render
Universal data-driven templates for generating textual output. Can be used as a single static binary (no dependencies)
or as a golang library.
Just some of the things to render
:
- configuration files
- Infrastructure as Code files (e.g. CloudFormation templates)
- Kubernetes manifests
The renderer extends
go-template and Sprig functions.
If you are interested in one of the use cases, take a look at this blog post
about Kubernetes resources rendering. Also see Helm compatibility.
Installation
Official binary releases
For binaries please visit the Releases Page.
The binaries are statically compiled and does not require any dependencies.
Usage
$ render --help
NAME:
render - Universal file renderer
USAGE:
render [global options] command [command options] [arguments...]
VERSION:
v0.3.0
AUTHOR:
VirtusLab
COMMANDS:
help, h Shows a list of commands or help for one command
GLOBAL OPTIONS:
--debug, -d run in debug mode
--indir value the input directory, can't be used with --out
--outdir value the output directory, the same as --outdir if empty, can't be used with --in
--in value the input template file, stdin if empty, can't be used with --outdir
--out value the output file, stdout if empty, can't be used with --indir
--config value optional configuration YAML file, can be used multiple times
--set value, --var value additional parameters in key=value format, can be used multiple times
--unsafe-ignore-missing-keys do not fail on missing map key and print '<no value>' ('missingkey=invalid')
--help, -h show help
--version, -v print the version
Notes:
--in
, --out
take only files (not directories), --in
will consume any file as long as it can be parsed
stdin
and stdout
can be used instead of --in
and --out
--config
accepts any YAML file, can be used multiple times, the values of the configs will be merged
--set
, --var
are the same (one is used in Helm, the other in Terraform), we provide both for convenience, any values set here will override values form configuration files
Command line
Example usage of render
with stdin
, stdout
and --var
:
$ echo "something {{ .value }}" | render --var "value=new"
something new
Example usage of render
with --in
, --out
and --config
:
$ echo "something {{ .value }}" > test.txt.tmpl
$ echo "value: new" > test.config.yaml
$ ./render --in test.txt.tmpl --out test.txt --config test.config.yaml
$ cat test.txt
something new
Also see a more advanced template example.
As a library
package example
import (
"github.com/VirtusLab/render/renderer"
"github.com/VirtusLab/render/renderer/parameters"
)
func CustomRender(template string, opts []string, params parameters.Parameters) (string, error) {
return renderer.New(
renderer.WithOptions(opts...),
renderer.WithParameters(params),
renderer.WithSprigFunctions(),
renderer.WithExtraFunctions(),
renderer.WithCryptFunctions(),
).Render(template)
}
See also other functions
.
Also see tests for more usage examples.
Notable standard and sprig functions
All syntax and functions:
Custom functions
render
- calls the render
from inside of the template, making the renderer recursive (also accepts an optional template parameters override)
toYaml
- provides a configuration data structure fragment as a YAML format
fromYaml
- marshalls YAML data to a data structure (supports multi-documents)
fromJson
- marshalls JSON data to a data structure
jsonPath
- provides data structure manipulation with JSONPath (kubectl
dialect)
n
- used with range
to allow easy iteration over integers form the given start to end (inclusive)
gzip
, ungzip
- use gzip
compression and extraction inside the templates, for best results use with b64enc
and b64dec
readFile
- reads a file from a path, relative paths are translated to absolute paths, based on root
function or property
writeFile
- writes a file to a path, relative paths are translated to absolute paths, based on root
function or property
root
- the root path, used for relative to absolute path translation in any file based operations; by default PWD
is used
cidrHost
- calculates a full host IP address for a given host number within a given IP network address prefix
cidrNetmask
- converts an IPv4 address prefix given in CIDR notation into a subnet mask address
cidrSubnets
- calculates a subnet address within given IP network address prefix
cidrSubnetSizes
- calculates a sequence of consecutive IP address ranges within a particular CIDR prefix
See also examples and a more
detailed documentation.
Cloud KMS (AWS, Amazon, Google) based cryptography functions form crypt
:
encryptAWS
- encrypts data using AWS KMS, for best results use with gzip
and b64enc
decryptAWS
- decrypts data using AWS KMS, for best results use with ungzip
and b64dec
encryptGCP
- encrypts data using GCP KMS, for best results use with gzip
and b64enc
decryptGCP
- decrypts data using GCP KMS, for best results use with ungzip
and b64dec
encryptAzure
- encrypts data using Azure Key Vault, for best results use with gzip
and b64enc
decryptAzure
- decrypts data using Azure Key Vault, for best results use with ungzip
and b64dec
Helm compatibility
As of now, there is a limited Helm 2 Chart compatibility, simple Charts will render just fine.
To mimic Helm behaviour regarding to missing keys use --unsafe-ignore-missing-keys
option.
There is no plan to implement full compatibility with Helm, because of unnecessary complexity that would bring.
If you need full Helm compatilble rendering see: helm-nomagic
.
Limitations and future work
Planned new features
Operating system support
We provide cross-compiled binaries for most platforms, but is currently used mainly with linux/amd64
.
There is a dedicated channel #render
on virtuslab-oss.slack.com (Invite form)
Feel free to file issues
or pull requests.
Before any big pull request please consult the maintainers to ensure a common direction.
Development
git clone git@github.com:VirtusLab/render.git
cd render
make init
make all
The name
We believe in obvious names. It renders. It's a verb. It's render
.