[GitHub] [couchdb] willholley opened a new issue #2265: Dreyfus is not detected in rebar scripts

[GitBox <gi...@apache.org>]

willholley opened a new issue #2265: Dreyfus is not detected in rebar scripts
URL: https://github.com/apache/couchdb/issues/2265
 
 
   [NOTE]: # ( ^^ Provide a general summary of the issue in the title above. ^^ )
   
   ## Description
   
   When building CouchDB master I noticed that `ken` was not updating search indexes. Upon further investigation, it transpired that the conditional compilation flag `HAVE_DREYFUS` (see [here](https://github.com/apache/couchdb-ken/blob/tmp/rebar.config.script#L13)) is not set when the build is run in a clean environment. The impact of this is that background indexing for search indexes is disabled, though every other piece of search functionality seems to work fine.
    
   I find that if I force `ken` to rebuild (e.g. delete the `ebin` directory from `src/ken` and run `make release`), the feature detection works!
   
   ## Steps to Reproduce
   
   In a local CouchDB git repository, add debug output to rebar by adding `-vvv` to the `couch` target in the `Makefile`:
   
   ```
   couch: config.erl
   	@COUCHDB_VERSION=$(COUCHDB_VERSION) COUCHDB_GIT_SHA=$(COUCHDB_GIT_SHA) $(REBAR) -vvv compile $(COMPILE_OPTS)
   	@cp src/couch/priv/couchjs bin/
   ```
   
   Then run a clean build:
   
   ```
   $ make clean
   $ ./configure -c
   $ make dist
   ```
   
   Observe the debug output when compiling `ken`. `erl_opts` is what we're interested in:
   
   ```
   ...
   ==> ken (compile)
   DEBUG: Matched required ERTS version: 8.3.5.6 -> .*
   DEBUG: Matched required OTP release: 19 -> 19|20|21|22
   DEBUG: Min OTP version unconfigured
   DEBUG: erl_opts [debug_info,{i,"../"}]
   ...
   ```
   
   If you then force `ken` to rebuild, you'll get the expected output:
   
   ```
   $ rm -rf src/ken/ebin`
   $ make dist
   
   ...
   ==> ken (compile)
   DEBUG: Matched required ERTS version: 8.3.5 -> .*
   DEBUG: Matched required OTP release: 19 -> 19|20|21|22
   DEBUG: Min OTP version unconfigured
   DEBUG: erl_opts [debug_info,{d,'HAVE_DREYFUS'},{i,"../"}]
   ...
   ```
   
   I first detected this when building packages using the couchdb-ci Dockerfiles but can reproduce it locally using the above steps.
   
   ## Expected Behaviour
   
   For CouchDB master, `HAVE_DREYFUS` should be set when `dreyfus` is present (which is now always?).
   
   ## Additional Context
   
   `ken` isn't the only module to use the `HAVE_DREYFUS` compilation flag - Mango also uses it [here](https://github.com/apache/couchdb/blob/master/src/mango/rebar.config.script#L14). Knowing very little about rebar, my guess is that it's significant that `mango` is "part" of the CouchDB application whereas `ken` is an external dependency. At least, they are specified differently in the [rebar.config](https://github.com/apache/couchdb/blob/master/rebar.config.script#L91) that perhaps impacts compilation order / dependency resolution.

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