logtail is a log tailing utility.
1. Features
- tailing command output
- support watch files under directory/sub-directories
- support (dynamically) multiple commands tailing
- support websocket tailing
- support log matching filter
- support transfer log to console/file/webhook (include dingtalk)
2. Architecture
3. Usage
3.2. install logtail
go install github.com/vogo/logtail@master
3.2. StartLoop logtail server using config file
logtail -file <config-file>config file examples.
3.3. StartLoop logtail server and config using webapi
usage: logtail -port=<port>
# start at port 54321
logtail -port=54321Then config using web api from web page http://<server-ip>:<port>/manage.
And you can browse http://<server-ip>:<port> to list all tailing logs.
4. log format
You can config log format globally, or config it for a server.
The config prefix of the format is the wildcard of the prefix of a new log record,
logtail will check whether a new line is the StartLoop of a new log record, or one of the following lines.
The wildcard does NOT support '*' for none or many chars, it supports the following tag:
- '?' as one byte char;
- '~' as one alphabet char;
- '!' as one number char;
- other chars must exact match.
example:
{
"default_format":{
"prefix": "!!!!-!!-!!" # global format config, Matches 2020-12-12
},
"servers": [
{
"name": "app1",
"command": "tail -f /logs/app/app1.log",
"format":{
"prefix": "!!!!-!!-!!" # server format config, Matches 2020-12-12
}
}
]
}4. command examples
The following are some useful commands which can be used in logtail.
# tail log file
tail -f /usr/local/myapp/myapp.log
# k8s: find and tail logs for the single pod of myapp
kubectl logs --tail 10 -f $(kubectl get pods --selector=app=myapp -o jsonpath='{.items[*].metadata.name}')
# k8s: find and tail logs for the myapp deployment (multiple pods)
kubectl logs --tail 10 -f deployment/$(kubectl get deployments --selector=project-name=myapp -o jsonpath='{.items[*].metadata.name}')
# k8s: find and tail logs for the latest version of the myapp deployment (single pod)
s=$(kubectl get deployments --selector=project-name=myapp -o jsonpath='{.items[*].metadata.name}');s=${s##* };kubectl logs --tail 10 -f deployment/$s
# k8s: find and tail logs for the latest version of the myapp deployment (multiple pods)
app=$(kubectl get deployments --selector=project-name=myapp -o jsonpath='{.items[*].metadata.name}');app=${app##* };pods=$(kubectl get pods --selector=app=$app -o jsonpath='{.items[*].metadata.name}');cmd='';for pod in $pods; do cmd=$cmd'kubectl logs --tail 2 -f pod/'$pod$'\n'; done;cmd=${cmd::-1}; echo "$cmd"