Simple recipe for how to regenerate swagger based apis without overwriting implementation

SwaggerApiUpdates.sh

java -jar swagger-codegen-cli.jar generate -l python-flask -i SWAGGER-YAML-FILE -o api

git add api
git commit ...

# this is just a convienience for the first time you change your api
git tag -a initial-api-scaffold -m "Initial swagger scaffold. Base point for future api changes"

# work on implementation, then:
git add, commit

# Now you want to change the api. *First* of all, go back to the commit we tagged above and create a new branch from there:
git checkout -b api-update initial-api-scaffold

# Now change the swagger file, then:
git add, commit

# Now checkout master again and merge the changes from the branch

git checkout master
git merge api-update

# Because you based your work on a line of commits that had no implementation in it, 
# if you merge this into master which does have implementation it will usually do the 
# right thing with the default merge strategy and leave the implemention changes alone.

# Important! If you do the next api update, the point to base your work on is the commits 
# to the api-update branch *before the merge* into master. This is the line of commits that 
# contains no implementation and just the api changes. If you should base your future api 
# updates on master, it will also work but when merging back into master you have to be 
# careful not to overwrite any implemenations from earlier on master.