10.c Perform container management using commands such as podman and skopeo

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You can use podman login [registry] and skopeo login [registry] to login to registries.

📌 EXAM TIP: If you need to execute podman {login,inspect,search} and skope [login,inspect] as another user, make sure to use SSH (and not sudo or su) otherwise it will not work.

You can list ports for a running container

# podman port [container]
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Or for all running containers

# podman port -a
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Example:

$ podman port -a
3da879abc394    8080/tcp -> 0.0.0.0:8000
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📌 EXAM TIP: Anytime you open a port, remember to also open the port with firewall-cmd

As we have seen before, some images can consume variables when you create a container

# skopeo inspect docker://registry.redhat.io/rhel8/mariadb-103 | egrep '(url|usage)'
    "io.openshift.s2i.scripts-url": "image:///usr/libexec/s2i",
    "io.s2i.scripts-url": "image:///usr/libexec/s2i",
    "url": "https://access.redhat.com/containers/#/registry.access.redhat.com/rhel8/mariadb-103/images/1-116",
    "usage": "podman run -d -e MYSQL_USER=user -e MYSQL_PASSWORD=pass -e MYSQL_DATABASE=db -p 3306:3306 rhel8/mariadb-103
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We can then create a container by feeding the variable values to podman run

# podman run -d -e MYSQL_USER=admin_user -e MYSQL_PASSWORD=my_secure_passwd -e MYSQL_DATABASE=db1 -p 3306:3306 rhel8/mariadb-103
Ac7554c6f7f8efd8a9dd93a7f9c05ec84e615c9a4902569afe08ce4fc5ed3905
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Here we confirm that the container is running and that the port is up

# podman ps
CONTAINER ID  IMAGE                                        COMMAND     CREATED         STATUS             PORTS                   NAMES
ac7554c6f7f8  registry.redhat.io/rhel8/mariadb-103:latest  run-mysqld  32 seconds ago  Up 29 seconds ago  0.0.0.0:3306->3306/tcp  distracted_chaum

# podman port -a
ac7554c6f7f8    3306/tcp -> 0.0.0.0:3306
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And successfully connect to the DB (out of scope)

# mysql -u admin_user -p -h 127.0.0.1  
Enter password:  
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 5.5.5-10.3.17-MariaDB MariaDB Server

Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| db1                |
| information_schema |
| test               |
+--------------------+
3 rows in set (0.00 sec)
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If the container was run with -i and -t, you can detach from a container and leave it running using the CTRL-p CTRL-q key sequence.

# podman rename [container] [new name]
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You can use podman exec to run commands inside a running container.

Run ps –ef | grep sql inside the 'mysql' container

# podman exec mysql ps -ef | grep sql
  |  
mysql          1       0  0 01:22 ?        00:00:00 /usr/libexec/mysqld --defaults-file=/etc/my.cnf
mysql        131       0  0 01:43 ?        00:00:00 ps -ef
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Open an interactive shell (with Bash) inside the container

[root@localhost ~]# podman exec -ti mysql /bin/bash
bash-4.4$ exit
exit
[root@localhost ~]#
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