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# Docker

# The choice of the base images - why not Alpine?

I tried to use Alpine based images for some services and I got troubles.

# PostgreSQL

PostgreSQL alpine based crashes with a Segmentation fault.

database_1             | PostgreSQL Database directory appears to contain a database; Skipping initialization
database_1             | 
database_1             | 2021-02-01 17:33:07.271 GMT [1] LOG:  starting PostgreSQL 13.0 on arm-unknown-linux-musleabihf, compiled by gcc (Alpine 9.3.0) 9.3.0, 32-bit
database_1             | 2021-02-01 17:33:07.272 GMT [1] LOG:  listening on IPv4 address "0.0.0.0", port 5432
database_1             | 2021-02-01 17:33:07.272 GMT [1] LOG:  listening on IPv6 address "::", port 5432
database_1             | 2021-02-01 17:33:07.281 GMT [1] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
database_1             | 2021-02-01 17:33:13.122 GMT [1] LOG:  startup process (PID 21) was terminated by signal 11: Segmentation fault
database_1             | 2021-02-01 17:33:13.122 GMT [1] LOG:  aborting startup due to startup process failure
database_1             | 2021-02-01 17:33:13.205 GMT [1] LOG:  database system is shut down

More information:

# Redis

Redis alpine based crashes with something like a segmentation fault, accessing memory address causes it to crash.

│redis-broker_1         | === REDIS BUG REPORT START: Cut & paste starting from here ===
│redis-broker_1         | 1:M 09 May 2071 21:19:36.000 # Redis 6.2.1 crashed by signal: 6, si_code: -6
│redis-broker_1         | 1:M 09 May 2071 21:19:36.000 # Killed by PID: 1, UID: 999
│redis-broker_1         | 
│redis-broker_1         | ------ INFO OUTPUT ------
│redis-broker_1         | Assertion failed: rc == 0 (monotonic.c: monotonicInit_posix: 149)
│redis-broker_1         | 1:M 09 May 2071 20:35:36.000 # Redis 6.2.1 crashed by signal: 11, si_code: 1
│redis-broker_1         | 1:M 09 May 2071 20:35:36.000 # Accessing address: 0x14
│redis-broker_1         | 1:M 09 May 2071 20:35:36.000 # Killed by PID: 20, UID: 0
│redis-broker_1         | 
│redis-broker_1         | ------ INFO OUTPUT ------
│core_redis-broker_1 exited with code 139

More information:

# Python

The package psycopg2-binary don't work out of the box with alpine based image. I do not have the time to make it works. And also, it throws errors because Python fails to initialize its clock.

More information:

# Conclusion

First of all, images do not work with Alpine OS on a raspberry pi. It seems to be related to the package libseccomp of the Raspbian os.

You can find more information for each section above and here (opens new window).

With all these issues, I decided to give up Alpine based images because they are causing troubles without giving me a lot of benefits. Of course images are smaller but at least debian based works well without spending hours/days trying to fix them.

# Networks

We are using an external network to make services from different docker-compose files possible (e.g smart-camera and core).

# Build Docker images for multi arch

We use an experimental feature of docker using buildx. Make sure you have buildx installed and functional.

You have to run que quemu-user-static to be able to build images for multi architectures.

docker run --rm --privileged multiarch/qemu-user-static --reset -p yes && \
sudo systemctl restart docker

Then you can build and push the image to the docker hub:

make version=<0.3.5 for ex> docker-build-release

It is the same make command for smart-camera and core applications.

Related issues:

  • 73 to build the OpenCV image for multiple architecture (amd64 / armv7)

# Use ENV

It can be tricky and lead to unexpected behavior. Please read https://vsupalov.com/override-docker-compose-dot-env/

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