Dockercon SF 2018: Self-upgrading Servers with Docker

Discover how we implemented a server that doesn’t require any downtime to be extended with new features.

Babelfish (bblf.sh) is an open source project created at source{d} that provides language parsing for *any* programming language.

Each parser is written in its own language, so we can’t just simply put everything in a binary.

So how does this work?

We are able to update and upgrade the API server by running Moby inside of Moby (we need to go deeper!) and using the Docker hub as our repository for parsers.

In addition to this, each container image for parsers needs to follow some quite strict specifications: and in order to do so we build a set of images via Makefile and multi-stage builds.

All in all creates an efficient system that although is architecturally complex provides a simple developer experience.

This talk covers all the juicy details of the architecture and the lessons we learned while developing it.

Transcript

1. Hello, I’m Francesc
   

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2. Machine Learning on Source Code
   #MLonCode
   

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3. '112', '97', '99', '107', '97', '103', '101', '32', '109',
   '97', '105', '110', '10', '10', '105', '109', '112', '111',
   '114', '116', '32', '40', '10', '9', '34', '102', '109', '116',
   '34', '10', '41', '10', '10', '102', '117', '110', '99', '32',
   '109', '97', '105', '110', '40', '41', '32', '123', '10', '9',
   '102', '109', '116', '46', '80', '114', '105', '110', '116',
   '108', '110', '40', '34', '72', '101', '108', '108', '111',
   '44', '32', '112', '108', '97', '121', '103', '114', '111',
   '117', '110', '100', '34', '41', '10', '125', '10'
   package main
   import “fmt”
   func main() {
   fmt.Println(“Hello, Chicago”)
   }
   What is Source Code
   

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4. package package
   IDENT main
   ;
   import import
   STRING "fmt"
   ;
   func func
   IDENT main
   (
   )
   package main
   import “fmt”
   func main() {
   fmt.Println(“Hello, Chicago”)
   }
   What is Source Code
   {
   IDENT fmt
   .
   IDENT Println
   (
   STRING "Hello, Chicago"
   )
   ;
   }
   ;
   

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5. package main
   import “fmt”
   func main() {
   fmt.Println(“Hello, Chicago”)
   }
   What is Source Code
   

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7. … a self-hosted server for universal source code parsing,
   turning code files into Universal Abstract Syntax Trees
   

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11. Parsing Go in Go is easy
    Parsing Java in Java is easy
    Parsing Go in Java is doable … I guess
    Parsing Java in Go is interesting …
    Parsing C++ in Go is why are you like this?
    Parsing X in Y
    

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12. N parsers in 1 language
    is way harder than
    N parsers in M languages
    

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15. ● Good UX
    ○ Intuitive commands, flags, args ...
    ○ Reasonable defaults
    ● Frictionless installation
    ○ As few dependencies as possible
    ○ One line to run is good
    ○ No lines to run is even better
    DevRel: reducing time to “wow”!
    

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16. docker run
    >>>
    apt-get + pip + brew + ....
    

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17. Bblfsh container
    docker run foo
    container foo
    

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19. Docker in Docker!
    Using Docker-in-Docker for
    your CI or testing
    environment?
    Think twice
    jpetazzo.github.io/2015/09/03/do-not-use-docker-in-docker-for-ci/
    

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20. Docker in Docker!
    However, contrary to popular belief,
    Docker-in-Docker is not 100% made
    of sparkles, ponies, and unicorns
    

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21. Actually …
    docker run \
    --privileged -d \
    docker:stable-dind
    Later on ...
    hub.docker.com/r/library/docker/
    

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22. Docker in Docker!
    jpetazzo.github.io/2015/09/03/do-not-use-docker-in-docker-for-ci/
    Just map /var/run/docker.sock !
    

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23. container
    Docker CLI
    /var/run/docker.sock
    

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24. container
    docker run foo
    /var/run/docker.sock
    container foo
    

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25. libcontainer
    

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28. Managing drivers (parsers)
    

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29. Scaling
    ● Pluggable strategy
    ● Default behavior:
    ○ 1 container per
    request
    ○ Extra time for reuse
    ● Not implemented yet
    ● Upgrade is for now
    Remove + Installation
    bblfshctl driver \
    install --update \
    foo
    Upgrading
    

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30. Docker in Docker Docker Socket
    - Hard to use, previously
    - Much easier now
    - Lots of features we don’t
    use
    - Requires Docker to be
    used no matter what
    libcontainer
    - Fewer features
    - Fewer dependencies
    - Runs on Linux without
    Docker
    

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31. References
    - bblf.sh / dashboard.bblf.sh
    - sourced.tech
    - github.com/bblfsh
    - @francesc @sourcedtech
    

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32. Thanks!
    

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