Debug Commands

AsafsMacBook:~ aahmadov$ docker ps -a
CONTAINER ID   IMAGE                    COMMAND                  CREATED          STATUS                        PORTS      NAMES
b7421b65d01a   redis:4.0                "docker-entrypoint.s…"   6 minutes ago    Up 6 minutes                  6379/tcp   quizzical_wilson
9e0452128f10   redis:latest             "docker-entrypoint.s…"   6 minutes ago    Up 6 minutes                  6379/tcp   strange_jones

Fetch the logs of a container

AsafsMacBook:~ aahmadov$ docker logs b7421b65d01a
1:C 28 May 14:04:15.360 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
1:C 28 May 14:04:15.360 # Redis version=4.0.14, bits=64, commit=00000000, modified=0, pid=1, just started
1:C 28 May 14:04:15.360 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
1:M 28 May 14:04:15.361 * Running mode=standalone, port=6379.
1:M 28 May 14:04:15.362 # Server initialized
1:M 28 May 14:04:15.362 # WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis. To fix this issue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain the setting after a reboot. Redis must be restarted after THP is disabled.
1:M 28 May 14:04:15.362 * Ready to accept connections

Assign a name to the container

AsafsMacBook:~ aahmadov$ docker run -d -p6000:6060 --name redis-old redis:4.0
cdcf56d4b7ba38b56f382e0ad6421cf72e267025a1a485d371ec8f97f7c49039

AsafsMacBook:~ aahmadov$ docker logs redis-old
1:C 28 May 15:20:06.472 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
1:C 28 May 15:20:06.472 # Redis version=4.0.14, bits=64, commit=00000000, modified=0, pid=1, just started
1:C 28 May 15:20:06.473 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
1:M 28 May 15:20:06.473 * Running mode=standalone, port=6379.
1:M 28 May 15:20:06.474 # Server initialized
1:M 28 May 15:20:06.474 # WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis. To fix this issue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain the setting after a reboot. Redis must be restarted after THP is disabled.
1:M 28 May 15:20:06.474 * Ready to accept connections

Run a command in a running container

AsafsMacBook:~ aahmadov$ docker ps
CONTAINER ID   IMAGE          COMMAND                  CREATED             STATUS             PORTS                              NAMES
cdcf56d4b7ba   redis:4.0      "docker-entrypoint.s…"   11 minutes ago      Up 11 minutes      6379/tcp, 0.0.0.0:6000->6060/tcp   redis-old
b7421b65d01a   redis:4.0      "docker-entrypoint.s…"   About an hour ago   Up About an hour   6379/tcp                           quizzical_wilson
9e0452128f10   redis:latest   "docker-entrypoint.s…"   About an hour ago   Up About an hour   6379/tcp                           strange_jones
AsafsMacBook:~ aahmadov$ docker exec -it cdcf56d4b7ba /bin/bash
root@cdcf56d4b7ba:/data# pwd
/data
root@cdcf56d4b7ba:/data# whoami
root
root@cdcf56d4b7ba:/data# 

Ports in Docker

▪ Multiple containers can run on your host machine

Problem:

▪ Your laptop has only certain ports available

▪ Conflict when same port on host machine, so we need to map to a free port on host machine: