Assuming you have a file called myapp.js in the current directory that you'd like to run a Docker container with Node 10.10.0:
FROM node:10.10.0-slim
COPY ./myapp.js /app/
CMD ["node","app/myapp.js"]You can build the Dockerfile in the current directory with docker build .. If you need to pull a newer version of the images (specified as part of FROM), you can use --pull as in docker build . --pull, otherwise the images will be cached. This is usually required when using a floating tag such as latest. To specify a Dockerfile other than the default use -f such as docker build -f some-other.dockerfile .
You can pass build arguments using the --build-arg switch like this:
docker build --build-arg MY_ARG_NAME=MY_VALUE --build-arg OTHER_ARG_NAME=OTHER_VALUE .
You can pull down an image from Dockerhub or another registry using a command like: docker pull redis or docker pull jaegertracing/all-in-one. Once you have pulled down an image, you can list the images available with docker images. These images can be run using the values of the REPOSITORY, TAG, and IMAGE ID fields in the output. Consider this example output of docker images:
REPOSITORY TAG IMAGE ID CREATED SIZE
redis latest 3e42dd4e79c7 6 days ago 117MB
redis <none> 53aa81e8adfa 2 months ago 117MB
postgres 11 60a93af0bba5 6 weeks ago 284MB
jaegertracing/all-in-one latest b4407f47570d 4 weeks ago 60.4MB
jaegertracing/all-in-one <none> 5dc67a620878 2 months ago 60.3MB
jaegertracing/all-in-one <none> 115e9ce6a360 6 months ago 57.5MB
You could run the latest redis locally by repository name with the command docker run redis or docker run redis:latest. The latest tag is implied if omitted when using a name. If you wanted to run the older version of redis (from "2 months ago" in the above output), you can use the image id instead: docker run 53aa81e8adfa.
If you want to refer to a particular image id by a custom tag, you can use docker tag command. For example, if I wanted to refer to the version of redis from "2 months ago" in the above listing of docker images as the old tag, I could do that by running this command using its image id: docker tag 53aa81e8adfa redis:old. Then I could run it as docker run redis:old, and when I run docker images, it would be shown like this in the output:
REPOSITORY TAG IMAGE ID CREATED SIZE
redis old 53aa81e8adfa 2 months ago 117MB
See the docker tag documentation for more details.
You can pass environment variables to a container that you launch with docker run via -e such as docker run -e SOME_VAR=FOO. If you don't put the = then the value of your local environment variable will be passed into the container. There is also support for env files. See https://docs.docker.com/engine/reference/commandline/run for more details.
You can expose ports in a container to the host OS. For example docker run -p 127.0.0.1:5432:5432/tcp will expose port 5432 in the container to port 5432 on 127.0.0.1 of the host OS. The "local" port is first and the port as it exists in the container is second.
Once you've built a Linux-based Dockerfile, you can run bash inside it using the image hash (will be shown at the end of each successful step in the build such as Successfully built 8ecf61de9be9). The command is typically docker run -it <image> bash, though bash may be bin/bash or even something else, depending on the setup of the image. If the Dockerfile has an ENTRYPOINT step, you may have to specify bash as an entrypoint instead: docker run -it --entrypoint /bin/bash <image> . For a Windows container, use cmd as the entrypoint instead of /bin/bash.
If you run docker ps to get the container ID, you can run docker exec -it <containerid> /bin/bash .
If your container is running in Kubernetes, the command is <kubectlalias> exec [--namespace <namespaceName>] -it <pod_name> -- /bin/bash
Launch a docker-compose service in daemon mode (non-interactive)
docker-compose up -d servicename
Stop a docker-compose service.
docker-compse down
(not docker-compose, but relevant to next item)
docker volume ls
Stop services and delete named volumes and anonymous volumes attached to containers
docker-compose down -v
Delete dangling images (generally safe, and may reclaim lots of storage)
docker image prune
Delete images not used by existing containers (don't do unless you can redownload stuff that's not running!!)
docker image prune -a
I wanted to run Postgres 10.11 using the postgres:10.11 image, but I also wanted to run some configuration on server startup in order to have a user there for doing local testing. I created a Dockerfile like this:
FROM postgres:10.11
COPY ./*.sql /docker-entrypoint-initdb.d/
I had a .sql file in the same directory as the Dockerfile which was then copied into the image in a special place that causes it to be executed by the Postgres container on startup. This SQL file contained the commands to create a test user and database.
Because I didn't make a new CMD, my new container kept the CMD of the existing image, so it ran postgres on boot.
I ran docker build . to build the image. I then copied the hash of the image from the success message (was Successfully built 09ec509c3bba) and was then able to launch the container in daemon mode (allows it to run in the background and returns your console to you). I also bound localhost port 5432 to port 5432 in the container (to allow connecting to the containerized postgres from my local computer only). Final command to run:
docker run -p 127.0.0.1:5432:5432 -d 09ec509c3bba
You can see the container running via docker ps, which will also show the port mapping. You can also see the port mappings alone via docker port <container id>
Example Windows 10 Dockerfile (for Windows 10, 2020 H2) that installs Chocolatey and kubectl - (note the two different examples of RUN syntax):
FROM mcr.microsoft.com/windows:20H2
RUN ["powershell", \
"Set-ExecutionPolicy Bypass -Scope Process -Force;", \
"[System.Net.ServicePointManager]::SecurityProtocol = [System.Net.ServicePointManager]::SecurityProtocol -bor 3072;", \
"iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))"]
RUN choco install kubernetes-cli --no-progress --yes
CMD ["cmd", "/c", "dir"]
Build with docker build . just like with Linux. Once built, docker run <image> to run as a script, or docker run -it <image> cmd.exe to run interactively.
To limit the memory that a particular container will use, docker build and docker run both take a -m switch, such as -m 2GB.
To set up a volume mapped between your computer and the container, you can use -v localpath:containerpath. For a Windows container, this might be -v c:/path/on/my/computer:c:/path/in/container.