Docker to Sealos Template Converter

Overview

Convert Docker Compose files or installation docs into production-grade Sealos templates. Execute end-to-end automatically (analysis, conversion, validation, output) without asking users for missing fields.

Governance and Rule Priority

Use the following precedence to prevent rule drift:

1. SKILL.md MUST rules (this file)
2. references/sealos-specs.md and references/database-templates.md
3. references/conversion-mappings.md and references/example-guide.md

If lower-priority references conflict with higher-priority MUST rules, update the lower-priority files. Do not keep conflicting examples.

Workflow

Step 1: Analyze input

Extract from Docker Compose/docs:

• application services vs database services
• volumes/config mounts/object storage requirements
• ports, dependencies, service communication
• env vars and secret usage
• resource limits/requests and health checks
• if official Kubernetes installation docs/manifests are available, also extract app-runtime behavior from them (bootstrap admin fields, external endpoint/protocol assumptions, health probes, startup/init flow)

Step 2: Infer metadata

Infer and normalize:

• app name, title, description, categories
• official URL, gitRepo, icon source
• locale/i18n metadata

Step 3: Plan resources in strict order

Generate resources in this order:

1. Template CR
2. ObjectStorageBucket (if needed)
3. Database resources (ServiceAccount → Role → RoleBinding → Cluster → Job if needed)
4. App workload resources (ConfigMap/Secret → Deployment/StatefulSet → Service → Ingress)
5. App resource (last)

Step 4: Apply conversion rules

Apply field-level mappings from references/conversion-mappings.md, including:

• image pinning and annotation mapping
• port/service/ingress conversion
• env var conversion and dependency ordering
• storage conversion and vn naming (scripts/path_converter.py)
• service-name to Kubernetes FQDN conversion
• for DB URL/DSN envs (for example *_DATABASE_URL, *_DB_URL), when Kubeblocks endpoint is host:port, inject host/port/username/password via approved secretKeyRef envs and compose the final URL with $(VAR) expansion
• edge gateway normalization: when Compose includes Traefik-like edge proxy plus business services, skip the proxy workload and expose business services via Sealos Ingress directly
• TLS offload normalization for Sealos Ingress: when a business service exposes both 80 and 443, drop 443 from workload/service ports and remove in-container TLS certificate mounts (for example /etc/nginx/ssl, /etc/ssl, /certs) unless official Kubernetes docs explicitly require HTTPS backend-to-service traffic
• prefer scripts/compose_to_template.py --kompose-mode always as deterministic conversion entrypoint (require kompose for reproducible workload shaping)
• when official Kubernetes installation docs/manifests exist, perform a dual-source merge: use Compose as baseline topology, then align app-runtime semantics with official Kubernetes guidance

Step 5: Apply database strategy

• PostgreSQL must follow the pinned version and structure requirements.
• MySQL/MongoDB/Redis/Kafka must use templates and secret naming from references/database-templates.md.
• Add DB init Job/initContainer when application database bootstrap requires it.
• For PostgreSQL custom databases (non-postgres), the init Job must wait for PostgreSQL readiness before execution and create the target database idempotently.

Step 6: Generate output files

Always produce:

• template/<app-name>/index.yaml
• template/<app-name>/logo.<ext> when official icon is resolvable

Step 7: Validate before output

Run validator and self-tests before delivering template output. If validation fails, fix template/rules/examples first.

MUST Rules (Condensed)

Naming and metadata

• Template metadata.name must be hardcoded lowercase; do not use ${{ defaults.app_name }}.
• Template CR folder name must match metadata.name.
• Template CR must include required metadata fields (title, url, gitRepo, author, description, icon, templateType, locale, i18n, categories).
• Template spec.readme must be https://raw.githubusercontent.com/labring-actions/templates/kb-0.9/template/<app-name>/README.md.
• Template spec.i18n.zh.readme must be https://raw.githubusercontent.com/labring-actions/templates/kb-0.9/template/<app-name>/README_zh.md.
• icon URL must point to template repo raw path for this app on kb-0.9 branch.
• i18n.zh.description must be written in Simplified Chinese.
• Omit i18n.zh.title when it is identical to title.
• categories must only use predefined values (tool, ai, game, database, low-code, monitor, dev-ops, blog, storage, frontend, backend).

App resource

• App resource must use spec.data.url.
• App resource spec.displayType must be normal.
• App resource spec.type must be link.
• Never use spec.template in App resource.
• cloud.sealos.io/app-deploy-manager label value must equal resource metadata.name.
• metadata.labels.app label value must equal resource metadata.name for managed app workloads.
• containers[*].name must equal workload metadata.name for managed app workloads.
• Application Service resources must define metadata.labels.app and metadata.labels.cloud.sealos.io/app-deploy-manager, and both labels must match spec.selector.app.
• Component-scoped ConfigMap resources must define metadata.labels.app and metadata.labels.cloud.sealos.io/app-deploy-manager, and both labels must match metadata.name.
• Application Service resources must use the same component name across metadata.name, metadata.labels.app, metadata.labels.cloud.sealos.io/app-deploy-manager, and spec.selector.app.
• Application Ingress resources must use the same component name across metadata.name, metadata.labels.cloud.sealos.io/app-deploy-manager, and backend service.name.
• Service spec.ports[*].name must be explicitly set (required for multi-port services).
• HTTP Ingress must include required nginx annotations (kubernetes.io/ingress.class, nginx.ingress.kubernetes.io/proxy-body-size, nginx.ingress.kubernetes.io/server-snippet, nginx.ingress.kubernetes.io/ssl-redirect, nginx.ingress.kubernetes.io/backend-protocol, nginx.ingress.kubernetes.io/client-body-buffer-size, nginx.ingress.kubernetes.io/proxy-buffer-size, nginx.ingress.kubernetes.io/proxy-send-timeout, nginx.ingress.kubernetes.io/proxy-read-timeout, nginx.ingress.kubernetes.io/configuration-snippet) with expected defaults.
• When official application health checks are available, managed workloads must define livenessProbe, readinessProbe, and (for slow bootstrap apps) startupProbe, aligned with official endpoints/commands.

Official Kubernetes alignment

• If official Kubernetes installation docs/manifests are available, conversion must reference them and align critical runtime settings before emitting template artifacts.
• When official Kubernetes docs/manifests and Compose differ, prefer official Kubernetes runtime semantics for app behavior (bootstrap admin fields, external endpoint/env/protocol, health probes), unless doing so violates higher-priority Sealos MUST/security constraints.

Images and pull policy

• Do not use :latest.
• Resolve versions with crane: prefer an explicit version tag (for example v2.2.0), and fallback to digest pin only when a deterministic version tag is unavailable.
• Avoid floating tags (for example :v2, :2.1, :stable); use an explicit version tag or digest.
• Managed workload image references must be concrete and must not contain Compose-style variable expressions (for example ${VAR}, ${VAR:-default}); resolve to explicit tag or digest before emitting template artifacts.
• Application originImageName must match container image.
• Managed app workloads must reference the app-scoped image pull Secret ${{ defaults.app_name }} via template.spec.imagePullSecrets.
• The registry pull Secret is runtime-managed by sealos-deploy using local gh CLI credentials for private GHCR images; do not expose raw registry credential inputs in generated templates.
• All containers must explicitly set imagePullPolicy: IfNotPresent.

Storage

• Do not use emptyDir.
• Use persistent storage patterns (volumeClaimTemplates) where storage is needed.
• PVC request must be <= 1Gi unless source spec explicitly requires less.
• ConfigMap keys and volume names must follow vn naming (scripts/path_converter.py).

Env and secrets

• Non-database sensitive values/inputs use direct env[].value.
• Business containers must source database connection fields (endpoint, host, port, username, password) from approved Kubeblocks database secrets via env[].valueFrom.secretKeyRef.
• Business containers must not use custom env/volume Secret references except approved Kubeblocks database secrets and object storage secrets.
• A dedicated app-scoped registry pull Secret is allowed and should be referenced only through template.spec.imagePullSecrets.
• Database connection/bootstrap may use Kubeblocks-provided secrets, and reserved Kubeblocks database secret names must not be redefined by custom Secret resources.
• Env vars must be declared before referenced (for example password before URL composition).
• Follow official app env var naming; do not invent prefixes.
• When the application requires its public URL configured via a file-based config system (e.g., node-config config/default.json, PHP config files), create a ConfigMap containing the config file with the public URL set to https://${{ defaults.app_host }}.${{ SEALOS_CLOUD_DOMAIN }}, and mount it to the application's config directory. The ConfigMap must follow standard naming and label conventions.
• For PostgreSQL custom databases (non-postgres), include ${{ defaults.app_name }}-pg-init Job and implement startup-safe/idempotent creation logic (readiness wait + existence check before create).

Database-specific constraints

• PostgreSQL version: postgresql-16.4.0.
• PostgreSQL API: apps.kubeblocks.io/v1alpha1.
• PostgreSQL RBAC unified naming: ${{ defaults.app_name }}-pg.
• PostgreSQL RBAC requires app.kubernetes.io/instance and app.kubernetes.io/managed-by labels.
• PostgreSQL role wildcard permission requirement remains as defined in current spec.
• PostgreSQL cluster must include required labels/fields (kb.io/database: postgresql-16.4.0, clusterdefinition.kubeblocks.io/name: postgresql, clusterversion.kubeblocks.io/name: postgresql-16.4.0, clusterVersionRef: postgresql-16.4.0, disableExporter: true, enabledLogs: [running], switchPolicy.type: Noop, serviceAccountName).
• MongoDB cluster must follow upgraded structure (componentDef: mongodb, serviceVersion: 8.0.4, labels kb.io/database and app.kubernetes.io/instance).
• MySQL cluster must follow upgraded structure (kb.io/database: ac-mysql-8.0.30-1, clusterDefinitionRef: apecloud-mysql, clusterVersionRef: ac-mysql-8.0.30-1, tolerations: []).
• Redis cluster must follow upgraded structure (componentDef: redis-7, componentDef: redis-sentinel-7, serviceVersion: 7.2.7, main data PVC 1Gi, topology replication).
• Database cluster component resources must use limits(cpu=500m,memory=512Mi) and requests(cpu=50m,memory=51Mi) unless source docs explicitly require otherwise.
• Secret naming:
  • MongoDB: ${{ defaults.app_name }}-mongodb-account-root
  • Redis: ${{ defaults.app_name }}-redis-redis-account-default
  • Kafka: ${{ defaults.app_name }}-broker-account-admin
  • Do not use legacy naming outside supported exceptions.

Baseline runtime defaults

Unless source docs explicitly require otherwise, use:

• container limits: cpu=200m, memory=256Mi
• container requests: cpu=20m, memory=25Mi
• revisionHistoryLimit: 1
• automountServiceAccountToken: false

Defaults vs inputs

• defaults for generated values (app_name, app_host, random passwords/keys).
• inputs only for truly user-provided operational values (email/SMTP/external API keys, etc.).
• inputs.description must be in English.

Validation Commands

Run all checks before final response:

1. python scripts/path_converter.py --self-test
2. python scripts/test_check_consistency.py
3. python scripts/test_compose_to_template.py
4. python scripts/test_check_must_coverage.py
5. python scripts/check_consistency.py --skill SKILL.md --references references --rules-file references/rules-registry.yaml
6. python scripts/check_consistency.py --skill SKILL.md --references references --rules-file references/rules-registry.yaml --artifacts template/<app-name>/index.yaml
7. python scripts/check_must_coverage.py --skill SKILL.md --mapping references/must-rules-map.yaml --rules-file references/rules-registry.yaml
8. (CI / one-shot) python scripts/quality_gate.py (requires template/*/index.yaml by default; set DOCKER_TO_SEALOS_ALLOW_EMPTY_ARTIFACTS=1 only for dev/debug without artifacts)

check_consistency.py is registry-driven. Keep references/rules-registry.yaml in sync with implemented rules. Registry rule entries support severity and optional scope.include_paths metadata.

Output Contract

When conversion is complete, provide:

1. brief conversion summary
2. target file path (template/<app-name>/index.yaml)
3. complete template YAML
4. key decisions only where ambiguity existed

Reference Navigation (Progressive Loading)

Load only needed references for current task:

• references/sealos-specs.md
  • authoritative ordering, labels, App/Ingress/ConfigMap conventions
• references/conversion-mappings.md
  • Docker→Sealos field-level mappings and edge conversions
• references/database-templates.md
  • database templates, RBAC structures, secret naming patterns
• references/example-guide.md
  • examples and pattern walkthroughs (non-authoritative)
• references/rules-registry.yaml
  • machine-readable validation scope/rules list
• references/must-rules-map.yaml
  • MUST bullet to enforcement mapping (rule or manual) for drift control

Script Utilities

• scripts/path_converter.py
  • convert paths to vn names
  • self-test support for regression checks
• scripts/compose_to_template.py
  • deterministic compose/docs-to-template generator entrypoint
  • supports --kompose-mode auto|always|never (always is default) to reuse kompose convert workload shapes
  • emits template/<app-name>/index.yaml
• scripts/test_compose_to_template.py
  • regression tests for compose conversion behavior
• scripts/check_consistency.py
  • registry-driven consistency validator
• scripts/test_check_consistency.py
  • regression tests for validator behavior
• scripts/check_must_coverage.py
  • validate MUST bullet coverage mapping against registry rules
• scripts/test_check_must_coverage.py
  • regression tests for MUST coverage validator

Edge Policies

• Never ask users for missing fields; infer from compose/docs and platform conventions.
• Keep App resource in spec.data.url format; never use spec.template.
• Keep App resource spec.displayType: normal and spec.type: link; do not infer alternative enum values.
• Keep business-env, object storage, and DB-secret policy consistent with MUST rules.
• Prefer Sealos-managed ingress over bundled edge proxies: if a Traefik gateway is only acting as ingress/front-proxy and at least one business service exists, do not emit Traefik workload resources.
• Prefer gateway TLS termination in Sealos Ingress over in-container TLS: for dual-port HTTP/HTTPS workloads, keep HTTP service port and remove redundant HTTPS/certificate mounts unless official docs require HTTPS backend.
• Prefer fixing references/examples over adding exceptions when conflicts appear.
• If official Kubernetes installation docs/manifests exist for the target app, do not ignore them; use them to refine runtime semantics beyond Compose defaults.