mirror of
https://github.com/mailscope/kumomta.git
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Ryan Bonnell
76 lines
3.3 KiB
Markdown
76 lines
3.3 KiB
Markdown
# Viewing Logs
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An important part of routine opperations is checking logs. KumoMTA compressed
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logs are found in `/var/log/kumomta/` and are named by date stamp. Logs are
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segmented by a combination of size/time and stored in compressed files named
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after the time that the segment was started. To read these, you need to unpack
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them first. You have many options for configuring logging.
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```
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/var/log/kumomta
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├── 20230311-033705
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├── 20230311-033844
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├── 20230312-182542
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└── 20230314-181435
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```
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## Using `tailer`
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The `tailer` utility, found at `/opt/kumomta/sbin/tailer`, is the easiest way to quickly
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review logs. The `--tail` flag will follow the log files in real time:
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```console
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$ sudo /opt/kumomta/sbin/tailer --tail /var/log/kumomta
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/var/log/kumomta/20230809-153944
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{"type":"Reception","id":"f68462cf36ca11ee99f450ebf67f93bd","sender":"wez@exa
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mple.com","recipient":"wez@example.com.org","queue":"example.com.org","site":
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"","size":518,"response":{"code":250,"enhanced_code":null,"content":"","comma
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nd":null},"peer_address":{"name":"foo.lan","addr":"127.0.0.1"},"timestamp":16
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91595584,"created":1691595584,"num_attempts":0,"bounce_classification":"Uncat
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egorized","egress_pool":null,"egress_source":null,"feedback_report":null,"met
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a":{},"headers":{},"delivery_protocol":null,"reception_protocol":"ESMTP","nod
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eid":"4eb22880-dc03-44dc-a4d1-4d0e68ac7845"}
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waiting for more files
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```
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The above example is shown artificially wrapped for the purposes of displaying
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nicely in this documentation. The actual log records are not output with wrapping.
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## Manually
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We can take a look at a specific log by decompressing it and since these are
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[zstd compressed](https://github.com/facebook/zstd#readme), you can view all
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but the current one with zstdcat. ZSTD is a streaming compression utility so
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the current file cannot be accessed until it is flushed and closed. You can
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force the current log to close by stopping KumoMTA.
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The default for log segments is to flush them after 1GB of data is written, but
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you can adjust them to flush after a certain amount of time if you find that
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you are regularly wanting to inspect the logs on a live system.
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[kumo.configure_local_logs](../../reference/kumo/configure_local_logs/index.md)
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has all of the available logging configuration options.
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Using the example above, we can see the content of the newest file after
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stopping KumoMTA with a `zstdcat /var/log/kumomta/20230314-181435`.
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If you have not done so already, you will want to install `zstd` with a (`dnf`
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or) `apt install zstd`. Below there is a sample of a decompressed received log:
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```console
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$ zstdcat /var/log/kumomta/20230428-201424_recv
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{"type":"Reception","id":"44d70f50e60111ed8162000d3afc4acf","sender":"noreply@example.com",
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"recipient":"recipient@example.com","queue":"example.com","site":"","size":27,
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"response":{"code":250,"enhanced_code":null,"content":"","command":null},
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"peer_address":{"name":"","addr":"127.0.0.1"},"timestamp":1682712864,"created":1682712864,
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"num_attempts":0,"bounce_classification":"Uncategorized","egress_pool":null,"egress_source":null,
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"feedback_report":null,"meta":{},"headers":{"Subject":"hello"}}
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```
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These JSON formatted logs can be programatically consumed or read manually as
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shown above for debugging and maintenance.
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[Formatting](../configuration/logging.md#customizing-the-log-format)
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can also be applied using the Mini Jinja templating engine.
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