stern
Stern allows you to tail multiple pods on Kubernetes and multiple containers
within the pod. Each result is color coded for quicker debugging.
The query is a regular expression so the pod name can easily be filtered and you don't need to specify the exact id (for instance omitting the deployment id). If a pod is deleted it gets removed from tail and if a new is added it automatically gets tailed.
When a pod contains multiple containers Stern can tail all of them too without
having to do this manually for each one. Simply specify the container flag to
limit what containers to show. By default all containers are listened to.
Installation
If you don't want to build from source go grab a binary release
Govendor is required to install vendored dependencies.
mkdir -p $GOPATH/src/github.com/wercker
cd $GOPATH/src/github.com/wercker
git clone https://github.com/wercker/stern.git && cd stern
govendor sync
go install
Homebrew
On macOS, you can also install Stern using Homebrew:
brew install stern
Usage
stern pod-query [flags]
The pod query is a regular expression so you could provide "web-\w" to tail
web-backend and web-frontend pods but not web-123.
cli flags
| flag | default | purpose |
|---|---|---|
--container |
.* |
Container name when multiple containers in pod (regular expression) |
--timestamps |
Print timestamps | |
--since |
Return logs newer than a relative duration like 52, 2m, or 3h. Displays all if omitted | |
--context |
Kubernetes context to use. Default to kubectl config current-context |
|
--exclude |
Log lines to exclude; specify multiple with additional --exclude; (regular expression) |
|
--namespace |
Kubernetes namespace to use. Default to namespace configured in Kubernetes context | |
--kubeconfig |
~/.kube/config |
Path to kubeconfig file to use |
--all-namespaces |
If present, tail across all namespaces. A specific namespace is ignored even if specified with --namespace. | |
--selector |
Selector (label query) to filter on. If present, default to .* for the pod-query. |
|
--tail |
-1 |
The number of lines from the end of the logs to show. Defaults to -1, showing all logs. |
--color |
auto |
Force set color output. auto: colorize if tty attached, always: always colorize, never: never colorize |
See stern --help for details
Stern will use the $KUBECONFIG environment variable if set. If both the
environment variable and --kubeconfig flag are passed the cli flag will be
used.
Examples:
Tail the gateway container running inside of the envvars pod on staging
stern envvars --context staging --container gateway
Show auth activity from 15min ago with timestamps
stern auth -t --since 15m
Follow the development of some-new-feature in minikube
stern some-new-feature --context minikube
View pods from another namespace
stern kubernetes-dashboard --namespace kube-system
Tail the pods filtered by run=nginx label selector across all namespaces
stern --all-namespaces -l run=nginx
Follow the frontend pods in canary release
stern frontend --selector release=canary
Completion
Stern supports command-line auto completion for bash or zsh. stern --completion=(bash|zsh) outputs the shell completion code which work by being evaluated in .bashrc, etc for the specified shell. In addition, Stern supports dynamic completion for --namespace and --context. In order to use that, kubectl must be installed on your environment.
If you use bash, stern bash completion code depends on the bash-completion. On the macOS, you can install it with homebrew as follows:
$ brew install bash-completion
Note that bash-completion must be sourced before sourcing the stern bash completion code in .bashrc.
source <(brew --prefix)/etc/bash-completion
source <(stern --completion=bash)If you use zsh, just source the stern zsh completion code in .zshrc.
source <(stern --completion=zsh)