optimize Dockerfile

[brownchow]

Hi all:

I modified the Dockerfile a bit to make it more consistent

1. as the docker documentation says: If the WORKDIR doesn’t exist, it will be created, so there is no need to use RUN mkdir /app

2. apk update is useless since we have already added --no-cache in apk add --no-cache gcc build-base linux-headers , if keep apk update it just make image size bigger, to prove this, I do it on a alpine container

just run apk add --no-cache gcc build-base linux-headers

/ # apk add --no-cache gcc build-base linux-headers
fetch http://mirrors.tools.huawei.com/alpine/v3.12/main/x86_64/APKINDEX.tar.gz
fetch http://mirrors.tools.huawei.com/alpine/v3.12/community/x86_64/APKINDEX.tar.gz
OK: 269 MiB in 82 packages
/ # ls -al /var/cache/apk/
total 12
drwxr-xr-x    2 root     root          4096 Oct 21 09:23 .
drwxr-xr-x    1 root     root          4096 Dec  3 02:13 ..

run apk update && apk add --no-cache gcc build-base linux-headers

/ # apk update && apk add --no-cache gcc build-base linux-headers
fetch http://mirrors.tools.huawei.com/alpine/v3.12/main/x86_64/APKINDEX.tar.gz
fetch http://mirrors.tools.huawei.com/alpine/v3.12/community/x86_64/APKINDEX.tar.gz
v3.12.0-429-gb9df8c9616 [http://mirrors.tools.huawei.com/alpine/v3.12/main]
v3.12.0-430-gc0f4e9959c [http://mirrors.tools.huawei.com/alpine/v3.12/community]
OK: 12744 distinct packages available
fetch http://mirrors.tools.huawei.com/alpine/v3.12/main/x86_64/APKINDEX.tar.gz
fetch http://mirrors.tools.huawei.com/alpine/v3.12/community/x86_64/APKINDEX.tar.gz
OK: 269 MiB in 82 packages
/ # ls -al /var/cache/apk/
total 1752
drwxr-xr-x    1 root     root          4096 Dec  3 02:15 .
drwxr-xr-x    1 root     root          4096 Dec  3 02:13 ..
-rw-r--r--    1 root     root       1145321 Dec  3 02:15 APKINDEX.18b70b67.tar.gz
-rw-r--r--    1 root     root        634615 Dec  3 02:15 APKINDEX.99eadc54.tar.gz

it produce index files , we don't need this in our image

and we can save 2MB disk sapce

docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
owncast/owncast     v0.2                c7e1b722a174        42 minutes ago      973MB
owncast/owncast     v0.1                e917e7dae6b9        About an hour ago   975MB

3. we can Minimize the number of layers by merge some command with &&

4. to test it works or not, I packed a config.json into image, docker build -t owncast/owncast:v0.2 .
   and then run docker container run --rm -p 8082:8080 -p 1937:1935 -v d:\\config.yaml:/config.yaml owncast/owncast:v0.2
   the output it produces is

time="2020-12-03T02:36:02Z" level=info msg="Owncast v0.0.0-localdev (unknown)"
time="2020-12-03T02:36:03Z" level=info msg="Web server is listening on port 8080, RTMP is accepting inbound streams on port 1935."
time="2020-12-03T02:36:03Z" level=info msg="The web admin interface is available at /admin."

and go to http://localhost:8082/ , it works!

[gabek]

Lots of good finds, very awesome. Thank you!

So confusingly we have two Dockerfiles, and we probably shouldn't. The one you are looking at is just a simple one that admittedly is probably not used much, hence the issues you see that nobody has noticed.

However, we have another Dockerfile that we use for making the release image that goes up to Dockerhub. And there I think it's probably better configured, but still doesn't get looked at much.
https://github.com/owncast/owncast/blob/master/build/release/Dockerfile-build#L25

So that being said, I'm all for fixing up that root Dockerfile with your changes and at some point in the future consolidating the two using your updates.

I added @geekgonecrazy and @muesli to see if they have any feedback, as they spend more time with Docker than I.

[geekgonecrazy]

To me these changes all look good. This same level of detail looking at main image used for build might also be good