76 lines
2.1 KiB
Markdown
76 lines
2.1 KiB
Markdown
# Design for FaaSO
|
|
|
|
## Introduction
|
|
|
|
This should explain the high-level plan. Of course once I start
|
|
writing the thing it will change, because I am *agile* like that.
|
|
|
|
So, here it is:
|
|
|
|
## Function Builder
|
|
|
|
Take the function code, some ancillary files, and build a docker
|
|
image using a template so that it can be executed.
|
|
|
|
Additionally:
|
|
|
|
* The image should be runnable with a standard `docker run` command
|
|
* A test can be defined to check if the function is working
|
|
|
|
## Function Runner
|
|
|
|
Given a description of what functions should be made available at
|
|
which endpoints, like
|
|
|
|
/sum -> sum
|
|
/mul -> multiply
|
|
|
|
It should:
|
|
|
|
* Start those functions via docker, running in specific ports
|
|
* Create a reverse proxy that routes the paths to the correct function
|
|
* Start/reload/configure the proxy as needed
|
|
* Periodically check the functions are still running
|
|
|
|
Intentionally: No HA yet, no multiple instances of functions, no
|
|
up/downscaling, no multiple versions routed by header.
|
|
|
|
Specifically: no downscaling to zero. It makes everything MUCH
|
|
more complicated.
|
|
|
|
# Function structure
|
|
|
|
Example using crystal, but it could be anything. Any function has
|
|
an associated runtime, for example "crystal" or "python".
|
|
|
|
That runtime has a template (see `templates/crystal` for example).
|
|
|
|
To build the function image, the builder will:
|
|
|
|
* Create a tmp directory
|
|
* Copy the template files to the tmp directory
|
|
* Overlay the function files on top of the template
|
|
* Build using the template Dockerfile
|
|
|
|
For docker that implies:
|
|
|
|
* Use an alpine builder, install crystal, shards, whatever
|
|
* Run "shards isntall" to get the dependencies
|
|
* Run "shards build" to build the function
|
|
* Copy the function binary to ~app
|
|
|
|
When running, it will just run that binary and map a port to port 3000.
|
|
|
|
Template metadata:
|
|
|
|
Probably some `metadata.yml` that is *not* in the template.
|
|
|
|
* Additional packages to install in the alpine builder
|
|
* Files that should be copied along the function
|
|
* Whatever
|
|
|
|
# Implementation Ideas
|
|
|
|
* caddy for proxy? It's simple, fast, API-configurable.
|
|
* Local docker registry for images? See https://www.docker.com/blog/how-to-use-your-own-registry-2/ (maybe later)
|