This repo contains sample Go code to publish and subscribe message from NATS Streaming using Keda to autoscale the consumers.
This project has been upgraded to use keda v2
The publisher will continuously publish messages to NATS Streaming Server.
The project is divided into several folders.
natss-chart- Contains the helm chart to install Nats Streaming server.pub- contains the publisher code.sub- contains the subscriber code.k8s-manifest/pub- contains the Helm chart to deploy the publisher.k8s-manifest/sub- contains the Helm chart to deploy the subscriber.keda-nats-scaler- contains theScaledObjectto feed Keda for autoscaling.
- skaffold - Use to build and deploy the application to Kubernetes. Use version v1.16.0
- helm - Use v3. Kubernetes package manager.
- Kubernetes cluster - such as Microk8s, with API Aggregation Layer enabled, version preferrably >= 1.15.
- kubectl
- keda - Use v2
Make sure you are using helm v3. From the root directory.
$ skaffold deploy -p stan
Verify that nats streaming is running
$ kubectl -n stan get pods
NAME READY STATUS RESTARTS AGE
stan-nats-ss-0 1/1 Running 0 82s
We use kaniko with skaffold to build our container image in-cluster
Setup kaniko registry access secret
kubectl -n gonuts create secret generic regcred --from-file $HOME/.docker/config.json
Modify the docker registry repository in the skaffold.yaml file. Example below:
apiVersion: skaffold/v2beta9
kind: Config
profiles:
- name: pub
build:
artifacts:
- image: 192.168.1.12:32000/gonuts-pub
context: pub
kaniko:
dockerfile: Dockerfile
cache:
repo: 192.168.1.12:32000/gonuts-pub
insecureRegistries:
- 192.168.1.12:32000
cluster:
namespace: gonuts
dockerConfig:
secretName: regcred
deploy:
helm:
releases:
- name: gonuts-pub
chartPath: k8s-manifest/pub
artifactOverrides:
image.repository: 192.168.1.12:32000/gonuts-pub
namespace: gonuts
wait: true
- name: sub
build:
artifacts:
- image: 192.168.1.12:32000/gonuts-sub
context: sub
kaniko:
dockerfile: Dockerfile
cache:
repo: 192.168.1.12:32000/gonuts-sub
insecureRegistries:
- 192.168.1.12:32000
cluster:
namespace: gonuts
dockerConfig:
secretName: regcred
deploy:
helm:
releases:
- name: gonuts-sub
chartPath: k8s-manifest/sub
artifactOverrides:
image.repository: 192.168.1.12:32000/gonuts-sub
namespace: gonuts
wait: true
Go to the project's root directory and execute the command below.
skaffold run -p pub
You should see some logs which looks like this.
$ skaffold run -p pub
Generating tags...
- 192.168.1.12:32000/gonuts-pub -> 192.168.1.12:32000/gonuts-pub:c0ce3d6-dirty
Checking cache...
- 192.168.1.12:32000/gonuts-pub: Not found. Building
Creating docker config secret [regcred]...
Building [192.168.1.12:32000/gonuts-pub]...
E1031 01:52:47.968630 1 aws_credentials.go:77] while getting AWS credentials NoCredentialProviders: no valid providers in chain. Deprecated.
For verbose messaging see aws.Config.CredentialsChainVerboseErrors
INFO[0006] Resolved base name golang:1.15.3 to build
INFO[0006] Retrieving image manifest golang:1.15.3
INFO[0006] Retrieving image golang:1.15.3
INFO[0009] Retrieving image manifest golang:1.15.3
INFO[0009] Retrieving image golang:1.15.3
INFO[0012] Retrieving image manifest gcr.io/distroless/base:debug
. . . .
github.com/nats-io/nats.go/encoders/builtin
golang.org/x/crypto/ed25519
github.com/nats-io/nuid
net
github.com/gogo/protobuf/proto
github.com/nats-io/nkeys
crypto/x509
crypto/tls
github.com/gogo/protobuf/protoc-gen-gogo/descriptor
github.com/gogo/protobuf/gogoproto
github.com/nats-io/stan.go/pb
github.com/nats-io/nats.go/util
github.com/nats-io/nats.go
github.com/nats-io/stan.go
github.com/balchua/gonuts/pub
INFO[0060] Taking snapshot of full filesystem...
INFO[0063] Pushing layer 192.168.1.12:32000/gonuts-pub:f60f6e0b1e43b1111d97637bb55947f5046d147feedce1f3187f4de7f3d11b67 to cache now
INFO[0065] Saving file app for later use
INFO[0065] Deleting filesystem...
INFO[0066] Retrieving image manifest gcr.io/distroless/base:debug
INFO[0066] Retrieving image gcr.io/distroless/base:debug
INFO[0067] Retrieving image manifest gcr.io/distroless/base:debug
INFO[0067] Retrieving image gcr.io/distroless/base:debug
INFO[0069] Executing 0 build triggers
INFO[0069] Unpacking rootfs as cmd COPY --from=build /app /app requires it.
INFO[0071] COPY --from=build /app /app
INFO[0071] Taking snapshot of files...
INFO[0071] ENV GOTRACEBACK=all
INFO[0071] No files changed in this command, skipping snapshotting.
INFO[0071] ENTRYPOINT ["/app", "-s", "nats://stan-nats-ss.stan.svc.cluster.local:4222", "Test"]
. . . .
Towards the end, you should see the logs and pub application deployed.
Starting deploy...
Helm release gonuts-pub not installed. Installing...
NAME: gonuts-pub
LAST DEPLOYED: Sat Oct 31 10:17:22 2020
NAMESPACE: gonuts
STATUS: deployed
REVISION: 1
TEST SUITE: None
NOTES:
1. Get the application URL by running these commands:
Waiting for deployments to stabilize...
- gonuts:deployment/gonuts-pub is ready.
Deployments stabilized in 1.413569237s
$ kubectl -n gonuts get pods
NAME READY STATUS RESTARTS AGE
gonuts-pub-75fbd86dd8-5z6b8 1/1 Running 0 51s
To install the publisher application, the process is the same, simply run the command below.
skaffold run -p sub
You should see something in the console which looks like this.
$ skaffold run -p sub
Generating tags...
- 192.168.1.12:32000/gonuts-sub -> 192.168.1.12:32000/gonuts-sub:c0ce3d6-dirty
Checking cache...
- 192.168.1.12:32000/gonuts-sub: Not found. Building
Creating docker config secret [regcred]...
Building [192.168.1.12:32000/gonuts-sub]...
E1031 02:19:59.968604 1 aws_credentials.go:77] while getting AWS credentials NoCredentialProviders: no valid providers in chain. Deprecated.
For verbose messaging see aws.Config.CredentialsChainVerboseErrors
INFO[0006] Resolved base name golang:1.15.3 to build
INFO[0006] Retrieving image manifest golang:1.15.3
INFO[0006] Retrieving image golang:1.15.3
INFO[0013] Retrieving image manifest golang:1.15.3
INFO[0013] Retrieving image golang:1.15.3
INFO[0017] Retrieving image manifest gcr.io/distroless/base
INFO[0017] Retrieving image gcr.io/distroless/base
INFO[0018] Retrieving image manifest gcr.io/distroless/base
INFO[0018] Retrieving image gcr.io/distroless/base
INFO[0021] Built cross stage deps: map[0:[/app]]
INFO[0021] Retrieving image manifest golang:1.15.3
INFO[0021] Retrieving image golang:1.15.3
INFO[0024] Retrieving image manifest golang:1.15.3
INFO[0024] Retrieving image golang:1.15.3
INFO[0027] Executing 0 build triggers
INFO[0027] Using files from context: [/kaniko/buildcontext/go.mod]
INFO[0027] Using files from context: [/kaniko/buildcontext/go.sum]
INFO[0027] Checking for cached layer 192.168.1.12:32000/gonuts-sub:c272aee5d3a35296e11ece19cf269d1372497a75a04a99b69345abc2fcc7b0c3...
INFO[0027] No cached layer found for cmd RUN go mod download
INFO[0027] Unpacking rootfs as cmd ADD ./go.mod /src/github.com/balchua/gonuts/ requires it.
INFO[0049] WORKDIR /src/github.com/balchua/gonuts
INFO[0049] cmd: workdir
INFO[0049] Changed working directory to /src/github.com/balchua/gonuts
INFO[0049] Creating directory /src/github.com/balchua/gonuts
INFO[0049] Taking snapshot of files...
INFO[0049] Using files from context: [/kaniko/buildcontext/go.mod]
INFO[0049] ADD ./go.mod /src/github.com/balchua/gonuts/
INFO[0049] Taking snapshot of files...
INFO[0049] Using files from context: [/kaniko/buildcontext/go.sum]
INFO[0049] ADD ./go.sum /src/github.com/balchua/gonuts/
INFO[0049] Taking snapshot of files...
Afterwards the subscriber application is successfully deployed.
Helm release gonuts-sub not installed. Installing...
NAME: gonuts-sub
LAST DEPLOYED: Sat Oct 31 10:21:08 2020
NAMESPACE: gonuts
STATUS: deployed
REVISION: 1
TEST SUITE: None
NOTES:
1. Get the application URL by running these commands:
Waiting for deployments to stabilize...
- gonuts:deployment/gonuts-sub is ready.
Deployments stabilized in 1.28934836s
You can also run [skaffold run --tail] to get the logs
$ kubectl -n gonuts get pods
NAME READY STATUS RESTARTS AGE
gonuts-pub-75fbd86dd8-5z6b8 1/1 Running 0 17m
gonuts-sub-55495c99cb-hr28q 1/1 Running 0 30s$ kubectl -n gonuts logs -f gonuts-sub-55495c99cb-hr28q
Client ID is 1604110869763282645
Connected to nats://stan-nats-ss.stan.svc.cluster.local:4222 clusterID: [local-stan] clientID: [1604110869763282645]
Listening on [Test], clientID=[1604110869763282645], qgroup=[grp1] durable=[ImDurable]
[#1] Received: sequence:475 subject:"Test" data:"Message is : 2020-10-31 02:21:09.950956691 +0000 UTC m=+226.009217578" timestamp:1604110869951160516
[#2] Received: sequence:476 subject:"Test" data:"Message is : 2020-10-31 02:21:10.460821108 +0000 UTC m=+226.519082124" timestamp:1604110870461246187
[#3] Received: sequence:477 subject:"Test" data:"Message is : 2020-10-31 02:21:10.969098067 +0000 UTC m=+227.027359057" timestamp:1604110870969558237
[#4] Received: sequence:478 subject:"Test" data:"Message is : 2020-10-31 02:21:11.475637567 +0000 UTC m=+227.533898578" timestamp:1604110871476110536
[#5] Received: sequence:479 subject:"Test" data:"Message is : 2020-10-31 02:21:11.982656597 +0000 UTC m=+228.040917627" timestamp:1604110871983130403
[#6] Received: sequence:480 subject:"Test" data:"Message is : 2020-10-31 02:21:12.490413572 +0000 UTC m=+228.548674564" timestamp:1604110872490996118
[#7] Received: sequence:481 subject:"Test" data:"Message is : 2020-10-31 02:21:12.999504956 +0000 UTC m=+229.057765958" timestamp:1604110873000274816
[#8] Received: sequence:482 subject:"Test" data:"Message is : 2020-10-31 02:21:13.508621089 +0000 UTC m=+229.566882000" timestamp:1604110873508890863
[#9] Received: sequence:483 subject:"Test" data:"Message is : 2020-10-31 02:21:14.014100946 +0000 UTC m=+230.072361830" timestamp:1604110874014319383
[#10] Received: sequence:484 subject:"Test" data:"Message is : 2020-10-31 02:21:14.519517361 +0000 UTC m=+230.577778496" timestamp:1604110874520109861
[#11] Received: sequence:485 subject:"Test" data:"Message is : 2020-10-31 02:21:15.025881262 +0000 UTC m=+231.084142288" timestamp:1604110875026322690
[#12] Received: sequence:486 subject:"Test" data:"Message is : 2020-10-31 02:21:15.53233631 +0000 UTC m=+231.590597396" timestamp:1604110875532910570
[#13] Received: sequence:487 subject:"Test" data:"Message is : 2020-10-31 02:21:16.042193082 +0000 UTC m=+232.100454069" timestamp:1604110876042678078
[#14] Received: sequence:488 subject:"Test" data:"Message is : 2020-10-31 02:21:16.548750654 +0000 UTC m=+232.607011699" timestamp:1604110876549303234
[#15] Received: sequence:489 subject:"Test" data:"Message is : 2020-10-31 02:21:17.055079978 +0000 UTC m=+233.113340949" timestamp:1604110877055623442
[#16] Received: sequence:490 subject:"Test" data:"Message is : 2020-10-31 02:21:17.560853054 +0000 UTC m=+233.619114038" timestamp:1604110877561431724
[#17] Received: sequence:491 subject:"Test" data:"Message is : 2020-10-31 02:21:18.067055717 +0000 UTC m=+234.125316734" timestamp:1604110878067530215
[#18] Received: sequence:492 subject:"Test" data:"Message is : 2020-10-31 02:21:18.572877241 +0000 UTC m=+234.631138219" timestamp:1604110878573454006
[#19] Received: sequence:493 subject:"Test" data:"Message is : 2020-10-31 02:21:19.079877334 +0000 UTC m=+235.138138306" timestamp:1604110879080454252
[#20] Received: sequence:494 subject:"Test" data:"Message is : 2020-10-31 02:21:19.587194439 +0000 UTC m=+235.645455367" timestamp:1604110879587422308
[#21] Received: sequence:495 subject:"Test" data:"Message is : 2020-10-31 02:21:20.093883361 +0000 UTC m=+236.152144375" timestamp:1604110880094427736
[#22] Received: sequence:496 subject:"Test" data:"Message is : 2020-10-31 02:21:20.599528333 +0000 UTC m=+236.657789400" timestamp:1604110880600084393
[#23] Received: sequence:497 subject:"Test" data:"Message is : 2020-10-31 02:21:21.109621159 +0000 UTC m=+237.167882147" timestamp:1604110881110171335
[#24] Received: sequence:498 subject:"Test" data:"Message is : 2020-10-31 02:21:21.616687622 +0000 UTC m=+237.674948609" timestamp:1604110881617122514
Follow the instructions from Keda site.
Verify if keda pod is running.
$ kubectl -n keda get pods
NAME READY STATUS RESTARTS AGE
keda-67df4596b6-4zkgr 1/1 Running 0 6sApply the keda-nats-scaler/stan_scaledobject.yaml
$ kubectl apply -f keda-nats-scaler/stan_scaledobject.yaml
Check that the ScaledObject is properly installed.
$ kubectl -n gonuts get scaledobject
NAME SCALETARGETKIND SCALETARGETNAME TRIGGERS AUTHENTICATION READY ACTIVE AGE
stan-scaledobject apps/v1.Deployment gonuts-sub stan True True 86s
After applying the scaler, you should see the pods scale up.
$ kubectl -n gonuts get pods
NAME READY STATUS RESTARTS AGE
gonuts-pub-cd6d75b8f-brsjj 1/1 Running 0 13m
gonuts-sub-5fbcb7765f-bgddz 1/1 Running 0 9m41s
gonuts-sub-5fbcb7765f-npd6n 1/1 Running 0 40s
gonuts-sub-5fbcb7765f-lsvnx 1/1 Running 0 40s
gonuts-sub-5fbcb7765f-b69kl 1/1 Running 0 40s
gonuts-sub-5fbcb7765f-ml5z8 1/1 Running 0 24s
gonuts-sub-5fbcb7765f-z8qll 1/1 Running 0 24s
gonuts-sub-5fbcb7765f-fjbr2 1/1 Running 0 24s
gonuts-sub-5fbcb7765f-kg9vs 1/1 Running 0 24s
gonuts-sub-5fbcb7765f-wcltj 1/1 Running 0 9s
gonuts-sub-5fbcb7765f-fwp85 1/1 Running 0 9s
gonuts-sub-5fbcb7765f-gjwfk 1/1 Running 0 9s
gonuts-sub-5fbcb7765f-gkfnb 1/1 Running 0 9s
gonuts-sub-5fbcb7765f-xrb5p 1/1 Running 0 9s
gonuts-sub-5fbcb7765f-vk9mq 1/1 Running 0 9s
gonuts-sub-5fbcb7765f-q49f8 1/1 Running 0 9s
gonuts-sub-5fbcb7765f-r8c8f 1/1 Running 0 9s
Check the Horizontal Pod Autoscaler status
$ kubectl -n gonuts get hpa
NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
keda-hpa-stan-scaledobject Deployment/gonuts-sub 28367m/10 (avg) 1 30 30 94s
You can modify the production rate of message by changing the value of delayInBetweenPublish in the file k8s-manifest/pub/value.yaml
For example,production rate of 1 message every 2 seconds:
# Default values for pub.
# This is a YAML-formatted file.
# Declare variables to be passed into your templates.
replicaCount: 1
image:
repository: localhost:32000/gonuts-pub:SNAPSHOT
pullPolicy: Always
imagePullSecrets: []
nameOverride: ""
fullnameOverride: ""
delayInBetweenPublish: 2000
subject: "Test"
natsStreamingServerEndpoint: "nats://stan-nats-ss.stan.svc.cluster.local:4222"
To test that Keda will successfully scale the subscriber pods to zero, simply delete the publisher application.
$ skaffold delete -p pub
Cleaning up...
release "gonuts-pub" deleted
Cleanup complete in 634.066199msWait for a few minutes, depending on the number of pending messages you have in the broker and the publisher pods will be scaled to zero.
$ kubectl -n gonuts get pods
NAME READY STATUS RESTARTS AGE
gonuts-sub-55495c99cb-26kb2 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-4ljw4 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-76nwr 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-bvzkt 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-bwr4n 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-dkdcd 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-fpc7t 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-h6rtz 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-hm76r 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-hr28q 1/1 Terminating 0 26m
gonuts-sub-55495c99cb-jj7fx 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-jmdfv 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-jn9h9 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-klwq7 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-kmttg 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-l67sv 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-lfhck 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-llvlr 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-qf4w7 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-qk8bq 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-rq9sh 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-sdblq 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-stbvq 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-wnm4n 1/1 Terminating 0 12m
gonuts-sub-55495c99cb-xk97t 1/1 Terminating 0 12m
$ kubectl -n gonuts get pods
No resources found in gonuts namespace.You can change the values in file keda-nats-scaler/stan_scaledobject.yaml
Example:
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
name: stan-scaledobject
namespace: gonuts
spec:
pollingInterval: 10 # Optional. Default: 30 seconds
cooldownPeriod: 30 # Optional. Default: 300 seconds
minReplicaCount: 0 # Optional. Default: 0
maxReplicaCount: 30 # Optional. Default: 100
scaleTargetRef:
name: gonuts-sub
triggers:
- type: stan
metadata:
natsServerMonitoringEndpoint: "stan-nats-ss.stan.svc.cluster.local:8222"
queueGroup: "grp1"
durableName: "ImDurable"
subject: "Test"
lagThreshold: "10"Where:
natsServerMonitoringEndpoint: Is the location of the Nats Streaming monitoring endpoint. In this example it is the FQDN of nats streaming deployed.queuGroup: The queue group name of the subscribers.durableName: Must identify the durability name used by the subscribers.subject: Sometimes called the channel name.lagThreshold: This value is used to tell the Horizontal Pod Autoscaler to use as TargetAverageValue.
$ skaffold delete -p sub
$ skaffold delete -p pub
$ skaffold delete -p stan
To Uninstall keda, follow the guide
