Show HN: Serve CSV Files as APIs

4 months ago 4

ROAPI automatically spins up read-only APIs for static datasets without requiring you to write a single line of code. It builds on top of Apache Arrow and Datafusion. The core of its design can be boiled down to the following:

Query frontends to translate SQL, FlightSQL, GraphQL and REST API queries into Datafusion plans.
Datafusion for query plan execution.
Data layer to load datasets from a variety of sources and formats with automatic schema inference.
Response encoding layer to serialize intermediate Arrow record batch into various formats requested by client.

See below for a high level diagram:

# if you are using homebrew brew install roapi # or if you prefer pip pip install roapi

Check out Github release page for pre-built binaries for each platform. Pre-built docker images are also available at ghcr.io/roapi/roapi.

cargo install --locked --git https://github.com/roapi/roapi --branch main --bins roapi

Spin up APIs for test_data/uk_cities_with_headers.csv and test_data/spacex_launches.json:

roapi \ --table "uk_cities=test_data/uk_cities_with_headers.csv" \ --table "test_data/spacex_launches.json"

Or using docker:

docker run -t --rm -p 8080:8080 ghcr.io/roapi/roapi:latest --addr-http 0.0.0.0:8080 \ --table "uk_cities=test_data/uk_cities_with_headers.csv" \ --table "test_data/spacex_launches.json"

Query data using the builtin web UI at http://localhost:8080/ui:

Query data using SQL, GraphQL or REST via curl:

curl -X POST -d "SELECT city, lat, lng FROM uk_cities LIMIT 2" localhost:8080/api/sql curl -X POST -d "query { uk_cities(limit: 2) {city, lat, lng} }" localhost:8080/api/graphql curl "localhost:8080/api/tables/uk_cities?columns=city,lat,lng&limit=2"

Get inferred schema for all tables:

curl 'localhost:8080/api/schema'

For MySQL and SQLite, specify the table argument like below:

--table "table_name=mysql://username:password@localhost:3306/database" --table "table_name=sqlite://path/to/database"

Want dynamic register data? Add parameter -d to command. --table parameter cannot be ignored for now.

roapi \ --table "uk_cities=test_data/uk_cities_with_headers.csv" \ -d

Then post config to /api/table register data.

curl -X POST http://172.24.16.1:8080/api/table \ -H 'Content-Type: application/json' \ -d '[ { "tableName": "uk_cities2", "uri": "./test_data/uk_cities_with_headers.csv" }, { "tableName": "table_name", "uri": "sqlite://path/to/database" } ]'

For windows, full scheme(file:// or filesystem://) must filled, and use double quote(") instead of single quote(') to escape windows cmdline limit:

roapi \ --table "uk_cities=file://d:/path/to/uk_cities_with_headers.csv" \ --table "file://d:/path/to/test_data/spacex_launches.json"

You can also configure multiple table sources using YAML or Toml config, which supports more advanced format specific table options:

addr: http: 0.0.0.0:8080 postgres: 0.0.0.0:5433 tables: - name: "blogs" uri: "test_data/blogs.parquet" - name: "ubuntu_ami" uri: "test_data/ubuntu-ami.json" option: format: "json" pointer: "/aaData" array_encoded: true schema: columns: - name: "zone" data_type: "Utf8" - name: "name" data_type: "Utf8" - name: "version" data_type: "Utf8" - name: "arch" data_type: "Utf8" - name: "instance_type" data_type: "Utf8" - name: "release" data_type: "Utf8" - name: "ami_id" data_type: "Utf8" - name: "aki_id" data_type: "Utf8" - name: "spacex_launches" uri: "https://api.spacexdata.com/v4/launches" option: format: "json" - name: "github_jobs" uri: "https://web.archive.org/web/20210507025928if_/https://jobs.github.com/positions.json"

To run serve tables using config file:

roapi -c ./roapi.yml # or .toml

See config documentation for more options including using Google spreadsheet as a table source.

By default, ROAPI encodes responses in JSON format, but you can request different encodings by specifying the ACCEPT header:

curl -X POST \ -H 'ACCEPT: application/vnd.apache.arrow.stream' \ -d "SELECT launch_library_id FROM spacex_launches WHERE launch_library_id IS NOT NULL" \ localhost:8080/api/sql

You can query tables through REST API by sending GET requests to /api/tables/{table_name}. Query operators are specified as query params.

REST query frontend currently supports the following query operators:

columns
sort
limit
filter

To sort column col1 in ascending order and col2 in descending order, set query param to: sort=col1,-col2.

To find all rows with col1 equal to string 'foo', set query param to: filter[col1]='foo'. You can also do basic comparisons with filters, for example predicate 0 <= col2 < 5 can be expressed as filter[col2]gte=0&filter[col2]lt=5.

To query tables using GraphQL, send the query through POST request to /api/graphql endpoint.

GraphQL query frontend supports the same set of operators supported by REST query frontend. Here how is you can apply various operators in a query:

{ table_name( filter: { col1: false, col2: { gteq: 4, lt: 1000 } } sort: [{ field: "col2", order: "desc" }, { field: "col3" }] limit: 100 ) { col1 col2 col3 } }

To query tables using a subset of standard SQL, send the query through POST request to /api/sql endpoint. This is the only query interface that supports table joins.

You can pick two columns from a table to use a key and value to create a quick keyvalue store API by adding the following lines to the config:

kvstores: - name: "launch_name" uri: "test_data/spacex_launches.json" key: id value: name

Key value lookup can be done through simple HTTP GET requests:

curl -v localhost:8080/api/kv/launch_name/600f9a8d8f798e2a4d5f979e Starlink-21 (v1.0)%

Query through Postgres wire protocol

ROAPI can present itself as a Postgres server so users can use Postgres clients to issue SQL queries.

$ psql -h 127.0.0.1 psql (12.10 (Ubuntu 12.10-0ubuntu0.20.04.1), server 13) WARNING: psql major version 12, server major version 13. Some psql features might not work. Type "help" for help. houqp=> select count(*) from uk_cities; COUNT(UInt8(1)) ----------------- 37 (1 row)

Query layer:

REST API GET
GraphQL
SQL
join between tables
access to array elements by index
access to nested struct fields by key
column index
protocol
- Postgres
- FlightSQL
Key value lookup

Response serialization:

JSON application/json
Arrow application/vnd.apache.arrow.stream
Parquet application/vnd.apache.parquet
msgpack

Data layer:

filesystem
HTTP/HTTPS
S3
GCS
Azure Storage
Google spreadsheet
MySQL
SQLite
Postgres
Airtable
Data format
- CSV
- JSON
- NDJSON
- parquet
- xls, xlsx, xlsb, ods: https://github.com/tafia/calamine
- DeltaLake

Misc:

auto gen OpenAPI doc for rest layer
query input type conversion based on table schema
stream arrow encoding response
authentication layer

The core of ROAPI, including query front-ends and data layer, lives in the self-contained columnq crate. It takes queries and outputs Arrow record batches. Data sources will also be loaded and stored in memory as Arrow record batches.

The roapi crate wraps columnq with a multi-protocol query layer. It serializes Arrow record batches produced by columnq into different formats based on client request.

To log all FlightSQL requests in console, set RUST_LOG=tower_http=trace.

docker build --rm -t ghcr.io/roapi/roapi:latest .

Vscode
Ensure this extension is installed on your vs code ms-vscode-remote.remote-containers

Once done you will see prompt from left side to reopen the project in dev container or open command palette and search for open with remote container: