Docker - Image and Process

   
   
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Table of Content

Preface

Goal: Examine docker image for docker compose.

We need to understand the difference between image and process.

Docker Image

Checking Image

Even when the process has been stopped. The docker image is still exist in your system.

You can check using docker image.

❯ docker image ls
REPOSITORY              TAG       IMAGE ID       CREATED        SIZE
composetest-web         latest    537a9d280280   21 hours ago   215MB
mysql                   5.7       0018a8d83892   12 days ago    455MB
redis                   alpine    5130e5ba7d24   2 weeks ago    29.9MB
phpmyadmin/phpmyadmin   latest    f50666f18b90   5 weeks ago    517MB

Delete One Image

You can delete the image that you don’t need.

❯ docker image rm 537a9d280280
Untagged: composetest-web:latest
Deleted: sha256:537a9d280280a459018c8148e41728c979b77509a9f516dea4c3a342ef9c3ece

For some image, the output of removing image might be a little bit longer.

❯ docker image ls
REPOSITORY              TAG       IMAGE ID       CREATED       SIZE
mysql                   5.7       0018a8d83892   12 days ago   455MB
redis                   alpine    5130e5ba7d24   2 weeks ago   29.9MB
phpmyadmin/phpmyadmin   latest    f50666f18b90   5 weeks ago   517MB
❯ docker image rm 0018a8d83892
Untagged: mysql:5.7
Untagged: mysql@sha256:9202fc6bc8fa63615e6bfc0049fc660f712d164220c5c54d86519870c305ea48
Deleted: sha256:0018a8d838923d94318aa8dd3195510226b31540901a6f4c643aacec69f7ab62
Deleted: sha256:9b5d92d35c0adf139172789ce721b36094b0ae9d82f3a9177837ebb63ab64041
Deleted: sha256:a5dcf3c1f9639ef1e0cfc9327f728d2c4bf433c6788904bcdaabc9bf801b8d95
Deleted: sha256:83ece01e2f548250a37ebb1da07201331d67e06bb75391ae2e587677795fbee1
Deleted: sha256:333192b3cc1ca102332db942aa66067c455cc086b5252817b6d2085637720e76
Deleted: sha256:e9bf9bde782fb6a391e5187979c29c4691bc35c125b94b5c4f6d898028cbd5cf
Deleted: sha256:e173168faa0ae439d00aefb5164db3e21938ecd117e67777a201a838a38590de
Deleted: sha256:474640eb47375fa6f63b7b1f955d6fbfa3bb306cc7fd6c32d9f2e6ba3773b247
Deleted: sha256:e7636df6ffe8ab322bcc32131f9c40e8e2be4bb9a97586d23ce2af39ed237f76
Deleted: sha256:42886e6940007f3f2d3b9d4006508ffd1481726af1077acfb28257e51776ce97
Deleted: sha256:f18aa902264806cbc034b3fceca35740b0d33aa6f2212cfeac8d242d36425f23
Deleted: sha256:6b4c150e3167b36440e566aa26380f5326233654cb991ed437c813b9f40c81f7

Docker Image: Remove

Delete All Images

Deleteing all image require just oneliner. But it is better to see how we do it step by step.

❯ docker image ls
REPOSITORY              TAG       IMAGE ID       CREATED       SIZE
redis                   alpine    5130e5ba7d24   2 weeks ago   29.9MB
phpmyadmin/phpmyadmin   latest    f50666f18b90   5 weeks ago   517MB
❯ docker images -a
REPOSITORY              TAG       IMAGE ID       CREATED       SIZE
redis                   alpine    5130e5ba7d24   2 weeks ago   29.9MB
phpmyadmin/phpmyadmin   latest    f50666f18b90   5 weeks ago   517MB
❯ docker images -aq
5130e5ba7d24
f50666f18b90
❯ docker ps
CONTAINER ID   IMAGE     COMMAND   CREATED   STATUS    PORTS     NAMES
❯ docker ps -aq
❯ docker rmi -f $(docker images -aq)

[...long output...]
❯ docker image ls
REPOSITORY   TAG       IMAGE ID   CREATED   SIZE

Docker Image: Remove All

The complete long output ias as below:

❯ docker rmi -f $(docker images -aq)
Untagged: redis:alpine
Untagged: redis@sha256:eda49a8747271c820ee64ae71b360154af91ab54e91dc382b6f4fa3ff9621b05
Deleted: sha256:5130e5ba7d244aa17bf8ad36f7a1ef08dff389090b42a25a3b6b6bcd22c4fb52
Deleted: sha256:42bcbd783d4639b1ba39e09f3d884016c035092d687b4c5f37fdb102346c9aea
Deleted: sha256:a79ae84c6cf7d817d478d73a99d158086b8d69e8dc704a73fa72da5a9b7b8810
Deleted: sha256:890fa9e354178f490a01777562516e38d3b4b516aa7d690353a7454ad4697680
Deleted: sha256:eaa19ca11530ff32146670b1d76ed56e9efba5e2ca62b1a52ab915f628371228
Deleted: sha256:329ac28098a660e2a85faea94f855bf543c729737af579b7b7ddf51ca757e4ec
Untagged: phpmyadmin/phpmyadmin:latest
Untagged: phpmyadmin/phpmyadmin@sha256:0d951ee3bec76c5d7083122f5db509ebfa6c209efc5e70f1d47af2e13a34f543
Deleted: sha256:f50666f18b90c95b8c7e3f2f93daa00666cc3a69204036881b79711332a628dd
Deleted: sha256:6093a43dad545c1cca199af423c5e21f804c85b0aed74ca6a16465071ec70c84
Deleted: sha256:856f01d6170c7187c517f7aa3e1eeefcba32bafd157cc4d9e7bb1957e7fc8087
Deleted: sha256:a3a5ecd3d3b3eda07e968ab297de28e26213797bc311411b7d0d1a5259f05ed1
Deleted: sha256:b31f7f6e341e4b687db40a6fdd410691b39ca7dd36ccfd72a75deabfb57e6d42
Deleted: sha256:a1a4ffacf41eaa427ea49fcf0d54828b949e75a63a9a35c3f9cf48cf358d1db4
Deleted: sha256:27c72d229c2ed4752111fcf6ff02db44c519dc3c584ccd3e6561a699d3eadf46
Deleted: sha256:2d15f6018ab0f65b3258a71c6711c463fd2f9766c973d1072de628874fa54774
Deleted: sha256:90027b1d1a269c12c87bf4be2de1b63a1410d45317033de1cbcd919eaf6558d6
Deleted: sha256:10958191be33d89418f39c8efd88d940381e9ad261381fe4bdee20521b17264d
Deleted: sha256:5f1f1a6749248aa7204470a421ff10eae69cd32bc823a4bab5008b3541535edf
Deleted: sha256:3c4183417a339f5f07e377bf25c8a526e9e8a40b8d8309797db5be020e9c6231
Deleted: sha256:e39d82c668fd1b729b122757bc9dee5a7d7fa7c1dbf357eb40d3ddf0e442070c
Deleted: sha256:c61d49ec3ffe439c30f49d9c503384b622cd707b3c485a152edc1d2f0a767a14
Deleted: sha256:dd5cc80bff5f1b7c5970b3e83bd3ff2d37c1664fa47445a67c9d6c29b80b9c3c
Deleted: sha256:b43ab0f805e45d47abff1115f5632e7d9f54eb0afa8ac4673ba9593633e6f473
Deleted: sha256:4feb79f80838285e4a63fc86b475ae43b369af78c827095981a903bcab16c4c2
Deleted: sha256:b94c14d92a9583071665f84d5050a63cc4a75c4b0a12580ee5862c206671fad3
Deleted: sha256:bd2fe8b74db65d82ea10db97368d35b92998d4ea0e7e7dc819481fe4a68f64cf

Docker Image: Remove All

Compose Up in Detail

Consider see our configuration once again, and see the pulling process in detail.

 
services:
  db:
    image: mysql:5.7
    container_name: db
    ...
  phpmyadmin:
    image: phpmyadmin/phpmyadmin
    container_name: pma
    ...
volumes:
  dbdata:

Docker Compose: Configuration

This can be done with compose up, but without running it as daemon. This will produce this long lines.

❯ docker compose up
[+] Running 3/2
 ⠿ Network dockerngadimin_default  Created                      0.0s
 ⠿ Container db                    Created                      0.0s
 ⠿ Container pma                   Created                      0.0s
Attaching to db, pma
db   | 2023-03-21 03:25:07+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 5.7.41-1.el7 started.
db   | 2023-03-21 03:25:07+00:00 [Note] [Entrypoint]: Switching to dedicated user 'mysql'
db   | 2023-03-21 03:25:07+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 5.7.41-1.el7 started.
pma  | AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.20.0.3. Set the 'ServerName' directive globally to suppress this message
db   | '/var/lib/mysql/mysql.sock' -> '/var/run/mysqld/mysqld.sock'
pma  | AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.20.0.3. Set the 'ServerName' directive globally to suppress this message
pma  | [Tue Mar 21 03:25:07.877599 2023] [mpm_prefork:notice] [pid 1] AH00163: Apache/2.4.54 (Debian) PHP/8.1.15 configured -- resuming normal operations
pma  | [Tue Mar 21 03:25:07.877691 2023] [core:notice] [pid 1] AH00094: Command line: 'apache2 -D FOREGROUND'
db   | 2023-03-21T03:25:08.009705Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
db   | 2023-03-21T03:25:08.011075Z 0 [Note] mysqld (mysqld 5.7.41) starting as process 1 ...
db   | 2023-03-21T03:25:08.015344Z 0 [Note] InnoDB: PUNCH HOLE support available
db   | 2023-03-21T03:25:08.015367Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
db   | 2023-03-21T03:25:08.015371Z 0 [Note] InnoDB: Uses event mutexes
db   | 2023-03-21T03:25:08.015375Z 0 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
db   | 2023-03-21T03:25:08.015378Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.12
db   | 2023-03-21T03:25:08.015383Z 0 [Note] InnoDB: Using Linux native AIO
db   | 2023-03-21T03:25:08.016453Z 0 [Note] InnoDB: Number of pools: 1
db   | 2023-03-21T03:25:08.017596Z 0 [Note] InnoDB: Using CPU crc32 instructions
db   | 2023-03-21T03:25:08.020348Z 0 [Note] InnoDB: Initializing buffer pool, total size = 128M, instances = 1, chunk size = 128M
db   | 2023-03-21T03:25:08.029770Z 0 [Note] InnoDB: Completed initialization of buffer pool
db   | 2023-03-21T03:25:08.031994Z 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority().
db   | 2023-03-21T03:25:08.056231Z 0 [Note] InnoDB: Highest supported file format is Barracuda.
db   | 2023-03-21T03:25:08.072076Z 0 [Note] InnoDB: Creating shared tablespace for temporary tables
db   | 2023-03-21T03:25:08.072175Z 0 [Note] InnoDB: Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ...
db   | 2023-03-21T03:25:08.101193Z 0 [Note] InnoDB: File './ibtmp1' size is now 12 MB.
db   | 2023-03-21T03:25:08.102053Z 0 [Note] InnoDB: 96 redo rollback segment(s) found. 96 redo rollback segment(s) are active.
db   | 2023-03-21T03:25:08.102063Z 0 [Note] InnoDB: 32 non-redo rollback segment(s) are active.
db   | 2023-03-21T03:25:08.102482Z 0 [Note] InnoDB: Waiting for purge to start
db   | 2023-03-21T03:25:08.152846Z 0 [Note] InnoDB: 5.7.41 started; log sequence number 12184432
db   | 2023-03-21T03:25:08.153138Z 0 [Note] InnoDB: Loading buffer pool(s) from /var/lib/mysql/ib_buffer_pool
db   | 2023-03-21T03:25:08.153353Z 0 [Note] Plugin 'FEDERATED' is disabled.
db   | 2023-03-21T03:25:08.167260Z 0 [Note] InnoDB: Buffer pool(s) load completed at 230321  3:25:08
db   | 2023-03-21T03:25:08.167432Z 0 [Note] Found ca.pem, server-cert.pem and server-key.pem in data directory. Trying to enable SSL support using them.
db   | 2023-03-21T03:25:08.167458Z 0 [Note] Skipping generation of SSL certificates as certificate files are present in data directory.
db   | 2023-03-21T03:25:08.167463Z 0 [Warning] A deprecated TLS version TLSv1 is enabled. Please use TLSv1.2 or higher.
db   | 2023-03-21T03:25:08.167466Z 0 [Warning] A deprecated TLS version TLSv1.1 is enabled. Please use TLSv1.2 or higher.
db   | 2023-03-21T03:25:08.171487Z 0 [Warning] CA certificate ca.pem is self signed.
db   | 2023-03-21T03:25:08.171537Z 0 [Note] Skipping generation of RSA key pair as key files are present in data directory.
db   | 2023-03-21T03:25:08.172057Z 0 [Note] Server hostname (bind-address): '*'; port: 3306
db   | 2023-03-21T03:25:08.172362Z 0 [Note] IPv6 is available.
db   | 2023-03-21T03:25:08.172378Z 0 [Note]   - '::' resolves to '::';
db   | 2023-03-21T03:25:08.172398Z 0 [Note] Server socket created on IP: '::'.
db   | 2023-03-21T03:25:08.173953Z 0 [Warning] Insecure configuration for --pid-file: Location '/var/run/mysqld' in the path is accessible to all OS users. Consider choosing a different directory.
db   | 2023-03-21T03:25:08.209210Z 0 [Note] Event Scheduler: Loaded 0 events
db   | 2023-03-21T03:25:08.209483Z 0 [Note] mysqld: ready for connections.
db   | Version: '5.7.41'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  MySQL Community Server (GPL)

I split the output into two:

Docker Compose: Up: Top

Docker Compose: Up: Bottom

Process

We can stop the process by issuing this command.

^CGracefully stopping... (press Ctrl+C again to force)
Aborting on container exit...
[+] Running 2/2
 ⠿ Container pma  Stopped                                       1.3s
 ⠿ Container db   Stopped                                       1.8s
canceled

Docker Compose: Stop

After the process stopped, we can check that the image is still persist.

❯ docker ps -a --format 'table {{.Image}}\t{{.Names}}\t{{.Status}}'
IMAGE                   NAMES     STATUS
phpmyadmin/phpmyadmin   pma       Exited (0) 3 minutes ago
mysql:5.7               db        Exited (0) 3 minutes ago

Docker Compose: Process

Or even shorter

❯ docker ps -a --format 'table {{.Names}}\t{{.Status}}'
NAMES     STATUS
pma       Exited (0) 2 minutes ago
db        Exited (0) 2 minutes ago

Docker Compose: Process

Prune

We can even prune the system or the image.

System Prune

❯ docker system prune
WARNING! This will remove:
  - all stopped containers
  - all networks not used by at least one container
  - all dangling images
  - all dangling build cache

Are you sure you want to continue? [y/N] y
Deleted Containers:
2763d8c19f8dfbd9cf9470311ab41313142423785eed3b464f9fada4b5513038
649718f6dd723ab227d7a69428e7a76e128b3265b160167e4acf2a0e61ebd9b6

Deleted Networks:
dockerngadimin_default

Total reclaimed space: 68B

Image Prune

❯ docker image prune
WARNING! This will remove all dangling images.
Are you sure you want to continue? [y/N] y
Total reclaimed space: 0B

I think that’s all.

What is Next 🤔?

How about setup LAMP in classic technique. Using the native system. We are going to start with setting MariaDB. Then Apache+PHP. And finally test with PHPMyAdmin.

Consider continue reading [ LAMP - MariaDB Setup ].

Thank you for reading.