuneva

Mikel Okuneva

1602317778

Ever Wondered Why We Use Containers In DevOps?

At some point we’ve all said the words, “But it works on my machine.” It usually happens during testing or when you’re trying to get a new project set up. Sometimes it happens when you pull down changes from an updated branch.

Every machine has different underlying states depending on the operating system, other installed programs, and permissions. Getting a project to run locally could take hours or even days because of weird system issues.

The worst part is that this can also happen in production. If the server is configured differently than what you’re running locally, your changes might not work as you expect and cause problems for users. There’s a way around all of these common issues using containers.

What is a container

A container is a piece of software that packages code and its dependencies so that the application can run in any computing environment. They basically create a little unit that you can put on any operating system and reliably and consistently run the application. You don’t have to worry about any of those underlying system issues creeping in later.

Although containers were already used in Linux for years, they became more popular in recent years. Most of the time when people are talking about containers, they’re referring to Docker containers. These containers are built from images that include all of the dependencies needed to run an application.

When you think of containers, virtual machines might also come to mind. They are very similar, but the big difference is that containers virtualize the operating system instead of the hardware. That’s what makes them so easy to run on all of the operating systems consistently.

What containers have to do with DevOps

Since we know how odd happenings occur when you move code from one computing environment to another, this is also a common issue with moving code to the different environments in our DevOps process. You don’t want to have to deal with system differences between staging and production. That would require more work than it should.

Once you have an artifact built, you should be able to use it in any environment from local to production. That’s the reason we use containers in DevOps. It’s also invaluable when you’re working with microservices. Docker containers used with something like Kubernetes will make it easier for you to handle larger systems with more moving pieces.

#devops #containers #containers-devops #devops-containers #devops-tools #devops-docker #docker #docker-image

Iliana  Welch

Iliana Welch

1597368540

Docker Tutorial for Beginners 8 - Build and Run C++ Applications in a Docker Container

Docker is an open platform that allows use package, develop, run, and ship software applications in different environments using containers.
In this course We will learn How to Write Dockerfiles, Working with the Docker Toolbox, How to Work with the Docker Machine, How to Use Docker Compose to fire up multiple containers, How to Work with Docker Kinematic, Push images to Docker Hub, Pull images from a Docker Registery, Push stacks of servers to Docker Hub.
How to install Docker on Mac.

#docker tutorial #c++ #docker container #docker #docker hub #devopstools

What is Docker Container? Learn Docker Vs Container Vs VM

In this video we will answer a critical question - what is docker? What is container? What is the difference between Docker Vs Container Vs Virtual Machine (VM)? We will also look at the full application flow of docker contrainer, and some advantages of Docker Container. Timestamps below:

TIMESTAMPS

00:00 - Docker basics
02:40 - Docker Vs Container
03:14 - Flow of Docker to running application
05:00 - VM Vs Container
06:40 - Advantages of Docker Container

#Docker #Docker Container #VM

#docker #docker container #vm