Add "print-config" subcommand #698

le-lenn · 2025-12-21T20:35:37Z

Addresses #628

Approach

I looked into how shouterrr pretty-prints its verify function and tried to find the best poor-mans approach to it.

I wanted to add a little bit of formatting, because without any formatting, the output is pretty hard to read. So I landed on a basic regex based formatter.
I played around with coloring the output as well, but I ended up with a lot of code for a nice-to-have, so I removed it again.

m90 · 2025-12-22T18:42:05Z

Just wanted to let you know I will need some more time in order to do a proper review here. I'm very happy the PR is here in any case.

le-lenn · 2025-12-22T18:52:22Z

No worries, frohe Weihnachten!

btw I’m not too happy with the flag parsing, I think my implementation could be improved

cmd/backup/show_config.go

cmd/backup/main.go

m90

This looks good, I left some comments inline, let me know what you think.

There's one bigger question left for me in this: should there also be an option that "resolves" configuration values as deeply as possible, i.e. reads Docker secrets, expands shell variables, and renders config options that are templates? Or should this be the default even?

cmd/backup/print_config.go

docs/how-tos/print-configuration.md

cmd/backup/main.go

cmd/backup/show_config.go

le-lenn · 2026-01-01T11:43:15Z

This looks good, I left some comments inline, let me know what you think.

There's one bigger question left for me in this: should there also be an option that "resolves" configuration values as deeply as possible, i.e. reads Docker secrets, expands shell variables, and renders config options that are templates? Or should this be the default even?

I was under the false impression that sourceConfiguration() would resolve all config values as deeply as possible already. Thanks for the hint! I think the default should be to resolve as deeply as possible, since the "resolved" values are the ones being used in the end.

I'll have a go to see if I can resolve without adding too much complexity.

m90 · 2026-01-01T15:54:42Z

I was under the false impression that sourceConfiguration() would resolve all config values as deeply as possible already.

I would think it'd be a good thing to at least evaluate how much effort modeling things like this would be.

le-lenn · 2026-01-01T16:19:11Z

I was under the false impression that sourceConfiguration() would resolve all config values as deeply as possible already.

I would think it'd be a good thing to at least evaluate how much effort modeling things like this would be.

I added some simple logic to resolve env vars when BackupFilenameExpand is set.

This is an AI analysis of what it would take to resolve all env variables:

Additional resolution happens later during runtime, not during sourcing:
- applyEnv is only called in runScript, so conf.d‑provided env vars are not present for
os.ExpandEnv in show-config (cmd/backup/run_script.go, cmd/backup/config.go).
- Backup filename template ({{ .Extension }}), optional ExpandEnv, and strftime are applied in
script.init (cmd/backup/script.go).
- EMAIL_* → derived NotificationURLs and NotificationLevel validation also happen in
script.init (cmd/backup/script.go).
- Azure endpoint templates are resolved when the Azure backend is created (internal/storage/
azure/azure.go).

Complexity to “resolve more”:
- Low/medium: extract a pure “resolve for display” helper to apply applyEnv, the backup filename
  template (extension + strftime using time.Now()), and ExpandEnv for the 3 fields. This is mostly
  moving logic out of script.init and would add some time‑dependent output.
- Medium/high: include derived NotificationURLs and NotificationLevel validation. That requires
  sharing more of script.init or duplicating logic, and deciding how to surface warnings in show-
  config.
- High: fully match runtime resolution (e.g., Azure endpoint template via backend constructors).
  That likely needs a refactor to split “config resolution” from “resource instantiation” in
  script.init to avoid side effects (sender setup, docker client, storage client creation).

m90 · 2026-01-04T07:29:12Z

cmd/backup/print_config.go

+func runPrintConfig() error {
+	configurations, err := sourceConfiguration(configStrategyConfd)
+	if err != nil {
+		fmt.Printf("error sourcing configuration: %v\n", err) // print error to stdout for debugging


I'm not sure this is needed as I would expect the returned error to be printed as well on exit? Or is that not happening and the mechanism is broken?

Also applies below.

m90 · 2026-01-04T07:32:29Z

cmd/backup/print_config.go

+)
+
+func runPrintConfig() error {
+	configurations, err := sourceConfiguration(configStrategyConfd)


What happens when no configuration directory is present and configuration is provided via env vars only? Does it fall back to env? Sorry, it's been a while since I have written this 😅

I am not sure I understand this comment. Is test/print-config/docker-compose.yml using only env variables?

It seems to fall back if no directory is mounted, so never mind. See:

docker-volume-backup/cmd/backup/config_provider.go

Lines 34 to 42 in 4531c60

case configStrategyConfd:

cs, err := loadConfigsFromEnvFiles("/etc/dockervolumebackup/conf.d")

if err != nil {

if os.IsNotExist(err) {

return sourceConfiguration(configStrategyEnv)

}

return nil, errwrap.Wrap(err, "error loading config files")

}

return cs, nil

cmd/backup/print_config.go

m90 · 2026-01-05T11:33:37Z

I had another look at the original issue: #628 which made me think we should check how the output handles trailing newlines here. Just writing this down so we don't forget.

le-lenn · 2026-01-10T22:30:29Z

I had another look at the original issue: #628 which made me think we should check how the output handles trailing newlines here. Just writing this down so we don't forget.

Do you have any ideas how to handle this?

m90 · 2026-01-11T10:51:30Z

I had another look at the original issue: #628 which made me think we should check how the output handles trailing newlines here. Just writing this down so we don't forget.

Do you have any ideas how to handle this?

How does the current mechanism display a value with a trailing new line? I don't necessarily have an opinion on how exactly this should look like, but it should be obvious that it's really the configuration that contains the newline, not the print-config output.

m90 · 2026-01-11T10:53:11Z

cmd/backup/print_config.go

+	formatter := regexp.MustCompile(`\s([A-Z])`)
+	for _, config := range configurations {
+		if err := func() error {
+			unset, warnings, err := config.resolve()


Is there any reason you don't use defer unset() here? Btw, it cannot be nil, so there's no need to check if it is.

le-lenn commented Dec 23, 2025

View reviewed changes

cmd/backup/show_config.go Outdated Show resolved Hide resolved

le-lenn commented Dec 26, 2025

View reviewed changes

cmd/backup/main.go Outdated Show resolved Hide resolved

le-lenn force-pushed the debug-subcommand branch from 18db772 to 13e54e1 Compare December 27, 2025 11:16

m90 reviewed Dec 31, 2025

View reviewed changes

cmd/backup/print_config.go Outdated Show resolved Hide resolved

docs/how-tos/print-configuration.md Show resolved Hide resolved

cmd/backup/main.go Outdated Show resolved Hide resolved

cmd/backup/show_config.go Outdated Show resolved Hide resolved

le-lenn changed the title ~~Add "show-config" subcommand~~ Add "print-config" subcommand Jan 1, 2026

m90 reviewed Jan 4, 2026

View reviewed changes

m90 mentioned this pull request Jan 4, 2026

Consolidate config value resolution at top level #705

Merged

le-lenn added 7 commits January 10, 2026 22:40

Add "show-config" subcommand

ae68a33

Add integration tests

16bca64

Handle wrong additional args

ff51740

Support "BackupFilenameExpand" option

eda807a

Rename to print-config

b46dcda

Remove config nil check as it will never be nil

766a0ce

Rework print config to work with config.resolve()

4875396

le-lenn force-pushed the debug-subcommand branch from 6b95191 to 4875396 Compare January 10, 2026 22:26

m90 reviewed Jan 11, 2026

View reviewed changes

	case configStrategyConfd:
	cs, err := loadConfigsFromEnvFiles("/etc/dockervolumebackup/conf.d")
	if err != nil {
	if os.IsNotExist(err) {
	return sourceConfiguration(configStrategyEnv)
	}
	return nil, errwrap.Wrap(err, "error loading config files")
	}
	return cs, nil

Uh oh!

Add "print-config" subcommand #698

Are you sure you want to change the base?

Add "print-config" subcommand #698

Uh oh!

Conversation

le-lenn commented Dec 21, 2025

Approach

Uh oh!

m90 commented Dec 22, 2025

Uh oh!

le-lenn commented Dec 22, 2025

Uh oh!

Uh oh!

Uh oh!

m90 left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

le-lenn commented Jan 1, 2026

Uh oh!

m90 commented Jan 1, 2026

Uh oh!

le-lenn commented Jan 1, 2026

Uh oh!

m90 Jan 4, 2026

Choose a reason for hiding this comment

Uh oh!

m90 Jan 4, 2026

Choose a reason for hiding this comment

Uh oh!

le-lenn Jan 10, 2026

Choose a reason for hiding this comment

Uh oh!

m90 Jan 11, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

m90 commented Jan 5, 2026

Uh oh!

le-lenn commented Jan 10, 2026

Uh oh!

m90 commented Jan 11, 2026

Uh oh!

m90 Jan 11, 2026

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants