48 lines
2 KiB
Markdown
48 lines
2 KiB
Markdown
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# patroniglue
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> Handle and cache basic Patroni API checks
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[Patroni](https://github.com/zalando/patroni) uses the built-in Python HTTP server to expose database states. It's perfect to be used by a load balancer like HAProxy to achieve high-availability. But, sometimes, this interface freezes. There's an [open issue](https://github.com/zalando/patroni/issues/857) we are trying to close actively. As production doesn't wait, `patroniglue` was created to offload those checks and release pressure by adding a little response cache.
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## Usage
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Start process using a configuration file:
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```
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patroniglue -config config.yml
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```
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Add more logging output:
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```
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patroniglue -config config.yml -verbose
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```
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Print usage:
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```
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patroniglue -help
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```
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## Configuration
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Configuration file format is YAML.
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* `frontend`: settings to handle incoming requests
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* `host`: address to handle requests (localhost by default)
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* `port`: port to handle requests (80 by default)
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* `certfile`: path to SSL certificate file (will use HTTP by default if not provided)
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* `keyfile`: path to SSL private key file (will use HTTP by default if not provided)
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* `backend`: settings for sending requests to a backend
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* `host`: patroni REST API `listen` address
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* `port`: patroni REST API `listen` port
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* `scheme`: patroni REST API scheme (either `http` or `https`)
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* `insecure`: disable certificate checks on HTTPS requests
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* `cache`: settings for the caching system
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* `ttl`: time in second before response will be evinced
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* `interval`: time in second used by the internal cache loop to check for keys to remove
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See [config.yml.example](config.yml.example) file for an example.
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## Internals
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* Frontend handles HTTP or HTTPS requests on "/master" and "/replica" routes available on Patroni API
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* Backend requests Patroni API using HTTP or HTTPS protocol and exposes state to frontend
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* Cache implements an in-memory key-value store to cache backend responses for some time
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## Build
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Run `./build.sh` script and enjoy!
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