# Helm charts

Three example charts for deploying [zddc-server](../zddc/) on Kubernetes.
All compile zddc-server from source via an init container — no
container image needs to be pulled from a registry, and no binary needs
to be built ahead of time. The init container clones the repo at a
configured git ref and runs `go build`; the main container is plain
alpine + the freshly built static binary.

## Charts

| Chart | When to use |
|---|---|
| **`zddc-server-prod/`** | Production **master**. Pin `zddc.gitRef` to a stable tag (`zddc-server-vX.Y.Z`). Slower probe cadence; image-pull policy `IfNotPresent`. Mounts the data PVC directly RW at `ZDDC_ROOT`. The token system is enabled automatically (tokens persist on the data PVC at `<ZDDC_ROOT>/.zddc.d/tokens/`); operators visit `/.tokens` to issue them. |
| **`zddc-server-dev/`** | Development / soak **master**. Tracks `main` by default; `helm upgrade` triggers a pod recreate so each rollout pulls the latest commit. Faster probes; debug-level logging (request headers logged — sensitive). Wraps the data PVC in **OverlayFS** (lower = PVC mounted RO, upper = ephemeral `emptyDir`) so dev-side writes never mutate the underlying store. Use this shape when the dev replica points at the same data as prod. |
| **`zddc-server-cache/`** | Downstream **client** (proxy / cache / mirror) of an upstream master. Set `zddc.upstream.url` + `zddc.upstream.mode`; the binary skips master-side machinery and forwards all requests to the master, persisting responses under the cache PVC (in cache or mirror modes). Bearer auth via a separately-created Kubernetes Secret. Use cases: corporate-master → DR-mirror, vendor-scoped mirror in a vendor's own cluster, regional edge cache, dev environment that mirrors prod read-only. Mirror mode adds an access-triggered subtree walker. |

The prod and dev chart values are nearly identical; the differences
are encoded as defaults in each chart's `values.yaml.example`. The
dev chart's overlay-isolation layer is a structural difference, not a
values-level toggle — see `zddc-server-dev/templates/deployment.yaml`
for the privileged init container and the `data-readonly` /
`overlay-scratch` / `data` volume sandwich.

The cache chart shares the same source-build pattern but adds
client-mode env wiring (`ZDDC_UPSTREAM`, `ZDDC_MODE`, `ZDDC_BEARER_FILE`,
`ZDDC_NO_AUTH`, `ZDDC_SKIP_TLS_VERIFY`, mirror-mode subtree config),
a Recreate strategy (single-instance — multiple replicas would race
the cache directory), and TCP-socket probes (HTTP probes against `/`
would fail when both upstream is down AND the cache is empty).

## Quick start

```sh
# Pre-requisite: a PersistentVolumeClaim for ZDDC_ROOT data
kubectl apply -f - <<'EOF'
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: zddc-root
spec:
  accessModes: [ReadWriteMany]    # or RWO if single replica is fine
  resources: { requests: { storage: 100Gi } }
  storageClassName: your-shared-fs   # NFS, CephFS, SMB, etc.
EOF

# Production install
cp helm/zddc-server-prod/values.yaml.example my-prod-values.yaml
$EDITOR my-prod-values.yaml          # set zddc.gitRef, hostnames, etc.
helm install zddc-server-prod helm/zddc-server-prod/ -f my-prod-values.yaml

# Dev install (tracks main HEAD)
cp helm/zddc-server-dev/values.yaml.example my-dev-values.yaml
$EDITOR my-dev-values.yaml
helm install zddc-server-dev helm/zddc-server-dev/ -f my-dev-values.yaml

# Trigger a rebuild from latest main HEAD (dev chart)
helm upgrade zddc-server-dev helm/zddc-server-dev/ -f my-dev-values.yaml

# Cache install (downstream client of an upstream master)
#
#   1) Issue a bearer token on the master at https://<master>/.tokens
#   2) Create the Secret (do NOT put the token in values.yaml):
kubectl create secret generic zddc-cache-bearer \
  --from-literal=token=<paste-token-here>

#   3) Create a cache PVC (separate from the master's data PVC; can
#      be smaller — sized to the working set you expect to mirror):
kubectl apply -f - <<'PVC'
apiVersion: v1
kind: PersistentVolumeClaim
metadata: { name: zddc-cache }
spec:
  accessModes: [ReadWriteOnce]
  resources: { requests: { storage: 50Gi } }
  storageClassName: your-block-storage
PVC

#   4) Install the chart, pointing at your master:
cp helm/zddc-server-cache/values.yaml.example my-cache-values.yaml
$EDITOR my-cache-values.yaml      # set zddc.upstream.url, mode, etc.
helm install zddc-server-cache helm/zddc-server-cache/ -f my-cache-values.yaml
```

## What the chart does and doesn't do

**Does:**

- Clones the configured `zddc.gitRepo` at `zddc.gitRef` in an init
  container, builds the Go binary, copies it to a shared `emptyDir`,
  and starts the main container against that binary.
- Wires the `ZDDC_*` environment-variable contract (root path, addr,
  email header, CORS allowlist, log level, index path).
- Mounts a caller-supplied PersistentVolumeClaim at `ZDDC_ROOT` (prod
  chart) or as the OverlayFS lowerdir behind a merged `ZDDC_ROOT`
  (dev chart).
- Optionally creates an Ingress (`ingress.enabled: true`).

**Does not:**

- Create the PVC. Operators provision storage themselves; the chart
  only references it by name.
- Manage TLS for the pod. zddc-server runs in plain HTTP mode behind
  whatever ingress / authenticating reverse proxy the cluster already
  has. `ZDDC_TLS_CERT=none` and `ZDDC_INSECURE_DIRECT=1` are hardcoded
  in the templates because the chart is opinionated about the
  TLS-terminated-upstream deployment shape.
- Authenticate users. zddc-server reads the user's email from a header
  set by the upstream proxy (`X-Auth-Request-Email` by default). The
  chart does not deploy oauth2-proxy / nginx-auth-request / Pomerium /
  etc. — bring your own.
- Manage secrets. `values.yaml.example` contains no secrets and never
  should. ACL email lists belong in `.zddc` files inside the data
  volume; image-pull credentials and TLS certs (if you enable ingress
  TLS) reference Kubernetes secrets you've created separately.

## Why build from source instead of using a registry image

Three reasons:

1. **Reproducibility.** The init container's logs show exactly which
   git ref was built. There's no opaque "what did I deploy" question
   that a registry tag can introduce.
2. **One distribution channel.** Codeberg release-asset binaries
   already exist for direct downloads; the chart compiles its own
   binary from the same source git ref so there's nothing extra to
   maintain (no separate image registry, no image-promotion pipeline).
3. **Smaller blast radius.** A compromised build image affects only
   pods that pull during the compromise window. A compromised registry
   image stays compromised across rollbacks until the digest is rotated.

The cost: every pod start takes 30-60s to clone + `go build` instead
of pulling a pre-baked image. Acceptable for both chart audiences
(production rollouts are infrequent; dev rollouts trade build time
for tracking-main convenience).

## Linting

```sh
helm lint helm/zddc-server-prod/
helm lint helm/zddc-server-dev/
helm lint helm/zddc-server-cache/

# Render to inspect (uses default values from values.yaml.example):
helm template test-prod helm/zddc-server-prod/ \
  --values helm/zddc-server-prod/values.yaml.example

helm template test-cache helm/zddc-server-cache/ \
  --values helm/zddc-server-cache/values.yaml.example
```
