Helm¶
Declarative¶
You can install Helm charts through the UI, or in the declarative GitOps way.
Helm is only used to inflate charts with helm template
. The lifecycle of the application is handled by Argo CD instead of Helm.
Here is an example:
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
name: sealed-secrets
namespace: argocd
spec:
project: default
source:
chart: sealed-secrets
repoURL: https://bitnami-labs.github.io/sealed-secrets
targetRevision: 1.16.1
helm:
releaseName: sealed-secrets
destination:
server: "https://kubernetes.default.svc"
namespace: kubeseal
When using multiple ways to provide values
Order of precedence is parameters > valuesObject > values > valueFiles > helm repository values.yaml
(see Here for a more detailed example)
Values Files¶
Helm has the ability to use a different, or even multiple "values.yaml" files to derive its
parameters from. Alternate or multiple values file(s), can be specified using the --values
flag. The flag can be repeated to support multiple values files:
argocd app set helm-guestbook --values values-production.yaml
Note
Before v2.6
of Argo CD, Values files must be in the same git repository as the Helm
chart. The files can be in a different location in which case it can be accessed using
a relative path relative to the root directory of the Helm chart.
As of v2.6
, values files can be sourced from a separate repository than the Helm chart
by taking advantage of multiple sources for Applications.
In the declarative syntax:
source:
helm:
valueFiles:
- values-production.yaml
Values¶
Argo CD supports the equivalent of a values file directly in the Application manifest using the source.helm.valuesObject
key.
source:
helm:
valuesObject:
ingress:
enabled: true
path: /
hosts:
- mydomain.example.com
annotations:
kubernetes.io/ingress.class: nginx
kubernetes.io/tls-acme: "true"
labels: {}
tls:
- secretName: mydomain-tls
hosts:
- mydomain.example.com
Alternatively, values can be passed in as a string using the source.helm.values
key.
source:
helm:
values: |
ingress:
enabled: true
path: /
hosts:
- mydomain.example.com
annotations:
kubernetes.io/ingress.class: nginx
kubernetes.io/tls-acme: "true"
labels: {}
tls:
- secretName: mydomain-tls
hosts:
- mydomain.example.com
Helm Parameters¶
Helm has the ability to set parameter values, which override any values in
a values.yaml
. For example, service.type
is a common parameter which is exposed in a Helm chart:
helm template . --set service.type=LoadBalancer
Similarly, Argo CD can override values in the values.yaml
parameters using argocd app set
command,
in the form of -p PARAM=VALUE
. For example:
argocd app set helm-guestbook -p service.type=LoadBalancer
In the declarative syntax:
source:
helm:
parameters:
- name: "service.type"
value: LoadBalancer
Helm Value Precedence¶
Values injections have the following order of precedence
parameters > valuesObject > values > valueFiles > helm repository values.yaml
Or rather
lowest -> valueFiles
-> values
-> valuesObject
highest -> parameters
so values/valuesObject trumps valueFiles, and parameters trump both.
Precedence of valueFiles themselves is the order they are defined in
if we have
valuesFile:
- values-file-2.yaml
- values-file-1.yaml
the last values-file i.e. values-file-1.yaml will trump the first
When multiple of the same key are found the last one wins i.e
e.g. if we only have values-file-1.yaml and it contains
param1: value1
param1: value3000
we get param1=value3000
parameters:
- name: "param1"
value: value2
- name: "param1"
value: value1
the result will be param1=value1
values: |
param1: value2
param1: value5
the result will be param1=value5
When valuesFiles or values is used
The list of parameters seen in the ui is not what is used for resources, rather it is the values/valuesObject merged with parameters (see this issue incase it has been resolved) As a workaround using parameters instead of values/valuesObject will provide a better overview of what will be used for resources
Helm Release Name¶
By default, the Helm release name is equal to the Application name to which it belongs. Sometimes, especially on a centralised Argo CD,
you may want to override that name, and it is possible with the release-name
flag on the cli:
argocd app set helm-guestbook --release-name myRelease
or using the releaseName for yaml:
source:
helm:
releaseName: myRelease
Important notice on overriding the release name
Please note that overriding the Helm release name might cause problems when the chart you are deploying is using the app.kubernetes.io/instance
label. Argo CD injects this label with the value of the Application name for tracking purposes. So when overriding the release name, the Application name will stop being equal to the release name. Because Argo CD will overwrite the label with the Application name it might cause some selectors on the resources to stop working. In order to avoid this we can configure Argo CD to use another label for tracking in the ArgoCD configmap argocd-cm.yaml - check the lines describing application.instanceLabelKey
.
Helm Hooks¶
Helm hooks are similar to Argo CD hooks. In Helm, a hook
is any normal Kubernetes resource annotated with the helm.sh/hook
annotation.
Argo CD supports many (most?) Helm hooks by mapping the Helm annotations onto Argo CD's own hook annotations:
Helm Annotation | Notes |
---|---|
helm.sh/hook: crd-install |
Supported as equivalent to argocd.argoproj.io/hook: PreSync . |
helm.sh/hook: pre-delete |
Not supported. In Helm stable there are 3 cases used to clean up CRDs and 3 to clean-up jobs. |
helm.sh/hook: pre-rollback |
Not supported. Never used in Helm stable. |
helm.sh/hook: pre-install |
Supported as equivalent to argocd.argoproj.io/hook: PreSync . |
helm.sh/hook: pre-upgrade |
Supported as equivalent to argocd.argoproj.io/hook: PreSync . |
helm.sh/hook: post-upgrade |
Supported as equivalent to argocd.argoproj.io/hook: PostSync . |
helm.sh/hook: post-install |
Supported as equivalent to argocd.argoproj.io/hook: PostSync . |
helm.sh/hook: post-delete |
Supported as equivalent to argocd.argoproj.io/hook: PostDelete . |
helm.sh/hook: post-rollback |
Not supported. Never used in Helm stable. |
helm.sh/hook: test-success |
Not supported. No equivalent in Argo CD. |
helm.sh/hook: test-failure |
Not supported. No equivalent in Argo CD. |
helm.sh/hook-delete-policy |
Supported. See also argocd.argoproj.io/hook-delete-policy ). |
helm.sh/hook-delete-timeout |
Not supported. Never used in Helm stable |
helm.sh/hook-weight |
Supported as equivalent to argocd.argoproj.io/sync-wave . |
helm.sh/resource-policy: keep |
Supported as equivalent to argocd.argoproj.io/sync-options: Delete=false . |
Unsupported hooks are ignored. In Argo CD, hooks are created by using kubectl apply
, rather than kubectl create
. This means that if the hook is named and already exists, it will not change unless you have annotated it with before-hook-creation
.
Helm hooks + ArgoCD hooks
If you define any Argo CD hooks, all Helm hooks will be ignored.
'install' vs 'upgrade' vs 'sync'
Argo CD cannot know if it is running a first-time "install" or an "upgrade" - every operation is a "sync'. This means that, by default, apps that have pre-install
and pre-upgrade
will have those hooks run at the same time.
Hook Tips¶
- Make your hook idempotent.
- Annotate
crd-install
withhook-weight: "-2"
to make sure it runs to success before any install or upgrade hooks. - Annotate
pre-install
andpost-install
withhook-weight: "-1"
. This will make sure it runs to success before any upgrade hooks. - Annotate
pre-upgrade
andpost-upgrade
withhook-delete-policy: before-hook-creation
to make sure it runs on every sync.
Read more about Argo hooks and Helm hooks.
Random Data¶
Helm templating has the ability to generate random data during chart rendering via the
randAlphaNum
function. Many helm charts from the charts repository
make use of this feature. For example, the following is the secret for the
redis helm chart:
data:
{{- if .Values.password }}
redis-password: {{ .Values.password | b64enc | quote }}
{{- else }}
redis-password: {{ randAlphaNum 10 | b64enc | quote }}
{{- end }}
The Argo CD application controller periodically compares Git state against the live state, running
the helm template <CHART>
command to generate the helm manifests. Because the random value is
regenerated every time the comparison is made, any application which makes use of the randAlphaNum
function will always be in an OutOfSync
state. This can be mitigated by explicitly setting a
value in the values.yaml or using argocd app set
command to overide the value such that the value
is stable between each comparison. For example:
argocd app set redis -p password=abc123
Build Environment¶
Helm apps have access to the standard build environment via substitution as parameters.
E.g. via the CLI:
argocd app create APPNAME \
--helm-set-string 'app=${ARGOCD_APP_NAME}'
Or via declarative syntax:
spec:
source:
helm:
parameters:
- name: app
value: $ARGOCD_APP_NAME
It's also possible to use build environment variables for the Helm values file path:
spec:
source:
helm:
valueFiles:
- values.yaml
- myprotocol://somepath/$ARGOCD_APP_NAME/$ARGOCD_APP_REVISION
Helm plugins¶
Argo CD is un-opinionated on what cloud provider you use and what kind of Helm plugins you are using, that's why there are no plugins delivered with the ArgoCD image.
But sometimes you want to use a custom plugin. Perhaps you would like to use Google Cloud Storage or Amazon S3 storage to save the Helm charts, for example: https://github.com/hayorov/helm-gcs where you can use gs://
protocol for Helm chart repository access.
There are two ways to install custom plugins; you can modify the ArgoCD container image, or you can use a Kubernetes initContainer
.
Modifying the ArgoCD container image¶
One way to use this plugin is to prepare your own ArgoCD image where it is included.
Example Dockerfile
:
FROM argoproj/argocd:v1.5.7
USER root
RUN apt-get update && \
apt-get install -y \
curl && \
apt-get clean && \
rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
USER argocd
ARG GCS_PLUGIN_VERSION="0.3.5"
ARG GCS_PLUGIN_REPO="https://github.com/hayorov/helm-gcs.git"
RUN helm plugin install ${GCS_PLUGIN_REPO} --version ${GCS_PLUGIN_VERSION}
ENV HELM_PLUGINS="/home/argocd/.local/share/helm/plugins/"
You have to remember about HELM_PLUGINS
environment property - this is required for plugins to work correctly.
After that you have to use your custom image for ArgoCD installation.
Using initContainers
¶
Another option is to install Helm plugins via Kubernetes initContainers
.
Some users find this pattern preferable to maintaining their own version of the ArgoCD container image.
Below is an example of how to add Helm plugins when installing ArgoCD with the official ArgoCD helm chart:
repoServer:
volumes:
- name: gcp-credentials
secret:
secretName: my-gcp-credentials
volumeMounts:
- name: gcp-credentials
mountPath: /gcp
env:
- name: HELM_CACHE_HOME
value: /helm-working-dir
- name: HELM_CONFIG_HOME
value: /helm-working-dir
- name: HELM_DATA_HOME
value: /helm-working-dir
initContainers:
- name: helm-gcp-authentication
image: alpine/helm:3.8.1
volumeMounts:
- name: helm-working-dir
mountPath: /helm-working-dir
- name: gcp-credentials
mountPath: /gcp
env:
- name: HELM_CACHE_HOME
value: /helm-working-dir
- name: HELM_CONFIG_HOME
value: /helm-working-dir
- name: HELM_DATA_HOME
value: /helm-working-dir
command: [ "/bin/sh", "-c" ]
args:
- apk --no-cache add curl;
helm plugin install https://github.com/hayorov/helm-gcs.git;
helm repo add my-gcs-repo gs://my-private-helm-gcs-repository;
chmod -R 777 $HELM_DATA_HOME;
Helm Version¶
Argo CD will assume that the Helm chart is v3 (even if the apiVersion field in the chart is Helm v2), unless v2 is explicitly specified within the Argo CD Application (see below).
If needed, it is possible to specifically set the Helm version to template with by setting the helm-version
flag on the cli (either v2 or v3):
argocd app set helm-guestbook --helm-version v3
Or using declarative syntax:
spec:
source:
helm:
version: v3
Helm --pass-credentials
¶
Helm, starting with v3.6.1, prevents sending repository credentials to download charts that are being served from a different domain than the repository.
If needed, it is possible to opt into passing credentials for all domains by setting the helm-pass-credentials
flag on the cli:
argocd app set helm-guestbook --helm-pass-credentials
Or using declarative syntax:
spec:
source:
helm:
passCredentials: true
Helm --skip-crds
¶
Helm installs custom resource definitions in the crds
folder by default if they are not existing.
See the CRD best practices for details.
If needed, it is possible to skip the CRD installation step with the helm-skip-crds
flag on the cli:
argocd app set helm-guestbook --helm-skip-crds
Or using declarative syntax:
spec:
source:
helm:
skipCrds: true