merlimat commented on a change in pull request #342: Issue 338: add first draft Docker image including community suggestions URL: https://github.com/apache/bookkeeper/pull/342#discussion_r131270226
########## File path: docker/README.md ########## @@ -0,0 +1,174 @@ + +# What is Apache Bookkeeper? + +Apache ZooKeeper is a software project of the Apache Software Foundation, providing a replicated log service which can be used to build replicated state machines. A log contains a sequence of events which can be applied to a state machine. BookKeeper guarantees that each replica state machine will see all the same entries, in the same order. + +> [Apache Bookkeeper](http://bookkeeper.apache.org/) + + +# How to use this image + +Bookkeeper needs [Zookeeper](https://zookeeper.apache.org/) in order to preserve its state and publish its bookies (bookkepeer servers). The client only need to connect to a Zookkeeper server in the ensamble in order to obtain the list of Bookkeeper servers. + +## TL;DR + +If you just want to see things working, you can play with Makefile hosted in this project and check its targets for a fairly complex set up example: +``` +git clone https://github.com/apache/bookkeeper +cd bookkeeper/docker +make run-demo +``` +While, if you don't have access to a X environment, e.g. on default MacOS, It has to run the last command manually in 6 terminals respectively. +``` +make run-zk +make run-bk BOOKIE=1 +make run-bk BOOKIE=2 +make run-bk BOOKIE=3 +make run-dice +make run-dice +``` +This will do all the following steps and start up a working ensemble with two dice applications. + +## Step by step + +The simplest way to let Bookkeeper servers publish themselves with a name, which could be resolved consistently across container runs, is through creation of a [docker network](https://docs.docker.com/engine/reference/commandline/network_create/): +``` +docker network create "my-bookkeeper-network" +``` +Then we can start a Zookeeper (from [Zookeeper official image](https://hub.docker.com/_/zookeeper/)) server in standalone mode on that network: +``` +docker run -d \ + --network "my-bookkeeper-network" \ + --name "my-zookeeper" \ + --hostname "my-zookeeper" \ + zookeeper +``` +And initialize the metadata store that bookies will use to store information: +``` +docker run -it --rm \ + --network "my-bookkeeper-network" \ + --env ZK_URL=my-zookeeper:2181 \ + bookkeeper \ + bookkeeper shell metaformat +``` +Now we can start our Bookkeeper ensemble (e.g. with three bookies): +``` +docker run -it\ + --network "my-bookkeeper-network" \ + --env ZK_URL=my-zookeeper:2181 \ + --name "bookie1" \ + --hostname "bookie1" \ + bookkeeper +``` +And so on for "bookie2" and "bookie3". We have now our fully functional ensemble, ready to accept clients. + +In order to play with our freshly created ensemble, you can use the simple application taken from [Bookkeeper Tutorial](http://bookkeeper.apache.org/docs/master/bookkeeperTutorial.html) and packaged in a [docker image](https://github.com/caiok/bookkeeper-tutorial) for convenience. + +This application check if it can be leader, if yes start to roll a dice and book this rolls on bookkeeper, otherwise it will start to follow the leader rolls. If leader stops, follower will try to become leader and so on. + +Start a dice application (you can run it several times to view the behavior in a concurrent environment): +``` +docker run -it --rm \ + --network "my-bookkeeper-network" \ + --env ZK_URL=my-zookkeeper:2181 \ + caiok/bookkeeper-tutorial +``` + +## Configuration + +Bookkeeper configuration is located in `/opt/bookkeeper/conf` in the docker container, it is a copy of [these files](https://github.com/apache/bookkeeper/tree/master/bookkeeper-server/conf) in bookkeeper repo. + +There are 2 ways to set bookkeeper configuration: + +1, Apply setted (e.g. docker -e kk=vv) environment variables into configuration files. Environment variable names is in format "BK_originalName", in which "originalName" is the key in config files. + +2, If you are able to handle your local volumes, use `docker --volume` command to bind-mount your local configure volumes to `/opt/bookkeeper/conf`. + +Example showing how to use your own configuration files: +``` +$ docker run --name bookie1 -d \ + -v $(local_configure_dir):/opt/bookkeeper/conf/ \ < == use 2nd approach, mount dir contains config_files + -e BK_bookiePort=3181 \ < == use 1st approach, set bookiePort + -e BK_zkServers=zk-server1:2181,zk-server2:2181 \ < == use 1st approach, set zookeeper servers + -e BK_journalPreAllocSizeMB=32 \ < == use 1st approach, set journalPreAllocSizeMB in [bk_server.conf](https://github.com/apache/bookkeeper/blob/master/bookkeeper-server/conf/bk_server.conf) + bookkeeper +``` + +### Override rules for bookkeeper configuration +If you have applied several ways to set the same config target, e.g. the environment variable names contained in [these files](https://github.com/apache/bookkeeper/tree/master/bookkeeper-server/conf) and conf_file in /opt/bookkeeper/conf/. + +Then the override rules is as this: + +Environment variable names contained in [these files](https://github.com/apache/bookkeeper/tree/master/bookkeeper-server/conf), e.g. `zkServers` + + Override + +Values in /opt/bookkeeper/conf/conf_files. + +Take above example, if in docker instance you have bind-mount your config file as /opt/bookkeeper/conf/bk_server.conf, and in it contains key-value pair: `zkServers=zk-server3:2181`, then the value that take effect finally is `zkServers=zk-server1:2181,zk-server2:2181` + +Because + +`-e zkServers=zk-server1:2181,zk-server2:2181` will override key-value pair: `zkServers=zk-server3:2181`, which contained in /opt/bookkeeper/conf/bk_server.conf. + + +### Environment variable names that mostly used for your configuration. + +#### `BK_bookiePort` + +This variable allows you to specify the port on which Bookkeeper should listen for incoming connections. + +This will override `bookiePort` in [bk_server.conf](https://github.com/apache/bookkeeper/blob/master/bookkeeper-server/conf/bk_server.conf). + +Default value is "3181". + +#### `BK_zkServers` + +This variable allows you to specify a list of machines of the Zookeeper ensemble. Each entry has the form of `host:port`. Entries are separated with a comma. + +This will override `zkServers` in [bk_server.conf](https://github.com/apache/bookkeeper/blob/master/bookkeeper-server/conf/bk_server.conf). + +Default value is "127.0.0.1:2181" + +#### `BK_zkLedgersRootPath` + +This variable allows you to specify the root directory bookkeeper will use on Zookeeper to store ledgers metadata. + +This will override `zkLedgersRootPath ` in [bk_server.conf](https://github.com/apache/bookkeeper/blob/master/bookkeeper-server/conf/bk_server.conf). + +Default value is "/bookkeeper/ledgers" + +#### `BK_CLUSTER_NAME` + +This variable allows you to specify the root directory bookkeeper will use on Zookeeper. + +Default value is "/bookkeeper" Review comment: By default, bookies should be writing in `/ledgers`, right? Would that make the cluster name empty by default? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
