In the previous post we built a docker image for an apt package cache. Here we will use it as part of a new base Debian image, from which future feature-filled images can be based on.
This will appear a little extra difficult only because I want to include torproject.org's Debian package repository. I'll call out below what you can ingore if you only want Debian's repos.
First the Dockerfile.
$ cat Dockerfile
FROM debian:bullseye
COPY sources.list /etc/apt/sources.list
# Don't include any of the following if you don't want to add additional
# sources.
RUN apt-get update -y && apt-get install -y gnupg && rm -r /var/lib/apt/lists/*
COPY *.asc .
RUN cat *.asc | apt-key add -
RUN rm *.asc
COPY torproject.list /etc/apt/sources.list.d/
RUN apt-get autoremove gnupg -y && rm -r /var/lib/apt/lists/*
Now the sources files. Notice the hostname is 'aptcache'.
$ cat sources.list
deb http://aptcache/debian/ bullseye main
deb-src http://aptcache/debian/ bullseye main
deb http://aptcache/debian/ bullseye-updates main contrib non-free
deb-src http://aptcache/debian/ bullseye-updates main contrib non-free
deb http://aptcache/debian-security bullseye-security main contrib non-free
deb-src http://aptcache/debian-security bullseye-security main contrib non-free
# Don't include torproject.list if you don't want to use their repo.
$ cat torproject.list
deb http://aptcache/torproject.org/ bullseye main
deb-src http://aptcache/torproject.org/ bullseye main
Finally the .asc file(s) for any custom repos. I have one (Tor's), and I
used these instructions to help
me find the key with which they sign their packages.
# It's a big ASCII-armored blob, and you don't need it if you don't want
# Tor's repos.
$ cat A3C4F0F979CAA22CDBA8F512EE8CBC9E886DDD89.asc | wc -l
771
Now we can build the image. Note we use the aptcache network during building
in order to use our caching webserver. This is the key.
$ docker build --network aptcache -t debianbase:bullseye .
The first time we use the cache, we see things go relatively slowly. See the last line of this snippit.
[...]
Get:18 http://aptcache/debian bullseye/main amd64 gpg-wks-client amd64 2.2.27-2 [523 kB]
Get:19 http://aptcache/debian bullseye/main amd64 gpg-wks-server amd64 2.2.27-2 [516 kB]
Get:20 http://aptcache/debian bullseye/main amd64 gpgsm amd64 2.2.27-2 [645 kB]
Get:21 http://aptcache/debian bullseye/main amd64 gnupg all 2.2.27-2 [825 kB]
Get:22 http://aptcache/debian bullseye/main amd64 libgpm2 amd64 1.20.7-8 [35.6 kB]
Get:23 http://aptcache/debian bullseye/main amd64 libldap-common all 2.4.57+dfsg-3 [95.9 kB]
Get:24 http://aptcache/debian bullseye/main amd64 libsasl2-modules amd64 2.1.27+dfsg-2.1 [104 kB]
debconf: delaying package configuration, since apt-utils is not installed
Fetched 9475 kB in 4s (2545 kB/s)
[...]
But if we build the the image again (and this time use --no-cache so that
docker doesn't use existing intermediate images), we see the package fetching
goes much faster.
$ docker build --no-cache --network aptcache -t debianbase:bullseye .
[...]
Get:18 http://aptcache/debian bullseye/main amd64 gpg-wks-client amd64 2.2.27-2 [523 kB]
Get:19 http://aptcache/debian bullseye/main amd64 gpg-wks-server amd64 2.2.27-2 [516 kB]
Get:20 http://aptcache/debian bullseye/main amd64 gpgsm amd64 2.2.27-2 [645 kB]
Get:21 http://aptcache/debian bullseye/main amd64 gnupg all 2.2.27-2 [825 kB]
Get:22 http://aptcache/debian bullseye/main amd64 libgpm2 amd64 1.20.7-8 [35.6 kB]
Get:23 http://aptcache/debian bullseye/main amd64 libldap-common all 2.4.57+dfsg-3 [95.9 kB]
Get:24 http://aptcache/debian bullseye/main amd64 libsasl2-modules amd64 2.1.27+dfsg-2.1 [104 kB]
debconf: delaying package configuration, since apt-utils is not installed
Fetched 9475 kB in 0s (159 MB/s)
[...]
Note: the --no-cache option has nothing to do with our package cache.
The flag is a docker thing to speed up builds when lines near the end of a
Dockerfile change; we're creating a proxy to Debian repositories that
intercepts HTTP requests and stores the responses for future use.
Now going forward, whenever you build a new image based on debianbase, as
long as you include --network aptcache when you call docker build, you will
use the package cache. You can't forget it, otherwise you'll get error messages
such as this:
$ docker build .
Sending build context to Docker daemon 2.048kB
Step 1/2 : FROM debianbase:bullseye
---> 578298174bde
Step 2/2 : RUN apt-get update -y && apt-get install -y htop && rm -r /var/lib/apt/lists/*
---> Running in 43c2e275628c
Err:1 http://aptcache/debian bullseye InRelease
Something wicked happened resolving 'aptcache:80' (-5 - No address associated with hostname)
Err:2 http://aptcache/debian bullseye-updates InRelease
Something wicked happened resolving 'aptcache:80' (-5 - No address associated with hostname)
Err:3 http://aptcache/debian-security bullseye-security InRelease
Something wicked happened resolving 'aptcache:80' (-5 - No address associated with hostname)
Err:4 http://aptcache/torproject.org bullseye InRelease
Something wicked happened resolving 'aptcache:80' (-5 - No address associated with hostname)
Reading package lists...
W: Failed to fetch http://aptcache/debian/dists/bullseye/InRelease Something wicked happened resolving 'aptcache:80' (-5 - No address associated with hostname)
W: Failed to fetch http://aptcache/debian/dists/bullseye-updates/InRelease Something wicked happened resolving 'aptcache:80' (-5 - No address associated with hostname)
W: Failed to fetch http://aptcache/debian-security/dists/bullseye-security/InRelease Something wicked happened resolving 'aptcache:80' (-5 - No address associated with hostname)
W: Failed to fetch http://aptcache/torproject.org/dists/bullseye/InRelease Something wicked happened resolving 'aptcache:80' (-5 - No address associated with hostname)
W: Some index files failed to download. They have been ignored, or old ones used instead.
Reading package lists...
Building dependency tree...
Reading state information...
E: Unable to locate package htop
The command '/bin/sh -c apt-get update -y && apt-get install -y htop && rm -r /var/lib/apt/lists/*' returned a non-zero code: 100
