Create a symlink to latest log file #1979
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@clia in general, we prefer to merge new features to the |
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Thanks for working on this, I agree that this is definitely a feature that's worth having!
I think we probably want to make the symlinking behavior configurable, rather than always doing it by default. I left some comments discussing this. Also, if you're able to, it would be nice to add some tests to ensure this works as intended?
| @@ -24,6 +24,7 @@ rust-version = "1.53.0" | |||
| crossbeam-channel = "0.5.0" | |||
| time = { version = "0.3", default-features = false, features = ["formatting"] } | |||
| parking_lot = { optional = true, version = "0.12.0" } | |||
| symlink = "0.1.0" | |||
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Since this adds a new dependency, and some users may not want the symlink feature, I think it would be preferable to feature flag this?
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| // Create a symlink to latest log file. | ||
| let latest_path = Path::new(&filename); | ||
| let symlink_path = Path::new(&log_directory).join(&log_filename_prefix); |
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I'm not sure if using the log filename prefix for the name of the symlink is the best solution. The prefix may contain a trailing separator character. For example, I might want my log files to have names like myapp-log-<DATE>, so the prefix might be myapp-log-. Therefore, I think we probably want to allow users to configure the name of the symlink separately from the log file's name. Also, some users may want to give the symlink a special name like <LOGFILE_NAME>.latest or similar.
PR #1779 adds a builder interface for configuring new RollingFileAppender instances, in order to support compression of log files. I think once that PR merges, we may want to add a builder method for configuring the symlink generation, instead?
| // Create a symlink to latest log file. | ||
| let latest_path = Path::new(&filename); | ||
| let symlink_path = Path::new(&log_directory).join(&log_filename_prefix); | ||
| let _ = remove_symlink_file(&symlink_path); | ||
| if let Err(err) = symlink_file(&latest_path, &symlink_path) { | ||
| eprintln!("Couldn't create symlink: {}", err); | ||
| } |
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take it or leave it: the code for re-creating the symlink in Inner::refresh_writer is identical to this code...I wonder if we want to consider making a function for creating/updating the symlink, and call it in both places?
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Any status on this? Would be a great feature to have. I'm willing to work on this |
Motivation
When monitoring logs of rotating files, it will be very helpful to create a symlink
to the latest log file when creating and rotating the log file.
Then you can
tail -F symlink_fileto keep watching the new created log file.Solution
Create a symlink file when creating and rotating the log file.
Use a
symlinkcrate to achieve a system compatible implementation.It's necessary to remove the old symlink file before creating it, otherwise it may cause failure.