Explains how Docker and Nix work as deployment solutions, in what ways they are similar and different, and how they can be combined to achieve interesting results.

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12. $ docker pull debian:buster
buster: Pulling from library/debian
57df1a1f1ad8: Pull complete
Digest: sha256:f744ed553780b84bf376fbfe7879de9a3aece6e611af110f95ca26188cf85cb6
Status: Downloaded newer image for debian:buster
$ docker run -it debian:buster /bin/bash
$ apt-get update
$ apt-get install -y mono-runtime
$ mono --version
Mono JIT compiler version 5.18.0.240 (Debian 5.18.0.240+dfsg-3 Wed Apr 17 16:37:36 UTC 2019)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
$ which mono
/usr/bin/mono

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FROM debian:buster
RUN apt-get update
RUN apt-get install -y mono-runtime

14. $ docker build . -t mymono:latest
$ docker run -it mymono:latest /bin/bash
$ mono --version
Mono JIT compiler version 5.18.0.240 (Debian 5.18.0.240+dfsg-3 Wed Apr 17
16:37:36 UTC 2019)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-
project.com

15. FROM debian:buster
RUN apt-get update
RUN apt-get install -y nginx
ADD nginx.conf /etc
ADD index.html /var/www
CMD ["nginx", "-g", "daemon off;", "-c", "/etc/nginx.conf"]
EXPOSE 80/tcp
$ docker build . -t mynginx:latest
$ docker run -it -p 8080:80 mynginx:latest

16. $ docker history mynginx:latest
IMAGE CREATED CREATED BY SIZE COMMENT
029491c6130e 13 minutes ago /bin/sh -c #(nop) EXPOSE 80/tcp 0B
ec94316b9ca2 13 minutes ago /bin/sh -c #(nop) CMD ["nginx" "-g" "daemon… 0B
0bb364d192db 13 minutes ago /bin/sh -c #(nop) ADD file:18aed37573327bee1… 129B
968ebde5fb5d 13 minutes ago /bin/sh -c #(nop) ADD file:f18afd18cfe2728b3… 189B
2c29120ff52b 13 minutes ago /bin/sh -c apt-get install -y nginx 64.2MB
c4974fb27d9a 28 minutes ago /bin/sh -c apt-get update 17.5MB
f6dcff9b59af 4 days ago /bin/sh -c #(nop) CMD ["bash"] 0B
<missing> 4 days ago /bin/sh -c #(nop) ADD file:07a6578d6f507bd9c… 114MB

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FROM debian:buster
RUN apt-get update
RUN apt-get install -y apache2
ADD index.html /var/www/html
CMD ["apachectl", "-D", "FOREGROUND"]
EXPOSE 80/tcp

18. $ docker history mynginx:latest
IMAGE CREATED CREATED BY SIZE COMMENT
029491c6130e 13 minutes ago /bin/sh -c #(nop) EXPOSE 80/tcp
0B
ec94316b9ca2 13 minutes ago /bin/sh -c #(nop) CMD ["nginx" "-
g" "daemon… 0B
0bb364d192db 13 minutes ago /bin/sh -c #(nop) ADD
file:18aed37573327bee1… 129B
968ebde5fb5d 13 minutes ago /bin/sh -c #(nop) ADD
file:f18afd18cfe2728b3… 189B
2c29120ff52b 13 minutes ago /bin/sh -c apt-get install -y
nginx 64.2MB
c4974fb27d9a 28 minutes ago /bin/sh -c apt-get update 17.5MB
f6dcff9b59af 4 days ago /bin/sh -c #(nop) CMD ["bash"] 0B
<missing> 4 days ago /bin/sh -c #(nop) ADD
file:07a6578d6f507bd9c… 114MB
$ docker history myapache:latest
IMAGE CREATED CREATED BY SIZE COMMENT
fc06c36e1d8b 7 minutes ago /bin/sh -c #(nop) EXPOSE 80/tcp 0B
d456baddadf5 7 minutes ago /bin/sh -c #(nop) CMD ["apachectl" "-D"
"FO… 0B
f4bbb25d31af 7 minutes ago /bin/sh -c #(nop) ADD
file:18aed37573327bee1… 129B
f7afa94e16b4 7 minutes ago /bin/sh -c apt-get install -y apache2
112MB
c4974fb27d9a 39 minutes ago /bin/sh -c apt-get update 17.5MB
f6dcff9b59af 4 days ago /bin/sh -c #(nop) CMD ["bash"] 0B
<missing> 4 days ago /bin/sh -c #(nop) ADD file:07a6578d6f507bd9c…
114MB

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21. #!/bin/bash -e
export MONO_VERSION=5.20.1.27
wget https://download.mono-project.com/sources/mono/mono-$MONO_VERSION.tar.bz2
tar xfv mono-$MONO_VERSION.tar.bz2
cd mono-*
./autogen.sh --prefix=/app/mono --enable-minimal=aot,profiler,debug,logging
--disable-libraries --disable-boehm --with-mcs-docs=no --with-profile2=no
make
make install
tar cfvz /out/mono-binary-tarball-$MONO_VERSION.tar.bz2 /app/mono

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FROM debian:jessie
RUN apt-get update
RUN apt-get -y install wget gcc g++ bzip2 make autoconf automake libtool
cmake python pkg-config libglib2.0-dev libcairo2-dev libpng-dev libjpeg-dev libgif-dev
ADD ./build /
CMD /build

23. $ docker build -t monobuildimage .
$ docker run -v $(pwd)/out:/out --rm -t monobuildimage
$ ls -lh out
total 77M
-rw-r--r-- 1 root root 77M sep 14 23:15 mono-binary-tarball-5.20.1.27.tar.bz2

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28. {stdenv, fetchurl, libgdiplus, pkgconfig, gettext, perl, xlibs, zlib}:
stdenv.mkDerivation rec {
name = "mono-${version}";
version = "3.10.0";
src = fetchurl {
url = "http://download.mono-project.com/sources/mono/${name}.tar.bz2";
sha256 = "1d5hib0qsmh3673k3rdd199633lmczdgpbxl6d3rnb8dh6kd2x7x";
};
buildInputs = [ pkgconfig gettext perl libgdiplus xlibs.libX11 zlib ];
NIX_LDFLAGS = "-lgcc_s" ;
dontDisableStatic = true; # To overcome the bug https://bugzilla.novell.com/show_bug.cgi?id=644723
dontStrip = true; # Fix: file /nix/store/xxx-mono-2.4.2.1/lib/mscorlib.dll is an invalid CIL image
# Fix mono DLLMap so it can find libX11 and gdiplus to run winforms apps
postBuild = ''
find . -name 'config' -type f | while read i; do
sed -i "s@libX11.so.6@${xlibs.libX11}/lib/libX11.so.6@g" $i
sed -i '2 i<dllmap dll="gdiplus.dll" target="${libgdiplus}/lib/libgdiplus.so" os="!windows"/>' $i
done
'';
}

29. rec {
stdenv = ...
fetchurl = ...
xlibs = ...
gettext = ...
perl = ...
pkgconfig = import ./pkgconfig { ... };
libgdiplus = import ./libgdiplus { ... };
zlib = import ./zlib {
inherit stdenv fetchurl;
}
mono = import ./mono {
inherit stdenv fetchurl libgdiplus pkgconfig gettext perl xlibs zlib;
};
...
}

30. $ nix-build pkgs.nix -A mono
/nix/store/0fkqp394m1pfzvjcrn4jisi0sm5c0q8n-mono-3.10.0
$ ls -l result
lrwxrwxrwx 1 sbu sbu 55 sep 16 12:07 result ->
/nix/store/0fkqp394m1pfzvjcrn4jisi0sm5c0q8n-mono-3.10.0
$ ./result/bin/mono --version
Mono JIT compiler version 3.10.0 (tarball Tue Sep 15 08:29:10 UTC 2020)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-
project.com

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/nix/store/0fkqp394m1pfzvjcrn4jisi0sm5c0q8n-mono-3.10.0

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/nix/store/0fkqp394m1pfzvjcrn4jisi0sm5c0q8n-mono-3.10.0
/nix/store/0fkqp394m1pfzvjcrn4jisi0sm5c0q8n-mono-3.10.0

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35. $ nix-store --query --graph $(nix-instantiate pkgs.nix -A mono) > out.dot
$ dot -Tsvg out.dot > out.svg

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$ nix-store -qR result
/nix/store/x76l1l04vnhw82hv6iwcvcchp3f51304-linux-headers-3.7.1
/nix/store/ikc9iziqc2rldacnbb2cdh7bdc1b2c3n-glibc-2.19
/nix/store/iyxa3l0knar229j4mbhn6a7mspp9nymd-zlib-1.2.8
...
/nix/store/whmb7k2f5xiykd3i0g26jzm16cia4s86-giflib-5.0.5
/nix/store/673zzsana5dlry0l22gwdjvyf1k30hw3-libgdiplus-2.10.9
/nix/store/0fkqp394m1pfzvjcrn4jisi0sm5c0q8n-mono-3.10.0

37. $ readelf -d ./result/bin/mono
Dynamic section at offset 0x3784b0 contains 32 entries:
Tag Type Name/Value
0x0000000000000001 (NEEDED) Shared library: [libstdc++.so.6]
0x0000000000000001 (NEEDED) Shared library: [libm.so.6]
0x0000000000000001 (NEEDED) Shared library: [librt.so.1]
0x0000000000000001 (NEEDED) Shared library: [libdl.so.2]
0x0000000000000001 (NEEDED) Shared library: [libpthread.so.0]
0x0000000000000001 (NEEDED) Shared library: [libgcc_s.so.1]
0x0000000000000001 (NEEDED) Shared library: [libc.so.6]
0x000000000000000f (RPATH) Library rpath: [/nix/store/ygqw3h96jg0h77r2kb6ac98caw1mchh4-gcc-4.8.3/lib/../lib64:/nix/store/ikc9iziqc2rldacnbb2cdh7bdc1b2c3n-glibc-
2.19/lib]
0x000000000000001d (RUNPATH) Library runpath: [/nix/store/ygqw3h96jg0h77r2kb6ac98caw1mchh4-gcc-4.8.3/lib/../lib64:/nix/store/ikc9iziqc2rldacnbb2cdh7bdc1b2c3n-glibc-
2.19/lib]
...

38. $ python --version
Python 2.7.17
$ which python
/usr/bin/python
$ nix-shell -p python3
$ python --version
Python 3.8.3
$ which python
/nix/store/f87w21b91cws0wbsvyfn5vnlyv491czi-python3-3.8.3/bin/python

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FROM nixos/nix
RUN nix-channel --add https://nixos.org/channels/nixpkgs-
unstable nixpkgs
RUN nix-channel --update
RUN nix-env -f '<nixpkgs>' -iA nginx
RUN mkdir -p /var/log/nginx /var/cache/nginx /var/www
ADD nginx.conf /etc
ADD index.html /var/www
CMD ["nginx", "-g", "daemon off;", "-c", "/etc/nginx.conf"]
EXPOSE 80/tcp

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43. with import <nixpkgs> {};
dockerTools.buildImage {
name = "nginxexp";
tag = "test";
contents = nginx;
runAsRoot = ''
${dockerTools.shadowSetup}
groupadd -r nogroup
useradd -r nobody -g nogroup -d /dev/null
mkdir -p /var/log/nginx /var/cache/nginx /var/www
cp ${./index.html} /var/www/index.html
'';
config = {
Cmd = [ "${nginx}/bin/nginx" "-g" "daemon off;" "-c" ./nginx.conf ];
Expose = {
"80/tcp" = {};
};
};
}

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$ nix-build
/nix/store/qx9cpvdxj78d98rwfk6a5z2qsmqvgzvk-docker-image-nginxexp.tar.gz
$ docker load -i result
d8847b6d0466: Loading layer
[==================================================>] 62.19MB/62.19MB
Loaded image: nginxexp:test
$ docker run -it -p 8080:80 nginxexp:test

45. $ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
mynginx latest 029491c6130e 14 hours ago 196MB
nginxexp test cde8298f025f 50 years ago 61MB

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47. with import <nixpkgs> {};
dockerTools.buildLayeredImage {
name = "nginxexp";
tag = "test";
contents = nginx;
maxLayers = 100;
extraCommands = ''
mkdir -p var/log/nginx var/cache/nginx var/www
cp ${./index.html} var/www/index.html
‘’;
config = {
Cmd = [ "${nginx}/bin/nginx" "-g" "daemon off;" "-c" ./nginx-root.conf ];
Expose = {
"80/tcp" = {};
};
};
}

48. $ docker history nginxexp:test
IMAGE CREATED CREATED BY SIZE COMMENT
b91799a04b99 50 years ago 1.47kB store paths: ['/nix/store/snxpdsksd4wxcn3niiyck0fry3wzri96-nginxexp-customisation-layer']
<missing> 50 years ago 200B store paths: ['/nix/store/6npz42nl2hhsrs98bq45aqkqsndpwvp1-nginx-root.conf']
<missing> 50 years ago 1.79MB store paths: ['/nix/store/qsq6ni4lxd8i4g9g4dvh3y7v1f43fqsp-nginx-1.18.0']
<missing> 50 years ago 492kB store paths: ['/nix/store/kdrdxhswaqm4dgdqs1vs2l4b4md7djma-pcre-8.44']
<missing> 50 years ago 4.17MB store paths: ['/nix/store/6glpgx3pypxzb09wxdqyagv33rrj03qp-openssl-1.1.1g']
...
<missing> 50 years ago 123kB store paths: ['/nix/store/5x6l9xm5dp6v113dpfv673qvhwjyb7p5-zlib-1.2.11']
<missing> 50 years ago 30.9MB store paths: ['/nix/store/bqbg6hb2jsl3kvf6jgmgfdqy06fpjrrn-glibc-2.30']
<missing> 50 years ago 209kB store paths: ['/nix/store/fhg84pzckx2igmcsvg92x1wpvl1dmybf-libidn2-2.3.0']
<missing> 50 years ago 1.63MB store paths: ['/nix/store/y8n2b9nwjrgfx3kvi3vywvfib2cw5xa6-libunistring-0.9.10']

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