NickPGSmith at 11:43, 12 February 2026

2026-02-12T11:43:25Z

← Older revision		Revision as of 11:43, 12 February 2026
Line 13:		Line 13:
	dnf install docker		dnf install docker
	systemctl start docker		systemctl start docker

			Login:
			docker login docker.io

	Control images:		Control images:

NickPGSmith: 2 revisions imported

2024-05-08T04:53:33Z

2 revisions imported

← Older revision		Revision as of 04:53, 8 May 2024
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NickPGSmith: 1 revision imported

2023-02-17T21:02:05Z

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NickPGSmith: /* Push image */

2022-05-30T19:56:15Z

Push image

New page

== General ==

* [https://hub.docker.com/ Docker Hub]
* [https://docs.docker.com/reference/ Docker Docs]
* [https://docs.docker.com/engine/reference/commandline/cli/ Docker command] reference
* [https://docs.docker.com/network/ Docker networking]
* [https://docs.docker.com/engine/reference/builder/ Dockerfile] reference
* Images:
** [https://hub.docker.com/_/alpine Alpine] Linux
** [https://hub.docker.com/_/fedora Fedora] Linux

Install/start docker
dnf install docker
systemctl start docker

Control images:
docker pull <name>
docker image ls
docker image rm <image>

Control containers:
* run creates a container from an image
* capture container stdin with -it
* map host filesystem into container in readonly mode and an SELinux label
docker run --name fedora -it --volume /home/docker:/mount:ro,Z fedora

* each container has its own network: need to bind container ports to host ports
docker run --name nginx -p 8080:80 -v /home/html:/usr/share/nginx/html:ro,Z nginx

docker start -d <container>
docker stop <container>
docker rm <container>
docker ps
docker ps -a
docker port <container>

== Networking ==

Network types:
* Bridge (default) : on separate 172. network
* host : no network isolation
* none : completely isolated
* ipvlan
* macvlan

Containers can communicate with a bridge network by IP, or better via built-in DNS (via container name) as long as the bridge network is named.

Show network drivers:
docker network ls

Show gateway and IPs that the containers have:
docker network inspect bridge

Create NewNetwork:
docker network create --driver bridge --subnet 192.168.7.0/24 NewNetwork

== Storage ==

on host, in /var/lib/docker
* containers
* image
* volumes

Data is copy-on-write to the container, and never updates the underlying image, so gets lots when the container is destroyed.

Create a volume (in volumes):
docker volume create NewVol

Volume Mount for MySQL container:
docker run -v NewVol:/var/lib/mysqql mysql

Bind Mount to anywhere on the host filesystem with full path:
docker run -v /data/MySQL:/var/lib/mysqql mysql

But the preferred way is:
--mount type=bind,source=/data/MySQL,target=/var/lib/mysql

== Create an image ==

Dockerfile:
# Some comment
FROM baseimage:tag
LABEL org.opencontainers.image.authors="me@example.com"
LABEL version="1.0"
WORKDIR /data
COPY somefile .
ENV PORT 8088
RUN somecommand
ENTRYPPOINT ["python", "manage.py", "runserver"]
CMD ["echo", "Hello World!]

Build:
docker build --rm -t name:tag .

=== Entrypoints / Commands ===

* ENTRYPOINT defines the command that is run as PID 1
* CMD adds options to it the entrypoint. If ENTRYPOINT is not specified, "/bin/sh -c" is assumed
* Anything added after image name in "docker run" command is treated as CMD arguments

=== Environment Variables ===

Pass into docker run:
docker run -e DBUSER=dbuser -e DBPORT=5432 <container>

Or using a value so it doesn't appear on process list:
docker run -e DBUSER=dbuser -e DBPASS <container>

Or from a file:
docker run --env-file ./env_vars

== Push image ==

* Create a repository on [https://hub.docker.com/ Docker Hub], someuser/somerepo

When building a local image use the tag "someuser/somerepo", or tag an existing local image "local-image" with the dockerhub tag:
docker tag local-image someuser/somerepo

Login to docker (credential store in /root/.docker/config.json):
docker login

Push the image to dockerhub (tagname defaults to latest):
docker push someuser/somerepo:tagname

Push a new image:
docker tag local-image:tagname somerepo:tagname
docker push somerepo:tagname

== Debugging ==

Look at stdout from PID 1:
docker logs -f <container>
File is stored on host (see inspect for path) until container is removed. Has options -f and -n which act like tail.

Attach terminal to container (CTRL-p CTRL-q to exit) and see stdout:
docker attach <container>

Start an interactive shell into the container:
docker exec -it <container> /bin/bash

Pause/unpause:
docker pause <container>
docker unpause <container>

See top for a container or stats for all containers on a host:
docker top container
docker stats

See container definition/state (JSON):
docker inspect <container>

especially:
* Current state of the container. in the “State” property
* Path to the log history file, in the “LogPath” field
* Values of set environment vars, in the “Config.Env” field
* Mapped ports, in the “NetworkSettings.Ports” field

Show container history:
docker history <container>

Override ENTRYPOINT:
docker run -d -p 80:80 --entrypoint /bin/sh /myrepo/mydjangoapp

== Docker Compose ==

TBC

Docker - Revision history

NickPGSmith at 11:43, 12 February 2026

NickPGSmith: 2 revisions imported

NickPGSmith: 1 revision imported

NickPGSmith: /* Push image */