Support Docker env variables based configuration

[agneevX]

Traefik supports specifying configuration within the docker-compose file.

pilot:
  token: test

# compose.yml
traefik:
  image: traefik
  labels:
    traefik.pilot.token: test

This would be great for blocky and would eliminate the need for maintaining a separate config file.

EDIT: Setting configuration via environment variables is a better fit rather than Docker labels.

[0xERR0R]

AFAIK it works only if traefik has access to docker daemon (and this is always a security risk). If not, there is no possibility to read labels inside the container. We can introduce environment variables for configuration, but it looks ugly for lists (e.g. for blocking list urls or custom blocking lists)

[kwitsch]

Agreed that the label based solution might be overkill for blocky.

But I would love an environment based configuration.
The blocky config is currently the only config file in my DNS stack. Everything else is configured though environment.

For other projects I use koanf to achieve this. There is an option to define conversion functions. With that it might be possible to convert map[int]string to []string. This would enable environment variables like BLOCKY_BLACKLISTS_ADS_1 for example.

[0xERR0R]

koanf looks nice, I'll take a look on it. We need something, which can read yaml and env (env should has precedence over yaml) with custom parsing functionality. Really cool would be a lib which can also set default values with tags and generate documentation.

[kwitsch]

Koanf can read yaml & env(and some more).
I personally often use a combination of defaults & koanf.helper lib
Haven't seen something for documentation jet.

[agneevX]

AFAIK it works only if traefik has access to docker daemon

Sorry, I had absolutely no idea.

This would enable environment variables like BLOCKY_BLACKLISTS_ADS_1 for example.

This is a good alternative.

[0xERR0R]

@kwitsch I tried koanf and it works well. As far I understand, uses koanf internally a map with string -> string if you parse env variables. There is no support to parse env variables to slices etc. Do you have experience with env variables and complex structures (map for example):

upstream:
  default:
    - 5.9.164.112
    - 1.1.1.1
  laptop*:
    - 123.123.123.123

This could be defines as

• "BLOCKY_UPSTREAM_DEFAULT=5.9.164.112;1.1.1.1" -> in this case a custom parse logic must be implemented to use ";" as delimiter in slices
• "BLOCKY_UPSTREAM_DEFAULT[0]=5.9.164.112" and "BLOCKY_UPSTREAM_DEFAULT[1]=1.1.1.1" -> custom logic needed to parse "[index]²
• "BLOCKY_UPSTREAM_DEFAULT=["5.9.164.112", "1.1.1.1"]" -> using JSON as value, custom logic to parse JSON needed

Parameter "laptop*" can't be used as variable name (reserved char afaik).

Of course, we can define JSON value for the whole map: "BLOCKY_UPSTREAM={"default": ...}" but this is not really handy.

Any though?

[kwitsch]

Slices in the same variable in a CSV notation should work out of the box.
Further are maps supported.
I try to prevent using variables with multiple values(slices) by using maps and convert them later. There is probably a better option, didn't investigate much as my focus was on other things.
Example usage with maps: TinyMacDns config

[kwitsch]

Using a map[int]string the env config would look like:

• BLOCKY_UPSTREAM_DEFAULT_0=5.9.164.112
• BLOCKY_UPSTREAM_DEFAULT_1=1.1.1.1

[agneevX]

What if this was specified in command?

logLevel: error

upstream:
  default:
    - https://8.8.8.8/dns-query
    - https://8.8.4.4/dns-query

services:
  blocky:
    image: spx01/blocky
    container_name: blocky
    restart: unless-stopped
    command:
      - --loglevel=error
      - --upstream.default=https://8.8.8.8/dns-query
      - --upstream.default=https://8.8.4.4/dns-query