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https://github.com/swagdevops/image-alpine_server
This image brings a 3 parts init system
https://github.com/swagdevops/image-alpine_server
alpine alpine-image alpine-linux docker-image runit
Last synced: 8 days ago
JSON representation
This image brings a 3 parts init system
- Host: GitHub
- URL: https://github.com/swagdevops/image-alpine_server
- Owner: SwagDevOps
- License: mit
- Created: 2018-06-24T13:00:07.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2021-05-21T18:20:45.000Z (over 3 years ago)
- Last Synced: 2024-11-06T20:15:13.950Z (about 2 months ago)
- Topics: alpine, alpine-image, alpine-linux, docker-image, runit
- Language: Ruby
- Homepage:
- Size: 308 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
# Alpine Server Image
Image based on ``alpine:3.10.3`` ([release notes][release:2019-10-21]).
This image SHOULD consume less than 6MB RAM on startup (depending on RAM installed).
```sh
rake restart && \
sleep 6 && \
docker ps | awk '{print $1}' | grep -v CONTAINER | while read line; do docker ps | grep $line | awk '{printf $NF" "}' && echo "scale=2; $(cat /sys/fs/cgroup/memory/docker/$line*/memory.usage_in_bytes)/1024/1024" | bc -l; done | sort | column -t
```
For an image size around ``56MB``.
This image brings a 3 parts init system, composed of:
1. [``ylem``][ylem] startup scripts execution
2. [``dumb-init``][dumb-init] minimal init system for Linux containers
3. [``runit``][runit] services management
It would solve [the PID 1 problem][blog.phusion.nl:docker-and-the-pid-1-zombie-reaping-problem].
| Component | Comment |
| ---------------- | ------------------- |
| Alpine Linux | Alpine Linux is a security-oriented, lightweight Linux distribution based on musl libc and busybox. |
| ``ylem`` | Startup scripts execution. |
| ``dumb-init`` | A minimal init system for Linux containers. |
| ``runit`` | Used as a service supervisor. Supports restarting daemons when they crash. See: [``runsvdir``][manpage:runsvdir]. |
| ``su-exec`` | Execute a program with different privileges. The program will be executed directly and not run as a child, like ``su`` and ``sudo`` does, which avoids TTY and signal issues (see [README][su-exec:README#parentchild-handling]). It is only ``10kb``. |
| ``sv-utils`` | [``sv-utils``][github.com:SwagDevOps/sv-utils] is an attempt to bring [DRY principle][dry-definition] to runit services creation. |
| ``syslog`` | Only listens locally. All syslog messages are forwarded to ``docker logs``. |
| ``dropbear`` | Dropbear is a relatively small SSH server. It has a small memory footprint and is compatible with OpenSSH ``~/.ssh/authorized_keys`` public key authentication. |
| ``crond`` | Comes with a cron system by default, provided by busybox. |
### From sources
```sh
git clone [email protected]:SwagDevOps/image-alpine_server.git
cd image-alpine_server
bundle install --path vendor/bundle --without development
bundle exec rake build start exec
```
### From docker hub
```sh
docker run -d --rm --name trying.alpine_server swagdevops/alpine_server:VERSION
```
```sh
docker exec -ti trying.alpine_server bash -l
```
```sh
mkdir -p ssh/authorized_keys
cp ~/.ssh/id_rsa.pub ssh/authorized_keys/root
bundle exec rake restart test
```
Tests are executed over ``SSH``, and rely on minimal (host) dependencies.
The image is called [``swagdevops/alpine_server``][docker_hub.com:swagdevops/alpine_server],
and is available on the Docker registry.
Use ``swagdevops/alpine_server`` as base image.
```dockerfile
FROM swagdevops/alpine_server:VERSION
```
To make your builds reproducible, you MUST lock down
to a specific version, DO NOT use [`latest`][vsupalov.com:wrong-with-latest].
ATM, `latest` tag does not exist, as a result: you CAN NOT use it.
See [releases][github.com:swagdevops/alpine/server/releases]
for a list of version numbers.
A daemon is a program which runs in the background of its system, such
as a web server.
You can add additional daemons (for example, your own app) to the image
by creating runit service directories.
You only have to write a small script to start your daemon.
[``runsv``][manpage:runsv] will execute your script,
and (by default) restart it upon its exit, after waiting one second.
The shell script must be called ``run``, executable, and placed in the directory
``/etc/services/``.
Additionally, a file ``manifest.yml`` must be present, with the following content:
```yaml
---
enabled: true
auto_start: true
```
``runsv`` will invoke ``run`` after your container starts.
#### Example for a ``run`` script
```ruby
#!/usr/bin/env svrun
# vim: ai ts=2 sts=2 et sw=2 ft=ruby
Dir.chdir('/var/www/localhost') do
service(['bundle',
'exec',
'rake',
'serve',
'serve_port=80',
"serve_storage=/var/serve"],
user: :'www-data',
group: 'www-data').call
end
```
#### Filesystem hierarchy
```
/etc/services
└── httpd
├── manifest.yml
└── run
```
For more information see: [sv-utils][github.com:swagdevops/sv-utils].
* [A minimal Ubuntu base image][phusion/baseimage-docker]
* [Alpine image with environment template and supervisord][qenv/alpine-base]
* [Petit état de l'art des systèmes d'initialisation][linuxfr:petit-etat-de-l-art]
[release:2019-10-21]: https://alpinelinux.org/posts/Alpine-3.10.3-released.html
[release:2019-08-20]: https://alpinelinux.org/posts/Alpine-3.10.2-released.html
[release:2019-05-09]: https://alpinelinux.org/posts/Alpine-3.9.4-released.html
[release:2019-01-29]: https://alpinelinux.org/posts/Alpine-3.9.0-released.html
[release:2018-06-26]: https://alpinelinux.org/posts/Alpine-3.8.0-released.html
[dumb-init]: https://github.com/Yelp/dumb-init
[ylem]: https://github.com/SwagDevOps/ylem
[runit]: http://smarden.org/runit/
[su-exec:README#parentchild-handling]: https://github.com/ncopa/su-exec/blob/master/README.md#tty--parentchild-handling
[blog.phusion.nl:docker-and-the-pid-1-zombie-reaping-problem]: https://blog.phusion.nl/2015/01/20/docker-and-the-pid-1-zombie-reaping-problem/
[manpage:runsvdir]: http://manpages.ubuntu.com/manpages/bionic/man8/runsvdir.8.html
[manpage:runsv]: http://smarden.org/runit/runsv.8.html
[phusion/baseimage-docker]: https://github.com/phusion/baseimage-docker
[qenv/alpine-base]: https://github.com/qenv/alpine-base
[linuxfr:petit-etat-de-l-art]: https://linuxfr.org/news/petit-etat-de-l-art-des-systemes-d-initialisation-1
[github.com:swagdevops/sv-utils]: https://github.com/SwagDevOps/sv-utils
[docker_hub.com:swagdevops/alpine_server]: https://hub.docker.com/r/swagdevops/alpine_server
[github.com:swagdevops/alpine/server/releases]: https://github.com/SwagDevOps/image-alpine_server/releases
[vsupalov.com:wrong-with-latest]: https://vsupalov.com/docker-latest-tag/
[dry-definition]: https://en.wikipedia.org/wiki/Don%27t_repeat_yourself