What is this?

It is Apache2 with Subversion's MOD_DAV_SVN Apache module and a Java process adding a merkle tree all in one Docker image (*). The key piece is that Java process that overlays the Subversion directories with extra meta-information resources giving Subversion a full merkle tree capability. That's SvnMerkleizer, and it obeys Subversion's user/group permissions, so the Merkle tree could differ per user, as you would want.

• two docker images would be more normal for this, as this is more than one dissimilar process. This single Docker container design is to reduce I/O distance between the pieces as the whole thing is very chatty, and latency can be high at times.

Building it and running (no version on Dockerhub yet)

1. Clone this repo

$ git clone git@github.com:paul-hammant/SvnMerkleizer-all-in-one.git
$ cd SvnMerkleizer-all-in-one

2. Getting the SvnMerkleizer fat jar dependency

Next you need the SvnMerkleizer fat jar

# In a new terminal window .....
$ git clone git@github.com:paul-hammant/SvnMerkleizer.git
$ cd SvnMerkleizer
$ mvn clean install -DskipTests  

Then copy that into the checkout from #1

cp ~/.m2/repository/com/paulhammant/svnmerkleizer/svnmerkleizer-service/1.0-SNAPSHOT/svnmerkleizer-service-1.0-SNAPSHOT.jar .

3. Building the Docker image

$ docker build -t paulhammant/svnmerkleizer-all-in-one .

4. Running it (no version on Dockerhub yet)

$ docker run -d -p 8098:80 -P paulhammant/svnmerkleizer-all-in-one

^ The container starts with a default superuser account: admin (password: adminpw) and a repository at http://localhost:8098/svn/root/

Simple using of it

Navigate to http://localhost:8098/svn/root/.merkle.txt using your browser to see the root of the Merkle tree. You'll have to authenticate: the user is admin and password is adminpw.

From the command line, using curl, to see the same thing:

curl -u admin:adminpw http://localhost:8098/svn/root/.merkle.txt

Lastly, you can do a regular Subversion checkout svn co --username admin http://localhost:8098/svn/root/, but with that the .merkle.* resources are not in the local checkout. That is because the Subversion client does not know about the those resources.

Testing it

Using Subversion, make some changes/additions (directories and files) and commit them back to the repo. Using the curl command above, look at the changing .merkle.txt files after you've done each commit.

Be aware that you also have .merkle.csv, .merkle.json, .merkle.xml and .merkle.html too.

TODO

1. Allow a parameterized admin password in the docker image
2. Allow a parameterized volume for the Subversion file system storage.
3. Upgrade past Alpine 3.7.1 & Java 8.

Credits

Thanks to 'Pika Do' for pikado/alpine-svn for getting me started with Subversion via WebDAV inside a Docker image.