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PoC: Alpine Linux Minimal Stateless Pharo

20 July 2019

Alpine Linux is a security-oriented, lightweight distro based on musl-libc and BusyBox. Official Docker images of Alpine Linux are about 5MB each.

I've successfully built the pharo.cog.spur.minheadless OpenSmalltalk VM on Alpine Linux. Dockerizing the Pharo VM files plus a built-from-source libsqlite3.so (without Pharo image/changes/etc) produces a Docker image weighing in at 12.5MB.

% sudo docker images | egrep "samadhiweb.*alpine"
samadhiweb/pharo7vm                    alpine              299420ff0e03        21 minutes ago      12.5MB

Pharo provides minimal images that contain basic Pharo packages without the integrated GUI, useful for building server-side applications.

From the Pharo 7.0.3 minimal image, I've built a "stateless" image containing FFI, Fuel, and UDBC-SQLite. "Stateless" means the image can be executed by the Pharo VM without the changes and sources files. Here are the sizes of the base minimal image and my SQLite image:

% ls -l udbcsqlite.image Pharo7.0.3-0-metacello-64bit-0903ade.image 
-rw-rw-r-- 1 pierce pierce 13863032 Apr 12 22:56 Pharo7.0.3-0-metacello-64bit-0903ade.image
-rw-rw-r-- 3 pierce pierce 17140552 Jul 20 14:11 udbcsqlite.image

Below, I run the image statelessly on my Ubuntu laptop. Note that this uses the regular Pharo VM, not the Alpine Linux one.

% mkdir stateless
% cd stateless
% ln ../udbcsqlite.image
% chmod 444 udbcsqlite.image
% cat > runtests.sh <<EOF
#!/bin/sh
~/pkg/pharo7vm/gofaro -vm-display-none udbcsqlite.image test --junit-xml-output "UDBC-Tests-SQLite-Base"
EOF
% chmod a+x runtests.sh
% ls -l
total 16744
-rwxr-xr-x 1 pierce pierce      116 Jul 20 15:25 runtests.sh*
-r--r--r-- 3 pierce pierce 17140552 Jul 20 14:11 udbcsqlite.image
% 
%
% ./runtests.sh
Running tests in 1 Packages
71 run, 71 passes, 0 failures, 0 errors.
% ls -l 
total 16764
-rw-r--r-- 1 pierce pierce     6360 Jul 20 15:26 progress.log
-rwxr-xr-x 1 pierce pierce      116 Jul 20 15:25 runtests.sh*
-r--r--r-- 3 pierce pierce 17140552 Jul 20 14:11 udbcsqlite.image
-rw-r--r-- 1 pierce pierce    11072 Jul 20 15:26 UDBC-Tests-SQLite-Base-Test.xml

Dockerizing udbcsqlite.image together with the aforementioned Alpine Linux Pharo VM produces a Docker image that is 46.8 MB in size.

% sudo docker images | egrep "samadhiweb.*alpine"
samadhiweb/p7minsqlite                 alpine              3a57853099d0        44 minutes ago      46.8MB
samadhiweb/pharo7vm                    alpine              299420ff0e03        About an hour ago   12.5MB

Run the Docker image:

% sudo docker run --ulimit rtprio=2 samadhiweb/p7minsqlite:alpine
Running tests in 1 Packages
71 run, 71 passes, 0 failures, 0 errors.

For comparison and contrast, here are the sizes of the regular Pharo 7.0.3 image, changes and sources files:

% ls -l Pharo7.0*-0903ade.* 
-rw-rw-r-- 1 pierce pierce      190 Apr 12 22:57 Pharo7.0.3-0-64bit-0903ade.changes
-rw-rw-r-- 1 pierce pierce 52455648 Apr 12 22:57 Pharo7.0.3-0-64bit-0903ade.image
-rw-rw-r-- 2 pierce pierce 34333231 Apr 12 22:55 Pharo7.0-32bit-0903ade.sources
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