faas/guide/troubleshooting.md

Troubleshooting guide

Watchdog

Debug your function without deploying it

Here's an example of how you can deploy a function without using an orchestrator - it's useful for testing:

$ docker run --name debug-alpine \
  -p 8081:8080 -ti functions/alpine:latest sh
# fprocess=date fwatchdog &

Now you can access the function with one of the supported HTTP methods such as GET/POST etc:

$ curl -4 localhost:8081

Edit your function without rebuilding it

You can bind-mount code straight into your function and work with it locally, until you are ready to re-build. This is a common flow with containers, but should be used sparingly.

Within the CLI directory for instance:

Build the samples:

$ git clone https://github.com/alexellis/faas-cli && \
  cd faas-cli
$ faas-cli -action build -f ./samples.yml

Now work with the Python-hello sample, with the code mounted live:

$ docker run -v `pwd`/sample/url-ping/:/root/function/ \
  --name debug-alpine -p 8081:8080 -ti alexellis/faas-url-ping sh
$ touch ./function/__init__.py
# fwatchdog

Now you can start editing the code in the sample/url-ping folder and it will reload live for every request.

$ curl localhost:8081 -d "https://www.google.com"
Handle this -> https://www.google.com
https://www.google.com => 200

Now you can edit handler.py and you'll see the change immediately:

$ echo "def handle(req):" > sample/url-ping/handler.py
$ echo '    print("Nothing to see here")' >> sample/url-ping/handler.py
$ curl localhost:8081 -d "https://www.google.com"
Nothing to see here

Docker Swarm

List all functions

$ docker service ls

Find a function's logs

$ docker swarm logs --tail 100 <function>

Find out if a function failed to start

$ docker swarm ps --no-trunc=true <function>

Kubernetes

List all functions

$ kubectl get deploy

Find a function's logs

$ kubectl logs deploy/<function>

Find out if a function failed to start

$ kubectl describe deploy/<function>