tmpl
Command tmpl renders a template with the current env vars as input.
tmpl packs a punch in under 200 lines of code: a single static binary supplies the capabilities of many more complicated templating engines.
It's especially helpful as an early entrypoint into containers to prepare configuration files.
$ tmpl -h
Usage of tmpl:
-f string
Input source (default "-")
-html
If true, use html/template instead of text/template
-r string
If provided, traverse the argument as a directory
-stripn int
If provided, strips this many directories from the output (only valid if -r and -w are provided)
-w string
Output destination (default "-")It effectively exposes Go's text/template for use in shells.
Reference text/template documentation for template language specification.
It includes all of the template helpers from sprig.
Safe Dockerfile Inclusion
To safely include in your build pipelines:
FROM ubuntu:bionic
RUN apt-get update
RUN apt-get install -y curl
ARG TMPL_URL=https://github.com/tmc/tmpl/releases/download/v1.9/tmpl_linux_amd64
ARG TMPL_SHA256SUM=6064853353391b947ccdbf5584dcfdf5d0ab448ef9631dc48e296a53095b32f9
RUN curl -fsSLo tmpl ${TMPL_URL} \
&& echo "${TMPL_SHA256SUM} tmpl" | sha256sum -c - \
&& chmod +x tmpl && mv tmpl /usr/local/bin/tmplSafe Shell Scripting Inclusion
To safely include in your shell scripts:
#!/bin/bash
set -euo pipefail
# Helper Functions
case "${OSTYPE}" in
linux*) platform=linux
;;
darwin*)
platform=darwin
;;
*) platform=unknown ;;
esac
function install_tmpl() {
if [[ "${platform}" == "darwin" ]]; then
TMPL_SHA256SUM=1e4cae660f2a28d66187df9a1549cd71e1e19397a92edd6cef946d62102b2794
else
TMPL_SHA256SUM=6064853353391b947ccdbf5584dcfdf5d0ab448ef9631dc48e296a53095b32f9
fi
TMPL_URL=https://github.com/tmc/tmpl/releases/download/v1.9/tmpl_${platform}_amd64
curl -fsSLo tmpl ${TMPL_URL} \
&& echo "${TMPL_SHA256SUM} tmpl" | sha256sum -c - \
&& chmod +x tmpl
mv tmpl /usr/local/bin/tmpl || echo "could not move tmpl into place"
}
command -v tmpl > /dev/null || install_tmplExample 1
Given a file 'a' with contents:
{{ range $key, $value := . }}
KEY:{{ $key }} VALUE:{{ $value }}
{{ end }}
Invoking
$ cat a | env -i ANSWER=42 ITEM=Towel `which tmpl`
Produces
KEY:ANSWER VALUE:42
KEY:ITEM VALUE:Towel
Example 2
Given a file 'b' with contents:
VERSION={{.HEAD}}
Invoking
$ cat b | HEAD="$(git rev-parse HEAD)" tmpl
Produces
VERSION=4dce1b0a03b59b5d63c876143e9a9a0605855748
Example 3
Given a directory via the -r flag, tmpl recurses, expanding each path and file and produces a tarball to the output destination.
Invoking
$ mkdir testdata/recursive-out
$ tmpl -r testdata/recursive-example | tar -C testdata/recursive-out --strip-components=2 -xvf -
$ cat testdata/recursive-out/user-tmc
Produces (for me, at time of writing)
For the current user tmc:
Shell: /bin/bash
EDITOR: vim
😎