As a followup of my post about the use of argocd-autopilot I’m going to deploy various applications to the cluster using Argo CD from the same repository we used on the previous post.

For our examples we are going to test a solution to the problem we had when we updated a ConfigMap used by the argocd-server (the resource was updated but the application Pod was not because there was no change on the argocd-server deployment); our original fix was to kill the pod manually, but the manual operation is something we want to avoid.

The proposed solution to this kind of issues on the helm documentation is to add annotations to the Deployments with values that are a hash of the ConfigMaps or Secrets used by them, this way if a file is updated the annotation is also updated and when the Deployment changes are applied a roll out of the pods is triggered.

On this post we will install a couple of controllers and an application to show how we can handle Secrets with argocd and solve the issue with updates on ConfigMaps and Secrets, to do it we will execute the following tasks:

  1. Deploy the Reloader controller to our cluster. It is a tool that watches changes in ConfigMaps and Secrets and does rolling upgrades on the Pods that use them from Deployment, StatefulSet, DaemonSet or DeploymentConfig objects when they are updated (by default we have to add some annotations to the objects to make things work).
  2. Deploy a simple application that can use ConfigMaps and Secrets and test that the Reloader controller does its job when we add or update a ConfigMap.
  3. Install the Sealed Secrets controller to manage secrets inside our cluster, use it to add a secret to our sample application and see that the application is reloaded automatically.

Creating the test project for argocd-autopilot

As we did our installation using argocd-autopilot we will use its structure to manage the applications.

The first thing to do is to create a project (we will name it test) as follows:

❯ argocd-autopilot project create test
INFO cloning git repository: https://forgejo.mixinet.net/blogops/argocd.git
Enumerating objects: 18, done.
Counting objects: 100% (18/18), done.
Compressing objects: 100% (16/16), done.
Total 18 (delta 1), reused 0 (delta 0), pack-reused 0
INFO using revision: "", installation path: "/"
INFO pushing new project manifest to repo
INFO project created: 'test'

Now that the test project is available we will use it on our argocd-autopilot invocations when creating applications.

Installing the reloader controller

To add the reloader application to the test project as a kustomize application and deploy it on the tools namespace with argocd-autopilot we do the following:

❯ argocd-autopilot app create reloader \
    --app 'github.com/stakater/Reloader/deployments/kubernetes/?ref=v1.4.2' \
    --project test --type kustomize --dest-namespace tools
INFO cloning git repository: https://forgejo.mixinet.net/blogops/argocd.git
Enumerating objects: 19, done.
Counting objects: 100% (19/19), done.
Compressing objects: 100% (18/18), done.
Total 19 (delta 2), reused 0 (delta 0), pack-reused 0
INFO using revision: "", installation path: "/"
INFO created 'application namespace' file at '/bootstrap/cluster-resources/in-cluster/tools-ns.yaml'
INFO committing changes to gitops repo...
INFO installed application: reloader

That command creates four files on the argocd repository:

  1. One to create the tools namespace:

    bootstrap/cluster-resources/in-cluster/tools-ns.yaml
    apiVersion: v1
kind: Namespace
metadata:
  annotations:
    argocd.argoproj.io/sync-options: Prune=false
  creationTimestamp: null
  name: tools
spec: {}
status: {}

  2. Another to include the reloader base application from the upstream repository:

    apps/reloader/base/kustomization.yaml
    apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- github.com/stakater/Reloader/deployments/kubernetes/?ref=v1.4.2

  3. The kustomization.yaml file for the test project (by default it includes the same configuration used on the base definition, but we could make other changes if needed):

    apps/reloader/overlays/test/kustomization.yaml
    apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
namespace: tools
resources:
- ../../base

  4. The config.json file used to define the application on argocd for the test project (it points to the folder that includes the previous kustomization.yaml file):

    apps/reloader/overlays/test/config.json
    {
  "appName": "reloader",
  "userGivenName": "reloader",
  "destNamespace": "tools",
  "destServer": "https://kubernetes.default.svc",
  "srcPath": "apps/reloader/overlays/test",
  "srcRepoURL": "https://forgejo.mixinet.net/blogops/argocd.git",
  "srcTargetRevision": "",
  "labels": null,
  "annotations": null
}

We can check that the application is working using the argocd command line application:

❯ argocd app get argocd/test-reloader -o tree
Name:               argocd/test-reloader
Project:            test
Server:             https://kubernetes.default.svc
Namespace:          tools
URL:                https://argocd.lo.mixinet.net:8443/applications/test-reloader
Source:
- Repo:             https://forgejo.mixinet.net/blogops/argocd.git
  Target:
  Path:             apps/reloader/overlays/test
SyncWindow:         Sync Allowed
Sync Policy:        Automated (Prune)
Sync Status:        Synced to  (2893b56)
Health Status:      Healthy

KIND/NAME                                          STATUS  HEALTH   MESSAGE
ClusterRole/reloader-reloader-role                 Synced
ClusterRoleBinding/reloader-reloader-role-binding  Synced
ServiceAccount/reloader-reloader                   Synced           serviceaccount/reloader-reloader created
Deployment/reloader-reloader                       Synced  Healthy  deployment.apps/reloader-reloader created
└─ReplicaSet/reloader-reloader-5b6dcc7b6f                  Healthy
  └─Pod/reloader-reloader-5b6dcc7b6f-vwjcx                 Healthy

Adding flags to the reloader server

The runtime configuration flags for the reloader server are described on the project README.md file, in our case we want to adjust three values:

  • We want to enable the option to reload a workload when a ConfigMap or Secret is created,
  • We want to enable the option to reload a workload when a ConfigMap or Secret is deleted,
  • We want to use the annotations strategy for reloads, as it is the recommended mode of operation when using argocd.

To pass them we edit the apps/reloader/overlays/test/kustomization.yaml file to patch the pod container template, the text added is the following:

patches:
# Add flags to reload workloads when ConfigMaps or Secrets are created or deleted
- target:
    kind: Deployment
    name: reloader-reloader
  patch: |-
    - op: add
      path: /spec/template/spec/containers/0/args
      value:
        - '--reload-on-create=true'
        - '--reload-on-delete=true'
        - '--reload-strategy=annotations'

After committing and pushing the updated file the system launches the application with the new options.

The dummyhttp application

To do a quick test we are going to deploy the dummyhttp web server using an image generated using the following Dockerfile:

# Image to run the dummyhttp application <https://github.com/svenstaro/dummyhttp>

# This arg could be passed by the container build command (used with mirrors)
ARG OCI_REGISTRY_PREFIX

# Latest tested version of alpine
FROM ${OCI_REGISTRY_PREFIX}alpine:3.21.3

# Tool versions
ARG DUMMYHTTP_VERS=1.1.1

# Download binary
RUN ARCH="$(apk --print-arch)" && \
  VERS="$DUMMYHTTP_VERS" && \
  URL="https://github.com/svenstaro/dummyhttp/releases/download/v$VERS/dummyhttp-$VERS-$ARCH-unknown-linux-musl" && \
  wget "$URL" -O "/tmp/dummyhttp" && \
  install /tmp/dummyhttp /usr/local/bin && \
  rm -f /tmp/dummyhttp

# Set the entrypoint to /usr/local/bin/dummyhttp
ENTRYPOINT [ "/usr/local/bin/dummyhttp" ]

The kustomize base application is available on a monorepo that contains the following files:

  1. A Deployment definition that uses the previous image but uses /bin/sh -c as its entrypoint (command in the k8s Pod terminology) and passes as its argument a string that runs the eval command to be able to expand environment variables passed to the pod (the definition includes two optional variables, one taken from a ConfigMap and another one from a Secret):

    apiVersion: apps/v1
kind: Deployment
metadata:
  name: dummyhttp
  labels:
    app: dummyhttp
spec:
  selector:
    matchLabels:
      app: dummyhttp
  template:
    metadata:
      labels:
        app: dummyhttp
    spec:
      containers:
      - name: dummyhttp
        image: forgejo.mixinet.net/oci/dummyhttp:1.0.0
        command: [ "/bin/sh", "-c" ]
        args:
        - 'eval dummyhttp -b \"{\\\"c\\\": \\\"$CM_VAR\\\", \\\"s\\\": \\\"$SECRET_VAR\\\"}\"'
        ports:
        - containerPort: 8080
        env:
        - name: CM_VAR
          valueFrom:
            configMapKeyRef:
              name: dummyhttp-configmap
              key: CM_VAR
              optional: true
        - name: SECRET_VAR
          valueFrom:
            secretKeyRef:
              name: dummyhttp-secret
              key: SECRET_VAR
              optional: true

  2. A Service that publishes the previous Deployment (the only relevant thing to mention is that the web server uses the port 8080 by default):

    apiVersion: v1
kind: Service
metadata:
  name: dummyhttp
spec:
  selector:
    app: dummyhttp
  ports:
  - name: http
    port: 80
    targetPort: 8080

  3. An Ingress definition to allow access to the application from the outside:

    apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: dummyhttp
  annotations:
    traefik.ingress.kubernetes.io/router.tls: "true"
spec:
  rules:
    - host: dummyhttp.localhost.mixinet.net
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: dummyhttp
                port:
                  number: 80

  4. And the kustomization.yaml file that includes the previous files:

    apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
- deployment.yaml
- service.yaml
- ingress.yaml

Deploying the dummyhttp application from argocd

We could create the dummyhttp application using the argocd-autopilot command as we’ve done on the reloader case, but we are going to do it manually to show how simple it is.

First we’ve created the apps/dummyhttp/base/kustomization.yaml file to include the application from the previous repository:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - https://forgejo.mixinet.net/blogops/argocd-applications.git//dummyhttp/?ref=dummyhttp-v1.0.0

As a second step we create the apps/dummyhttp/overlays/test/kustomization.yaml file to include the previous file:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- ../../base

And finally we add the apps/dummyhttp/overlays/test/config.json file to configure the application as the ApplicationSet defined by argocd-autopilot expects:

{
  "appName": "dummyhttp",
  "userGivenName": "dummyhttp",
  "destNamespace": "default",
  "destServer": "https://kubernetes.default.svc",
  "srcPath": "apps/dummyhttp/overlays/test",
  "srcRepoURL": "https://forgejo.mixinet.net/blogops/argocd.git",
  "srcTargetRevision": "",
  "labels": null,
  "annotations": null
}

Once we have the three files we commit and push the changes and argocd deploys the application; we can check that things are working using curl:

❯ curl -s https://dummyhttp.lo.mixinet.net:8443/ | jq -M .
{
  "c": "",
  "s": ""
}

Patching the application

Now we will add patches to the apps/dummyhttp/overlays/test/kustomization.yaml file:

  • One to add annotations for reloader (one to enable it and another one to set the roll out strategy to restart to avoid touching the deployments, as that can generate issues with argocd).
  • Another to change the ingress hostname (not really needed, but something quite reasonable for a specific project).

The file diff is as follows:

--- a/apps/dummyhttp/overlays/test/kustomization.yaml
+++ b/apps/dummyhttp/overlays/test/kustomization.yaml
@@ -2,3 +2,22 @@ apiVersion: kustomize.config.k8s.io/v1beta1
 kind: Kustomization
 resources:
 - ../../base
+patches:
+# Add reloader annotations
+- target:
+    kind: Deployment
+    name: dummyhttp
+  patch: |-
+    - op: add
+      path: /metadata/annotations
+      value:
+        reloader.stakater.com/auto: "true"
+        reloader.stakater.com/rollout-strategy: "restart"
+# Change the ingress host name
+- target:
+    kind: Ingress
+    name: dummyhttp
+  patch: |-
+    - op: replace
+      path: /spec/rules/0/host
+      value: test-dummyhttp.lo.mixinet.net

After committing and pushing the changes we can use the argocd cli to check the status of the application:

❯ argocd app get argocd/test-dummyhttp -o tree
Name:               argocd/test-dummyhttp
Project:            test
Server:             https://kubernetes.default.svc
Namespace:          default
URL:                https://argocd.lo.mixinet.net:8443/applications/test-dummyhttp
Source:
- Repo:             https://forgejo.mixinet.net/blogops/argocd.git
  Target:
  Path:             apps/dummyhttp/overlays/test
SyncWindow:         Sync Allowed
Sync Policy:        Automated (Prune)
Sync Status:        Synced to  (fbc6031)
Health Status:      Healthy

KIND/NAME                           STATUS  HEALTH   MESSAGE
Deployment/dummyhttp                Synced  Healthy  deployment.apps/dummyhttp configured
└─ReplicaSet/dummyhttp-55569589bc           Healthy
  └─Pod/dummyhttp-55569589bc-qhnfk          Healthy
Ingress/dummyhttp                   Synced  Healthy  ingress.networking.k8s.io/dummyhttp configured
Service/dummyhttp                   Synced  Healthy  service/dummyhttp unchanged
├─Endpoints/dummyhttp
└─EndpointSlice/dummyhttp-x57bl

As we can see, the Deployment and Ingress where updated, but the Service is unchanged.

To validate that the ingress is using the new hostname we can use curl:

❯ curl -s https://dummyhttp.lo.mixinet.net:8443/
404 page not found
❯ curl -s https://test-dummyhttp.lo.mixinet.net:8443/
{"c": "", "s": ""}

Adding a ConfigMap

Now that the system is adjusted to reload the application when the ConfigMap or Secret is created, deleted or updated we are ready to add one file and see how the system reacts.

We modify the apps/dummyhttp/overlays/test/kustomization.yaml file to create the ConfigMap using the configMapGenerator as follows:

--- a/apps/dummyhttp/overlays/test/kustomization.yaml
+++ b/apps/dummyhttp/overlays/test/kustomization.yaml
@@ -2,6 +2,14 @@ apiVersion: kustomize.config.k8s.io/v1beta1
 kind: Kustomization
 resources:
 - ../../base
+# Add the config map
+configMapGenerator:
+- name: dummyhttp-configmap
+  literals:
+  - CM_VAR="Default Test Value"
+  behavior: create
+  options:
+    disableNameSuffixHash: true
 patches:
 # Add reloader annotations
 - target:

After committing and pushing the changes we can see that the ConfigMap is available, the pod has been deleted and started again and the curl output includes the new value:

❯ kubectl get configmaps,pods
NAME                             READY   STATUS        RESTARTS   AGE
configmap/dummyhttp-configmap   1      11s
configmap/kube-root-ca.crt      1      4d7h

NAME                            DATA   AGE
pod/dummyhttp-779c96c44b-pjq4d   1/1     Running       0          11s
pod/dummyhttp-fc964557f-jvpkx    1/1     Terminating   0          2m42s
❯ curl -s https://test-dummyhttp.lo.mixinet.net:8443 | jq -M .
{
  "c": "Default Test Value",
  "s": ""
}

Using helm with argocd-autopilot

Right now there is no direct support in argocd-autopilot to manage applications using helm (see the issue #38 on the project), but we want to use a chart in our next example.

There are multiple ways to add the support, but the simplest one that allows us to keep using argocd-autopilot is to use kustomize applications that call helm as described here.

The only thing needed before being able to use the approach is to add the kustomize.buildOptions flag to the argocd-cm on the bootstrap/argo-cd/kustomization.yaml file, its contents now are follows:

bootstrap/argo-cd/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
configMapGenerator:
- behavior: merge
  literals:
  # Enable helm usage from kustomize (see https://github.com/argoproj/argo-cd/issues/2789#issuecomment-960271294)
  - kustomize.buildOptions="--enable-helm"
  - |
    repository.credentials=- passwordSecret:
        key: git_token
        name: autopilot-secret
      url: https://forgejo.mixinet.net/
      usernameSecret:
        key: git_username
        name: autopilot-secret
  name: argocd-cm
  # Disable TLS for the Argo Server (see https://argo-cd.readthedocs.io/en/stable/operator-manual/ingress/#traefik-v30)
- behavior: merge
  literals:
  - "server.insecure=true"
  name: argocd-cmd-params-cm
kind: Kustomization
namespace: argocd
resources:
- github.com/argoproj-labs/argocd-autopilot/manifests/base?ref=v0.4.19
- ingress_route.yaml

On the following section we will explain how the application is defined to make things work.

Installing the sealed-secrets controller

To manage secrets in our cluster we are going to use the sealed-secrets controller and to install it we are going to use its chart.

As we mentioned on the previous section, the idea is to create a kustomize application and use that to deploy the chart, but we are going to create the files manually, as we are not going import the base kustomization files from a remote repository.

As there is no clear way to override helm Chart values using overlays we are going to use a generator to create the helm configuration from an external resource and include it from our overlays (the idea has been taken from this repository, which was referenced from a comment on the kustomize issue #38 mentioned earlier).

The sealed-secrets application

We have created the following files and folders manually:

apps/sealed-secrets/
├── helm
│   ├── chart.yaml
│   └── kustomization.yaml
└── overlays
    └── test
        ├── config.json
        ├── kustomization.yaml
        └── values.yaml

The helm folder contains the generator template that will be included from our overlays.

The kustomization.yaml includes the chart.yaml as a resource:

apps/sealed-secrets/helm/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- chart.yaml

And the chart.yaml file defines the HelmChartInflationGenerator:

apps/sealed-secrets/helm/chart.yaml
apiVersion: builtin
kind: HelmChartInflationGenerator
metadata:
  name: sealed-secrets
releaseName: sealed-secrets
name: sealed-secrets
namespace: kube-system
repo: https://bitnami-labs.github.io/sealed-secrets
version: 2.17.2
includeCRDs: true
# Add common values to all argo-cd projects inline
valuesInline:
  fullnameOverride: sealed-secrets-controller
# Load a values.yaml file from the same directory that uses this generator
valuesFile: values.yaml

For this chart the template adjusts the namespace to kube-system and adds the fullnameOverride on the valuesInline key because we want to use those settings on all the projects (they are the values expected by the kubeseal command line application, so we adjust them to avoid the need to add additional parameters to it).

We adjust global values as inline to be able to use a the valuesFile from our overlays; as we are using a generator the path is relative to the folder that contains the kustomization.yaml file that calls it, in our case we will need to have a values.yaml file on each overlay folder (if we don’t want to overwrite any values for a project we can create an empty file, but it has to exist).

Finally, our overlay folder contains three files, a kustomization.yaml file that includes the generator from the helm folder, the values.yaml file needed by the chart and the config.json file used by argocd-autopilot to install the application.

The kustomization.yaml file contents are:

apps/sealed-secrets/overlays/test/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
# Uncomment if you want to add additional resources using kustomize
#resources:
#- ../../base
generators:
- ../../helm

The values.yaml file enables the ingress for the application and adjusts its hostname:

apps/sealed-secrets/overlays/test/values.yaml
ingress:
  enabled: true
  hostname: test-sealed-secrets.lo.mixinet.net

And the config.json file is similar to the ones used with the other applications we have installed:

apps/sealed-secrets/overlays/test/config.json
{
  "appName": "sealed-secrets",
  "userGivenName": "sealed-secrets",
  "destNamespace": "kube-system",
  "destServer": "https://kubernetes.default.svc",
  "srcPath": "apps/sealed-secrets/overlays/test",
  "srcRepoURL": "https://forgejo.mixinet.net/blogops/argocd.git",
  "srcTargetRevision": "",
  "labels": null,
  "annotations": null
}

Once we commit and push the files the sealed-secrets application is installed in our cluster, we can check it using curl to get the public certificate used by it:

❯ curl -s https://test-sealed-secrets.lo.mixinet.net:8443/v1/cert.pem
-----BEGIN CERTIFICATE-----
[...]
-----END CERTIFICATE-----

The dummyhttp-secret

To create sealed secrets we need to install the kubeseal tool:

❯ arkade get kubeseal

Now we create a local version of the dummyhttp-secret that contains some value on the SECRET_VAR key (the easiest way for doing it is to use kubectl):

❯ echo -n "Boo" | kubectl create secret generic dummyhttp-secret \
    --dry-run=client --from-file=SECRET_VAR=/dev/stdin -o yaml \
    >/tmp/dummyhttp-secret.yaml

The secret definition in yaml format is:

apiVersion: v1
data:
  SECRET_VAR: Qm9v
kind: Secret
metadata:
  creationTimestamp: null
  name: dummyhttp-secret

To create a sealed version using the kubeseal tool we can do the following:

❯ kubeseal -f /tmp/dummyhttp-secret.yaml -w /tmp/dummyhttp-sealed-secret.yaml

That invocation needs to have access to the cluster to do its job and in our case it works because we modified the chart to use the kube-system namespace and set the controller name to sealed-secrets-controller as the tool expects.

If we need to create the secrets without credentials we can connect to the ingress address we added to retrieve the public key:

❯ kubeseal -f /tmp/dummyhttp-secret.yaml -w /tmp/dummyhttp-sealed-secret.yaml \
    --cert https://test-sealed-secrets.lo.mixinet.net:8443/v1/cert.pem

Or, if we don’t have access to the ingress address, we can save the certificate on a file and use it instead of the URL.

The sealed version of the secret looks like this:

apiVersion: bitnami.com/v1alpha1
kind: SealedSecret
metadata:
  creationTimestamp: null
  name: dummyhttp-secret
  namespace: default
spec:
  encryptedData:
    SECRET_VAR: [...]
  template:
    metadata:
      creationTimestamp: null
      name: dummyhttp-secret
      namespace: default

This file can be deployed to the cluster to create the secret (in our case we will add it to the argocd application), but before doing that we are going to check the output of our dummyhttp service and get the list of Secrets and SealedSecrets in the default namespace:

❯ curl -s https://test-dummyhttp.lo.mixinet.net:8443 | jq -M .
{
  "c": "Default Test Value",
  "s": ""
}
❯ kubectl get sealedsecrets,secrets
No resources found in default namespace.

Now we add the SealedSecret to the dummyapp copying the file and adding it to the kustomization.yaml file:

--- a/apps/dummyhttp/overlays/test/kustomization.yaml
+++ b/apps/dummyhttp/overlays/test/kustomization.yaml
@@ -2,6 +2,7 @@ apiVersion: kustomize.config.k8s.io/v1beta1
 kind: Kustomization
 resources:
 - ../../base
+- dummyhttp-sealed-secret.yaml
 # Create the config map value
 configMapGenerator:
 - name: dummyhttp-configmap

Once we commit and push the files Argo CD creates the SealedSecret and the controller generates the Secret:

❯ kubectl apply -f /tmp/dummyhttp-sealed-secret.yaml
sealedsecret.bitnami.com/dummyhttp-secret created
❯ kubectl get sealedsecrets,secrets
NAME                                        STATUS   SYNCED   AGE
sealedsecret.bitnami.com/dummyhttp-secret            True     3s

NAME                      TYPE     DATA   AGE
secret/dummyhttp-secret   Opaque   1      3s

If we check the command output we can see the new value of the secret:

❯ curl -s https://test-dummyhttp.lo.mixinet.net:8443 | jq -M .
{
  "c": "Default Test Value",
  "s": "Boo"
}

Using sealed-secrets in production clusters

If you plan to use sealed-secrets look into its documentation to understand how it manages the private keys, how to backup things and keep in mind that, as the documentation explains, you can rotate your sealed version of the secrets, but that doesn’t change the actual secrets.

If you want to rotate your secrets you have to update them and commit the sealed version of the updates (as the controller also rotates the encryption keys your new sealed version will also be using a newer key, so you will be doing both things at the same time).

Final remarks

On this post we have seen how to deploy applications using the argocd-autopilot model, including the use of helm charts inside kustomize applications and how to install and use the sealed-secrets controller.

It has been interesting and I’ve learnt a lot about argocd in the process, but I believe that if I ever want to use it in production I will also review the native helm support in argocd using a separate repository to manage the applications, at least to be able to compare it to the model explained here.