frep
Generate file using template from environment, arguments, json/yaml/toml config files.
NAME:
frep - Generate file using template
USAGE:
frep [options] input-file[:output-file] ...
VERSION:
1.3.x
AUTHORS:
Guoqiang Chen <[email protected]>
OPTIONS:
-e, --env name=value set variable name=value, can be passed multiple times
--json jsonstring load variables from json object string
--load file load variables from json/yaml/toml file
--no-sys-env exclude system environments, default false
--overwrite overwrite if destination file exists
--dryrun just output result to console instead of file
--strict exit on any error during template processing
--delims value template tag delimiters (default: {{:}})
--missing handling of missing vars, one of: default/invalid, zero, error (default: default)
--help print this usage
--version print version information
EXAMPLES:
frep nginx.conf.in -e webroot=/usr/share/nginx/html -e port=8080
frep nginx.conf.in:/etc/nginx.conf -e webroot=/usr/share/nginx/html -e port=8080
frep nginx.conf.in --json '{"webroot": "/usr/share/nginx/html", "port": 8080}'
frep nginx.conf.in --load config.json --overwrite
echo "{{ .Env.PATH }}" | frep -
Downloads
v1.3.12 Release: https://github.com/subchen/frep/releases/tag/v1.3.12
-
Linux
curl -fSL https://github.com/subchen/frep/releases/download/v1.3.12/frep-1.3.12-linux-amd64 -o /usr/local/bin/frep chmod +x /usr/local/bin/frep # centos / redhat yum install https://github.com/subchen/frep/releases/download/v1.3.12/frep-1.3.12-74.x86_64.rpm # ubuntu curl -fSL https://github.com/subchen/frep/releases/download/v1.3.12/frep_1.3.12-74_amd64.deb -o frep_1.3.12-74_amd64.deb dpkg -i frep_1.3.12-74_amd64.deb -
macOS
brew install subchen/tap/frep -
Windows
wget https://github.com/subchen/frep/releases/download/v1.3.12/frep-1.3.12-windows-amd64.exe
Docker
You can run frep using docker container
docker run -it --rm subchen/frep --help
Examples
Load template variables
-
Load from environment
export webroot=/usr/share/nginx/html export port=8080 frep nginx.conf.in -
Load from arguments
frep nginx.conf.in -e webroot=/usr/share/nginx/html -e port=8080 -
Load from JSON String
frep nginx.conf.in --json '{"webroot": "/usr/share/nginx/html", "port": 8080}' -
Load from JSON file
cat > config.json << EOF { "webroot": "/usr/share/nginx/html", "port": 8080, "servers": [ "127.0.0.1:8081", "127.0.0.1:8082" ] } EOF frep nginx.conf.in --load config.json -
Load from YAML file
cat > config.yaml << EOF webroot: /usr/share/nginx/html port: 8080 servers: - 127.0.0.1:8081 - 127.0.0.1:8082 EOF frep nginx.conf.in --load config.yaml -
Load from TOML file
cat > config.toml << EOF webroot = /usr/share/nginx/html port = 8080 servers = [ "127.0.0.1:8081", "127.0.0.1:8082" ] EOF frep nginx.conf.in --load config.toml
Input/Output
-
Input from file
// input file: nginx.conf frep nginx.conf.in -
Input from console(stdin)
// input from stdin pipe echo "{{ .Env.PATH }}" | frep - -
Output to default file (Removed last file ext)
// output file: nginx.conf frep nginx.conf.in --overwrite -
Output to the specified file
// output file: /etc/nginx.conf frep nginx.conf.in:/etc/nginx.conf --overwrite -e port=8080 -
Output to console(stdout)
frep nginx.conf.in --dryrun frep nginx.conf.in:- -
Output multiple files
frep nginx.conf.in redis.conf.in ...
Template
Templates use Golang text/template.
You can access environment variables within a template
Env.PATH = {{ .Env.PATH }}
If your template file uses {{ and }} as part of it's syntax, you can change the template escape characters using the --delims.
frep --delims "<%:%>" ...
There are some built-in functions as well: Masterminds/sprig v2.22.0
More funcs added:
- toJson
- toYaml
- toToml
- toBool
- fileSize
- fileLastModified
- fileGetBytes
- fileGetString
- fileExists
- include
- countRune
- pipeline compatible regex functions from sprig
- reReplaceAll
- reReplaceAllLiteral
- reSplit
- awsSecret
- awsParameterStore
Sample of nginx.conf.in
server {
listen {{ .port }} default_server;
root {{ .webroot | default "/usr/share/nginx/html" }};
index index.html index.htm;
location /api {
{{ include "shared/log.nginx" | indent 8 | trim }}
proxy_pass http://backend;
}
}
upstream backend {
ip_hash;
{{- range .servers }}
server {{.}};
{{- end }}
}
Sample using secrets, first of all take into account that in order to use the secret functionality you need to have a proper AWS configuration in place and permissions enough to read secrets from AWS Secrets Manager. More details of how to configure AWSCLI can be found at https://docs.aws.amazon.com/cli/latest/userguide/cli-chap-configure.html
Once you have all the requirements just create a template like this one:
# application.conf
mysql_host: {{ .mysql_host }}
mysql_user: {{ .mysql_user }}
mysql_pass: {{ awsSecret "application/mysql/password" }}
In above example mysql_host and mysql_user will be filled as usual by using frep config file or environment variables but mysql_pass will be fetch straight from AWS Secrets Manager by looking at secret name application/mysql/password
If you have multiple items in a single secret you can retrieve an specific key by specifying the key you want in template, for example:
# application.conf
mysql_host: {{ .mysql_host }}
mysql_user: {{ .mysql_user }}
mysql_pass: {{ awsSecret "application/mysql/password" }}
external_api_client: {{ awsSecret "application/external_api" "client_id" }}
external_api_secret: {{ awsSecret "application/external_api" "secret_key" }}
Sample using AWS Parameter Store, first of all take into account that in order to use the ssm functionality you need to have a proper AWS configuration in place and permissions enough to read parameters from AWS Parameter Store. More details of how to configure AWSCLI can be found at https://docs.aws.amazon.com/cli/latest/userguide/cli-chap-configure.html
Once you have all the requirements just create a template like this one:
# application.conf
mysql_host: {{ .mysql_host }}
mysql_user: {{ .mysql_user }}
mysql_pass: {{ awsSecret "application/mysql/password" }}
mysql_dns: {{ awsParameterStore "application/mysql/dns" }}
In above example mysql_dns will be filled as usual by using frep config file or environment variables but mysql_pass will be fetch straight from AWS Parameter Store by looking at application/mysql/dns
SSM Limitation: You can get parameter from ParameterStore just in textplain.
