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tRPC-Python etcd configuration plugin

This plugin wraps the etcd3 client so you can quickly read configurations stored in etcd from the tRPC-Python framework.

Features

• Registered as a CONFIG_PROVIDER plugin named etcd. Importing the package registers it.
• load: read the raw bytes of one configuration by key (the prefix is applied automatically), for use with the framework's ConfigLoaderFactory and YAML/JSON decoders.
• hot_reload: watch a single key on a daemon thread. A PUT event delivers the new bytes, a DELETE event delivers b"", and after a disconnect the watch reconnects with exponential backoff and resumes from the last revision.

Quick start

Step 1: install

pip install trpc-config-etcd

Step 2: configure

In the trpc_python.yaml startup configuration, set the etcd address under plugins.config.etcd:

plugins:
  config:
    etcd:
      endpoints:
        - 127.0.0.1:2379
      dial_timeout: 5
      prefix: ""

Configuration fields:

• name (string, default etcd): provider name.
• endpoints (list of strings, default ["127.0.0.1:2379"]): etcd addresses in host:port or http://host:port form, tried in order when connecting.
• prefix (string, default ""): a shared prefix prepended to every configuration key, used to isolate data of different applications in the same etcd cluster.
• dial_timeout (number, default 5): connect and read timeout, in seconds.
• username / password (string, default ""): etcd username and password.
• ca_cert / cert_key / cert_cert (string, default ""): TLS certificate paths.

Per-call options passed to load(key, options) / hot_reload(key, cb, options) override the startup configuration fields of the same name.

Step 3: use

After the framework has loaded the startup configuration, read a configuration item from etcd:

import trpc_config_etcd  # noqa: F401  (importing registers the etcd provider)
from trpc_sdk.config import ConfigLoaderFactory, TrpcConfig
from trpc_sdk.config import with_codec, with_provider

TrpcConfig.load("trpc_python.yaml")

# Get the configuration item whose key is "salutation_config.json"
loader = ConfigLoaderFactory.sync_load(
    "salutation_config.json", with_provider("etcd"), with_codec("json"))
print(loader.get("hello", ""))

# Watch the same key; the callback receives the decoded dict
loader.hot_reload(lambda data: print("changed:", data))

Decoder names are those already registered by the framework: json, yaml, and noop.

You can also access a key directly without a Loader:

from trpc_config_etcd import EtcdClient

client = EtcdClient({"endpoints": ["127.0.0.1:2379"], "prefix": "/app"})
rsp = client.get("server_config.yaml")
print(rsp.value, rsp.event, rsp.metadata)
cancel = client.watch("server_config.yaml", lambda rsp: print(rsp.value))

To isolate multiple providers, instantiate several EtcdConfigProvider(config=EtcdProviderConfig(...)) objects and pass them to ConfigLoader(path, provider=..., decoder=...). The framework's named registry keeps only one instance named etcd.

Example

A runnable example is in examples. It demonstrates the two keys salutation_config.json and server_config.yaml.

Development setup

# Install this package and the test dependencies
pip install -e .
pip install -r requirements-test.txt

# Run tests
pytest

# Format the code
./format.sh

License

This project is licensed under Apache-2.0.