TileCloud-chain

TileCloud Chain is a comprehensive toolset for generating, serving, and managing map tiles. It supports WMS and Mapnik sources, multiple cloud and local storage backends, distributed master/slave generation with configurable queue backends, and a built-in WMTS tile server with an administrative web interface.

Sources

• Web Map Service (WMS)
• Mapnik rendering engine (legacy)

Destination Formats and Storage

• Web Map Tile Service (WMTS) layout
• Amazon S3 storage
• Azure Blob storage
• Local filesystem
• SQLite (MBTiles) support (legacy)
• Berkeley DB integration (legacy)

Key Features

• Tile generation in three modes: local (single machine), master (prepares jobs for a queue), slave (consumes jobs from the queue)
• Distributed generation with configurable queue backends: Redis, Amazon SQS, or PostgreSQL
• Daemon mode for continuous slave operation
• Zoom separation via min_resolution_seed: pre-generate low zooms, serve high zooms dynamically through the internal MapCache
• Geometry-based filtering using PostGIS SQL queries or GDAL datasources (e.g. Shapefile) — only generate tiles that intersect your areas of interest
• Bounding box filtering to restrict tile generation to a geographic extent
• Multi-grid support: multiple grids per layer with TileMatrixSetLimits in WMTS capabilities
• Layer dimensions: multi-variant tilesets (e.g. time, date) with WMTS dimension support
• MetaTiles: efficient generation by fetching multiple tiles in a single WMS request, with configurable size and border buffer
• Empty tile detection via SHA-1 hashing at both metatile and tile level
• Tile post-processing: run external tools (optipng, jpegoptim, pngquant) and configure Pillow save options
• Legend image generation: per-layer, per-zoom legend images with SHA-1 deduplication
• WMTS GetCapabilities: automatic XML generation with TileMatrixSetLimits, legend URLs, and ResourceURLs for GetFeatureInfo
• GetFeatureInfo (interrogation): WMS feature info proxy, available via REST and KVP interfaces
• WMTS tile server: built-in FastAPI server serving tiles via RESTful URLs and KVP interface, with caching, CORS, CSP, GZip compression, and configurable cache expiration
• Internal MapCache: Redis-based dynamic tile cache with locking for concurrent generation, WMS fallback for cache misses, and geometry-based redirect
• Administration web interface: job status monitoring, PostgreSQL job lifecycle (create/cancel/retry), command execution with ACL validation, OAuth2 GitHub authentication, and configuration validation
• OpenLayers demo page: interactive map with WMTS layers, dimension selectors, GetFeatureInfo on click, and state persistence in the URL
• Multi-tenant mode: host-based configuration resolution for serving multiple projects from a single deployment
• Monitoring: Prometheus metrics (tilecloud_chain_* counters) and Sentry error reporting
• Empty tile detection via hashing
• Geographic filtering (bbox and geometry-based)

Legacy Support

The following features are maintained for backward compatibility:

• Mapnik rendering
• Mapnik UTFGrid (interactive tile grids)
• Berkeley DB integration
• SQLite (MBTiles) support
• Error file generation and tile retry (--tiles)

Visual Preview

The admin interface with PostgreSQL queue integration:

The test page:

Demo.

Getting Started

Create a configuration file at tilegeneration/config.yaml.

Reference the example configuration.

Commands

Command	Description
generate-tiles	Generate tiles from WMS or Mapnik sources. Supports local, master, and slave roles, and --get-hash for computing empty tile hashes
generate-controller	Generate WMTS capabilities, legend images, display queue status, or dump the effective configuration

Generation Pipeline

The generate-tiles command supports four execution modes:

• local: generate tiles directly and store them in the target cache.
• master: prepare metatile jobs and push them to the queue store.
• slave: read jobs from the queue store, generate tiles, and store them.
• --get-hash: switch to hash mode to print metatile/tile hashes.

flowchart TD
    A["generate-tiles CLI"] --> B{"Mode"}

    B -->|local| L1["Build metatile stream"]
    B -->|master| M1["Build metatile stream"]
    B -->|slave| S1["Read metatiles from queue"]
    B -->|hash via --get-hash| H1["Build tile or metatile selection"]

    L1 --> L2["Apply geometry filter"]
    L2 --> C["Fetch source tile data"]
    M1 --> M2["Apply geometry filter"]
    M2 --> O3["Push metatile jobs to queue (Redis, SQS, PostgreSQL)"]
    S1 --> C
    H1 --> C

    C --> D["Split metatiles into tiles"]
    D --> E{"Hash handling"}

    E -->|hash mode| H2["Print hash values"]
    E -->|normal modes| F["Drop empty tiles/metatiles with configured hashes"]

    F --> G["Run post-process chain"]
    G --> I{"Mode output"}

    I -->|local| O1["Store tiles to cache (S3, local, etc.)"]
    I -->|slave| O2["Store tiles to cache and delete processed queue items"]
    I -->|hash| O4["Console output only"]

Loading

Server

TileCloud Chain includes a built-in WMTS tile server powered by FastAPI:

• WMTS REST API: tile serving with and without dimensions
• KVP interface: supports GetCapabilities, GetTile, and GetFeatureInfo via query parameters
• Internal MapCache: Redis-based dynamic tile cache with locking for concurrent generation and WMS fallback on cache miss
• GetFeatureInfo: proxies feature info requests to the configured WMS backend
• Cache headers: configurable Expires and Cache-Control
• CORS: configurable origins, methods, headers, and credentials
• CSP: Content Security Policy with nonce-based scripts
• Prometheus metrics: request counters and resource usage
• Sentry: error reporting integration
• Multi-tenant: host-based configuration resolution
• Tile-Backend header: reports whether a tile came from cache, Redis, or WMS generation

Admin Interface

The web admin interface provides:

• Job status: per-job counters (to generate, pending, error) with PostgreSQL, or queue counters with Redis/SQS
• PostgreSQL job management: create, cancel, and retry jobs (retry only errored metatiles)
• Command execution: run generate-tiles and generate-controller with validated arguments
• Configuration validation: schema validation errors and deprecation warnings
• Predefined commands: quick-run buttons for common operations
• OAuth2 authentication: GitHub OAuth2 with configurable access control
• Test page: OpenLayers map with WMTS layers, dimension selectors, GetFeatureInfo, and URL-based state persistence

Development

Building

make build

Quality Assurance

make prospector

Testing

make tests

Documentation

• Usage Guide
• Configuration Reference
• Environment variables

Contributing

Set up pre-commit hooks:

pip install pre-commit
pre-commit install --allow-missing-config