docker-compose build出来なかったから調べた件

docke-composer build時間掛かるし、コーヒーでも飲んでたら終わるだろうって思ってたら終わってなかった・・


```
$ docker-compose build
Building ocroboticspagecreater
[+] Building 31.6s (9/27)                                                                                                                                                                                    
 => [internal] load build definition from Dockerfile                    

 => ERROR [ 4/22] RUN apt-get -y update
------                                                                
 > [ 4/22] RUN apt-get -y update:                                     
#8 0.696 Get:1 http://deb.debian.org/debian bullseye InRelease [116 kB]                                                                   
#8 0.791 Get:2 http://deb.debian.org/debian-security bullseye-security InRelease [48.4 kB]                                          
#8 0.833 Err:1 http://deb.debian.org/debian bullseye InRelease        
#8 0.833   At least one invalid signature was encountered.            
#8 0.840 Get:3 http://deb.debian.org/debian bullseye-updates InRelease [44.1 kB]
#8 0.892 Err:2 http://deb.debian.org/debian-security bullseye-security InRelease
#8 0.892   At least one invalid signature was encountered.
#8 0.949 Err:3 http://deb.debian.org/debian bullseye-updates InRelease
#8 0.949   At least one invalid signature was encountered.
#8 0.954 Reading package lists...
#8 0.977 W: GPG error: http://deb.debian.org/debian bullseye InRelease: At least one invalid signature was encountered.
#8 0.977 E: The repository 'http://deb.debian.org/debian bullseye InRelease' is not signed.
#8 0.977 W: GPG error: http://deb.debian.org/debian-security bullseye-security InRelease: At least one invalid signature was encountered.
#8 0.977 E: The repository 'http://deb.debian.org/debian-security bullseye-security InRelease' is not signed.
#8 0.977 W: GPG error: http://deb.debian.org/debian bullseye-updates InRelease: At least one invalid signature was encountered.
#8 0.977 E: The repository 'http://deb.debian.org/debian bullseye-updates InRelease' is not signed.
------
executor failed running [/bin/sh -c apt-get -y update]: exit code: 100
ERROR: Service 'xxxxxxxxxx' failed to build: Build failed
```

apt-get -y updateがなんで通らんねん？？
って適当にググったらDocker imageでVolumeが埋め尽くされていることらしい・・

```
$ docker image prune
WARNING! This will remove all dangling images.
Are you sure you want to continue? [y/N] y
Deleted Images:
deleted: sha256:677bba134526f65e40d68a9484ba856ef5b2cfde6f6ccf334512bbfd029c80c6
deleted: sha256:b24bae40fba0d77f1a54e371c972af1bb2317b9153f1dee2790905e2f1acbc28
deleted: sha256:0a741cdf38bf69944e10904d629e4d9390ca1e340a008aa15a958ede7f6a9886
deleted: sha256:1c492451ac9f1af249b14ed9a1809f121e2
                                  〜
                             59c8bbd00fd82a24fef88f229c9287fdcc0a1e34dd50e371913
deleted: sha256:bf9b5db5ee64d73b3f768622996c5b4f826bf4eebc48ad4aba4d3ce903127f8f
deleted: sha256:b1447be47d6e6a9e454954d239d2d356cd5f646a3eaa4ad201b535106428b78d

Total reclaimed space: 6.427GB
```
随分削除したな・・

``
docker image prune
``

は、
https://docs.docker.jp/config/pruning.html
を見ると、

``
宙ぶらりんイメージ（dangling image）のみ削除します。宙ぶらりんイメージとは、タグを持たず、他のコンテナからも参照されないイメージです。宙ぶらりんイメージを削除するには、次のようにします。
``

というように、ぷらぷらしているイメージを削除する機能の様子。

同じ様に、コンテナのpruneもできるようなので
docker image pruneだけでは駄目な場合、こちらもやってみると良いかもですね
自分は、今回はdocker image pruneだけで事足りました。