Docker Cheat Sheet
Mithun Technologies Bangalore +91-9980923226, +91-8296242028
Docker Cheat Sheet
Introduction
Containers allow the packaging of your application (and everything that you need to run it) in a
"container image". Inside a container you can include a base operational-system, libraries, files
and folders, environment variables, volumes mount-points, and the application binaries.
A "Docker image" is a template for the execution of a container --- It means that you can have
multiple containers running from the same image, all sharing the same behavior, which
promotes the scaling and distribution of the application. These images can be stored in a remote
registry to ease the distribution.
Once a container is created, the execution is managed by the "Docker Engine" aka "Docker
Daemon". You can interact with the the Docker Engine through the "docker" command. These
three primary components of Docker (client, engine and registry) are diagramed below:
Docker Cheat Sheet
Mithun Technologies Bangalore +91-9980923226, +91-8296242028
Docker Engine
Container related commands
docker [CMD] [OPTS] CONTAINER
Examples:
All examples provided here work in RHEL
1. Run a container in interactive mode:
$ docker run -it ubuntu /bin/bash # Run a bash shell inside an image
2. Run a container in detached mode:
$ docker run --name mywildfly -d -p 8080:8080 jboss/wildfly
3. Run a detached container in a previously created docker network:
$ docker network create mynetwork
$ docker run --name mywildfly-net -d --net mynetwork -p 8080:8080 jboss/wildfly
4. Run a detached container mounting a local folder inside the container:
$ docker run --name mywildfly-volume -d \
-v myfolder/:/opt/jboss/wildfly/standalone/deployments/ \
-p 8080:8080 jboss/wildfly
5. Follow the logs of a specific container
$ docker logs -f mywildfly
$ docker logs -f <container-name>
6. List containers
$ docker ps # List only active containers
$ docker ps -a # List all containers
7. Stop a container
$ docker stop <container-name> # Stop a container
$ docker stop -t 1 <container-name> # Stop a container (timeout = 1 second)
8. Remove a container
$ docker rm <container-name> # Remove a stopped container
Docker Cheat Sheet
Mithun Technologies Bangalore +91-9980923226, +91-8296242028
$ docker rm -f <container-name> # Remove a stopped container. Force stop if it is active
$ docker rm -f $(docker ps -aq) # Remove all containers
$ docker rm $(docker ps -q -f "status=exited”) # Remove all stopped containers
9. Execute a new process in an existing container
$ docker exec -it mywildfly /bin/bash # Executes and access bash inside a WildFly container
attach Attach a running container to view its ongoing output or to control it
interactively
commit Create a new image from a container’s changes
cp Copy files/folders between a container and the local filesystem
create Create a new container
diff Inspect changes on a container’s filesystem
exec Run a command in a running container
export Export the contents of a container’s filesystem as a ‘.tar’ archive
kill Kill a running container using SIGKILL or a specified signal
logs Fetch the logs of a container
pause Pause all processes within a container
port List port-mappings, or lookup the public-facing port that is NAT-ed to the
PRIVATE_PORT
ps List all containers
rename Rename a container
restart Restart a container
rm Remove/delete one or more containers
run Run a command in a new container
start Start one or more containers
stop Stop a container by sending SIGTERM then SIGKILL after a grace
Docker Cheat Sheet
Mithun Technologies Bangalore +91-9980923226, +91-8296242028
period.
top Display the running processes of a container
unpause Unpause all processes within a container
Image related commands
docker [CMD] [OPTS] IMAGE
Examples
1. Build an image using a Dockerfile
$ docker build -t [username/]<image-name>[:tag] <dockerfile-path> # Build an image
$ docker build -t myimage:latest . # Build an image called myimage using the
Dockerfile in the same folder where the command was executed.
2. Check the history of an image
$ docker history jboss/wildfly #Check the history of the jboss/wildfly image
$ docker history [username/]<image-name>[:tag] # Check the history of an image
3. List the images
$ docker images
4. Remove an image from the local registry
$ docker rmi [username/]<image-name>[:tag]
5. Tag an image
$ docker tag jboss/wildfly myimage:v1 # Creates an image called
"myimage" with the tag "v1" for the image jboss/wildfly:latest
$ docker tag <image-name> <new-image-name> # Creates a new image with
the latest tag
Docker Cheat Sheet
Mithun Technologies Bangalore +91-9980923226, +91-8296242028
$ docker tag <image-name>[:tag] [username/]<new-image-name>[:new-tag] # Creates a
new image specifying the "new tag" from an existing image and tag.
6. Exporting and Importing and image to an external file
$ docker save -o <filename>.tar [username/]<image-name>[:tag] # Export the image to an
external file
$ docker load -i <filename>.tar # Import an image from an external file
7. Push an image to a registry.
$ docker push [registry/][username/]<image-name>[:tag]
build Build Docker images from a Dockerfile
history Show the history of an image
images List images
import Create an empty filesystem image and import the contents of the tarball
into it
inspect Return low-level information on a container or image
load Load an image from a ‘.tar’ archive or STDIN
pull Pull an image or a repository from the registry
push Push an image or a repository to the registry
rmi Remove one or more images
save Save one or more images to a ‘.tar’ archive (streamed to STDOUT by
default)
search Search the Docker registry for images
tag Tag an image into a repository
Network related commands
docker network [CMD] [OPTS]
connect Connects a container to a network
create Creates a new network with the specified name
Docker Cheat Sheet
Mithun Technologies Bangalore +91-9980923226, +91-8296242028
disconnect Disconnects a container from a network
inspect Displays detailed information about on a network
ls Lists all the networks created by the user
rm Deletes one or more networks
Registry related commands
Default is https://index.docker.io/v1/
login Log in to a Docker registry server. If no server is specified, then the
default is used
logout Log out from a Docker registry server. If no server is specified then the
default is used.
Volume related commands
docker volume [CMD] [OPTS]
create Create a volume
inspect Return low-level information on a volume
ls List volumes
rm Remove a volume
Related commands
docker events Get real-time information from the server
docker info Display system-wide information
docker version Show the docker version information
systemctl status Check if the docker service is running
docker
Docker Cheat Sheet
Mithun Technologies Bangalore +91-9980923226, +91-8296242028
Dockerfile
The Dockerfile provides the instructions to build a container image through the `docker build -t
[username/]<image-name>[:tag] <dockerfile-path>` command. It starts from a previous existing
Base image (through the FROM clause) followed by any other needed Dockerfile instructions.
This process is very similar to a compilation of a source code into a binary output, but in this
case the output of the Dockerfile will be a container image.
Example Dockerfile
# Use the existing WildFly image
FROM jboss/wildfly
# Add an administrative user
RUN /opt/jboss/wildfly/bin/add-user.sh admin Admin#70365 --silent
#Expose the Administrative port
EXPOSE 8080 9990
# Bind the WildFly management to all IP addresses
CMD ["/opt/jboss/wildfly/bin/standalone.sh", "-b", "0.0.0.0", "-bmanagement", "0.0.0.0"]
Using the example Dockerfile
# Build the WildFly image
$ docker build -t mywildfly .
# Run a WidFly server
$ docker run -it -p 8080:8080 -p 9990:9990 mywildfly
# Access the WildFly administrative console and log in with the
credentials admin/Admin#70365
open http://<docker-daemon-ip>:9990 in a browser
Dockerfile INSTRUCTION arguments
FROM Sets the Base image for subsequent instructions
Docker Cheat Sheet
Mithun Technologies Bangalore +91-9980923226, +91-8296242028
MAINTAINER Sets the author field of the the generated images
RUN Executes commands in a new layer on top of the current image and
commits the results
CMD Allowed only once (if many, then only the last one takes effect)
LABEL Adds metadata to an image
EXPOSE Informs Docker that the container listens on the specified network ports
at runtime.
ENV Sets an environment variable
ADD Copies new files, directories or remote file URLs into the filesystem of
the container
COPY Copies new files or directories into the filesystem of the container
ENTRYPOINT Allows you to configure a container that will run as an executable
VOLUME Creates a mount point and marks it as holding externally mounted
volumes from native host or other containers
USER Sets the user name or UID to use when running an image
WORKDIR Sets the working directory for any RUN, CMD, ENTRYPOINT, COPY,
and ADD commands
ARG Defines a variable that users can pass at build-time to the builder using
--build-arg
ONBUILD Adds an instruction to be executed later, when the image is used as the
base for another build
