git-lfs/docker

README

TL;DR version

1. Run the dockers

    ./docker/run_dockers.bsh
   

2. Enjoy all your new package files in

    ./repos/
   

Slightly longer version

1. Generate GPG keys for everything (See GPG Signing)

2. export REPO_HOSTNAME=repo.something.com

3. Generate all of the dependency RPMS

    ./docker/run_dockers.bsh ./docker/git-lfs-full-build_*.dockerfile`
   

4. Generate git-lfs/repo packages and sign all packages (including the previous dependencies)

    ./docker/run_dockers.bsh
   

5. Host the /repo on the REPO_HOSTNAME server

6. Test the repos and git-lfs in a client environment

    ./docker/test_dockers.bsh
   

##Using the Dockers##

All docker commands need to either be run as root or as a user with docker permissions. Adding your user name to the docker group (or setting up boot2docker environment) is probably the easiest.

Running Dockers

In order to run the dockers, the docker has to be built, and then run with a lot of arguments to get the mount points right, etc... A convenient script is supplied to make this all easy. Simply run

./docker/run_docker.bsh

All the git-lfs_* images are built automatically, and then run.

To only run certain docker images, supply them as arguments, e.g.

./docker/run_docker.bsh ./docker/git-lfs_debian_7.dockerfile
./docker/run_docker.bsh ./docker/git-lfs_debian_*.dockerfile
./docker/run_docker.bsh ./docker/git-lfs_*[6-8].dockerfile

And only those images will be run.

Building Dockers (Optional)

run_dockers.bsh calls build_dockers.bsh, but you can still call the script manually to get the building out of the way once while you go make a cup of tea/coffee.

In order to use the docker images, they have to be built so that they are ready to be used. For OSes like Debian, this is a fairly quick process. However CentOS takes considerably longer time, since it has to build go, ruby, or git from source, depending on the version. Fortunately, you can build the docker images JUST once, and you won't have to build it again (until the DOCKER_LFS_BUILD_VERSION changes.) The build script uses a downloaded release from github of git-lfs to bootstrap the CentOS image and build/install all the necessary software.

This means all the compiling, yum/apt-get/custom dependency compiling is done once and saved. (This is done in CentOS by using the already existing ./rpm/rpm_build.bsh script to bootstrap the image and saving the image.)

The script that takes care of ALL of these details for you is

./docker/build_dockers.bsh

###Development in Dockers###

Sometimes you don't want to just build git-lfs and destroy the container, you want to get in there, run a lot of command, debug, develop, etc... To do this, the best command to run is bash, and then you have an interactive shell to use

./docker/run_docker.bsh {image name(s)}.dockerfile -- bash

After listing the image(s) you want to run, add a double dash (--) and then any command (and arguments) you want executed in the docker. Remember, the command you are executing has to be in the docker image.

Docker images

There are currently three types of docker images:

1. Building images: git-lfs_{OS NAME}_{OS VERSION}.dockerfile - These build git-lfs and save the package/repository in the /repo direrctory. This image also signs all rpms/debs if gpg signing is setup
2. Environment building images: git-lfs-full-build_{OS_NAME}_{OS_VERSION}.dockerfile - These build or install the environment (dependencies) for building git-lfs. These are mostly important for CentOS because without these, many dependencies have to be built by a developer. These containers should create packages for these dependencies and place them in /repo
3. Testing images: git-lfs-test_{OS_NAME}_{OS_VERSION}.dockerfile - These images should install the repo and download the git-lfs packages and dependencies to test that everything is working, including the GPG signatures. Unlike the first two types, testing images are not guaranteed to work without GPG signatures. They should also run the test and integration scripts after installing git-lfs to verify everything is working in a non-developer setup. (With the exception that go is needed to build the tests...)

This default behavior for both ./docker/run_dockers.bsh and ./docker/build_dockers.bsh is to run/build all of the building images. These containers will use the currently checked-out version of git-lfs and copied it into the docker, and run git clean -xdf to remove any non-tracked files, (but non-committed changes are kept). git-lfs is built, and a packages/repo is created for each container.

These are all a developer would need to test the different OSes. And create the git-lfs rpm or deb packages in the /repo directory.

In order to distribute git-lfs and build dependencies, the dependencies that that were built for you by build_docker.bsh need to be saved too. Most of these are downloaded by yum/apt-get and do not need to be saved, but a few are not. In order to save the necessary dependencies, call ./docker/run_dockers.bsh on git-lfs-full-build_*.dockerfile before git-lfs_*.dockerfile and the rpms will be extracted from the bootstrapped images and saved in the ./repo directory. (This can be done in one command. Order matters)

./docker/run_dockers.bsh ./docker/git-lfs-full-build_*.dockerfile ./docker/git-lfs_*.dockerfile

This is most important for CentOS 6 where git 1.8.2 or newer is not available, only git 1.7.1 is available, so every user either has to build git from source, or use the rpms generated by the git-lfs-full-build_centos_6 image. Calling the environment building images only needs to be done once, they should remain in the ./repo directory afterwards.

Run Docker Environment Variables

There are a few environment variables you can set to easily adjust the behavior of the run_docker.bsh script.

export before calling run_docker.bsh

REPO_HOSTNAME - Override the hostname for all the repos generated/tested (see below)

DOCKER_AUTOBUILD - Default 1. run_docker.bsh always calls build_docker.bsh to ensure your docker image is up-to-date. Sometimes you may not want this. If set to 0, it will not build docker images before running.

AUTO_REMOVE - Default 1. Docker containers are automatically deleted on exit. If set to 0, the docker containers will not be automatically deleted upon exit. This can be useful for a post mortem analysis (using other docker commands not covered here). Just make sure you clean up the docker containers manually.

Build Docker Environment Variables

export before calling run_docker.bsh/build_docker.bsh.

DOCKER_LFS_BUILD_VERSION - The version of LFS used to bootstrap the (CentOS) environment. This does not need to be bumped every version. This can be a tag or a sha.

##Deploying/Building Repositories##

When ./docker/run_dockers.bsh is done building git-lfs and generating packages, it automatically creates a repository for distribution too. Each distro gets a repo generated in ./repos/{DISTRO_NAME}/{VERSION #}. Just drop the repo directory onto a webserver and you have a fully functioning Linux repo. (See Testing the Repositories below for more detail)

The two major packages included are: git-lfs-....* - the git-lfs package git-lfs-repo-release....* - A package to install the repo.

When building, all untracked files are removed during RPM generation (except any stray directories containing a .git folder will not be cleared. This shouldn't be the case, unless you are temporarily storing another git repo in the git repo. This is a safety mechanism in git, so just keep in mind if you are producing packages.)

Setting the website URL

The git-lfs-repo-release must contain the URL where the repo is to be hosted. The current default value is git-lfs.github.com but this can be overridden using the REPO_HOSTNAME env var, e.g.

export REPO_HOSTNAME=www.notgithub.uk.co 
./docker/run_dockers.bsh

Now all the git-lfs-repo-release....* files will point to that URL instead

Hint: REPO_HOSTNAME can also be www.notgithub.uk.co:2213/not_root_dir

Testing the Repositories

To test that all the OSes can download the packages, install, and run the tests again, run

./test_dockers.bsh

(which is basically just ./docker/run_dockers.bsh ./docker/git-lfs-test_*)

Remember to set REPO_HOSTNAME if you changed it for ./docker/build_docker.bsh This can also be used to run a local test (on localhost:{Port Number}, for example)

An easy way to test the repositories locally, is to run them on a simple webserver such as

cd ./repos
python -m SimpleHTTPServer {Port number}

or

cd ./repos
ruby -run -ehttpd . -p{Port Number}

GPG signing

For private repo testing, GPG signing can be skipped. apt-get and yum can install .deb/.rpm directly without gpg keys and everything will work (with certain flags). This section is for distribution in a repo. Most if not all this functionality is automatically disabled when there is no signing key (./docker/git-lfs_*.key).

In order to sign packages, you need to generate and place GPG keys in the right place. The general procedure for this is

gpg --gen-key

1. 4 - RSA
2. 4096 bits
3. Some length of time or 0 for infinite
4. y for yes
5. Signer name (Will become part of the key and uid)
6. Email address (Will become part of the key and uid)
7. Comment (Will become part of the key)
8. O for Okay
9. Enter a secure password, make sure you will not forget it
10. Generate Entropy!

gpg --export-secret-key '<key ID>!' >

e.g. gpg --export-secret-key '547CF247!' > ./docker/git-lfs_centos_7.key

NOTE: the ! is important in this command

Keep in mind, .key files must NEVER be accidentally committed to the repo.

What if you don't have gpg handy? Just enter one of the dockers (-- bash) and generate them in there, and save them in the /src dir to get them out of the docker.

GPG Agent

To prevent MANY passphrase entries at random times, a gpg-agent docker is used to cache your signing key. This is done automatically for you, whenever you call ./docker/run_dockers.bsh on a building image (git-lfs_*.dockerfile). It can be manually preloaded by calling ./docker/gpg-agent_preload.bsh. It will ask you for your passphrase, once for each unique key out of all the dockers. So if you use the same key for every docker, it will only prompt once. If you have 5 different keys, you'll have prompts, with only the the key ID to tell you which is which.

The gpg agent TTL is set to 1 year. If this is not acceptable for you, set the GPG_MAX_CACHE and GPG_DEFAULT_CACHE environment variables (in seconds) before starting the gpg-agent daemon.

./docker/gpg-agent_start.bsh starts the gpg-agent daemon. It is called automatically by ./docker/gpg-agent_preload.bsh

./docker/gpg-agent_stop.bsh stops the gpg-agent daemon. It is called automatically by ./docker/gpg-agent_preload.bsh

./docker/gpg-agent_preload.bsh is called automatically by ./docker/run_dockers.bsh when running any of the signing dockers.

./docker/gpg-agent_preload.bsh -r - Stops and restarts the gpg agent daemon. This is useful for reloading keys when you update them in your host.

GPG capabilities by Distro

Every distro has its own GPG signing capability. This is why every signing docker (git-lfs_*.dockerfile) can have an associated key (git-lfs_*.key)

Debian will work with 4096 bit RSA signing subkeys like [1] suggests, but will also work with 4096 bit RSA signing keys.

CentOS will not work with subkeys[3]. CentOS 6 and 7 will work with 4096 bit RSA signing keys

CentOS 5 will not work with v4 signatures. The rpms will be so unrecognizable that it can't even be installed with --nogpgcheck. It should work with RSA on v3. However, it does not. It builds v3 correctly, but for some reason the GPG check fails for RSA. CentOS 5 will not work with 2048 bit DSA keys... I suspect 2048 is too big for it to fathom. CentOS 5 will work with 1024 bit DSA keys.

You can make a 4096 RSA key for Debian and CentOS 6/7 (4 for step 1 above, and 4096 for step 2) and a 1024 DSA key for CentOS 5 (3 for step 1 above, and 1024 for step 2). And only have two keys... Or optionally a 4096 RSA subkey for Debain [1]. Or a key for each distro. Dealers choice. You should have least two since 1024 bit isn't that great and you are only using it for CentOS 5 because nothing else works.

[1] https://www.digitalocean.com/community/tutorials/how-to-use-reprepro-for-a-secure-package-repository-on-ubuntu-14-04

[2] https://iuscommunity.org/pages/CreatingAGPGKeyandSigningRPMs.html#exporting-the-public-gpg-key

[3] http://www.redhat.com/archives/rpm-list/2006-November/msg00105.html

Adding additional OSes

To add another operating system, simply follow the already existing pattern, and all the scripts will pick them up. A new dockerfile should be named to

./docker/git-lfs_{OS NAME}_{OS VERSION #}.dockerfile

where {OS NAME} and {OS VERSION #} should not contain underscores (_). Any files that needs to be added to the docker image must be in the ./docker directory. This is the docker context root that all of the dockers are built in.

The docker image should run a script that builds using the files in /src (but don't modify them...) and write its repo files to the /repo directory inside the docker container. Writing to /repo in the docker will cause the files to end up in

./repos/{OS NAME}/{OS VERSION #}/

Unlike standard Dockerfiles, these support two extra features. The first one is the command SOURCE. Similar to FROM, only instead of inheriting the image, it just includes all the commands from another Dockerfile (Minus FROM and MAINTAINER commands) instead. This is useful to make multiple images that work off of each other without having to know the container image names, and without manually making multiple Dockerfiles have the exact same commands.

The second feature is a variable substitution in the form of [{ENV_VAR_NAME}] These will be replaced with values from calling environment or blanked out if the environment variable is not defined.

Docker Cheat sheet

Install https://docs.docker.com/installation/

• list running dockers

  docker ps

• list stopped dockers too

  docker ps -a

• Remove all stopped dockers

  docker rm $(docker ps --filter=status=exited -q)

• List docker images

  docker images

• Remove unused docker images

  docker rmi $(docker images -a --filter=dangling=true -q)

• Run another command (like bash) in a running docker

  docker exec -i {docker name} {command}

• Stopping a docker (signal 15 to the main pid)

  docker stop {docker name}

• Killing a docker (signal 9 to the main pid)

  docker kill {docker name}

Troubleshooting

1. I started one of the script, and am trying to stop it with Ctrl+C. It is ignoring many Ctrl+C's

   This happens a lot when calling programs like apt-get, yum, etc... From the host, you can still use ps, pgrep, kill, pkill, etc... commands to kill the PIDs in a docker. You can also use docker ps to find the container name/id and then used docker stop (signal 15) or docker kill (signal 9) to stop the docker. You can also use 'docker exec' to start another bash or kill command inside that container

2. How do I re-enter a docker after it failed/succeeded?

   Dockers are immediately deleted upon exit. The best way to work in a docker is to run bash (See Development in Dockers). This will let you to run the main build command and then continue.

3. That answer's not good enough. How do I resume a docker?

   Well, first you have to set the environment variable AUTO_REMOVE=0 before running the image you want to resume. This will keep the docker around after stopping. (Be careful! They multiply like rabbits.) Then

    docker commit {container name/id} {new_name}
   

   Then you can docker run that new image.