I'm trying to implement canary deployment with Istio but first I have to deploy chart pods from the old version (Already managed to do it) and chart pods from the new version.
I created a new version of my chart. The chart has been created successfully.
Now I try to use helm install command to deploy the new version side by side with the old one.
I pass a new release name to the command in order to avoid overriding the old version my-release-v2 but I get an error that the release name in the chart must match the release name.
At this stage I'm a bit puzzled. Should I override it in the values.yaml if so - How exactly? Is this a best practice?
OK, I got this one is case it helps someone.
The release name should be unique. A good practice is to use our application name Chart.AppName.fullname along with the intended version in our helm install conmmand.
Then, we can use the same practice for our Deployment object that deploys our pods so it will be unique to the version. (Relevant part in the deployment.yaml)
apiVersion: apps/v1
kind: Deployment
metadata:
name: {{ include ".Chart.Name.fullname" . }}-{{ .Chart.AppVersion }}
And of course for a future selector in Istio create a version label in the pods (Relevant part in the deployment.yaml):
apiVersion: apps/v1
kind: Deployment
spec:
replicas: {{ .Values.replicaCount }}
template:
metadata:
labels:
app.kubernetes.io/version: {{ .Chart.AppVersion }}
Related
I am new to helm and liked the idea of helm to create versions for the deployments and package them as artifact in jfrog articatory but one thing that I am unclear about is easiness of creating it.
I am comfortable with kubernetes mainfest and creating it is very simple where you don't have to handcraft a yaml.
You can simply run kubectl command in dry-run mode and export most of the yaml tags as below:
kubectl run nginx --image=nginx --dry-run=client -o yaml > nginx-manifest.yaml
Now for creating helm, I need to run helm create and key in all the values needed by helm yaml files.
Curious if helm has such shortcuts that kubectl provides to create charts easily which keys in required value through command line while generating charts?
Also is there a migration utility available that supports converting the deployment manifest to helm charts?
helm create does what you are looking for. It creates a directory with all the basic stuff so that you don't need to manually create each file/directory. However, it can't create the content of a Chart it has no clue about.
But, there is no magic behind the scenes, a chart consists in templates and values. The templates are the same YAML files you are used to work with, except that you can replace whatever you want to make "dynamic" with the placeholders used by Helm. That's it.
So, in other words, just keep exporting as you are (I strongly suggest stopping doing this and create proper files suited for your needs) and add placeholders ({{ .Values.foo }})
For example, this is the template for a service I have:
apiVersion: v1
kind: Service
metadata:
name: {{ .Values.name | default .Chart.Name }}
spec:
ports:
- port: {{ .Values.port }}
protocol: TCP
targetPort: {{ .Values.port }}
selector:
app: {{ .Values.name | default .Chart.Name }}
i'm trying to assign pods to a specific node as part of helm command, so by the end the deployment yaml should look like this
spec:
containers:
- name: nginx
image: nginx
imagePullPolicy: IfNotPresent
nodeSelector:
node-name: dev-cpu-pool
i'm using this command as part of Jenkins file deployment
`sh "helm upgrade -f charts/${job_name}/default.yaml --set nodeSelector.name=${deployNamespace}-cpu-pool --install ${deployNamespace}-${name} helm/${name} --namespace=${deployNamespace} --recreate-pods --version=${version}`"
the deployment works good and the pod is up and running but from some reason i cannot see the nodeSelector key and value as part of the deployment yaml and as a results pods not assign to the specific node i want. any idea what is wrong ? should i put any place holder as part of my chart template or is not must ?
The artifacts that Helm submits to the Kubernetes API are exactly the result of rendering the chart templates; nothing more, nothing less. If your templates don't include a nodeSelector: block then the resulting Deployment never will either. Even if you helm install --set ... things that could match Kubernetes API fields, nothing will implicitly fill them in.
If you want an option to specify rarely-used fields like nodeSelector: then your chart code needs to include them. You can make the presence of the field conditional on the value being set, but you do need to explicitly list it out:
apiVersion: apps/v1
kind: Deployment
spec:
template:
spec:
{{- if .Values.nodeSelector }}
nodeSelector: {{- .Values.nodeSelector | toYaml | nindent 8 }}
{{- end }}
I'm doing a very simple chart with helm.
It consists on deploying a chart with just one object ("/templates/pod.yaml"), that have to be deployed just if a parameter of file Values.yaml is true.
To provide an example of my case, this is what I have:
/templates/pod.yaml
{{- if eq .Values.shoudBeDeployed true }}
apiVersion: v1
kind: Pod
metadata:
name: nginx
labels:
name: nginx
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
{{- end}}
Values.yaml
shoudBeDeployed: true
So when I use shoudBeDeployed with true value, helm installs it correctly.
My problem is that when shoudBeDeployed is false, helm doesn't deploy anything (as I expected), but helm shows the following message:
Error: release CHART_NAME failed: no objects visited
And if I execute helm ls I get that CHART_NAME is deployed with STATUS FAILED.
My question is if there is a way to not have it as a failed helm deploy. So I would like to not see it when using the command helm ls
I know that I could move the logic of shoudBeDeployed variable outside the chart, and then deploy the chart or not depending on its value, but I would like to know if there is a solution just using helm.
#pcampana I think there is no way to stop helm deployment if there is nothing to deploy. But here is a trick that you can use to delete a helm chart if it is
FAILED.
helm install --name temp demo --atomic
where demo is the helm chart directory and temp is release name .
release name is mandatory for this to work.
One scenario is when you see error
Error: release temp failed: no objects visited
you can use above command to deploy helm chart.
I think this might be useful for you.
I have a helm chart that deploys a number of Kubernetes resources. One of them is a resource that is of a Custom Resource Definition (CRD) type (ServiceMonitor used by prometheus-operator).
I am looking for a way, how to "tell" helm that I'd want to create this resource only if such a CRD is defined in the cluster OR to ignore errors only caused by the fact that such a CRD is missing.
Is that possible and how can I achieve that?
Helm's Capabilities object can tell you if an entire API class is installed in the cluster. I don't think it can test for a specific custom resource type.
In your .tpl files, you can wrap the entire file in a {{ if }}...{{ end }} block. Helm doesn't especially care if the rendered version of a file is empty.
That would lead you to a file like:
{{ if .Capabilities.APIVersions.Has "monitoring.coreos.com/v1" -}}
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
...
{{ end -}}
That would get installed if the operator is installed in the cluster, and skipped if not.
If you are on Helm 3 you can put your CRD in the crds/ directory. Helm will treat it differently, see the docs here.
In Helm 2 there is another mechanism using the crd-install hook. You can add the following to your CRD:
annotations:
"helm.sh/hook": crd-install
There are some limitations with this approach so if you are using Helm 3 that would be preferred.
In Helm v3, you can test for specific resources:
{{ if .Capabilities.APIVersions.Has "monitoring.coreos.com/v1/ServiceMonitor" -}}
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
...
spec:
...
{{- end }}
https://helm.sh/docs/chart_template_guide/builtin_objects/
We Could deploy applications using 'Helm Charts' with
helm install --name the-release helm/the-service-helm --namespace myns
And we cold 'Rolling Upgrade' the deployment using,
helm upgrade --recreate-pods the-release helm/the-service-helm --namespace myns
Is there a way to use 'Helm Charts' to achieve 'Blue/Green' Deployments?
Let's start from definitions
Since there are many deployment strategies, let's start from the definition.
As per Martin Flower:
The blue-green deployment approach does this by ensuring you have two production environments, as identical as possible. At any time one of them, let's say blue for the example, is live. As you prepare a new release of your software you do your final stage of testing in the green environment. Once the software is working in the green environment, you switch the router so that all incoming requests go to the green environment - the blue one is now idle.
Blue/Green is not recommended in Helm. But there are workaround solutions
As per to helm issue #3518, it's not recommended to use Helm for blue/green or canary deployment.
There are at least 3 solutions based on top of Helm, see below
However there is a Helm chart for that case.
Helm itself (TL;DR: not recommended)
Helm itself is not intended for the case. See their explanation:
direct support for blue / green deployment pattern in helm · Issue #3518 · helm/helm
Helm works more in the sense of a traditional package manager, upgrading charts from one version to the next in a graceful manner (thanks to pod liveness/readiness probes and deployment update strategies), much like how one expects something like apt upgrade to work. Blue/green deployments are a very different beast compared to the package manager style of upgrade workflows; blue/green sits at a level higher in the toolchain because the use cases around these deployments require step-in/step-out policies, gradual traffic migrations and rollbacks. Because of that, we decided that blue/green deployments are something out of scope for Helm, though a tool that utilizes Helm under the covers (or something parallel like istio) could more than likely be able to handle that use case.
Other solutions based on Helm
There are at least three solution based on top of Helm, described and compared here:
Shipper
Istio
Flagger.
Shipper by Booking.com - DEPRECATED
bookingcom/shipper: Kubernetes native multi-cluster canary or blue-green rollouts using Helm
It does this by relying on Helm, and using Helm Charts as the unit of configuration deployment. Shipper's Application object provides an interface for specifying values to a Chart just like the helm command line tool.
Shipper consumes Charts directly from a Chart repository like ChartMuseum, and installs objects into clusters itself. This has the nice property that regular Kubernetes authentication and RBAC controls can be used to manage access to Shipper APIs.
Kubernetes native multi-cluster canary or blue-green rollouts using Helm
Istio
You can try something like this:
kubectl create -f <(istioctl kube-inject -f cowsay-v1.yaml) # deploy v1
kubectl create -f <(istioctl kube-inject -f cowsay-v2.yaml) # deploy v1
Flagger.
There is guide written by Flagger team: Blue/Green Deployments - Flagger
This guide shows you how to automate Blue/Green deployments with Flagger and Kubernetes
You might try Helm itself
Also, as Kamol Hasan recommended, you can try that chart: puneetsaraswat/HelmCharts/blue-green.
blue.yml sample
{{ if .Values.blue.enabled }}
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: {{ template "blue-green.fullname" . }}-blue
labels:
release: {{ .Release.Name }}
chart: {{ .Chart.Name }}-{{ .Chart.Version }}
app: {{ template "blue-green.name" . }}
spec:
replicas: {{ .Values.replicaCount }}
template:
metadata:
labels:
app: {{ template "blue-green.name" . }}
release: {{ .Release.Name }}
slot: blue
spec:
containers:
- name: {{ template "blue-green.name" . }}-blue
image: nginx:stable
imagePullPolicy: IfNotPresent
ports:
- name: http
containerPort: 80
protocol: TCP
# This (and the volumes section below) mount the config map as a volume.
volumeMounts:
- mountPath: /usr/share/nginx/html
name: wwwdata-volume
volumes:
- name: wwwdata-volume
configMap:
name: {{ template "blue-green.fullname" . }}
{{ end }}
Medium blog post: Blue/Green Deployments using Helm Charts