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It certainly doesn't say "use a logging library" it says: A twelve-factor app never concerns itself with routing or storage of its output stream. It should not

by cduzz 3y ago

It certainly doesn't say "use a logging library" it says: A twelve-factor app never concerns itself with routing or storage of its output stream. It should not attempt to write to or manage logfiles. Instead, each running process writes its event stream, unbuffered, to stdout. During local development, the developer will view this stream in the foreground of their terminal to observe the app’s behavior. In staging or production deploys, each process’ stream will be captured by the execution environment, collated together with all other streams from the app, and routed to one or more final destinations for viewing and long-term archival. These archival destinations are not visible to or configurable by the app, and instead are completely managed by the execution environment. Open-source log routers (such as Logplex and Fluentd) are available for this purpose. The event stream for an app can be routed to a file, or watched via realtime tail in a terminal. Most significantly, the stream can be sent to a log indexing and analysis system such as Splunk, or a general-purpose data warehousing system such as Hadoop/Hive. These systems allow for great power and flexibility for introspecting an app’s behavior over time, including: This is, at scale, utter horseshit. If it said "do what's expedient, but use a library and be flexible in how you generate logs, but for goodness sake use any of the publicly available libraries to be expedient now and reliable and flexible later" I'd shrug and move on, but it's just absolute garbage. "Do a shitty job and someone else will fix it for you" is not good advice, even if it lets you get to market quickly.

lmm 3y ago
> It certainly doesn't say "use a logging library" Right. It's not telling you anything about whether to use a library or not. All it's talking about is where you output your logging streams to, not about how you produce or format those streams. Is it bad advice because it doesn't tell you you should wear sunscreen when you go outside in summer? (FWIW I haven't seen any logging library add enough value to be worthwhile. Eventually graduating to structured event logs is a good idea, but having started with a logging library doesn't actually get you any closer to that).
jameshart 3y ago
It's clear you haven't actually taken the time to understand what 12 factor is saying, and you're assuming that anything left unsaid is an implied permission to just screw everything up. A more reasonable reading of 12 factor is to see that since it suggests that the output streams should be gathered up from multiple running instances of the application, and collated together in a system like splunk, that it behooves you as a 12 factor app developer to build your app such that your output stream is amenable to that approach. I.e., that your output is a stream of structured serialized data. You haven't clarified what you think is a better practice than this.
- cduzz 3y ago
  I've had the pleasure of dealing with devs who read this and decide it says "emit json formatted text to stdout and let someone else figure it out, just like it says in some web page." The guidance is explicitly "send it to stdout and let someone else figure it out." Which is terrible advice. The words don't suggest anything else. Maybe your experience suggests maybe you should use a library and reserve the ability to serialize that data to a proper api if necessary, but that's you not the words in the 12 factor app, and some large subset of people just do the minimum necessary to get the ticket off their queue, and if that means "printf log" that's what this advice in this suggests they'll do. It's splunk's problem now! And my advice is "use a damned logging library; understand the distinction between using a networking stack and API that manages abstractions like event size and retrying and such and stdout, which offers none of that."
  - morelisp 3y ago
    Sir, this is a Wendy's.

by cduzz 3y ago

lmm 3y ago

> It certainly doesn't say "use a logging library" Right. It's not telling you anything about whether to use a library or not. All it's talking about is where you output your logging streams to, not about how you produce or format those streams. Is it bad advice because it doesn't tell you you should wear sunscreen when you go outside in summer? (FWIW I haven't seen any logging library add enough value to be worthwhile. Eventually graduating to structured event logs is a good idea, but having started with a logging library doesn't actually get you any closer to that).

jameshart 3y ago

It's clear you haven't actually taken the time to understand what 12 factor is saying, and you're assuming that anything left unsaid is an implied permission to just screw everything up. A more reasonable reading of 12 factor is to see that since it suggests that the output streams should be gathered up from multiple running instances of the application, and collated together in a system like splunk, that it behooves you as a 12 factor app developer to build your app such that your output stream is amenable to that approach. I.e., that your output is a stream of structured serialized data. You haven't clarified what you think is a better practice than this.

cduzz 3y ago
I've had the pleasure of dealing with devs who read this and decide it says "emit json formatted text to stdout and let someone else figure it out, just like it says in some web page." The guidance is explicitly "send it to stdout and let someone else figure it out." Which is terrible advice. The words don't suggest anything else. Maybe your experience suggests maybe you should use a library and reserve the ability to serialize that data to a proper api if necessary, but that's you not the words in the 12 factor app, and some large subset of people just do the minimum necessary to get the ticket off their queue, and if that means "printf log" that's what this advice in this suggests they'll do. It's splunk's problem now! And my advice is "use a damned logging library; understand the distinction between using a networking stack and API that manages abstractions like event size and retrying and such and stdout, which offers none of that."
- morelisp 3y ago
  Sir, this is a Wendy's.