Helm install in certain order

Question

I am trying to create a Helm Chart with the following resources:

1. Secret
2. ConfigMap
3. Service
4. Job
5. Deployment

These are also in the order that I would like them to be deployed. I have put a hook in the Deployment so that it is post-install, but then Helm does not see it as a resource and I have to manually manage it.

The Job needs the information in the Secret and ConfigMap, otherwise I would make that a pre-install hook. But I can't make everything a hook or nothing will be managed in my release.

Does anyone have a solution or idea to be able to manage all of the resources within the Helm release AND make sure the Job finishes before the Deployment begins?

My only thought right now is two make two Charts: One with 1-4 and the second with 5 which would depend on the first.

Pogue

Have you already tried using a multi-document YAML file? Multi-document YAML is an ordered list, but I don't know if they are applied in that order. I would hope so but I hope lots of things – Anarch

Out of interest what does the Job do? – Subjective

I ask partly because I'm wondering if you could put an initContainer in the Deployment and move the Job's logic there instead. The configmap and secret should be created first anyway with helm's resource ordering – Subjective

@RyanDawson The Job prepares the Database and I wouldn't want it running for each Deployment Pod. – Pogue

If you choose to do so you could make it idempotent with a check at the beginning. For examples of doing this from the official helm/charts repo see any of github.com/helm/charts/… or github.com/helm/charts/blob/master/stable/keycloak/templates/… – Subjective

Answer 1

Helm collects all of the resources in a given Chart and it's dependencies, groups them by resource type, and then installs them in the following order (see here - Helm 2.10):

1. Namespace
2. ResourceQuota
3. LimitRange
4. PodSecurityPolicy
5. Secret
6. ConfigMap
7. StorageClass
8. PersistentVolume
9. PersistentVolumeClaim
10. ServiceAccount
11. CustomResourceDefinition
12. ClusterRole
13. ClusterRoleBinding
14. Role
15. RoleBinding
16. Service
17. DaemonSet
18. Pod
19. ReplicationController
20. ReplicaSet
21. Deployment
22. StatefulSet
23. Job
24. CronJob
25. Ingress
26. APIService

During uninstallation of a release, the order is reversed (see here).

Following this logic, in your case when your Job resource is created, both the Secret and the ConfigMap will already be applied, but Helm won't wait for the Job to complete before applying the Deployment. If you split your Chart to two parts (1-4, 5) and install them sequentially you would still have the problem of the Deployment being possibly applied before the Job is completed. What I would suggest is splitting your Chart to two parts (1-3, 4-5), in which the the Job has a pre-install hook, which would make sure it completes before your Deployment is applied.

Akilahakili

thank you for your suggestion, I will read more about Chart dependencies and try out splitting it into (1-3,4-5). My follow-up question is then, is this a 'best practice' or am I already straying from that ideal with my problem to begin with? Also, thank you for the links to the code, it is hard for me to find helpful things like that! – Pogue

I'm not sure what the best practice here is, but as far as I see it there are two options - splitting your chart or using init containers to make your k8s resource idempotent. There are pros and cons for both (mainly having simpler k8s resources with less complex logic when choosing to split your charts, but requires more complex logic when applying your Helm charts and managing releases). IMHO I'd go with splitting the charts in your case. – Akilahakili

Nice answer and a simple explaination – Furey

Link to source for v3 of helm:github.com/helm/helm/blob/release-3.0/pkg/releaseutil/… – Cantone

what's the order of type List? – Edaedacious

And if I haver another kind not in that list like SecretProviderClass? – Outbalance

@Outbalance I had the same question in my mind as well and it seems to be answered here: github.com/helm/helm/blob/… – Rancher

What about custom resources? Facing an issue with OPA templates and constraints not installing in the right order. – Mellow

what's the order of HorizontalPodAutoscaler? – Edaedacious

Answer 2

Helm tries to install things in a certain order, but doesn't check if pods / deployments / jobs are running / completed before moving on. Also note that a chart and its dependencies are installed simultaneously, so you cannot use a chart with a dependency to re-order how Helm installs resources.

You can use chart hooks to change the order, but these aren't managed resources. In my case, the problem was that we needed custom resources up, then we needed a short script to run, and then we needed to start our deployments. With --wait, if the pod the script was in completed, Helm would mark the upgrade/install as a failure and rollback. The solution in this case was just to use a Job instead of a Pod, which commenters on that issue had more problems with than I did, and then accept that the deployments would restart a few times before everything finally became ready.

Helm 3.7 install order:

1. Namespace
2. NetworkPolicy
3. ResourceQuota
4. LimitRange
5. PodSecurityPolicy
6. PodDisruptionBudget
7. ServiceAccount
8. Secret
9. SecretList
10. ConfigMap
11. StorageClass
12. PersistentVolume
13. PersistentVolumeClaim
14. CustomResourceDefinition
15. ClusterRole
16. ClusterRoleList
17. ClusterRoleBinding
18. ClusterRoleBindingList
19. Role
20. RoleList
21. RoleBinding
22. RoleBindingList
23. Service
24. DaemonSet
25. Pod
26. ReplicationController
27. ReplicaSet
28. Deployment
29. HorizontalPodAutoscaler
30. StatefulSet
31. Job
32. CronJob
33. Ingress
34. APIService
35. this closed git issue tells us CustomResources are last to be installed.

Source. Only difference from above is more resource types and the ServiceAccount got pushed up slightly in the list.

Cheremkhovo

Answer 3

Warning: The order of v2 & v3 is very different. So you should be carefully.

You should check the order from latest release with InstallOrder like below helm/pkg/releaseutil/kind_sorter.go

P/s: You can easily guest the order of "Uninstall" via var UninstallOrder KindSortOrder = []string{...} with reversely order.

// Those occurring earlier in the list get installed before those occurring later in the list.
var InstallOrder KindSortOrder = []string{
    "PriorityClass",
    "Namespace",
    "NetworkPolicy",
    "ResourceQuota",
    "LimitRange",
    "PodSecurityPolicy",
    "PodDisruptionBudget",
    "ServiceAccount",
    "Secret",
    "SecretList",
    "ConfigMap",
    "StorageClass",
    "PersistentVolume",
    "PersistentVolumeClaim",
    "CustomResourceDefinition",
    "ClusterRole",
    "ClusterRoleList",
    "ClusterRoleBinding",
    "ClusterRoleBindingList",
    "Role",
    "RoleList",
    "RoleBinding",
    "RoleBindingList",
    "Service",
    "DaemonSet",
    "Pod",
    "ReplicationController",
    "ReplicaSet",
    "Deployment",
    "HorizontalPodAutoscaler",
    "StatefulSet",
    "Job",
    "CronJob",
    "IngressClass",
    "Ingress",
    "APIService",
}

Oidium