mbtileserver

A simple Go-based server for map tiles stored in mbtiles format.

It currently provides support for png, jpg, webp, and pbf (vector tile) tilesets according to version 1.0 of the mbtiles specification. Tiles are served following the XYZ tile scheme, based on the Web Mercator coordinate reference system. UTF8 Grids are no longer supported.

In addition to tile-level access, it provides:

• TileJSON 2.1.0 endpoint for each tileset, with full metadata from the mbtiles file.
• a preview map for exploring each tileset.
• a minimal ArcGIS tile map service API

We have been able to host a bunch of tilesets on an AWS t2.nano virtual machine without any issues.

Goals

• Provide a web tile API for map tiles stored in mbtiles format
• Be fast
• Run on small resource cloud hosted machines (limited memory & CPU)
• Be easy to install and operate

Supported Go versions

Requires Go >= 1.21+.

mbtileserver uses go modules and follows standard practices as of Go 1.21.

Installation

You can install this project with

go install github.com/consbio/mbtileserver@latest

This will create and install an executable called mbtileserver.

Usage

From within the repository root ($GOPATH/bin needs to be in your $PATH):

$  mbtileserver --help
Serve tiles from mbtiles files

Usage:
  mbtileserver [flags]

Flags:
      --basemap-style-url string   Basemap style URL for preview endpoint (can include authorization token parameter if required by host)
      --basemap-tiles-url string   Basemap raster tiles URL pattern for preview endpoint (can include authorization token parameter if required by host): https://some.host/{z}/{x}/{y}.png
  -c, --cert string                X.509 TLS certificate filename.  If present, will be used to enable SSL on the server.
  -d, --dir string                 Directory containing mbtiles files.  Can be a comma-delimited list of directories. (default "./tilesets")
      --disable-preview            Disable map preview for each tileset (enabled by default)
      --disable-svc-list           Disable services list endpoint (enabled by default)
      --disable-tilejson           Disable TileJSON endpoint for each tileset (enabled by default)
      --domain string              Domain name of this server.  NOTE: only used for Auto TLS.
      --dsn string                 Sentry DSN
      --enable-arcgis              Enable ArcGIS Mapserver endpoints
      --enable-fs-watch            Enable reloading of tilesets by watching filesystem
      --enable-reload-signal       Enable graceful reload using HUP signal to the server process
      --generate-ids               Automatically generate tileset IDs instead of using relative path
  -h, --help                       help for mbtileserver
      --host string                IP address to listen on. Default is all interfaces. (default "0.0.0.0")
  -k, --key string                 TLS private key
      --missing-image-tile-404     Return HTTP 404 error code when image tile is misssing instead of default behavior to return blank PNG
  -p, --port int                   Server port.  Default is 443 if --cert or --tls options are used, otherwise 8000. (default -1)
  -r, --redirect                   Redirect HTTP to HTTPS
      --root-url string            Root URL of services endpoint (default "/services")
  -s, --secret-key string          Shared secret key used for HMAC request authentication
      --tiles-only                 Only enable tile endpoints (shortcut for --disable-svc-list --disable-tilejson --disable-preview)
  -t, --tls                        Auto TLS via Let's Encrypt.  Requires domain to be set
  -v, --verbose                    Verbose logging

So hosting tiles is as easy as putting your mbtiles files in the tilesets directory and starting the server. Woo hoo!

You can have multiple directories in your tilesets directory; these will be converted into appropriate URLs:

<tile_dir>/foo/bar/baz.mbtiles will be available at /services/foo/bar/baz.

If --generate-ids is provided, tileset IDs are automatically generated using a SHA1 hash of the path to each tileset. By default, tileset IDs are based on the relative path of each tileset to the base directory provided using --dir.

When you want to remove, modify, or add new tilesets, simply restart the server process or use one of the reloading processes below.

If a valid Sentry DSN is provided, warnings, errors, fatal errors, and panics will be reported to Sentry.

If redirect option is provided, the server also listens on port 80 and redirects to port 443.

If the --tls option is provided, the Let's Encrypt Terms of Service are accepted automatically on your behalf. Please review them here. Certificates are cached in a .certs folder created where you are executing mbtileserver. Please make sure this folder can be written by the mbtileserver process or you will get errors. Certificates are not requested until the first request is made to the server. We recommend that you initialize these after startup by making a request against https://<hostname>/services and watching the logs from the server to make sure that certificates were processed correctly. Common errors include Let's Encrypt not being able to access your server at the domain you provided. localhost or internal-only domains will not work.

If either --cert or --tls are provided, the default port is 443.

You can also use environment variables instead of flags, which may be more helpful when deploying in a docker image. Use the associated flag to determine usage. The following variables are available:

• PORT (--port)
• TILE_DIR (--dir)
• GENERATE_IDS (--generate-ids)
• ROOT_URL (--root-url)
• DOMAIN (--domain)
• TLS_CERT (--cert)
• TLS_PRIVATE_KEY (--key)
• HMAC_SECRET_KEY (--secret-key)
• AUTO_TLS (--tls)
• REDIRECT (--redirect)
• DSN (--dsn)
• VERBOSE (--verbose)

Example:

PORT=7777 TILE_DIR=./path/to/your/tiles VERBOSE=true mbtileserver

In a docker-compose.yml file it will look like:

mbtileserver:
  ...

  environment:
    PORT: 7777
    TILE_DIR: "./path/to/your/tiles"
    VERBOSE: true
  entrypoint: mbtileserver

  ...

Reloading

Reload using a signal

mbtileserver optionally supports graceful reload (without interrupting any in-progress requests). This functionality must be enabled with the --enable-reload-signal flag. When enabled, the server can be reloaded by sending it a HUP signal:

kill -HUP <pid>

Reloading the server will cause it to pick up changes to the tiles directory, adding new tilesets and removing any that are no longer present.

Reload using a filesystem watcher

mbtileserver optionally supports reload of individual tilesets by watching for filesystem changes. This functionality must be enabled with the --enable-fs-watch flag.

All directories specified by -d / --dir and any subdirectories that exist at the time the server is started will be watched for changes to the tilesets.

An existing tileset that is being updated will be locked while the file on disk is being updated. This will cause incoming requests to that tileset to stall for up to 30 seconds and will return as soon as the tileset is completely updated and unlocked. If it takes longer than 30 seconds for the tileset to be updated, HTTP 503 errors will be returned for that tileset until the tileset is completely updated and unlocked.

Under very high request volumes, requests that come in between when the file is first modified and when that modification is first detected (and tileset locked) may encounter errors.

WARNING: Do not remove the top-level watched directories while the server is running.

WARNING: Do not create or delete subdirectories within the watched directories while the server is running.

WARNING: do not generate tiles directly in the watched directories. Instead, create them in separate directories and copy them into the watched directories when complete.

Using with a reverse proxy

You can use a reverse proxy in front of mbtileserver to intercept incoming requests, provide TLS, etc.

We have used both Caddy and NGINX for our production setups in various projects, usually when we need to proxy to additional backend services.

To make sure that the correct request URL is passed to mbtileserver so that TileJSON and map preview endpoints work correctly, make sure to have your reverse proxy send the following headers:

Scheme (HTTP vs HTTPS): one of X-Forwarded-Proto, X-Forwarded-Protocol, X-Url-Scheme to set the scheme of the request. OR X-Forwarded-Ssl to automatically set the scheme to HTTPS.

Host: Set X-Forwarded-Host to the correct host for the request.

Caddy v2 Example:

For mbtileserver running on port 8000 locally, add the following to the block for your domain name:

<domain_name> {
  route /services* {
    reverse_proxy localhost:8000
  }
}

You may want to consider adding cache control headers within the route block depending on how often the contents of your tilesets change. For instance, to prevent clients from caching tiles longer than 1 hour:

  route /services* {
    header Cache-Control "public, max-age=3600, must-revalidate"
    localhost mbtileserver:8000
  }

NGINX Example:

For mbtileserver running on port 8000 locally, add the following to your server block:

server {
   <other config options>

    location /services {
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-Host $server_name;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-Ssl on;
        proxy_pass http://localhost:8000;
    }
}

Docker

Pull the latest image from Github Container Registry:

docker pull ghcr.io/consbio/mbtileserver:latest

To build the Docker image locally (named mbtileserver):

docker build -t mbtileserver -f Dockerfile .

To run the Docker container on port 8080 with your tilesets in <host tile dir>. Note that by default, mbtileserver runs on port 8000 in the container.

docker run --rm -p 8080:8000 -v <host tile dir>:/tilesets  consbio/mbtileserver

You can pass in additional command-line arguments to mbtileserver, for example, to use certificates and files in <host cert dir> so that you can access the server via HTTPS. The example below uses self-signed certificates generated using mkcert. This example uses automatic redirects, which causes mbtileserver to also listen on port 80 and automatically redirect to 443.

docker run  --rm -p 80:80 -p 443:443 -v <host tile dir>:/tilesets -v <host cert dir>:/certs/ consbio/mbtileserver -c /certs/localhost.pem -k /certs/localhost-key.pem -p 443 --redirect

Alternately, use docker-compose to run:

docker-compose up -d

The default docker-compose.yml configures mbtileserver to connect to port 8080 on the host, and uses the ./mbtiles/testdata folder for tilesets. You can use your own docker-compose.override.yml or environment specific files to set these how you like.

To reload the server:

docker exec -it mbtileserver sh -c "kill -HUP 1"

Specifications

• expects mbtiles files to follow version 1.0 of the mbtiles specification. Version 1.1 is preferred.
• implements TileJSON 2.1.0

Creating Tiles

You can create mbtiles files using a variety of tools. We have created tiles for use with mbtileserver using:

• TileMill (image tiles)
• tippecanoe (vector tiles)
• pymbtiles (tiles created using Python)
• tpkutils (image tiles from ArcGIS tile packages)

The root name of each mbtiles file becomes the "tileset_id" as used below.

XYZ Tile API

The primary use of mbtileserver is as a host for XYZ tiles.

These are provided at: /services/<tileset_id>/tiles/{z}/{x}/{y}.<format>

where <format> is one of png, jpg, webp, pbf depending on the type of data in the tileset.

Missing tiles

Missing vector tiles are always returned as HTTP 204.

Missing image tiles are returned as blank PNGs with the same dimensions as the tileset to give seamless display of these tiles in interactive maps.

When serving image tiles that encode data (e.g., terrain) instead of purely for display, this can cause issues. In this case, you can use the --missing-image-tile-404 option. This behavior will be applied to all image tilesets.

TileJSON API

mbtileserver automatically creates a TileJSON endpoint for each service at /services/<tileset_id>. The TileJSON uses the same scheme and domain name as is used for the incoming request; the --domain setting does not affect auto-generated URLs.

This API provides most elements of the `meta