Docker Usage Issues

This article offers solutions for various Docker-related problems, including reducing image size, diagnosing and resolving connectivity issues, managing volumes effectively, and assigning IP addresses to containers. It further explains how to determine the IP address of a container using the `docker inspect` command, which can be useful when communicating without port mappings.

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use slim toolkit to shrink docker image size

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with iptable, you can constrain docker container network

sudo iptables -I DOCKER-USER -d <ip_range> -j DROP

it does not work if you block all local ip ranges.

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to use host provided proxy servers, one can set environment variables before running containers.

docker run -e http_proxy=<proxy_addr> -e https_proxy=<proxy_addr> -e all_proxy=<proxy_addr> -e no_proxy=<bypass_addrs>

or better, use tun2proxy (linux only)

run server:

docker run -d -v /dev/net/tun:/dev/net/tun --sysctl net.ipv6.conf.default.disable_ipv6=0 --cap-add NET_ADMIN --name tun2proxy tun2proxy --proxy <proto>://[username[:password]@]host:port

container forced to use proxy:

docker run -it --network "container:tun2proxy" <image_name>[:tag]

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with docker for mac, you can use the following domain name to get host and gateway ip:

• host.docker.internal

• gateway.docker.internal

for podman:

• host.containers.internal

• gateway.containers.internal

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latest docker mirror:

https://zhuanlan.zhihu.com/p/704011584

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login mysql with empty password then execute command to make it remotely available:

mysql -uroot --password= -e "grant all privileges on *.* to root@'%' identified by '' with grant option; commit;"

create volume and attach volume to container, since containers will be reset after system restarts.

docker volume create <volume_name>
docker run -it -d --rm -v <volume_name>:<container_mountpoint> --name <container_name> <image_name>
docker volume inspect <volume_name> # get info on created volume

when using mindsdb, it sucks because having bad pypi mirrors.

set pip index url globally:

pip config set global.index-url https://pypi.tuna.tsinghua.edu.cn/simple

or pass it as environment variable:

docker run -it -d -e PIP_INDEX_URL=https://pypi.tuna.tsinghua.edu.cn/simple -n <container_name> <image_name>

if you want to save container states into images, use docker commit <container_name> <image_name>[:image_tag]

Keep in mind that the docker commit command only saves the changes made to a container’s file system. It does not save any changes made to the container’s settings or network configurations. To save all changes made to a container, including settings and network configurations, you can use the docker export and docker import commands instead.

when exporting ports, if not specifying host ip, you cannot reach the service inside the container. do this instead: docker run -p 0.0.0.0:<host_port>:<container_port> <rest_commands>

it seems to be the proxy (fastgithub). disable http proxy so we can connect to container again, or use clash to make rules to let “localhost” or subnet requests passing through.

if you want to change ip routings or some other configurations passed when docker run, you need to change the file called hostconfig.json located in /var/lib/docker/containers/<container_id> with PortBindings sections. you stop the container first. find and change the config file then start it. tutorial

seems not working. fuck.

"PortBindings": {
"80/tcp": [
{
"HostPort": "8080"
}
],
}

containers can only contact each other if they share the same network. better give unique ip for each container within same network. it can also use container name as host name instead of static ip. tutorial

create a network (not overlapping with anything shown in ifconfig, notice the subnet mask):

docker network create --subnet=172.18.0.0/16 <network_name>

start container with given network (again not overlapping with addresses in ifconfig, not the starting address):

docker run --rm -d -it --net <network_name> --ip <ipaddress> --name <container_name>

to check what ip the container is at:

docker inspect <container_id/container_name> | grep IPAddress

now you might can talk to the container without port mappings.