helm-template.sh

#!/bin/bash
set -e

DIR="$( cd "$(dirname "$0")" ; pwd -P )"

HELM_BIN=${HELM_BIN:-"helm"}
FAQ_BIN=${FAQ_BIN:-"faq"}

FETCH_GIT_REPO="${FETCH_GIT_REPO:-false}"

if ! [ -x "$(command -v "$HELM_BIN")" ]; then
    echo "Error $HELM_BIN is not installed"
    exit 1
fi
if ! [ -x "$(command -v "$FAQ_BIN")" ]; then
    echo "Error $FAQ_BIN is not installed"
    exit 1
fi

if [ $# -ne 7 ]; then
    echo "Usage: $0 REPO_URL CHART_NAME CHART_VERSION NAMESPACE RELEASE_NAME VALUES_FILE OUTPUT_DIR"
    exit 1
fi

REPO_URL=$1
CHART_NAME=$2
CHART_VERSION=$3
NAMESPACE=$4
RELEASE_NAME=$5
VALUES_FILE=$6
OUTPUT_DIR=$7

if [ -e "$OUTPUT_DIR" ]; then
    echo "OUTPUT_DIR $OUTPUT_DIR already exists, must be a path that does not yet exist."
    exit 1
fi

TMP_DIR="$(mktemp -d)"
trap 'rm -rf $TMP_DIR' EXIT

echo Fetching Chart
if [ "$FETCH_GIT_REPO" == "true" ]; then
    git clone --branch "$CHART_VERSION" "$REPO_URL" "$TMP_DIR/$CHART_NAME"
else
    "$HELM_BIN" fetch "$CHART_NAME" \
        --repo "$REPO_URL" \
        --version "$CHART_VERSION" \
        --destination "$TMP_DIR" \
        --untar
fi

RESOURCE_FILES_DIR="$TMP_DIR/resource_manifests"
mkdir "$RESOURCE_FILES_DIR"

CHART_DIR="$TMP_DIR/$CHART_NAME"
TEMPLATE_FILES="$(find "$CHART_DIR" -path '*templates/*.yaml' -type f)"

echo Rendering Chart templates

HELM_TEMPLATE_ARGS=(\
    --namespace "$NAMESPACE" \
    --name "$RELEASE_NAME" \
    "$CHART_DIR" \
)

if [ "$VALUES_FILE" != "-" ]; then
    HELM_TEMPLATE_ARGS+=(-f "$VALUES_FILE")
fi

while read -r template_file_path; do
    template=${template_file_path#"$CHART_DIR/"}
    OUTPUT_FILE="$RESOURCE_FILES_DIR/$template"
    echo "Templating $template"
    mkdir -p "$(dirname "$OUTPUT_FILE")"
    export NAMESPACE
    "$HELM_BIN" template "${HELM_TEMPLATE_ARGS[@]}" -x "$template_file_path" \
        | faq -f yaml -o yaml -M -s '.[] | select(. != null) | . * (if .kind != "Namespace" and .metadata.namespace == null then {"metadata": {"namespace": $ENV.NAMESPACE}} else {} end)' \
        > "$OUTPUT_FILE"
    if [[ ! $(sed -f "$DIR/remove-helm-template-header.sed" "$OUTPUT_FILE" | grep -v '^#' | tr -d '[:space:]') ]]; then
        echo "Templating $template resulted in an empty file, not storing."
        rm "$OUTPUT_FILE"
    fi
done <<< "$TEMPLATE_FILES"

mkdir -p "$(dirname "$OUTPUT_DIR")"
mv "$RESOURCE_FILES_DIR" "$OUTPUT_DIR"

remove-helm-template-header.sed

# This script post-processes helm template output

# Removes headers of the following form
# Example helm template header:
# ---
# # Source: foo-chart/templates/deployment.yaml
s/^---$//g
s/# Source.*$//g
# Delete trailing whitespace (spaces, tabs) from end of each line
s/[ 	]*$//
# Deletes all blank lines from top and end of file
/./,/^$/!d