Geo2Tz

A self-host-able service to get the timezone given geo-coordinates (lat/long)

It does it by exposing the library from github.com/evanoberholster/timezoneLookup

Timezone data comes from github.com/evansiroky/timezone-boundary-builder (release 2020d)

Motivations

Geo-coordinates might be sensitive information to share in any context, and I needed a self-hosted solution to ensure that coordinates were not leaked to 3rd party services. On another side, this feature is nicely self-contained and having one service to expose it spares the effort to bundle the TZ database everywhere.

API

the service exposes only one API:

GET /tz/${LATITUDE}/${LONGITUDE}

that returns a JSON reply (http/200):

{
    "tz": "${TIMEZONE}",
    "coords": {
        "lat": ${LATITUDE},
        "lon": ${LONGITUDE}
    }
}

or in case of errors (http/4**):

{
    "message": "${DESCRIPTION}"
}

Authorization

Geo2Tz supports a basic token authorization mechanism, if the configuration value for web.auth_token_value is a non-empty string, geo2tz will check the query parameter value to authorize incoming requests.

For example, running the service with:

docker run -p 2004:2004 -e GEO2TZ_WEB_AUTH_TOKEN_VALUE=secret noandrea/geo2tz

will enable authorization. With the authorization enabled, a query that does not specify the token will fail with an HTTP code 401:

> curl -sv http://localhost:2004/tz/41.902782/12.496365 | jq

*   Trying 127.0.0.1:2004...
* Connected to localhost (127.0.0.1) port 2004 (#0)
> GET /tz/41.902782/12.496365 HTTP/1.1
> Host: localhost:2004
> User-Agent: curl/7.81.0
> Accept: */*
> 
* Mark bundle as not supporting multiuse
< HTTP/1.1 401 Unauthorized
< Content-Type: application/json; charset=UTF-8
< Vary: Origin
< Date: Sun, 31 Jul 2022 20:06:56 GMT
< Content-Length: 27
< 
{ [27 bytes data]
* Connection #0 to host localhost left intact
{
  "message": "unauthorized"
}

Passing the token in the query parameters will succeed instead:

> curl -s http://localhost:2004/tz/41.902782/12.496365\?t\=secret | jq

{
  "coords": {
    "lat": 41.902782,
    "lon": 12.496365
  },
  "tz": "Europe/Rome"
}

Docker

Docker image is available at geo2tzt

docker run -p 2004:2004 github.com/noandrea/geo2tz

The image is built on scratch, the image size is ~92MB:

Docker compose

Docker compose YAML example

version: '3'
services:
  geo2tz:
    container_name: geo2tz
    image: github.com/noandrea/geo2tz
    ports:
    - 2004:2004
    # uncomment to enable authorization via request token
    # environment:
    # - GEO2TZ_WEB_AUTH_TOKEN_VALUE=somerandomstringhere
    # - GEO2TZ_WEB_AUTH_TOKEN_PARAM_NAME=t
    # - GEO2TZ_WEB_LISTEN_ADDRESS=":2004"

K8s

Kubernetes configuration example:

---
# Deployment
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  labels:
    app: geo2tz
  name: geo2tz
spec:
  replicas: 1
  revisionHistoryLimit: 3
  selector:
    matchLabels:
      app: geo2tz
  template:
    metadata:
      labels:
        app: geo2tz
    spec:
      containers:
      - env:
        # if this var is not empty it will enabled token authorization for requests
        #- name: GEO2TZ_WEB_AUTH_TOKEN_VALUE
        #  value: "secretsmaybebetter" # default is empty
        #- name: GEO2TZ_WEB_AUTH_TOKEN_PARAM_NAME
        #  value: "t" # default value
        #- name: GEO2TZ_WEB_LISTEN_ADDRESS
        #  value: ":2004" # default value
        image: github.com/noandrea/geo2tz:latest
        imagePullPolicy: Always
        name: geo2tz
        ports:
        - name: http
          containerPort: 2004
---
# Service
# the service for the above deployment
apiVersion: v1
kind: Service
metadata:
  name: geo2tz-service
spec:
  type: ClusterIP
  ports:
  - name: http
    port: 80
    protocol: TCP
    targetPort: http
  selector:
    app: geo2tz

Release process

Before you begin, choose the release version (following Semver), as a convention, this project uses the form of vX.Y.Z for version information.

Once you choose the appropriate release version run the following commands from the main branch. Note that at this point all the relevant branches should be merged.

Check out the main branch:

git checkout main

Make sure to have the last version

In this example, we assume that you want to release the version v1.0.0.

Generate the changelog and prepare the release:

make release-prepare APP_VERSION=v1.0.0

Prepare the tag:

make git-tag APP_VERSION=v1.0.0

Push the tag and the main branch:

git push && git push --tags

Create a git release:

make gh-publish-release APP_VERSION=v1.0.0

That's it!