Quick Docker Exec

10 February, 2022

What and why?

I use Docker a lot, and have always found it annoying that in order to run exec commands, i first need to use docker ps to look up the ID for the contrainer i’m trying to interact with.

I decided expedite this process by writing a handly little bash script, which you can check out here.

Features

Lists all running containers with custom format string
Enables container selection via text input
Passes optional script argument(s) as an exec command
If no argument is provided, attempts to acquire /bin/bash and /bin/sh shells in that order

Script parses all of the arguments given to it into a single exec command - no quotes necessary!

quickdocker.sh /bin/bash -c 'ps aux' 
# will turn into --> 
docker exec -it <POD ID> /bin/bash -c 'ps aux'

Example output

# no arguments provided, tries acquiring shells in order
$ bash quickdocker.sh 
   CONTAINER ID   IMAGE           COMMAND                  STATUS              PORTS
1) dab88fc067db   ubuntu:latest   "bash"                   Up 32 minutes   
2) 61be819285e7   beanmaster      "/entrypoint.sh"         Up 16 minutes      
3) e408febcc43d   835490db8cd7    "/docker-entrypoint.…"   Up 54 minutes   0.0.0.0:80->80/tcp, :::80->80/tcp
Container to exec: 2
Running /bin/bash
OCI runtime exec failed: exec failed: container_linux.go:380: starting container process caused: exec: "/bin/bash": stat /bin/bash: no such file or directory: unknown
/bin/bash not available in container
Running /bin/sh
~ # 

# arguments provided, attempts running them as exec command
$ bash quickdocker.sh /bin/bash -c "hostname -I"
   CONTAINER ID   IMAGE           COMMAND                  STATUS             PORTS
1) dab88fc067db   ubuntu:latest   "bash"                   Up 35 minutes      
2) 61be819285e7   beanmaster      "/entrypoint.sh"         Up 19 minutes      
3) e408febcc43d   835490db8cd7    "/docker-entrypoint.…"   Up 54 minutes   0.0.0.0:80->80/tcp, :::80->80/tcp
Container to exec: 1
Running '/bin/bash -c hostname -I'

172.17.0.5

Conclusions

This admittedly simple bash script has really improved my Docker workflow, and i hope you find it useful as well.

administrivia

Revised the script to count OUTPUT array’s indexes instead of relying on wc -l to get that information