.envrc-kubernetes

#!/usr/bin/env bash
#  vim:ts=4:sts=4:sw=4:et
#
#  Author: Hari Sekhon
#  Date: 2021-02-25 10:10:53 +0000 (Thu, 25 Feb 2021)
#
#  https://github.com/HariSekhon/DevOps-Bash-tools
#
#  License: see accompanying Hari Sekhon LICENSE file
#
#  If you're using my code you're welcome to connect with me on LinkedIn and optionally send me feedback to help steer this or other code I publish
#
#  https://www.linkedin.com/in/HariSekhon
#

# ============================================================================ #
#                       K u b e r n e t e s   D i r E n v
# ============================================================================ #

# https://direnv.net/man/direnv-stdlib.1.html

# See Also:
#
#   .envrc
#   .envrc-aws
#   .envrc-gcp

# direnv stdlib - loads .envrc from parent dir up to /
#
# useful to accumulate parent and child directory .envrc settings eg. adding Kubernetes namespace, ArgoCD app etc.
#
# bypasses security authorization though - use with care
#source_up
#
# source_up must be loaded before set -u otherwise gets this error:
#
#   direnv: loading .envrc
#   /bin/bash: line 226: $1: unbound variable

set -euo pipefail
[ -n "${DEBUG:-}" ] && set -x

arg="${1:-}"
if [ "${arg##*/}" = "${BASH_SOURCE[0]##*/}" ]; then
    shift
fi

# XXX: Edit this - hardcode for localized convenience
CONTEXT="${1:-docker-desktop}"
# if set will also set the namespace for extra convenience
NAMESPACE="${2:-}"
#NAMESPACE="jenkins"

# function so can place in topdir .envrc and have subdirs 'source_up' or simply . ../.envrc to reuse this code among many .envrc environments
kube_context(){
    local context="$1"
    local namespace="${2:-}"
    if command -v kubectl &>/dev/null; then
        local tmpdir="/tmp/.kube"

        mkdir -pv "$tmpdir"

        local default_kubeconfig="${HOME:-$(cd ~ && pwd)}/.kube/config"
        local original_kubeconfig="${KUBECONFIG:-$default_kubeconfig}"

        # reload safety - do not source from new tmpdir - not necessary for direnv but useful for local sourcing tests
        #if [[ "$original_kubeconfig" =~ $tmpdir ]]; then
        #    echo "ignoring \$KUBECONFIG=$original_kubeconfig, using default home location $default_kubeconfig"
        #    original_kubeconfig="$default_kubeconfig"
        #fi

        # isolate the kubernetes context to avoid a race condition affecting any other shells or scripts
        # epoch is added because $$ and $PPID are direnv sub-processes and may be reused later, so using epoch to add uniqueness
        local epoch
        epoch="$(date +%s)"
        export KUBECONFIG="$tmpdir/config.${EUID:-${UID:-$(id -u)}}.$$.$epoch"

        # load your real kube config to isolated staging area to source the context info
        local src_kubeconfig=""
        local kubeconfig_source_locations="
            $original_kubeconfig
            $default_kubeconfig
            $PWD/.kube/config
            /etc/rancher/k3s/k3s.yaml"
        for kubeconfig in $kubeconfig_source_locations; do
            if [ -f "$kubeconfig" ]; then
                src_kubeconfig="$kubeconfig"
                break
            fi
        done
        if [ -n "$src_kubeconfig" ]; then
            if [ "$src_kubeconfig" != "$KUBECONFIG" ]; then
                cp -f -- "$src_kubeconfig" "$KUBECONFIG"
            fi
        else
            if [[ "$PWD" =~ k8|kube ]]; then
                echo "WARNING: failed to find one of:" >&2
                echo "$kubeconfig_source_locations" | sort -u >&2
                echo >&2
            fi
        fi

        # race condition - 'kubectl config get-contexts' fails to find the context and switch in many runs without this sleep
        context_found=0
        local i
        for ((i=0; i < 5; i++)); do
            # surprisingly unreliable - if kubectl config get-contexts -o name | grep -Fxq "$context" can miss even after these succeed
            #if [ -s "$KUBECONFIG" ]; then
            #if cmp --quiet "$from_kubeconfig" "$KUBECONFIG"; then
            if kubectl config get-contexts -o name | grep -Fxq "$context"; then
                context_found=1
                break
            fi
            sleep 0.1
        done

        # this randomly misses the context, and not even 'sync; sync; sleep 1' is reliable to stop that happening in testing
        #if kubectl config get-contexts -o name 2>/dev/null | grep -Fxq "$context"; then
        if [ "$context_found" = 1 ]; then
            kubectl config use-context "$CONTEXT"
            echo

            if [ -n "${namespace:-}" ]; then
                kubectl config set-context "$context" --namespace "$namespace"
                echo
            fi
        fi
    fi
}

gke_kube_context(){
    local CONTEXT
    for _ in CLOUDSDK_CORE_PROJECT CLOUDSDK_COMPUTE_REGION CLOUDSDK_CONTAINER_CLUSTER; do
        if [ -z "${!_}" ]; then
            echo "WARNING: \$$_ is not set" >&2
        fi
    done
    # if CLOUDSDK_CONTAINER_CLUSTER and it's generated as a naming convention such as "${CLOUDSDK_CORE_PROJECT}-${CLOUDSDK_COMPUTE_REGION}"
    #export CLOUDSDK_CONTAINER_CLUSTER="${CLOUDSDK_CONTAINER_CLUSTER:-${CLOUDSDK_CORE_PROJECT}-${CLOUDSDK_COMPUTE_REGION}}"

    # the context naming convention for GKE clusters imported via:
    #
    #   gcloud container clusters get-credentials "$cluster" --zone "$zone"
    #
    # use gke_kube_creds.sh to auto-populate this for all GKE clusters in the current project
    # and gcp_foreach_project.sh to do this for all GCP projects. Both scripts are found here:
    #
    #   https://github.com/HariSekhon/DevOps-Bash-tools
    #
    # should be using a regional cluster
    CONTEXT="gke_${CLOUDSDK_CORE_PROJECT}_${CLOUDSDK_COMPUTE_REGION}_${CLOUDSDK_CONTAINER_CLUSTER}"
    # not a zonal cluster
    #CONTEXT="gke_${CLOUDSDK_CORE_PROJECT}_${CLOUDSDK_COMPUTE_ZONE}_${CLOUDSDK_CONTAINER_CLUSTER}"
    kube_context "$CONTEXT" "${NAMESPACE:-}"
}

kube_context "$CONTEXT" "$NAMESPACE"

#export ARGOCD_SERVER="argocd.mycompany.com"
#export ARGOCD_OPTS="${ARGOCD_OPTS:-} --grpc-web"
#if [ -n "${ARGOCD_AUTH_TOKEN_MYCOMPANY_OR_ENV:-}" ]; then
#    export ARGOCD_AUTH_TOKEN="$ARGOCD_AUTH_TOKEN_MYCOMPANY_OR_ENV"
#fi
#export ARGOCD_APP="myapp"