A simple multi-tool TCP echo server for testing traffic patterns.
$ ./echo -h
Usage of ./echo:
-counter
Server prints how many connections it has had and closes the connection
-host string
Host to bind server to, empty means binding to all interfaces (default "0.0.0.0")
-httpcounter
Server becomes a Labstack Echo http server printing number of requests served as html on / and as json on /ping
-oneliner
Disconnect after receiving one line
-port int
Port to listen to (default 8080)$ go install github.com/sa6mwa/echo/cmd/echo@latestThere is a Makefile. make will run targets clean and build. You need
Go installed on your system. There is also make docker which
is using an intermediate build image (golang:1.19-alpine) to compile the
app...
$ make
rm -f echo
CGO_ENABLED=0 go get -v -d ./...
CGO_ENABLED=0 go test -cover ./...
? github.com/sa6mwa/echo/cmd/echo [no test files]
CGO_ENABLED=0 go build -v -ldflags=-s -o echo github.com/sa6mwa/echo/cmd/echo
github.com/sa6mwa/echo/cmd/echo
# Docker build
$ make docker
docker build --network none --build-arg "VERSION=c5e0ab8-dirty" -t echo:latest .
Sending build context to Docker daemon 5.398MB
Step 1/16 : FROM golang:1.19-alpine AS builder
.
.
.
Step 13/13 : ENTRYPOINT [ "/app/echo" ]
---> Using cache
---> fe7bb4f7d65a
Successfully built fe7bb4f7d65a
Successfully tagged echo:latestIf you would like another tag, you can change repository and tag using the
Makefile variables REPO and TAG...
$ make docker REPO=my-ecr-registry/echo TAG=v0.1.0
.
.
.
Step 13/13 : ENTRYPOINT [ "/app/echo" ]
---> Using cache
---> fe7bb4f7d65a
Successfully built fe7bb4f7d65a
Successfully tagged my-ecr-registry/echo:v0.1.0From here you can push the image to your target repository...
# Assuming latest tag was not used...
$ docker tag echo:v0.1.0 my-ecr-registry/echo:v0.1.0
$ docker tag echo:v0.1.0 my-ecr-registry/echo:latest
$ docker push my-ecr-registry/echoUsing -httpcounter with the docker container...
$ docker run -ti echo -httpcounter
2023/02/05 19:21:42 github.com/sa6mwa/echo version c5e0ab8-dirty
____ __
/ __/___/ / ___
/ _// __/ _ \/ _ \
/___/\__/_//_/\___/ v4.10.0
High performance, minimalist Go web framework
https://echo.labstack.com
____________________________________O/_______
O\
⇨ http server started on 0.0.0.0:8080
{"time":"2022-11-09T21:50:36.565849978Z","id":"","remote_ip":"172.31.0.1","host":"172.31.0.2:8080","method":"GET","uri":"/ping","user_agent":"curl/7.68.0","status":200,"error":"","latency":52015,"latency_human":"52.015µs","bytes_in":0,"bytes_out":44
In another window...
$ curl 172.31.0.2:8080/ping
{"remoteAddr":"172.31.0.1:50800","count":1}
$ To find out which IP the docker container has, you might do something like...
$ docker inspect `docker ps | grep /app/echo | awk '{print $1}'` | jq -r .[].NetworkSettings.IPAddress
172.31.0.2Subsequent requests increases the counter...
$ while true ; do curl 172.31.0.2:8080/ping ; sleep 1 ; done
{"remoteAddr":"172.31.0.1:37948","count":2}
{"remoteAddr":"172.31.0.1:37952","count":3}
{"remoteAddr":"172.31.0.1:37958","count":4}
{"remoteAddr":"172.31.0.1:37966","count":5}
{"remoteAddr":"172.31.0.1:37982","count":6}
{"remoteAddr":"172.31.0.1:37990","count":7}Another example using socat and -counter...
$ docker run -ti echo -counter
2022/11/09 21:54:11 echo -counter is running on 0.0.0.0:8080Client-side...
$ while true ; do socat - tcp4:172.31.0.2:8080 ; sleep 0.5 ; done
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4Below is a testing scenario. This may appear when a single-instance container is
restarted and the socat loop continues (a daemon pod/task or e.g when AWS ECS
deploymentConfiguration says MinimumHealthPercent=0 and MaximumPercent=100). In
case of a replica container scheduler, two pods/tasks will run simultaneously
and when the new container is ready, traffic will switch from the old to the new
pod/task through the LB and you should only notice that the count restarts at 1
again (no downtime).
$ while true ; do socat - tcp4:172.31.0.2:8080 ; sleep 0.5 ; done
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2022/11/09 22:58:57 socat[1400263] E connect(5, AF=2 172.31.0.2:8080, 16): Connection refused
2022/11/09 22:59:00 socat[1400488] E connect(5, AF=2 172.31.0.2:8080, 16): Connection refused
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