supercell

A supercell is a thunderstorm characterized by the presence of a mesocyclone, a deep, persistently rotating updraft.

Supercell is a lightweight and configurable atproto feed generator.

Configuration

The following environment variables are used:

• HTTP_PORT - The port to listen on for HTTP requests.
• EXTERNAL_BASE - The hostname of the feed generator.
• DATABASE_URL - The URL of the database to use.
• JETSTREAM_HOSTNAME - The hostname of the JetStream server to consume events from.
• COMPRESSION - Use zstd compression. Default false.
• ZSTD_DICTIONARY - The path to the ZSTD dictionary to use. Required when compression is enabled.
• CONSUMER_TASK_ENABLE - Whether or not to enable the consumer tasks. Default true.
• VMC_TASK_ENABLE - Whether or not to enable the VMC (verification method cache) tasks. Default true.
• CACHE_TASK_ENABLE - Whether or not to enable the cache tasks. Default true.
• CACHE_TASK_INTERVAL - The interval to run the cache tasks. Default 3m.
• CLEANUP_TASK_ENABLE - Whether or not to enable the cleanup tasks. Default true.
• CLEANUP_TASK_INTERVAL - The interval to run the cleanup tasks. Default 1h.
• CLEANUP_TASK_MAX_AGE - The maximum age of a post before it is considered stale and deleted from storage. Default 48h.
• PLC_HOSTNAME - The hostname of the PLC server to use for VMC tasks. Default plc.directory.
• FEEDS - The path to the feeds configuration file.
• COLLECTIONS - The collections to consume. Default app.bsky.feed.post.
• RUST_LOG - Logging configuration. Defaults to supercell=debug,info

The feed configuration file is a YAML file that contains the feeds to serve and how to match events to the feed. It supports a variable number of matchers with different rules. Matching is done in order and uses json path plus the matcher implementation.

feeds:
- uri: "at://did:plc:4acsffvbo4niovge362ptijz/app.bsky.feed.generator/3la5azib4xe2c"
  name: "Smoke Signal Support"
  description: "The Smoke Signal Support feed."
  allow: ["did:plc:cbkjy5n7bk3ax2wplmtjofq2"]
  deny: "at://did:plc:4acsffvbo4niovge362ptijz/app.bsky.feed.post/3la5bsyzj3j23"
  matchers:
  - path: "$.did"
    value: "did:plc:tgudj2fjm77pzkuawquqhsxm"
    type: equal
  - path: "$.commit.record.facets[*].features[?(@['$type'] == 'app.bsky.richtext.facet#tag')].tag"
    values: ["smoke", "signal"]
    type: sequence
  - path: "$.commit.record.facets[*].features[?(@['$type'] == 'app.bsky.richtext.facet#link')].uri"
    value: "https://smokesignal.events/"
    type: prefix
  - path: "$.commit.record.embed.external.uri"
    value: "https://smokesignal.events/"
    type: prefix

The equal matcher performs an exact string match matched paths.

The prefix matcher performs a prefix string match on matched paths. Given the value "foo bar baz", the following prefixes would match: "foo", "foo ", etc.

The sequence matcher performs a sequence string match on matched paths. This is used to match a list of values in order making flexible ordered matching without needing regex or complex reverse lookups.

Consider the example string "The quick brown fox jumps over the lazy dog". The following sequences would match:

• "the" "quick"
• "brown"
• "brow" "fox" "lazy" "dog"
• "the" "dog"

JSONPath is a query language for JSON. When used with matchers, JSONPath will use all nodes as inputs and each matcher will match against any of the values.

For example, the following json would match the equal matcher with both $.text and $.tags.*:

{
    "text": "foo",
    "tags": ["foo", "bar"],
}

The site https://jsonpath.com/ is a great resource for testing JSONPath queries.

See the config.example.yml file for additional examples.

License

This project is open source under the MIT license.

Copyright (c) 2023 Astrenox Cooperative. All Rights Reserved.