Support conninfo string to connect to postgis provider

[flacombe]

Dear maintainers,

Currently, postgis provider can only be reached with several arguments like host, port, dbname, etc... while libpq actually offers a more concise way to connect to a postgresql database. Unless I skip some existing issue, this hasn't been asked for yet.

See 33.1.1 here: https://www.postgresql.org/docs/13/libpq-connect.html

Example:

[[providers]]
name = "test_postgis"   # provider name is referenced from map layers
type = "postgis"        # the type of data provider.
uri = "postgres://tegola:tegolapwd@localhost:5432/tegola"
srid = 3857             # The default srid for this provider. If not provided it will be WebMercator (3857)

instead of

[[providers]]
name = "test_postgis"   # provider name is referenced from map layers
type = "postgis"        # the type of data provider.
host = "localhost"      # postgis database host
port = 5432             # postgis database port
database = "tegola"     # postgis database name
user = "tegola"         # postgis database user
password = "tegolapwd"           # postgis database password
srid = 3857             # The default srid for this provider. If not provided it will be WebMercator (3857)

It would be great to add this support in Tegola configuration please :)

Many thanks in advance

[ARolek]

I'm all for this support, we just need someone to run with plumbing this trough. We have a couple of related issues: #370 and #125. Would you be interested in working on this feature?

It might make sense to tackle this one along with upgrading the pgx driver so we can squash #748 at the same time.

[flacombe]

Thank you for this acknowledgment

Even if I wish to get involved in opensource projects I use, there are two main challenges I have to tackle prior to bring this to Tegola:

• No practice experience of postgresql's libpq API.
• Don't have any experience in Go so far (that's a nice occasion to begin however).

That's barely possible for me to take this time now, dealing with my workload. Wait and see

[ARolek]

No worries! I figured I would throw out the offer in case you were interested in sending in some code. I'm always happy to help.

[wielski]

It's also very important to make this feature bacause of in current implementation it's impossible to use multiple hosts for replication. PostgtreSQL allows to use multiple hosts like this:

postgresql://user:password@host1.example.com:1234,host2.example.com:1234,host3.example.com:1324?options

[ARolek]

I think it would make sense to implement this after the pgx v4 upgrade is addressed (#748)

[ARolek]

@flacombe and @wielski This is now in the v0.15.x branch (thanks to @iwpnd!) if you would like to give it a test.