aida_2012 VS rust-prometheus

Some years ago I wrote a JSON parser, see for example https://github.com/joakim-strandberg/aida_2012/blob/master/src/tests/aida-json_dom_parser_tests.adb. I've been thinking of refactoring but never gotten around to do it. One of the ideas for writing the code was minimizing external dependencies. The JSON parser is written in SPARK and at the time 2018 when the code was written SPARK did not allow heap allocations which means all the data-structures used are statically allocated. I can imagine onox json-ada has a nicer API.

For getting UTF-8 support one can also use Dmitry Kazakovs Simple components (http://www.dmitry-kazakov.de/ada/components). Based on it have made a UTF-8 version which is Ada/Spark based (https://github.com/joakim-strandberg/aida_2012). Another one I have been toying with is cross-compiler: https://github.com/joakim-strandberg/portable_ada . To print to standard out using UTF-8 the easiest way is probably enabling "-gnatW8" in order for normal String types be interpreted as UTF-8 strings. Using the UTF-8 support in the links I would recommend making one's own Ada bindings to the OS. It should be easy to do on Mac OS X and Linux where UTF-8 is enabled by default but more of an issue on Windows where the UTF-8 encoded strings need to be converted to UTF-16 before being handed over to the OS.

I used the prometheus library because it was the most popular and easiest to find. Some unusual and unexpected aspects were that, to delete metrics, all labels must be specified at once, and to record metrics, I always needed the full list of labels that were used during creation. However, these issues were manageable.

[dependencies] prometheus = { git = "https://github.com/tikv/rust-prometheus", rev = "ac86a264223c8d918a43e739ca3c48bb4aaedb90", features = ["process"] }

Metrics exposition is implemented with prometheus crate.

The new Elasticsearch exporter is written in the Rust programming language and is open-sourced on GitHub: github.com/vinted/elasticsearch-exporter-rs. The exporter uses asynchronous Tokio runtime, Rust Prometheus instrumentation library and the official Elasticsearch client library. Metrics collection is decoupled from the serving /metrics endpoint. In addition, Elasticsearch time-based metrics in milliseconds are converted into seconds to comply with Prometheus best practices (metrics ending in “millis” are replaced by “seconds”, “_bytes” and “_seconds” and postfixes are added where appropriate).

Rust has a popular binding: https://github.com/tikv/rust-prometheus