https://github.com/boxboat/config-merge

Tool for merging JSON/TOML/YAML files and performing environment variable substitution
https://github.com/boxboat/config-merge

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Tool for merging JSON/TOML/YAML files and performing environment variable substitution

• Host: GitHub
• URL: https://github.com/boxboat/config-merge
• Owner: boxboat
• License: mit
• Created: 2017-12-04T03:17:41.000Z (almost 7 years ago)
• Default Branch: master
• Last Pushed: 2024-06-25T16:05:51.000Z (5 months ago)
• Last Synced: 2024-08-17T08:06:23.055Z (3 months ago)
• Language: JavaScript
• Homepage:
• Size: 34.2 KB
• Stars: 36
• Watchers: 4
• Forks: 8
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Config Merge

![test](https://github.com/boxboat/config-merge/workflows/test/badge.svg)

Tool for merging JSON/JSON5/TOML/YAML files and performing environment variable substitution.  Runs in a Docker Container.

## Usage

`config-merge` is released on [DockerHub](https://hub.docker.com/r/boxboat/config-merge/).  Usage can be seen by running with the `-h` flag

```bash

$ docker pull boxboat/config-merge

$ docker run --rm boxboat/config-merge -h

boxboat/config-merge [flags] file1 [file2] ... [fileN]

-a, --array         merge|overwrite|concat   whether to merge, overwrite, or concatenate arrays.  defaults to merge

-f, --format        json|json5|toml|yaml   whether to output json, json5, toml, or yaml.  defaults to yaml

-h  --help          print the help message

    --no-envsubst   disable substituting env vars

    files ending in .env and .sh will be sourced and used for environment variable substitution

    files ending in .json, .js, .json5, .toml, .yaml, and .yml will be merged

    files ending in .patch.json, .patch.js, .patch.json5, .patch.toml, .patch.yaml, and .patch.yml will be applied as JSONPatch

```

The working directory of the container is `/home/node` and files/directories that get merged should be mounted into this directory.

## Example

This example considers building a Docker Compose file that can be used for production, but also tested locally.  The production compose file contains an extra network that is not available to the local developer.  We are able to use the patching feature of `config-merge` to remove the unneeded network, and use the environment variable substitution feature to add a custom network.

```bash

docker_compose_config=$(

    docker run --rm \

    -v "$(pwd)/test/docker-compose/:/home/node/" \

    boxboat/config-merge \

    local.env docker-compose.yml docker-compose-local.patch.yml docker-compose-local.yml

)

# Run with Docker Compose

docker-compose -f - -p nginx-local up < Source properties that resolve to undefined are skipped if a destination value exists. Array and plain object properties are merged recursively. Other objects and value types are overridden by assignment. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources.

Use the `-a`/`--array` argument to configure the merging behavior for arrays.

## Patching

Files ending in `.patch.json`, `.patch.js`, `.patch.json5`, `.patch.toml`, `.patch.yaml`, and `.patch.yml` are applied as [JSON Patch](http://jsonpatch.com/)

## Environment Variable Substitution

Files ending in `.env` and `.sh` are sourced into the environment.  Environment variables are substituted using [a8m/envsubst](https://github.com/a8m/envsubst), a go version of `envsubst` that supports the following default variables:

|__Expression__     | __Meaning__    |

| ----------------- | -------------- |

|`${var}`	   | Value of var (same as `$var`)

|`${var-$DEFAULT}`  | If var not set, evaluate expression as $DEFAULT

|`${var:-$DEFAULT}` | If var not set or is empty, evaluate expression as $DEFAULT

|`${var=$DEFAULT}`  | If var not set, evaluate expression as $DEFAULT

|`${var:=$DEFAULT}` | If var not set or is empty, evaluate expression as $DEFAULT

|`${var+$OTHER}`	   | If var set, evaluate expression as $OTHER, otherwise as empty string

|`${var:+$OTHER}`   | If var set, evaluate expression as $OTHER, otherwise as empty string

table taken from [here](http://www.tldp.org/LDP/abs/html/refcards.html#AEN22728)