jmespath.py VS Logback

The Azure CLI lets us write queries to filter the results of the az storage blob list command. The queries are written in JMESPath, which is a query language for JSON. In this case, we are filtering the results to only include blobs that end with the .bacpac extension and then selecting the first one as ordered by the lastModified property. If there are no blobs found, the script exits with a failure code. If we find a blob, we download it to the local path specified by the localPath variable.

For JSON there is the `jmespath` library which might help.

https://github.com/jmespath/jmespath.py

I love jq, but I also use JMESPath (especially with AWS CLI), yq (bundled with tomlq and xq as well), and dasel [2]. I also wish hclq [3] wasn't so dead!

[0]: https://jmespath.org/

Probably writing the query side of things is a lot of the fun here, but there is actually a spec (and a complying Rust impl) you can hook into for this JQ-like querying: https://jmespath.org/ ( https://github.com/jmespath/jmespath.rs ).

Thanks to custom variables that use labels, we can create various filters for the dashboard. You can look up my configuration of variables and extend it with an analogy way for your own needs. At the top, I marked the filter with detected pods in selected namespace. In the lower part, you can see a preview of all labels that are associated with a single log line. Most labels are meta information that Promtail adds during scraping targets. This part of the Promtail configuration provides it. In this section, I also marked a few labels that not comes out-of-the box e.g. leavel , class , thread . We added these labels using the Promtail json stage. You need to know that Promtail processes scraped logs in a pipeline. A pipeline is comprised of a set of stages. json stage is a parsing stage that reads the log line as JSON and accepts JMESPath expressions to extract data.

The tester on the official website for JMESPath (what json_query is doing) has been useful to me: https://jmespath.org/

Interesting. How does this compared to Jmespath? Not saying Jmespath is superior, just wondering whether you were aware of it.

Java -> Logback, Log4j2, JDK (Java Util Logging), Slf4j, e.t.c.

This is a GitHub link to my demo app. It’s simple Spring Boot web app used to debugging various stuff. There are many ways to configure JSON logging in Spring Boot. I decided to use Logback because it is easy to configure and one of the most widely used logging library in the Java Community. To enable JSON logging we need to add below dependencies.

Logback(https://logback.qos.ch/) is another non-commercial Java logging framework. It labels itself as a successor to the previously discussed Log4j framework.

> Then apache decides to put new people on log4j, do a backward incompatible v2 design that nevertheless is worse than slf4j. Why?

slf4j itself isn't a logging framework. It's a facade to logging frameworks.

Simple Logging Facade for Java ( https://www.slf4j.org )

It needs a logging framework behind it - log4j, log4j2, logback, commons, JUL.

The question is "why do log4j2?"

Logback went from the log4j1.x path ( https://logback.qos.ch )

Log4j2 has a lot of features that weren't present when the project started ( https://en.wikipedia.org/wiki/Log4j#Apache_Log4j_2 ).

There is a licensing difference between Logback (LGPL) and Log4jx (Apache Commons).

Also, I'd like you to pay attention to the log consumer. You see, when the E2E scenario fails, it's not always obvious why. Sometimes to understand the source of the problem you have to dig into containers' logs. Thankfully the log consumer allows us to forward a container's logs to any SLF4J logger instance. In this project, containers' logs are forwarded to regular text files (you can find the Logback configuration in the repository). Though it's much better to transfer logs to external logging facility (e.g. Kibana).

This shows that the MariaDB JDBC driver uses Logback as a logging framework. Although Logback is not affected by Log4Shell, it has a related vulnerability (of much lesser severity, no need to panic) fixed in version 1.2.8 and 1.3.0-alpha11. I checked the version used by the connector and found that it used 1.3.0-alpha10. Even though Logback is included as a test dependency in the MariaDB driver, I sent a pull request on GitHub to update it. I encourage you to do the same in any open-source project you find and that includes a vulnerable dependency.

Dependencing on the project, changing the logger might range from easy peasy to a multi-week task. I'm ready to bet that in many (most?) cases, it'd actually be quite easy, so let's explore how to do it, using Logback as the target (there aren't that many alternatives actually).