stern

Stern allows you to tail multiple pods on Kubernetes and multiple containerswithin the pod. Each result is color coded for quicker debugging.

The query is a regular expression so the pod name can easily be filtered andyou don't need to specify the exact id (for instance omitting the deploymentid). If a pod is deleted it gets removed from tail and if a new pod is added itautomatically gets tailed.

When a pod contains multiple containers Stern can tail all of them too withouthaving to do this manually for each one. Simply specify the container flag tolimit 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 tailweb-backend and web-frontend pods but not web-123.

cli flags

See stern --help for details

Stern will use the $KUBECONFIG environment variable if set. If both theenvironment variable and --kubeconfig flag are passed the cli flag will beused.

templates

stern supports outputting custom log messages. There are a few predefinedtemplates which you can use by specifying the --output flag:

It accepts a custom template through the --template flag, which will becompiled to a Go template and then used for every log message. This Go templatewill receive the following struct:

The following functions are available within the template (besides the builtinfunctions):

Examples:

Tail the gateway container running inside of the envvars pod on staging

stern envvars --context staging --container gateway

Tail the staging namespace excluding logs from istio-proxy container

stern -n staging --exclude-container istio-proxy .

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

Pipe the log message to jq:

stern backend -o json | jq .

Only output the log message itself:

stern backend -o raw

Output using a custom template:

stern --template '{{.Message}} ({{.Namespace}}/{{.PodName}}/{{.ContainerName}})' backend

Output using a custom template with stern-provided colors:

stern --template '{{.Message}} ({{.Namespace}}/{{color .PodColor .PodName}}/{{color .ContainerColor .ContainerName}})' backend

Completion

Stern supports command-line auto completion for bash or zsh. stern --completion=(bash|zsh) outputs the shell completion code which work by beingevaluated in .bashrc, etc for the specified shell. In addition, Sternsupports dynamic completion for --namespace and --context. In order to usethat, kubectl must be installed on your environment.

If you use bash, stern bash completion code depends on thebash-completion. On the macOS, youcan install it with homebrew as follows:

$ brew install bash-completion

Note that bash-completion must be sourced before sourcing the stern bashcompletion 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)

Contributing to this repository

Oracle welcomes contributions to this repository from anyone. Please seeCONTRIBUTING for details.