deco is short for Docker Environment Control
deco has three options currently, validate, show, and run.
deco gets your app ready to run when a container
starts. For example: the filters allow you to specify
individual files to filter and key/value pairs to use when
filtering. By default, it works from the current directory and
will filter files in place.
Usage:
deco [command]
Available Commands:
encryption Manage encryption
help Help about any command
run Run executes the tasks in the given control file
show Reads and displays a control file on STDOUT
validate Validates the control file
version Displays version information
Flags:
--config string deco config file -- _not_ the control file (default is $HOME/.deco.yaml)
-d, --dir string Base directory for filtered files/templates
-h, --help help for deco
--key string 256bit encryption key
Use "deco [command] --help" for more information about a command.
deco takes a JSON file, the control file, as input and defaults to /var/run/secrets/deco.json. This allows it to work
out of the box in docker swarm with swarm secrets. The control file can be base64 encoded (standard encoding)
using the --encoded flag
The JSON control file has the format:
{
"filters": {
"path/to/file1": {
"replace": "withThis",
"doThis": "true"
},
"path/to/file2": {
"base64encodedstuff": "IMKvXF8o44OEKV8vwq8="
}
}
}It's possible it could do more than just filter in the future.
deco can currently source its JSON control file from:
/var/run/secrets/deco.json(default)- a local filesystem with an absolute or relative path
- an http(s) endpoint
- AWS SSM parameter store
deco also supports passing custom headers for doing things like basic auth to the http(s) endpoint
deco show http://127.0.0.1:8888/v1/deco.json -H 'Authorization=Basic YWRtaW46cGFzc3dvcmQ='
The deco control file has basic support value modifiers. Instead of a string value, the value can be a JSON object referencing the type of modification and the value to be modified. The type will be the same as the filters in the template described in the Templates Section. Using modifiers will modify the value before the template is processed. Using template functions will modify the values during template processing.
{
"filters": {
"path/to/file1": {
"decryptThis": {
"type": "decrypt",
"value": "wengoiwengoiwengoiwegnoewing"
},
},
"path/to/file2": {
"base64decodethis": {
"type": "b64dec",
"value": "IMKvXF8o44OEKV8vwq8="
}
}
}
}Templates are the file paths referenced as the key for the filters object in the control file. They should exist in place as templates before deco is run. They use standard Go template expansion.
Deco also supports a few custom functions in the template file:
| b64enc | base64 encode the value |
| b64dec | base64 decode the value |
| decrypt | decrypt the value |
These can be used by piping the value through the functions. ie.
{{ .foobarVariableToEncode | b64enc }}
{{ .foobarVariableToDecode | b64dec }}
{{ .foobarVariableToDecrypt | decrypt }}Values are encrypted using symmetric authenticated encryption using 256-bit AES-GCM with a random nonce. The key can be passed to deco on the command line using the --key flag or by setting the DECO_ENCRYPTION_KEY environment variable. During the validate, show and run steps, we recommend providing the key to the environment at runtime through a secrets manager.
The examples use the following key: d11bff052877151ef88e68374a509f38b91ff756d43757e5827bb30ba2b11aec.
The encryption subcommand provides management facilities to generate new encryption keys, decrypt values and encrypt values.
Manage encryption mechanisms for deco values.
Usage:
deco encryption [command]
Available Commands:
decrypt Decrypt a value
encrypt Encrypt a value
genkey Generate a new encryption key
Flags:
-h, --help help for encryption
Global Flags:
--config string deco config file -- _not_ the control file (default is $HOME/.deco.yaml)
-d, --dir string Base directory for filtered files/templates
--key string 256bit encryption key
Use "deco encryption [command] --help" for more information about a command.
Note: the examples directory has several working cases, including base64 encoding/decoding.
The most basic usage is a control file in the default location and simply running deco run.
deco run
[INFO] Using control from file /var/run/secrets/deco.json
...deco allows you to set a base directory for filtering. This directory will be prepended to the filter paths in the control file.
With the following params.json file:
{
"filters": {
"configdir/configfile.yaml": {
"bar": "bar-app",
"host01": "host01.example.org",
"path01": "/tmp"
}
}
}running
deco run params.json -d /appIf the template file /app/configdir/configfile.yaml exists, it will be written over in place, replacing {{ .bar }} with bar-app, {{ .host01 }} with host01.example.org, and {{ .path01 }} with /tmp.
if [ -n "$SSMPATH" ]; then
echo "Getting config file from SSM Parameter Store (${SSMPATH}) ..."
deco version
if [[ $? -ne 0 ]]; then
echo "ERROR: deco not found!"
exit 1
fi
deco validate -e ssm://${SSMPATH} || exit 1
deco run -e ssm://${SSMPATH}
else
echo "ERROR: SSMPATH variable not set!"
exit 1
fiE Camden Fisher camden.fisher@yale.edu Brandon Tassone brandon.tassone@yale.edu
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