The newest versions of docker-compose want to have some values double-quoted in the env file while old versions failing to process such files.
The solution is simple, move some of the parameters to the `docker-compose.yml` and rely on anchors for inheritance.
Since the main idea behind env files was to keep "secret" information off the main YAML we also get rid of any non-secret stuff, mainly located in the etcd.env.
The only python-etcd3 client working directly via gRPC still supports only a single endpoint, which is not very nice for high-availability.
Since Patroni is already using a heavily hacked version of python-etcd with smart retries and auto-discovery out-of-the-box, I decided to enhance the existing code with limited support of v3 protocol via gRPC-gateway.
Unfortunately, watches via gRPC-gateway requires us to open and keep the second connection to the etcd.
Known limitations:
* The very minimal supported version is 3.0.4. On earlier versions transactions don't work due to bugs in grpc-gateway. Without transactions we can't do atomic operations, i.e. leader locks.
* Watches work only starting from 3.1.0
* Authentication works only starting from 3.3.0
* gRPC-gateway does not support authentication using TLS Common Name. This is because gRPC-proxy terminates TLS from its client so all the clients share a cert of the proxy: https://github.com/etcd-io/etcd/blob/master/Documentation/op-guide/authentication.md#using-tls-common-name
1. Multi-stage build with an extensive cleanup of useless files and optional image compression
2. Start three-node etcd cluster
3. Start three-node Patroni cluster
4. One container with haproxy
5. All container names are prefixed with "demo-" and don't have suffixes
6. Decommission dev_patroni_cluster.sh script, docker-compose is now standard de-facto.
7. Provide more examples in the docker/README.md
For starting up cluster easy with docker-compose.
And unify Dockerfile and scripts to be able to work with docker-compose
and the old one dev_patroni_cluster.sh script
For easier development using Docker the $HOSTNAME variable will be used to
name the running Patroni. Bumped some _segments postgresql settings to ensure
WAL files are not removed very quickly.
Increased the timeout for the post request for Patroni, as some operations
(failover) may take considerable time to complete.
The failover to a specific member was broken in patronictl as it used a wrong
key to specify the member to failover to.
Pretty printing fix for xlog lag, to prevent false negatives to show up and have
good alignment.
For managing Patroni clusters, the Patroni api can be used. For many tasks, a command line interface for
this api would be a useful addition. This commit adds patroncli (The name is still under debate).
The command line interface needs access to the DCS; this is required for any operation. For some tasks it is required
to have access to the Patroni api.
A small summary of the additions to get the cli/ctl started:
* Updated Docker image to use 'true' as the archive_command, to ensure disk not filling up during failover
testing.
* The cli currently can list members, failover a master and remove a given cluster from DCS.
* The cli can be configured with a command, for repeated access to the same DCS
* Added some simple tests for the cli, code coverage is very low
As the Dockerfile is there mainly to support developers, we want to build the Dockerfile using the current working
directory instead of a previously released version.
To help in developing features, the Dockerfile and its entrypoint have been extended.
The README.md explains stuff in detail, in short:
- you can now run a Patroni cluster with a single command
