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Migrating from mod_dims

Migrating from mod-dims to go-dims is straightforward. Most settings have either been renamed for clarity or removed if no longer necessary. This guide outlines the key differences and how to map your existing dims.conf settings to environment variables used by go-dims.

DimsClient​

The DimsClient directive has been removed. Each of its options is now configured globally via environment variables.

Original DimsClient format:

<appId> <noImageUrl> <cache control max-age> <edge control downstream-ttl> <trustSource?> <minSourceCache> <maxSourceCache> <password>

Mapping to go-dims:

mod-dims Fieldgo-dims Equivalent
<appId>No longer used
<noImageUrl>DIMS_ERROR_BACKGROUND
<cache control max-age>DIMS_CACHE_CONTROL_DEFAULT
<edge control downstream>DIMS_EDGE_CONTROL_DOWNSTREAM_TTL
<trustSource?>DIMS_CACHE_CONTROL_USE_ORIGIN
<minSourceCache>DIMS_CACHE_CONTROL_MIN
<maxSourceCache>DIMS_CACHE_CONTROL_MAX
<password>DIMS_SIGNING_KEY

✏️ Renamed​

mod-dimsgo-dims
DimsCacheExpireDIMS_CACHE_CONTROL_DEFAULT
DimsNoImageCacheExpireDIMS_CACHE_CONTROL_ERROR

📦 Moved​

All DimsImagemagick* settings have been removed. go-dims does not use Imagemagick.

Removed settings:

  • DimsImagemagickTimeout
  • DimsImagemagickMemorySize
  • DimsImagemagickAreaSize
  • DimsImagemagickMapSize
  • DimsImagemagickDiskSize

❌ Removed​

These options are no longer supported in go-dims:

  • DimsClient
  • DimsDefaultImageURL - Replaced by DIMS_ERROR_BACKGROUND
  • DimsAddWhitelist - This was only used /dims3/ endpoint in mod_dims.
  • DimsDisableEncodedFetch
  • DimsUserAgentEnabled - This is now automatic.
  • DimsUserAgentOverride
  • DimsOptimizeResize - This is the default behavior in go-dims.

🧪 Example: dims.conf to go-dims​

Original:

DimsDownloadTimeout 60000
DimsImagemagickTimeout 20000

# DimsClient <appId> <noImageUrl> <cache control max-age> <edge control downstream-ttl> <trustSource?> <minSourceCache> <maxSourceCache> <password>
DimsAddClient TEST http://placehold.it/350x150 604800 604800 trust 604800 604800 t3st

DimsDefaultImageURL http://placehold.it/350x150
DimsCacheExpire 604800
DimsNoImageCacheExpire 60
DimsDefaultImagePrefix

DimsAddWhitelist www.google.com

Migration:

DIMS_SIGNING_KEY=t3st
DIMS_ERROR_BACKGROUND="#cccccc"
DIMS_CACHE_CONTROL_DEFAULT=604800
DIMS_CACHE_CONTROL_ERROR=60
DIMS_EDGE_CONTROL_DOWNSTREAM_TTL=604800
DIMS_CACHE_CONTROL_USE_ORIGIN=true
DIMS_CACHE_CONTROL_MIN=604800
DIMS_CACHE_CONTROL_MAX=604800
DIMS_DOWNLOAD_TIMEOUT=60000

You can skip any removed or deprecated options. Most behaviors are now automatic or unnecessary in go-dims.