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Feature-Request: Placeholder with default value #1793

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blaubaer opened this issue Jul 29, 2017 · 5 comments · May be fixed by #5275
Open

Feature-Request: Placeholder with default value #1793

blaubaer opened this issue Jul 29, 2017 · 5 comments · May be fixed by #5275
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feature ⚙️ New feature or request help wanted 🆘 Extra attention is needed
Milestone
2.x

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@blaubaer
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blaubaer commented Jul 29, 2017 •
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If there is no/empty for a placeholder use default/fallback value/placeholder.

Acceptance Test

Pattern

{foo:-{bar}}

Expectations

foo bar Result
John Mark John
John empty John
empty Mark Mark
empty empty empty

Usage example

proxy /api my-api:80 {
    transparent
    websocket
    without /api
    header_upstream X-Forwarded-Path {>X-Forwarded-Path:-{path}}
}

If this caddy is also behind a reverse proxy it also will set the header X-Forwarded-Path ... in this case use this header. If not set we expect to be not behind a reverse proxy and directly called ... in this case use path.

Other software which uses this pattern

https://logback.qos.ch/manual/configuration.html#defaultValuesForVariables
@mholt mholt added the feature ⚙️ New feature or request label Jul 29, 2017
@mholt
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mholt commented May 9, 2019

Will be mostly irrelevant in Caddy 2, which provides this capability through other means.

@mholt mholt closed this as completed May 9, 2019
@mholt mholt added this to the 2.0 milestone May 9, 2019
@mholt mholt mentioned this issue Dec 2, 2019
Closed
@mholt mholt reopened this Dec 2, 2019
@mholt mholt mentioned this issue Mar 23, 2020
Closed
@mholt mholt mentioned this issue Jan 14, 2021
Closed
@yesiyan01
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Any updates on this one?

@francislavoie
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francislavoie commented Mar 19, 2021 •
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@yesiyan01 what exactly are you looking for? Could you be more specific? What you want is probably possible another way.

@yesiyan01
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@francislavoie

I have a reverse proxy handler that overrides authorization header e.g.

handler: reverse_proxy
headers:
  request:
    set:
      Authorization:
        - '{http.oauth1}'
transport:
   protocol: http
   tls: {}
upstreams:
   - dial: 'xxx.com:443'

where 'http.oauth1' is a custom header value set from a custom module.

I'd like the ability to use 'http.oauth1' in the placeholder but fallback to a static API-KEY when http.oauth1 is not present.

@francislavoie
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francislavoie commented Mar 19, 2021 •
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Thanks for the example!

The changes would need to be made to https://github.com/caddyserver/caddy/blob/master/replacer.go, if you'd like to take a crack at it.

We recently implemented defaults for environment variables in the Caddyfile, so I think we should follow suit in this case and use the same syntax, i.e. : as the delimiter for the default value.

This change would need to be thoroughly tested (see replacer_test.go)

@mholt mholt changed the title Feature-Request: Placeholder with default handling Feature-Request: Placeholder with default value Jul 14, 2021
@mholt mholt added the help wanted 🆘 Extra attention is needed label Sep 13, 2022
JensErat added a commit to mercedes-benz/caddy that referenced this issue Dec 29, 2022
@JensErat
Support default values in placeholders
cccdd3f 
Support variable expansion also in placeholders, like in
`{unsetPlaceholder:default value}`. Implemented similarly to caddyserver#3682,
which provided defaults for environment variable expansion.

Closes caddyserver#1793.

Signed-off-by: Jens Erat <[email protected]>
@JensErat JensErat linked a pull request Dec 29, 2022 that will close this issue
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JensErat added a commit to mercedes-benz/caddy that referenced this issue Feb 7, 2023
@JensErat
Support default values in placeholders
c4b6f23 
Support variable expansion also in placeholders, like in
`{unsetPlaceholder:default value}`. Implemented similarly to caddyserver#3682,
which provided defaults for environment variable expansion.

Closes caddyserver#1793.

Signed-off-by: Jens Erat <[email protected]>
@crazygolem crazygolem mentioned this issue Apr 30, 2024
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Support default values in placeholders mercedes-benz/caddy
4 participants
@blaubaer @mholt @francislavoie @yesiyan01