150 lines
7.2 KiB
Markdown
150 lines
7.2 KiB
Markdown
# Helm charts
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Three example charts for deploying [zddc-server](../zddc/) on Kubernetes.
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All compile zddc-server from source via an init container — no
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container image needs to be pulled from a registry, and no binary needs
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to be built ahead of time. The init container clones the repo at a
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configured git ref and runs `go build`; the main container is plain
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alpine + the freshly built static binary.
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## Charts
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| Chart | When to use |
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| **`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. |
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| **`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. |
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| **`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. |
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The prod and dev chart values are nearly identical; the differences
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are encoded as defaults in each chart's `values.yaml.example`. The
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dev chart's overlay-isolation layer is a structural difference, not a
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values-level toggle — see `zddc-server-dev/templates/deployment.yaml`
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for the privileged init container and the `data-readonly` /
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`overlay-scratch` / `data` volume sandwich.
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The cache chart shares the same source-build pattern but adds
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client-mode env wiring (`ZDDC_UPSTREAM`, `ZDDC_MODE`, `ZDDC_BEARER_FILE`,
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`ZDDC_NO_AUTH`, `ZDDC_SKIP_TLS_VERIFY`, mirror-mode subtree config),
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a Recreate strategy (single-instance — multiple replicas would race
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the cache directory), and TCP-socket probes (HTTP probes against `/`
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would fail when both upstream is down AND the cache is empty).
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## Quick start
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```sh
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# Pre-requisite: a PersistentVolumeClaim for ZDDC_ROOT data
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kubectl apply -f - <<'EOF'
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apiVersion: v1
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kind: PersistentVolumeClaim
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metadata:
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name: zddc-root
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spec:
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accessModes: [ReadWriteMany] # or RWO if single replica is fine
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resources: { requests: { storage: 100Gi } }
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storageClassName: your-shared-fs # NFS, CephFS, SMB, etc.
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EOF
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# Production install
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cp helm/zddc-server-prod/values.yaml.example my-prod-values.yaml
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$EDITOR my-prod-values.yaml # set zddc.gitRef, hostnames, etc.
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helm install zddc-server-prod helm/zddc-server-prod/ -f my-prod-values.yaml
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# Dev install (tracks main HEAD)
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cp helm/zddc-server-dev/values.yaml.example my-dev-values.yaml
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$EDITOR my-dev-values.yaml
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helm install zddc-server-dev helm/zddc-server-dev/ -f my-dev-values.yaml
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# Trigger a rebuild from latest main HEAD (dev chart)
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helm upgrade zddc-server-dev helm/zddc-server-dev/ -f my-dev-values.yaml
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# Cache install (downstream client of an upstream master)
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#
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# 1) Issue a bearer token on the master at https://<master>/.tokens
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# 2) Create the Secret (do NOT put the token in values.yaml):
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kubectl create secret generic zddc-cache-bearer \
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--from-literal=token=<paste-token-here>
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# 3) Create a cache PVC (separate from the master's data PVC; can
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# be smaller — sized to the working set you expect to mirror):
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kubectl apply -f - <<'PVC'
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apiVersion: v1
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kind: PersistentVolumeClaim
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metadata: { name: zddc-cache }
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spec:
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accessModes: [ReadWriteOnce]
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resources: { requests: { storage: 50Gi } }
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storageClassName: your-block-storage
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PVC
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# 4) Install the chart, pointing at your master:
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cp helm/zddc-server-cache/values.yaml.example my-cache-values.yaml
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$EDITOR my-cache-values.yaml # set zddc.upstream.url, mode, etc.
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helm install zddc-server-cache helm/zddc-server-cache/ -f my-cache-values.yaml
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```
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## What the chart does and doesn't do
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**Does:**
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- Clones the configured `zddc.gitRepo` at `zddc.gitRef` in an init
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container, builds the Go binary, copies it to a shared `emptyDir`,
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and starts the main container against that binary.
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- Wires the `ZDDC_*` environment-variable contract (root path, addr,
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email header, CORS allowlist, log level, index path).
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- Mounts a caller-supplied PersistentVolumeClaim at `ZDDC_ROOT` (prod
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chart) or as the OverlayFS lowerdir behind a merged `ZDDC_ROOT`
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(dev chart).
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- Optionally creates an Ingress (`ingress.enabled: true`).
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**Does not:**
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- Create the PVC. Operators provision storage themselves; the chart
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only references it by name.
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- Manage TLS for the pod. zddc-server runs in plain HTTP mode behind
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whatever ingress / authenticating reverse proxy the cluster already
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has. `ZDDC_TLS_CERT=none` and `ZDDC_INSECURE_DIRECT=1` are hardcoded
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in the templates because the chart is opinionated about the
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TLS-terminated-upstream deployment shape.
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- Authenticate users. zddc-server reads the user's email from a header
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set by the upstream proxy (`X-Auth-Request-Email` by default). The
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chart does not deploy oauth2-proxy / nginx-auth-request / Pomerium /
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etc. — bring your own.
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- Manage secrets. `values.yaml.example` contains no secrets and never
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should. ACL email lists belong in `.zddc` files inside the data
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volume; image-pull credentials and TLS certs (if you enable ingress
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TLS) reference Kubernetes secrets you've created separately.
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## Why build from source instead of using a registry image
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Three reasons:
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1. **Reproducibility.** The init container's logs show exactly which
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git ref was built. There's no opaque "what did I deploy" question
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that a registry tag can introduce.
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2. **One distribution channel.** Codeberg release-asset binaries
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already exist for direct downloads; the chart compiles its own
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binary from the same source git ref so there's nothing extra to
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maintain (no separate image registry, no image-promotion pipeline).
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3. **Smaller blast radius.** A compromised build image affects only
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pods that pull during the compromise window. A compromised registry
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image stays compromised across rollbacks until the digest is rotated.
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The cost: every pod start takes 30-60s to clone + `go build` instead
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of pulling a pre-baked image. Acceptable for both chart audiences
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(production rollouts are infrequent; dev rollouts trade build time
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for tracking-main convenience).
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## Linting
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```sh
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helm lint helm/zddc-server-prod/
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helm lint helm/zddc-server-dev/
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helm lint helm/zddc-server-cache/
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# Render to inspect (uses default values from values.yaml.example):
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helm template test-prod helm/zddc-server-prod/ \
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--values helm/zddc-server-prod/values.yaml.example
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helm template test-cache helm/zddc-server-cache/ \
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--values helm/zddc-server-cache/values.yaml.example
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```
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