chore: fallback log sink example (#122)

Signed-off-by: Yashash H L <[email protected]>

.github/workflows/build-push.yaml

@@ -22,7 +22,8 @@ jobs:
           "pkg/reducer/examples/counter", "pkg/reducer/examples/sum", "pkg/reducestreamer/examples/counter",
           "pkg/reducestreamer/examples/sum", "pkg/sessionreducer/examples/counter", "pkg/sessionreducer/examples/sum",
           "pkg/sideinput/examples/simple-sideinput/udf", "pkg/sideinput/examples/simple-sideinput", "pkg/sinker/examples/log",
-          "pkg/sourcer/examples/simple_source", "pkg/sourcetransformer/examples/assign_event_time", "pkg/sourcetransformer/examples/event_time_filter"
+          "pkg/sourcer/examples/simple_source", "pkg/sourcetransformer/examples/assign_event_time", "pkg/sourcetransformer/examples/event_time_filter",
+          "pkg/sinker/examples/fallback"
         ]
 
     steps:

pkg/sinker/examples/fallback/Dockerfile

@@ -0,0 +1,20 @@
+####################################################################################################
+# base
+####################################################################################################
+FROM alpine:3.12.3 as base
+RUN apk update && apk upgrade && \
+    apk add ca-certificates && \
+    apk --no-cache add tzdata
+
+COPY dist/fallback-example /bin/fallback-example
+RUN chmod +x /bin/fallback-example
+
+####################################################################################################
+# fallback
+####################################################################################################
+FROM scratch as fallback
+ARG ARCH
+COPY --from=base /usr/share/zoneinfo /usr/share/zoneinfo
+COPY --from=base /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
+COPY --from=base /bin/fallback-example /bin/fallback-example
+ENTRYPOINT [ "/bin/fallback-example" ]

pkg/sinker/examples/fallback/Makefile

@@ -0,0 +1,18 @@
+TAG ?= stable
+PUSH ?= false
+
+.PHONY: build
+build:
+	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -v -o ./dist/log-example main.go
+
+.PHONY: image-push
+image-push: build
+	docker buildx build -t "quay.io/numaio/numaflow-go/fb-sink-log:${TAG}" --platform linux/amd64,linux/arm64 --target log . --push
+
+.PHONY: image
+image: build
+	docker build -t "quay.io/numaio/numaflow-go/fb-sink-log:${TAG}" --target log .
+	@if [ "$(PUSH)" = "true" ]; then docker push "quay.io/numaio/numaflow-go/fb-sink-log:${TAG}"; fi
+
+clean:
+	-rm -rf ./dist

pkg/sinker/examples/fallback/README.md

@@ -0,0 +1,3 @@
+# Fallback Sink Example
+
+An example User Defined Sink that returns a fallback response so that the payload will be sent to the fallback sink.

pkg/sinker/examples/fallback/go.mod

@@ -0,0 +1,17 @@
+module log_sink
+
+go 1.20
+
+replace github.com/numaproj/numaflow-go => ../../../..
+
+require github.com/numaproj/numaflow-go v0.7.0-rc2
+
+require (
+	github.com/golang/protobuf v1.5.3 // indirect
+	golang.org/x/net v0.9.0 // indirect
+	golang.org/x/sys v0.7.0 // indirect
+	golang.org/x/text v0.9.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20230525234030-28d5490b6b19 // indirect
+	google.golang.org/grpc v1.57.0 // indirect
+	google.golang.org/protobuf v1.31.0 // indirect
+)

pkg/sinker/examples/fallback/go.sum

@@ -0,0 +1,24 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
+github.com/golang/protobuf v1.5.3 h1:KhyjKVUg7Usr/dYsdSqoFveMYd5ko72D+zANwlG1mmg=
+github.com/golang/protobuf v1.5.3/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
+github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
+golang.org/x/net v0.9.0 h1:aWJ/m6xSmxWBx+V0XRHTlrYrPG56jKsLdTFmsSsCzOM=
+golang.org/x/net v0.9.0/go.mod h1:d48xBJpPfHeWQsugry2m+kC02ZBRGRgulfHnEXEuWns=
+golang.org/x/sys v0.7.0 h1:3jlCCIQZPdOYu1h8BkNvLz8Kgwtae2cagcG/VamtZRU=
+golang.org/x/sys v0.7.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/text v0.9.0 h1:2sjJmO8cDvYveuX97RDLsxlyUxLl+GHoLxBiRdHllBE=
+golang.org/x/text v0.9.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20230525234030-28d5490b6b19 h1:0nDDozoAU19Qb2HwhXadU8OcsiO/09cnTqhUtq2MEOM=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20230525234030-28d5490b6b19/go.mod h1:66JfowdXAEgad5O9NnYcsNPLCPZJD++2L9X0PCMODrA=
+google.golang.org/grpc v1.57.0 h1:kfzNeI/klCGD2YPMUlaGNT3pxvYfga7smW3Vth8Zsiw=
+google.golang.org/grpc v1.57.0/go.mod h1:Sd+9RMTACXwmub0zcNY2c4arhtrbBYD1AUHI/dt16Mo=
+google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
+google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
+google.golang.org/protobuf v1.31.0 h1:g0LDEJHgrBl9N9r17Ru3sqWhkIx2NB67okBHPwC7hs8=
+google.golang.org/protobuf v1.31.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

pkg/sinker/examples/fallback/main.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+
+	sinksdk "github.com/numaproj/numaflow-go/pkg/sinker"
+)
+
+// fbLogSink is a sinker implementation that logs the input to stdout
+type fbLogSink struct {
+}
+
+func (l *fbLogSink) Sink(ctx context.Context, datumStreamCh <-chan sinksdk.Datum) sinksdk.Responses {
+	result := sinksdk.ResponsesBuilder()
+	for d := range datumStreamCh {
+		_ = d.EventTime()
+		_ = d.Watermark()
+		id := d.ID()
+		fmt.Println("Primary sink under maintenance, writing to fallback sink - ", string(d.Value()))
+		// write to fallback sink
+		result = result.Append(sinksdk.ResponseFallback(id))
+	}
+	return result
+}
+
+func main() {
+	err := sinksdk.NewServer(&fbLogSink{}).Start(context.Background())
+	if err != nil {
+		log.Panic("Failed to start sink function server: ", err)
+	}
+}