July 13, 2021 • ––– views
Docker Linux commands
Overview
This page covers Docker specific commands on Linux. You can use it as a reference in case you want to do some task quickly, or you might find something new and beneficial when using Docker.
Docker compose
This builds the images and run their containers assuming the default compose file name is docker-compose.yml, or by specifying the file name.
Default file name
docker-compose up --build -d
Different file name
docker-compose -f docker-compose.development.yml up --build -d
More than one file. This gives you the ability to add more than one file, and docker will combine them into and single configuration. Docker will build the configuration by the order of the files supplied, so subsequent files will add configuration or override (in case the configuration directive was in two files) to their predecessors
docker-compose -f docker-compose.base.yml -f docker-compose.proxy.yml -f docker-compose.migration.yml up --build -d
Build images and run their containers while ignoring the current existing images cache (useful for multi-stage builds, when you just want to re-build everything with fresh layers)
docker-compose build --no-cache
The same as above but this time also attempt to pull the latest version of the images. The pull argument might be useless for you if your images are pinned to an exact version. For example this NodeJS image node:14.16.1-alpine specifies the major, minor and patch with the tag alpine, so the pull argument will do nothing. Meanwhile this NodeJS image node:alpine will attempt to pull the latest non-breaking changes LTS version, basically it will update the minor and patch versions.
docker-compose build --no-cache --pull
Although I said non-breaking, you never know with docker. So I always prefer the pinning to exact version and update the image myself manually. Unless ofcourse I'm too lazy to do that, then I use the second method. Which is the case in this site!
exec command
This executes a command from a container
docker exec -it node_app npm install
Exporting MySQL database
Export data from a Docker MySQL container to a directory using mysqldump and execute command
-
Full database structure and data
docker exec -i app_mysql-server-57_1 mysqldump \ -uroot -proot --databases mydb_name --skip-comments > /Documents/db.sql -
Specified table structure and data
docker exec -i app_mysql-server-57_1 mysqldump \ -uroot -proot mydb_name mytable_name > /Documents/db.sql -
Specific table structure and data that matches a where clause
docker exec app_mysql mysqldump \ -uroot -proot mydb_name --tables mytable_name --where="id>5 limit 5000000" > mytable_name.sql
SSH into a container
-
For alpine images, only sh is available
docker exec -it app_server sh -
For other images, bash is available
docker exec -it app_server bash
Testing config
Preview and validate a docker compose file configuration found in the specified path
docker-compose -f docker-compose.development.yml config
Deleting data
Delete all stopped containers and unused images/networks/volumes and non persistent volumes and their networks
WARNING: Beware that all stopped containers, and unused images/networks/volumes will be deleted, so if you have something stopped but want to use it later, or you want the image cache layers, then don't do this.
docker system prune -a
docker network prune
docker volume ls -qf dangling=true | xargs -r docker volume rm
Note: If you are using volumes managed by docker instead of bind volumes by declaring them in a docker-compose file. Beware that you might accidentally wipe the whole data by issuing the following
docker-compose down -v
down tells docker to remove all containers and images from the running compose file. -v tells docker to also wipe any managed volumes
Tailing logs
This gets you the latest 100 line from a container
docker logs --tail 100 -f app_server
This finds lines that contains a phrase and print the containing line, 3 lines before it and 3 lines after it
docker logs -f --tail 10000 app_server | grep -B3 -A3 "api/users"
System wide info
docker system info
Disk usage
docker system df -v
docker system df