As an alternative to using a Dev Space in the SAP Business Application Studio, we are experimenting with a container based approach to your working environment. This README will guide you through the steps you need to take to work through this CodeJam inside a container, instead of inside a Dev Space on App Studio.
These steps assume you have Docker Desktop installed (as described in the Docker Desktop section of the Prerequisites document) and can execute the docker command on the command line. It also assumes you can execute the git command, to clone a repository. Don't worry if you don't have these tools or are not comfortable with these instructions, you can always just use a Dev Space which is the default for this CodeJam. If so, just head on back to the Set up your working environment section of Exercise 01.
You can download the Dockerfile from this directory directly, or just clone the whole repository and then move into the repository locally.
👉 Do the latter:
git clone https://github.com/SAP-samples/cloud-btp-cli-api-codejam.git
cd cloud-btp-cli-api-codejamJust a note on context here - you're cloning the repository here to get to the
Dockerfilein order to build your working environment. Later on, in Exercise 05, you'll be directed to clone this repository into your working environment as part of the tasks for that part of the CodeJam. Don't confuse this "outer" clone with the second clone action that you will eventually do "within" the working environment!
If you look in the Dockerfile you'll see that there are instructions for installing various command line tools including:
- the
cfCLI for working with Cloud Foundry resources - core tools such as
curl,gitandvim(andnano) - the command line JSON processor
jq - a Node.js runtime
These are all tools that are also made available automatically in a basic Dev Space in App Studio (cf actually comes from the "MTA Tools" extension) - see A basic Dev Space set up in the prerequisites). You'll also see that the executable that is invoked when a container is instantiated is bash, the Bash shell. This is the same shell that's also made available automatically for you in the terminals you invoke within a Dev Space in App Studio. There's even a line to set the shell prompt to be the same as what's shown in the Dev Space terminals.
The reason for this is that it's important to make the image's environment as similar as possible to the environment in the Dev Space so folks can work in the same way and have a similar shared experience.
With the Dockerfile in this directory, an image is built, and then you can instantiate a container from the image and work within that.
👉 Move to the directory containing the Dockerfile file, and build the image like this:
cd container
docker build -t codejam .If you see a message like this: "Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?", make sure you've started Docker Desktop.
If you're running on a MacBook with an Apple silicon (ARM architecture) chip, you'll need to add a parameter to get this to build for the x86 architecture and then macOS will take care of running the container via Rosetta:
docker build -t codejam --platform linux/amd64 .
You should see build output that looks something like this:
[+] Building 0.1s (15/15) FINISHED
=> [internal] load build definition from Dockerfile 0.0s
=> => transferring dockerfile: 37B 0.0s
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [internal] load metadata for docker.io/library/debian:11 0.0s
=> [ 1/11] FROM docker.io/library/debian:11 0.0s
=> CACHED [ 2/11] RUN apt-get update && apt-get install -y curl gpg lsb-release && apt-get clean && rm -rf /var/lib/apt/lists/* && curl -fsSL https://do 0.0s
=> CACHED [ 3/11] RUN curl -fsSL "https://packages.cloudfoundry.org/debian/cli.cloudfoundry.org.key" | apt-key add - && echo "deb https://packages.cloudfo 0.0s
=> CACHED [ 4/11] RUN apt-get update && apt-get install -y ca-certificates cf7-cli fzf git jq shellcheck vim-nox && apt-get cl 0.0s
=> CACHED [ 5/11] WORKDIR /tmp/ 0.0s
=> CACHED [ 6/11] RUN curl -fsSL "https://deb.nodesource.com/setup_lts.x" | bash - && apt-get install -y nodejs 0.0s
=> CACHED [ 7/11] RUN curl -fsSL "https://github.com/mvdan/sh/releases/download/v3.4.1/shfmt_v3.4.1_linux_amd64" -o "/usr/local/bin/shfmt" && chmod +x "/usr 0.0s
=> CACHED [ 8/11] RUN rm -rf /tmp/* 0.0s
=> CACHED [ 9/11] RUN adduser --uid 1031 --quiet --disabled-password --shell /bin/bash --home /home/user --gecos "Dev User" user && chown use 0.0s
=> CACHED [10/11] WORKDIR /home/user 0.0s
=> CACHED [11/11] RUN mkdir /home/user/projects 0.0s
=> exporting to image 0.0s
=> => exporting layers 0.0s
=> => writing image sha256:8b91a99b383b53a74b7a5797c0eb27db00e978fd0d6359274d16df409d051d8a 0.0s
=> => naming to docker.io/library/codejam 0.0s
👉 Check the image was created successfully like this:
docker image ls codejamYou should see something similar to this:
REPOSITORY TAG IMAGE ID CREATED SIZE
codejam latest 48f9875c7529 2 minutes ago 541MB
You have an image and you're all set to create your first container from it.
Now create a container from the image.
👉 Do it like this:
docker run --interactive --tty --name my-codejam-container codejamAgain, for Apple silicon macOS devices, add the
--platform linux/amd64option here too.
Don't confuse this with launching a container instance from the Docker Desktop GUI, and then using the "CLI" option on that running container. This is something quite different, not least because when you launch a container instance from the GUI, you cannot ask for
--interactiveor--ttymode, and connecting to it subsequently is in theexeccontext.
You'll be presented with a new prompt, which (if you've not worked inside containers before) may look slightly unfamiliar:
user: user $
The first user before the colon shows that your username is user and the second user in between the colon and the $ symbol shows that you're in a directory (/home/user) which has user as the most significant part of the name (this is how the prompt looks in the shell that starts up when you open a terminal in an SAP Business Application Studio Dev Space). You're not in Kansas any more, you're in a container!
Now you're in your container, you can work happily away through the exercises.
If for whatever reason (perhaps you typed exit or used Ctrl-D) you find yourself back "outside", in your host environment, and you're wondering where everything went and how to get back in, you should know that because the container was instantiated without using the --rm option (which causes the container to be automatically removed when it exits), it is actually still hanging around.
If you were to run this command:
docker container lsyou wouldn't see it:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
This is because without the use of the --all option, stopped containers are not shown. So re-run the command with this option:
docker container ls --alland it will be there:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
807eeed3cdc6 codejam "bash" 10 minutes ago Exited (0) 3 minutes ago my-codejam-container
If you have many containers and want to pick out this one, you can add a
--filteroption, like this:docker container ls --all --filter "name=my-codejam-container"
You must first restart the container:
docker start my-codejam-containerThen you can re-attach to it:
docker attach my-codejam-containerAny files you created should still be there, and you can continue.
At some point you may wish to clean up and remove your container. It might be because you've finished the CodeJam, or that you want to start over with a freshly instantiated container.
You can remove your container by name. If it's still running and you still want to remove it, you must stop it first, like this:
docker container stop my-codejam-containerThen you can remove it:
docker container rm my-codejam-containerIn case you're wondering, the long, more explicit and modern form of the docker commands are used here. For example:
docker container ls --allis used instead of
docker ps --allIn addition, options are expressed here mostly in their long form. For example:
docker run --interactive --tty --name my-codejam-container codejamis used instead of
docker run -it --name my-codejam-container codejamand
docker container ls --allis used instead of
docker container ls -aThis is simply to be more explicit as to what's going on. Feel free to use the shorter commands and options if you wish.
- Video series on Docker and containerization: 2 minutes of Cloud Native