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This is part of the following activity: https://github.com/openfaas/docs/pull/249 Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>
107 lines
2.7 KiB
Markdown
107 lines
2.7 KiB
Markdown
## Develop your own function
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### Working on the API Gateway or Watchdog
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To work on either of the FaaS Golang components checkout the "./build.sh" scripts and acompanying Dockerfiles.
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* [Roadmap and Contributing](https://github.com/openfaas/faas/blob/master/ROADMAP.md)
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### Creating a function
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Functions run as Docker containers with the Watchdog component embedded to handle communication with the API Gateway.
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You can find the [reference documentation for the Watchdog here](https://github.com/openfaas/faas/tree/master/watchdog).
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**Markdown Parser**
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This is the basis of a function which generates HTML from MarkDown:
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```
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FROM golang:1.9.7
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RUN mkdir -p /go/src/app
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COPY handler.go /go/src/app
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WORKDIR /go/src/app
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RUN go get github.com/microcosm-cc/bluemonday && \
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go get github.com/russross/blackfriday
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RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o app .
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ADD https://github.com/openfaas/faas/releases/download/0.9.14/fwatchdog /usr/bin
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RUN chmod +x /usr/bin/fwatchdog
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ENV fprocess="/go/src/app/app"
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CMD ["/usr/bin/fwatchdog"]
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```
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The base Docker container is not important, you just need to add the watchdog component and then set the fprocess to execute your binary at runtime.
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Update the Docker stack with this:
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```
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markdown:
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image: alexellis2/faas-markdownrender:latest
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labels:
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function: "true"
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networks:
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- functions
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```
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**Word counter with busybox**
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```
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FROM alpine:latest
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ADD https://github.com/openfaas/faas/releases/download/0.9.14/fwatchdog /usr/bin
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RUN chmod +x /usr/bin/fwatchdog
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ENV fprocess="wc"
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CMD ["fwatchdog"]
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```
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Update your Docker stack with this definition:
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```
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wordcount:
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image: alexellis2/faas-alpinefunction:latest
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labels:
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function: "true"
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networks:
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- functions
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environment:
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fprocess: "wc"
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```
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**Tip:**
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You can optimize Docker to cache getting the watchdog by using curl, instead of ADD.
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To do so, replace the related lines with:
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```
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RUN apt-get update && apt-get install -y curl \
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&& curl -sL https://github.com/openfaas/faas/releases/download/0.9.14/fwatchdog > /usr/bin/fwatchdog \
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&& chmod +x /usr/bin/fwatchdog \
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&& rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
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```
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or with the following for Alpine based images:
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```
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RUN apk --no-cache add curl \
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&& curl -sL https://github.com/openfaas/faas/releases/download/0.9.14/fwatchdog > /usr/bin/fwatchdog \
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&& chmod +x /usr/bin/fwatchdog
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```
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### Testing your function
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You can test your function through a webbrowser against the UI portal on port 8080.
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http://localhost:8080/
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You can also invoke a function by name with curl:
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```
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curl --data-binary @README.md http://localhost:8080/function/func_wordcount
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```
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