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README.md

kail: kubernetes tail Build Status

Kubernetes tail. Streams logs from all containers of all matched pods. Match pods by service, replicaset, deployment, and others. Adjusts to a changing cluster - pods are added and removed from logging as they fall in or out of the selection.

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Usage

With no arguments, kail matches all pods in the cluster. You can control the matching pods with arguments which select pods based on various criteria.

Selectors

Flag Selection
--label LABEL-SELECTOR match pods based on a standard label selector
--pod NAME match pods by name
--ns NAMESPACE-NAME match pods in the given namespace
--svc NAME match pods belonging to the given service
--rc NAME match pods belonging to the given replication controller
--rs NAME match pods belonging to the given replica set
--deploy NAME match pods belonging to the given deployment
--node NODE-NAME match pods running on the given node
--ing NAME match pods belonging to services targeted by the given ingress
--containers CONTAINER-NAME restrict which containers logs are shown for
--ignore LABEL-SELECTOR Ignore pods that the selector matches. (default: kail.ignore=true)

Name Selection

When selecting objects by NAME (--svc, --pod, etc...), you can either qualify it with a namespace to restrict the selection to the given namespace, or select across all namespaces by giving just the object name.

Example:

# match pods belonging to a replicaset named 'workers' in any namespace.
$ kail --rs workers

# match pods belonging to the replicaset named 'workers' only in the 'staging' namespace
$ kail --rs staging/workers

Combining Selectors

If the same flag is used more than once, the selectors for that flag are "OR"ed together.

# match pods belonging to a replicaset named "workers" or "db"
$ kail --rs workers --rs db

Different flags are "AND"ed together:

# match pods belonging to both the service "frontend" and the deployment "webapp"
$ kail --svc frontend --deploy webapp

Other Flags

Flag Description
--help Display help and usage
--context CONTEXT-NAME Use the given Kubernetes context
--dry-run Print initial matched pods and exit
--log-level LEVEL Set the logging level (default: error)
--log-file PATH Write output to PATH (default: /dev/stderr)
--since DURATION Display logs as old as given duration. Ex: 5s, 2m, 1.5h or 2h45m (defaults: 1s)
See here for more information on the duration format.

Installing

Homebrew

$ brew tap boz/repo
$ brew install boz/repo/kail

Downloading

Kail binaries for Linux and OSX can be found on the latest release page. Download and install into your $GOPATH/bin with:

$ bash <( curl -sfL https://raw.githubusercontent.com/boz/kail/master/godownloader.sh) -b "$GOPATH/bin"

Running in a cluster with kubectl

The docker image abozanich/kail is available for running kail from within a kubernetes pod via kubectl.

Note: be sure to include the kail.ignore=true label, otherwise... it's logging all the way down.

Example:

# match all pods - synonymous with 'kail' from the command line
$ kubectl run -it --rm -l kail.ignore=true --restart=Never --image=abozanich/kail kail

# match pods belonging to service 'api' in any namespace - synonymous with 'kail --svc api'
$ kubectl run -it --rm -l kail.ignore=true --restart=Never --image=abozanich/kail kail -- --svc api

Building

Install build and dev dependencies

Install source code and golang dependencies

$ go get -d github.com/boz/kail
$ cd $GOPATH/src/github.com/boz/kail
$ make install-deps

Build binary

$ make

Install run against a demo cluster

$ minikube start
$ ./_example/demo.sh start
$ ./kail

# install image into minikube and run via kubectl
$ make image-minikube
$ kubectl run -it --rm -l kail.ignore=true --restart=Never --image=kail kail

Stress testing

Start minikube with a fair amount of CPU and memory.

$ minikube start --cpus 4 --memory 8192

Start stress.yml resources.

$ kubectl create -f _example/stress.yml

Wait a while for the pods to run

$ kubectl get pods --namespace stress | grep Running | wc -l
100

Run kail

./kail --ns stress