Managing go versions with gvm

gvm is a way to manage multiple go versions. It has some strange behaviour with go paths that I don't really understand. It essentially sets your GOPATH to a different directory for every version. You could just append your real go path, but it seems like there might be tooling that doesn't expect gopath to be a list. My solution was to:

gvm install go1.8
gvm use go1.8
gvm pkgenv

This pops $EDITOR which you can use to set your go path to $HOME/go. Check it with:

go env

kubectl Kubernetes Cheat Sheet

A complement to the official kubectl cheat sheet.

Getting kubectl

There's better ways to install it for permanent use, but here's a quick way for temporary use:

export PATH=/tmp:$PATH
cd /tmp; curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/linux/amd64/kubectl; chmod 555 kubectl

Nodes

$ kubectl get nodes
$ kubectl get nodes/gke-hello-world-default-pool-9dbb0d2c-5qkl --show-labels
$ kubectl label nodes --all mylabel=myvalue
$ kubectl label nodes --all mylabel-

Namespaces

$ kubectl get all -n mynamespace

RBAC

What permissions do I have?

kubectl auth can-i --list

All clusterrolebindings:

kubectl get clusterrolebinding -o yaml

Role bindings for all namespaces:

kubectl get rolebinding --all-namespaces -o yaml

Privileges of current user:

kubectl create -f - -o yaml << EOF
apiVersion: authorization.k8s.io/v1
kind: SelfSubjectRulesReview      
spec:
  namespace: system
EOF

DaemonSet

Creating a daemonset:

$ echo 'apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
  name: daemonset-example
spec:
  template:
    metadata:
      labels:
        app: daemonset-example
    spec:
      containers:
      - name: daemonset-example
        image: ubuntu:trusty
        command:
        - /bin/sh
        args:
        - -c
        - >-
          while [ true ]; do
          echo "DaemonSet running on $(hostname)" ;
          sleep 10 ;
          done
' | kubectl create -f -

$ kubectl delete daemonset daemonset-example

Get a shell in a container

$ kubectl run --rm=true -i --tty ubuntu --image=ubuntu -- /bin/bash
# Or with an existing container
$ kubectl exec -it shell-demo -- /bin/bash

gcloud cheatsheet for GKE

This is by no means comprehensive, it's just some things I've found useful.

Get installed and auth'd:

gcloud components install kubectl
gcloud auth application-default login

Creating a cluster with a specific version:

gcloud config set compute/zone us-west1-b
gcloud beta container clusters create permissions-test-cluster \
    --cluster-version=1.6.1 \
    --no-enable-legacy-authorization

Upgrading GKE:

# Get available versions
$ gcloud container get-server-config 
Fetching server config for us-west1-b
defaultClusterVersion: 1.5.7
defaultImageType: COS
validImageTypes:
- COS
- CONTAINER_VM
validMasterVersions:
- 1.6.4
- 1.5.7
validNodeVersions:
- 1.6.4
- 1.6.2
- 1.5.7
- 1.5.6
- 1.4.9

$ CLUSTER_NAME="testing"
$ CLUSTER_VERSION="1.6.4"

# Nodes
$ gcloud container clusters upgrade $CLUSTER_NAME --cluster-version=$CLUSTER_VERSION

# Master
$ gcloud container clusters upgrade $CLUSTER_NAME --master --cluster-version=$CLUSTER_VERSION

List containers in the google-containers project:

gcloud container images list --repository gcr.io/google-containers

Tags for a given container:

gcloud container images list-tags gcr.io/gke-release/auditproxy

Google gcloud tool cheatsheet

Some gcloud commands I've found useful:

# See config
gcloud config list

# Change default zone
gcloud config set compute/zone us-central1-a

# Copy a file, default zone
gcloud compute copy-files some/file.txt cloud-machine-name:~/

# Copy a file, specifying zone for machine
gcloud compute copy-files some/file.txt cloud-machine-name:~/ --zone=us-west1-a

# Forward a port with ssh
gcloud compute ssh client-machine-name -- -L 8080:localhost:8080

Mac OS X Sierra and SSH keys

With OS X Sierra Apple changed the ssh client key handling behavior. They aligned with OpenSSH behavior by not automatically loading passphrases from the keychain on login. More surprisingly, it now remembers your ssh key passphrase automatically by default. To disable this behavior you can add this to ~/.ssh/config:

Host *
    UseKeyChain no

As you can see in the radar report, deleting keys using "ssh-add -D" seems to be just as problematic and confusing as it is with gnome-keyring, i.e. "All identities removed" is a lie.

For deleting already saved passwords and re-instating the El-Cap ssh behavior see here.

Prevent system management from installing over a test package on Ubuntu

When you are testing a new package version it's annoying to have your system management come and install the old version over the top of your test one. There's a bunch of ways to stop this, the one I tend to use on Ubuntu is:

echo "package hold" | sudo dpkg --set-selections

To undo the hold and go back to normal:

echo "package install" | sudo dpkg --set-selections

Running modern python on Ubuntu LTS

The python version on your Ubunutu LTS may be slightly behind latest, or years behind, depending on the release cycle. Here's how to run a newer python without interfering with the system one.

Note that setting an install prefix is necessary to avoid making this the default system python (which will break cinnamon-settings apps as well as possibly other things). The prefix I chose puts it in a directory with my username.

Download the latest python source and install it:

sudo apt-get install build-essential libreadline-dev libsqlite3-dev
./configure --enable-ipv6 --enable-unicode=ucs4 --prefix=/usr/local/${USER}/
make
sudo make install

Your new python is now in /usr/local/${USER}/bin/python2.7. To use it, specify it in any virtualenvs you create. Make it an alias so you never forget:

alias virtualenv='virtualenv --python=/usr/local/${USER}/bin/python'