DKDTPL

• Simplify the config and secret rotation in docker SwarmMode
• fill default values for volumes driver and options

BTW: This is not perfect ... like me ... but it works !

Time line

20260119

• public repo
• extend documentation

20250116

• initial commit

Secret/config rotation

If you are using docker swarm, you know that secret and config rotation is a s...t. You need to give a new name to the config and change it in the stack file .

But there is a trick !!

Config ans secret can have a name !!

configs:
    bookmarks.yaml:
        file: ./config/bookmarks.yaml
        name: bookmarks.yaml.5b8497360c6aa8ae96e30b4a63257a51

• And this name is used in the effective docker configuration
• And a name can be modified with a md5 (or any) tail.

So if , before the load of the stack, you can evaluate the md5 of the config and add the correct name in a temporary file, you do not need to modify the stack at each load.

That's the first purpose of dkdtpl

dkdtpl stack.yml tmpstack.yml  

Give you something like the example above for each config or secrets

Now,

docker stack deploy -c tmpstack.yml mystackname

will (re)load the ad-hoc config like a breeze !

Volume driver

If, like me , you are using multiple docker swarm with multiple storages configuration. But don't like to change or multiply stack file on purpose. You need a solution to inject driver and options on purpose

That's the other purpose of DKDTPL

dkdtpl: with <3 by UnclePhil - 1.0.0
    Usage: dkdtpl <INfilename> <OUTfilename> [voldriver  [voldriveropts]]

Set some variables for the specific cluster

VOLDRIVER=rclone 
VOLDRIVEROPTS=remote=s3fs:dcltst01/$STNAME/$VOLNAME,allow_other=true,vfs_cache_mode=full,poll_interval=0

Then run

DKDTPL stack.yml tmpstack.yml $VOLDRIVER $VOLDRIVEROPTS

Any volume definition in stack.yml without driver definition , will be filled with the ad-hoc VOLDRIVER and VOLOPTIONS