Docker To Sealos

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
• startup-time validation rules for bootstrap credentials, API keys, salts, secrets, and feature flags
• multi-service web roles: browser entry, REST API, OpenAI/API gateway, docs, workers, and one-shot jobs
• 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, migration ordering)
• if official compose/docs provide multiple cooperating services, record the official runtime bundle source, component list, image versions, public entry routes, and critical env vars

Step 2: Infer metadata

Infer and normalize:

• app name, title, description, categories
• official URL, gitRepo, icon source (prefer square/circular icon-first assets such as app icons, favicons, or avatars; avoid rectangular wordmark/text logos)
• 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
• multi-service web normalization: expose the verified browser entry in the App resource, expose API/gateway/docs only when they are intended public surfaces, and keep workers private with no Service/Ingress
• URL topology: browser-facing env vars must use public HTTPS URLs, while server-to-server env vars must use Kubernetes Service FQDNs unless the app explicitly requires public callbacks
• 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
• when official compose/docs define a multi-component runtime bundle, keep runtime-required components, entry routes, critical env vars, and component image versions aligned to one official release/compose source

Step 5: Apply database strategy

• Database services must be generated as KubeBlocks Cluster resources. Do not convert PostgreSQL/MySQL/MongoDB/Redis/Kafka Compose database services into raw Kubernetes Deployment or StatefulSet workloads.
• 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.
• Critical application compatibility objects must be verified in live database state. Use idempotent initContainer self-healing for compatibility views, legacy tables/views, indexes, extensions, search paths, and bootstrap state that the app requires on every cold start.
• One-shot init Jobs may create initial databases or seed state, but app startup gates must verify the final database objects directly. Treat TTL-expired Jobs as historical evidence and rely on database state for acceptance.
• Worker, gateway, and background services that depend on app migrations must wait for the required tables, migration markers, or app-specific readiness objects, not only for the database port.
• Redis readiness probes or initContainers must tolerate authenticated Redis responses such as NOAUTH or Authentication required when credentials are not needed for readiness.
• PostgreSQL bootstrap shell must use safe quoting patterns. Prefer shell-level existence checks plus simple SQL statements when possible. Use single-quoted heredocs or SQL files for psql variable interpolation, and avoid PL/pgSQL DO $$ blocks in inline shell commands when a guard query can express the same logic.
• Do not use psql -c "..." for :'var' variable interpolation. Use psql -v name=value <<'SQL' ... :'name' ... SQL or pass already-safe literal SQL.

Step 6: Generate output files

Always produce:

• template/<app-name>/index.yaml
• template/<app-name>/logo.<ext> when official icon is resolvable, prioritizing square/circular icon-first artwork and avoiding rectangular wordmark/text logos

Never create:

• template/<app-name>/README.md
• template/<app-name>/README_zh.md

README authoring is out of scope for this skill. If the Template CR requires README URLs, populate URL fields in index.yaml only and leave file creation to a dedicated README skill.

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 point to https://raw.githubusercontent.com/labring-actions/templates/kb-0.9/template/<app-name>/README.md.
• Template spec.i18n.zh.readme must point to https://raw.githubusercontent.com/labring-actions/templates/kb-0.9/template/<app-name>/README_zh.md.
• These README fields are URL references in index.yaml only; this skill must not create or update the referenced README files.
• icon URL must point to template repo raw path for this app on kb-0.9 branch.
• template/<app-name>/logo.<ext> must use square/circular icon-first artwork (for example app icon/favicon/avatar), and must not use rectangular wordmark/text logos.
• 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.
• App resource spec.data.url must be the browser entry URL that succeeds from a fresh Sealos launch. For apps with safe-path, setup-path, or entrance-path behavior, verify the configured path and root path, then choose the URL that supports login or first-run setup without hidden prior navigation.
• SSR/Next.js/React server apps must not use a path that renders a server-side exception as the App URL or HTTP probe. Treat visible Application error, server-side exception, Internal Server Error, or Unhandled Runtime Error text as a failed entry path even if the HTTP status is 2xx/3xx.
• 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.
• The primary business container name must equal workload metadata.name for managed app workloads; sidecar/helper containers may use distinct descriptive names.
• 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.
• Runtime 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; bootstrap-only ConfigMaps used only by init containers to copy initial config into persistent storage must not define either label.
• 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.
• Root-path Ingress resources (pathType: Prefix, path: /) must use the same component name across metadata.name, metadata.labels.cloud.sealos.io/app-deploy-manager, and backend service.name; non-root or non-Prefix Ingress rules may route to a different backend service.
• 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.
• CronJob resources must define labels cloud.sealos.io/cronjob, cronjob-launchpad-name, and cronjob-type; cloud.sealos.io/cronjob must equal metadata.name, cronjob-launchpad-name must be "", and cronjob-type must be image.
• 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.
• When official compose/docs provide a multi-component runtime bundle, template artifacts must preserve runtime-required components, public entry routes, critical env vars, and image versions from the same official release/compose source.
• Templates using official multi-component runtime evidence must provide a separate RuntimeBundleEvidence YAML file during validation, while final Sealos Template artifacts stay free of runtime-bundle validator metadata.

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.
• Public-image managed app workloads must omit template.spec.imagePullSecrets; private-registry workloads may reference only the app-scoped pull Secret ${{ defaults.app_name }}.
• 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.
• StatefulSet resources with volumeClaimTemplates must set metadata.labels.cloud.sealos.io/deploy-on-sealos: ${{ defaults.app_name }} and every volumeClaimTemplates[].metadata.labels.cloud.sealos.io/deploy-on-sealos: ${{ defaults.app_name }} so Template can track and clean PVCs.
• PVC request must be <= 1Gi unless source spec explicitly requires less.
• ConfigMap data keys must follow vn naming (scripts/path_converter.py), including /, -, ., and other special characters.
• ConfigMaps mounted by managed Deployment/StatefulSet workloads must use metadata.name == workload.metadata.name.
• ConfigMap workload volumes must use <workload-name>-cm, and every ConfigMap data key must be mounted as its own volumeMount with subPath exactly equal to that key.
• Avoid long inline startup scripts or heredocs in command/args; place initialization/start scripts in ConfigMap files and invoke them with a short command.

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; exception: Redis host/port may use Sealos Redis Service FQDN and 6379 when the Redis secret only exposes credentials, and MongoDB host/port or connection URLs may use the Sealos MongoDB Service FQDN plus 27017 when the MongoDB secret exposes credentials only.
• 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 only for private-registry images and must be referenced only through template.spec.imagePullSecrets; public images must not add pull secrets.
• 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.
• For split frontend/API/gateway apps, keep public browser URLs and internal service URLs separate. Frontend/browser callback variables use https://${{ defaults.<host> }}.${{ SEALOS_CLOUD_DOMAIN }}; backend-to-backend variables use http://<service>.$(SEALOS_NAMESPACE).svc.cluster.local:<port> or the fully rendered Service FQDN.
• When the application requires its public URL configured via a file-based config system (e.g., node-config config/default.json, PHP config files), create a ConfigMap containing the config file with the public URL set to https://${{ 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).
• For application-specific database compatibility, include an initContainer or startup gate that idempotently creates or repairs required views, aliases, indexes, extensions, privileges, role search paths, and legacy compatibility objects before the business container starts.
• Managed app main container command/args must stay close to the image's official entrypoint. Keep only official startup commands, Compose-native args, or a short exec wrapper; move file preparation, permission repair, database bootstrap, and compatibility self-healing into initContainers, Jobs, or ConfigMap scripts.
• Shell wrappers in the main business container must exec the final process so signal handling remains correct.
• Database bootstrap SQL must be safe under shell execution: prefer shell-level guard queries plus simple SQL, use single-quoted heredocs for psql variables, and avoid unguarded inline DO $$ blocks.
• psql -c must not contain :'var' psql variable syntax; use heredocs for SQL that needs -v interpolation.

Database-specific constraints

• Database services must use KubeBlocks Cluster resources, not application Deployment or StatefulSet workloads. StatefulSet is allowed for stateful application components only, never for PostgreSQL/MySQL/MongoDB/Redis/Kafka database services.
• 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.
• Every KubeBlocks database Cluster must include kb.io/database, sealos-db-provider-cr, and clusterdefinition.kubeblocks.io/name labels; sealos-db-provider-cr must equal metadata.name so dbprovider can list and classify the database. Related Pods, Services, and OpsRequests should carry app.kubernetes.io/instance=<database name> for detail views.
• 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.
• All managed workload container resources must use the Sealos resource ladder: limits.cpu only 100m/200m/500m/1/2/3/4/8, limits.memory only 128Mi/256Mi/512Mi/1024Mi/2048Mi/4096Mi/8192Mi/16384Mi, and requests must be derived from limits by dropping the last numeric digit (500m→50m, 512Mi→51Mi, 1→100m, 1024Mi→102Mi, 4096Mi→409Mi). Do not invent non-ladder values, and never use 2G/4G/8G/16G because Sealos Template API quota preview can parse bare G memory as 0.
• Secret naming:
  • MongoDB: ${{ defaults.app_name }}-mongo-mongodb-account-root (or ${{ defaults.app_name }}-mongodb-mongodb-account-root when the MongoDB cluster name uses -mongodb)
  • Redis: ${{ defaults.app_name }}-redis-redis-account-default (legacy ${{ defaults.app_name }}-redis-account-default may be accepted for backward compatibility)
  • 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 the lightweight app ladder entry:

• container limits: cpu=200m, memory=256Mi
• container requests: cpu=20m, memory=25Mi
• revisionHistoryLimit: 1
• automountServiceAccountToken: false by default; set it to true only when the application has explicit Kubernetes API/service account token requirements, evidenced by Kubernetes integration settings, serviceAccountName, or a sealos.io/service-account-token-reason workload annotation.

For higher resource needs, move only to another allowed limits ladder entry and recompute requests from that limits value.

Browser / remote desktop resource validation

For browser, VNC, WebRTC desktop, Xvfb, Selkies, noVNC, Kasm, or remote-desktop-style containers:

• Do not treat a short smoke test as proof of a stable minimum memory value.
• Validate memory with a fresh deployment, not only a patched warm pod.
• Exercise cold start until readiness, a lightweight page, a real/medium page, an interactive/search page, and a 60s post-smoke stability check.
• If observed cgroup memory reaches more than 80% of the limit during smoke, move to the next allowed Sealos memory ladder value.
• Keep requests derived from limits according to the Sealos resource ladder.

Example:

• Bad: Chrome passes a short smoke at 512Mi but reaches 503Mi; shipping 512Mi as the stable minimum is unsafe.
• Good: raise to 1024Mi, set request to 102Mi, rerun smoke and stability checks.

For Chrome + Xvfb + Selkies with 4K max display, use at least:

• limits: cpu=200m, memory=1024Mi
• requests: cpu=20m, memory=102Mi

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.).
• When the user explicitly asks to enter application administrator credentials, declare the administrator username/password in spec.inputs, pass them as direct env values, and apply them through the application's documented bootstrap or initialization path. Keep database credentials on KubeBlocks secrets.
• Every ${{ inputs.<name> }} reference in a template artifact must have a matching spec.inputs.<name> declaration in the same Template CR.
• inputs.description must be in English.
• Startup-critical inputs[*].default values must satisfy the application's documented startup validation. For admin/bootstrap passwords with complexity rules, do not use '', weak examples, or bare ${{ random(n) }} because generated characters may not include required classes; include deterministic required classes around the random segment, for example "AppName@${{ random(16) }}!1".
• If an application exits when a required input is weak or empty, treat the input default as part of the runtime contract. Live validation must include the first boot logs and login/setup path with the generated default value.
• For binary object storage choices, use a boolean input (for example enable_s3_storage) and test with inputs.<name> === 'true'.

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)
9. Live deploy acceptance: after sealos-deploy creates the app, verify the actual App URL, login/setup flow for web apps, recent logs, expected database objects, and full resource footprint before reporting success.

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

Do not create or output README content in this skill. README generation is delegated to another skill.

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/frappe-bench.md
  • Frappe/ERPNext/HRMS/bench conversion patterns, init resources, idempotent site bootstrap, and common failure signatures
• 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 square/circular icon-first logo assets (app icon/favicon/avatar) and avoid rectangular wordmark/text logos.
• 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.
• Never create template/<app-name>/README.md or template/<app-name>/README_zh.md; only keep README URL references inside index.yaml when required by the template schema.
• 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.
• If the project mentions Frappe, ERPNext, HRMS, or bench, load references/frappe-bench.md before generating app workloads.