Support vault agent sidecar injector

[M0NsTeRRR]

Hello,

I'm using hashicorp vault to provide environment variables to configure exertnal-dns, unfortunately the current helm chart doesn't allow us to edit the container command that is needed to source environment variables as stated by hashicorp vault documentation.

If you agree with the idea, I can create a PR to add this feature.

Here is my current deployment

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: external-dns
  namespace: external-dns-internal
spec:
  replicas: 1
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: external-dns
  template:
    metadata:
      labels:
        app: external-dns
      annotations:
        vault.hashicorp.com/agent-inject: 'true'
        vault.hashicorp.com/agent-inject-secret-config: secret/data/homelab/prod/external_dns/internal
        vault.hashicorp.com/agent-inject-secret-tls-ca: secret/data/homelab/prod/external_dns/internal
        vault.hashicorp.com/agent-inject-template-config: |
          {{- with secret "secret/data/homelab/prod/external_dns/internal" -}}
            export EXTERNAL_DNS_PDNS_SERVER="{{ .Data.data.EXTERNAL_DNS_PDNS_SERVER }}"
            export EXTERNAL_DNS_PDNS_API_KEY="{{ .Data.data.EXTERNAL_DNS_PDNS_API_KEY }}"
            export EXTERNAL_DNS_PDNS_TLS_ENABLED="{{ .Data.data.EXTERNAL_DNS_PDNS_TLS_ENABLED }}"
            export EXTERNAL_DNS_TLS_CA="/vault/secrets/tls-ca"
          {{- end }}
        vault.hashicorp.com/agent-inject-template-tls-ca: |
          {{- with secret "secret/data/homelab/prod/external_dns/internal" -}}
            {{ .Data.data.EXTERNAL_DNS_TLS_CA }}
          {{- end }}
        vault.hashicorp.com/ca-cert: /vault/tls/ca.crt
        vault.hashicorp.com/role: external-dns-internal
        vault.hashicorp.com/tls-secret: vault-ca
    spec:
      serviceAccountName: external-dns
      containers:
        - name: external-dns
          image: registry.k8s.io/external-dns/external-dns:v0.13.5
          command:
            - sh
            - '-c'
          args:
            - >-
              source /vault/secrets/config && /bin/external-dns --source=ingress
              --provider=pdns --domain-filter=unicornafk.fr --registry=txt
              --txt-owner-id=homelab.kubernetes --ingress-class=traefik-internal
              --default-targets=192.168.10.101
              --default-targets=2a0c:b641:2c0:110::101

[M0NsTeRRR]

It appears that this deployment no longer works with v0.13.6 because the new image has no shell

[M0NsTeRRR]

As a workaround (really ugly), i'm using an init container to add shell back to external-dns image

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: external-dns
  namespace: external-dns-internal
spec:
  replicas: 1
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: external-dns
  template:
    metadata:
      labels:
        app: external-dns
      annotations:
        vault.hashicorp.com/agent-inject: 'true'
        vault.hashicorp.com/agent-inject-secret-config: secret/data/homelab/prod/external_dns/internal
        vault.hashicorp.com/agent-inject-secret-tls-ca: secret/data/homelab/prod/external_dns/internal
        vault.hashicorp.com/agent-inject-template-config: |
          {{- with secret "secret/data/homelab/prod/external_dns/internal" -}}
            export EXTERNAL_DNS_PDNS_SERVER="{{ .Data.data.EXTERNAL_DNS_PDNS_SERVER }}"
            export EXTERNAL_DNS_PDNS_API_KEY="{{ .Data.data.EXTERNAL_DNS_PDNS_API_KEY }}"
            export EXTERNAL_DNS_PDNS_TLS_ENABLED="{{ .Data.data.EXTERNAL_DNS_PDNS_TLS_ENABLED }}"
            export EXTERNAL_DNS_TLS_CA="/vault/secrets/tls-ca"
          {{- end }}
        vault.hashicorp.com/agent-inject-template-tls-ca: |
          {{- with secret "secret/data/homelab/prod/external_dns/internal" -}}
            {{ .Data.data.EXTERNAL_DNS_TLS_CA }}
          {{- end }}
        vault.hashicorp.com/ca-cert: /vault/tls/ca.crt
        vault.hashicorp.com/role: external-dns-internal
        vault.hashicorp.com/tls-secret: vault-ca
    spec:
      serviceAccountName: external-dns
      initContainers:
        - name: copy-shell
          image: busybox:uclibc
          command: ["cp", "/bin/sh", "/shell/sh"]
          volumeMounts:
            - name: shell
              mountPath: /shell
      containers:
        - name: external-dns
          image: registry.k8s.io/external-dns/external-dns:v0.13.6
          command:
            - /shell/sh
            - '-c'
          args:
            - >-
              source /vault/secrets/config && /bin/external-dns --source=ingress
              --provider=pdns --domain-filter=unicornafk.fr --registry=txt
              --txt-owner-id=homelab.kubernetes --ingress-class=traefik-internal
              --default-targets=192.168.10.101
              --default-targets=2a0c:b641:2c0:110::101
          volumeMounts:
            - name: shell
              mountPath: /shell
      volumes:
        - name: shell
          emptyDir: {}

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/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues.

This bot triages un-triaged issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
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You can:

• Mark this issue as fresh with /remove-lifecycle rotten
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• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle rotten

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

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/close not-planned

[k8s-ci-robot]

@k8s-triage-robot: Closing this issue, marking it as "Not Planned".

In response to this:

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Reopen this issue with /reopen
• Mark this issue as fresh with /remove-lifecycle rotten
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/close not-planned

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