aslsp

ASLSP (... originally a piece by John Cage that means: As SLow aS Possible ...) is an extremely simple HTTP app written in Go, packaged with Docker, and deployable in Kubernetes.

Originally used for testing Chaos Engineering tests, now a general purpose app that can operate in two modes: client or server.

The client on port 8888 is called: CRAQUE The server on port 9999 is called: BACQUE

Local Startup

Open two terminals. Start up CRAQUE, the client, on the first:

1. go build aslsp
2. export BACQUE="http://localhost:9999/fetch"
3. ./aslsp

Start up BACQUE, the server, on the second:

1. ./aslsp -nofetch

Local Test

Client

• Test the client in a browser at: http://localhost:8888/dt
• In a terminal: curl localhost:8888/dt

The result will look like (in macOS the IPv6 localhost shows up as the requestor):

DateTime=202406211513
RequestIP=::1
LocalIP=10.10.10.28

When the Server is Down

The client will fall-back in the case of BACQUE being unavailable. It will respond with HTTP Error Code 418 to indicate: "I'm not supposed to be showing you this, but the server is down so I am." In other words: I am a teapot, not a coffee maker. I know you want coffee, but here's some tea. This is a real response code that can be tracked.

I'm a teapot
DateTime=202406211524

Server

• Test the server in a browser at: http://localhost:9999/fetch
• In a terminal: curl localhost:9999/fetch
• Prometheus scrape: curl localhost:9999/metrics

The result will look identical to the client, because this is what the client fetches:

DateTime=202406211513
RequestIP=::1
LocalIP=10.10.10.28

Kubernetes Deploy

Using kubectl install these yaml files in order:

1. aslsp.yaml (namespace)
2. bacque.yaml (server should be up first)
3. craque.yaml (BACQUE is set in the yaml)

Kubernetes Test

Client

• Get the server LoadBalancer address with something like: kubectl -n aslsp get svc craque
• Test the server in a browser, my local example is: http://198.19.249.2/dt

The result:

>>> curl 198.19.249.2/dt
DateTime=202406212249
RequestIP=192.168.194.20
LocalIP=192.168.194.16

Server

• Shell into one of the craque containers.
• Test from the commandline: wget -q -O - http://bacque/fetch

The result will be identical to what the client gets:

/go/src/aslsp # wget -q -O - http://bacque/fetch
DateTime=202406212356
RequestIP=192.168.194.20
LocalIP=192.168.194.15

TODO

• Tests
• Can Codefresh do latest?
• Push to internal reg?
• Sync to public aslsp & publish to github via codefresh, using the same code